ADOPTS WITH AMENDMENTS:

International Residential Code 2018 (IRC 2018)

Part I — Administrative

Part II — Definitions

Part III — Building Planning and Construction

Part IV — Energy Conservation

Part V — Mechanical

Part VI — Fuel Gas

Part VII — Plumbing

Part VIII — Electrical

Part IX — Referenced Standards

Heads up: There are no amended sections in this chapter.
Buildings and structures, and parts thereof, shall be constructed to safely support all loads, including dead loads, live loads, roof loads, flood loads, snow loads, wind loads and seismic loads as prescribed by this code. The construction of buildings and structures in accordance with the provisions of this code shall result in a system that provides a complete load path that meets the requirements for the transfer of loads from their point of origin through the load-resisting elements to the foundation. Buildings and structures constructed as prescribed by this code are deemed to comply with the requirements of this section.

As an alternative to the requirements in Section R301.1, the following standards are permitted subject to the limitations of this code and the limitations therein. Where engineered design is used in conjunction with these standards, the design shall comply with the International Building Code.

  1. AWC Wood Frame Construction Manual (WFCM).
  2. AISI Standard for Cold-Formed Steel Framing—Prescriptive Method for One- and Two-Family Dwellings (AISI S230).
  3. ICC Standard on the Design and Construction of Log Structures (ICC 400).
The requirements of this code are based on platform and balloon-frame construction for light-frame buildings. The requirements for concrete and masonry buildings are based on a balloon framing system. Other framing systems must have equivalent detailing to ensure force transfer, continuity and compatible deformations.
Where a building of otherwise conventional construction contains structural elements exceeding the limits of Section R301 or otherwise not conforming to this code, these elements shall be designed in accordance with accepted engineering practice. The extent of such design need only demonstrate compliance of nonconventional elements with other applicable provisions and shall be compatible with the performance of the conventional framed system. Engineered design in accordance with the International Building Code is permitted for buildings and structures, and parts thereof, included in the scope of this code.

Buildings shall be constructed in accordance with the provisions of this code as limited by the provisions of this section. Additional criteria shall be established by the local jurisdiction and set forth in Table R301.2(1). The local jurisdiction shall designate the salt water coastal areas within their jurisdiction.

TABLE R301.2(1)

CLIMATIC AND GEOGRAPHIC DESIGN CRITERIA

GROUND
SNOW
LOADo
WIND DESIGN SEISMIC
DESIGN
CATEGORYf
SUBJECT TO DAMAGE FROM WINTER
DESIGN
TEMPe
ICE BARRIER REQUIREDh FLOOD
HAZARDSg
AIR
FREEZING
INDEXi
MEAN
ANNUAL
TEMPj
Speedd
(mph)
Topographic
effectsk
Special wind
regionl
Wind-borne
debris zonem
Weatheringa Frost line
depthb
Termitec
MANUAL J DESIGN CRITERIAn
Elevation Latitude Winter
heating
Summer
cooling
Altitude
correction factor
Indoor design
temperature
Design
temperature cooling
Heating temperature
difference
Cooling
temperature difference
Wind
velocity heating
Wind velocity
cooling
Coincident
wet bulb
Daily
range
Winter
humidity
Summer
humidity

For SI: 1 pound per square foot = 0.0479 kPa, 1 mile per hour = 0.447 m/s.

  1. Where weathering requires a higher strength concrete or grade of masonry than necessary to satisfy the structural requirements of this code, the frost line depth strength required for weathering shall govern. The weathering column shall be filled in with the weathering index, "negligible," "moderate" or "severe" for concrete as determined from Figure R301.2(4). The grade of masonry units shall be determined from ASTM C34, C55, C62, C73, C90, C129, C145, C216 or C652.
  2. Where the frost line depth requires deeper footings than indicated in Figure R403.1(1), the frost line depth strength required for weathering shall govern. The jurisdiction shall fill in the frost line depth column with the minimum depth of footing below finish grade.
  3. The jurisdiction shall fill in this part of the table to indicate the need for protection depending on whether there has been a history of local subterranean termite damage.
  4. The jurisdiction shall fill in this part of the table with the wind speed from the basic wind speed map [Figure R301.2(5)A]. Wind exposure category shall be determined on a site-specific basis in accordance with Section R301.2.1.4.
  5. The outdoor design dry-bulb temperature shall be selected from the columns of 971/2-percent values for winter from Appendix D of the International Plumbing Code. Deviations from the Appendix D temperatures shall be permitted to reflect local climates or local weather experience as determined by the building official. [Also see Figure R301.2(1).]
  6. The jurisdiction shall fill in this part of the table with the seismic design category determined from Section R301.2.2.1.
  7. The jurisdiction shall fill in this part of the table with (a) the date of the jurisdiction's entry into the National Flood Insurance Program (date of adoption of the first code or ordinance for management of flood hazard areas), (b) the date(s) of the Flood Insurance Study and (c) the panel numbers and dates of the currently effective FIRMs and FBFMs or other flood hazard map adopted by the authority having jurisdiction, as amended.
  8. In accordance with Sections R905.1.2, R905.4.3.1, R905.5.3.1, R905.6.3.1, R905.7.3.1 and R905.8.3.1, where there has been a history of local damage from the effects of ice damming, the jurisdiction shall fill in this part of the table with "YES." Otherwise, the jurisdiction shall fill in this part of the table with "NO."
  9. The jurisdiction shall fill in this part of the table with the 100-year return period air freezing index (BF-days) from Figure R403.3(2) or from the 100-year (99 percent) value on the National Climatic Data Center data table "Air Freezing Index-USA Method (Base 32°F)."
  10. The jurisdiction shall fill in this part of the table with the mean annual temperature from the National Climatic Data Center data table "Air Freezing Index-USA Method (Base 32°F)."
  11. In accordance with Section R301.2.1.5, where there is local historical data documenting structural damage to buildings due to topographic wind speed-up effects, the jurisdiction shall fill in this part of the table with "YES." Otherwise, the jurisdiction shall indicate "NO" in this part of the table.
  12. In accordance with Figure R301.2(5)A, where there is local historical data documenting unusual wind conditions, the jurisdiction shall fill in this part of the table with "YES" and identify any specific requirements. Otherwise, the jurisdiction shall indicate "NO" in this part of the table.
  13. In accordance with Section R301.2.1.2 the jurisdiction shall indicate the wind-borne debris wind zone(s). Otherwise, the jurisdiction shall indicate "NO" in this part of the table.
  14. The jurisdiction shall fill in these sections of the table to establish the design criteria using Table 1a or 1b from ACCA Manual J or established criteria determined by the jurisdiction.
  15. The jurisdiction shall fill in this section of the table using the Ground Snow Loads in Figure R301.2(6).

TABLE R301.2(2)

COMPONENT AND CLADDING LOADS FOR A BUILDING WITH A MEAN ROOF HEIGHT OF 30 FEET LOCATED IN EXPOSURE B (ASD) (psf)a, b, c, d, e

ZONE EFFECTIVE
WIND AREA
(feet2)
ULTIMATE DESIGN WIND SPEED, VULT (mph)
110 115 120 130 140 150 160 170 180
Roof 0 to 7 degrees 1 10 10.0 -13.0 10.0 -14.0 10.0 -15.0 10.0 -18.0 10.0 -21.0 9.9 -24.0 11.2 -27.0 12.6 -31.0 14.2 -35.0
1 20 10.0 -12.0 10.0 -13.0 10.0 -15.0 10.0 -17.0 10.0 -20.0 9.2 -23.0 10.6 -26.0 11.9 -30.0 13.3 -34.1
1 50 10.0 -12.0 10.0 -13.0 10.0 -14.0 10.0 -17.0 10.0 -19.0 8.5 -22.0 10.0 -26.0 10.8 -29.0 12.2 -32.9
1 100 10.0 -11.0 10.0 -13.0 10.0 -14.0 10.0 -16.0 10.0 -19.0 7.8 -22.0 10.0 -25.0 10.0 -28.0 11.3 -32.0
2 10 10.0 -21.0 10.0 -23.0 10.0 -26.0 10.0 -30.0 10.0 -35.0 9.9 -40.0 11.2 -46.0 12.6 -52.0 14.2 -58.7
2 20 10.0 -19.0 10.0 -21.0 10.0 -23.0 10.0 -27.0 10.0 -31.0 9.2 -36.0 10.6 -41.0 11.9 -46.0 13.3 -52.4
2 50 10.0 -16.0 10.0 -18.0 10.0 -19.0 10.0 -23.0 10.0 -26.0 8.5 -30.0 10.0 -34.0 10.8 -39.0 12.2 -44.1
2 100 10.0 -14.0 10.0 -15.0 10.0 -16.0 10.0 -19.0 10.0 -22.0 7.8 -26.0 10.0 -30.0 10.0 -33.0 11.3 -37.9
3 10 10.0 -33.0 10.0 -36.0 10.0 -39.0 10.0 -46.0 10.0 -53.0 9.9 -61.0 11.2 -69.0 12.6 -78.0 14.2 -88.3
3 20 10.0 -27.0 10.0 -29.0 10.0 -32.0 10.0 -38.0 10.0 -44.0 9.2 -50.0 10.6 -57.0 11.9 -65.0 13.3 -73.1
3 50 10.0 -19.0 10.0 -21.0 10.0 -23.0 10.0 -27.0 10.0 -32.0 8.5 -36.0 10.0 -41.0 10.8 -47.0 12.2 -53.1
3 100 10.0 -14.0 10.0 -15.0 10.0 -16.0 10.0 -19.0 10.0 -22.0 7.8 -26.0 10.0 -30.0 10.0 -33.0 11.3 -37.9
Roof > 7 to 27 degrees 1 10 10.0 -11.0 10.0 -13.0 10.0 -14.0 10.5 -16.0 12.2 -19.0 14.0 -22.0 15.9 -25.0 17.9 -28.0 20.2 -32.0
1 20 10.0 -11.0 10.0 -12.0 10.0 -13.0 10.0 -16.0 11.1 -18.0 12.8 -21.0 14.5 -24.0 16.4 -27.0 18.4 -31.1
1 50 10.0 -11.0 10.0 -12.0 10.0 -13.0 10.0 -15.0 10.0 -18.0 11.1 -20.0 12.7 -23.0 14.3 -26.0 16.0 -29.9
1 100 10.0 -10.0 10.0 -11.0 10.0 -12.0 10.0 -15.0 10.0 -17.0 9.9 -20.0 11.2 -22.0 12.6 -25.0 14.2 -29.0
2 10 10.0 -20.0 10.0 -22.0 10.0 -24.0 10.5 -29.0 12.2 -33.0 14.0 -38.0 15.9 -44.0 17.9 -49.0 20.2 -55.8
2 20 10.0 -19.0 10.0 -20.0 10.0 -22.0 10.0 -26.0 11.1 -31.0 12.8 -35.0 14.5 -40.0 16.4 -45.0 18.4 -51.2
2 50 10.0 -16.0 10.0 -18.0 10.0 -20.0 10.0 -23.0 10.0 -27.0 11.1 -31.0 12.7 -35.0 14.3 -40.0 16.0 -45.4
2 100 10.0 -15.0 10.0 -16.0 10.0 -18.0 10.0 -21.0 10.0 -24.0 9.9 -28.0 11.2 -32.0 12.6 -36.0 14.2 -40.9
3 10 10.0 -30.0 10.0 -33.0 10.0 -36.0 10.5 -43.0 12.2 -49.0 14.0 -57.0 15.9 -65.0 17.9 -73.0 20.2 -82.4
3 20 10.0 -28.0 10.0 -31.0 10.0 -34.0 10.0 -40.0 11.1 -46.0 12.8 -53.0 14.5 -60.0 16.4 -68.0 18.4 -77.0
3 50 10.0 -26.0 10.0 -28.0 10.0 -31.0 10.0 -36.0 10.0 -42.0 11.1 -48.0 12.7 -55.0 14.3 -62.0 16.0 -69.9
3 100 10.0 -24.0 10.0 -26.0 10.0 -28.0 10.0 -33.0 10.0 -39.0 9.9 -44.0 11.2 -51.0 12.6 -57.0 14.2 -64.6
Roof > 27 to 45 degrees 1 10 11.9 -13.0 13.1 -14.0 14.2 -15.0 16.7 -18.0 19.4 -21.0 22.2 -24.0 25.3 -27.0 28.5 -31.0 32.0 -35.0
1 20 11.6 -12.0 12.7 -13.0 13.8 -14.0 16.2 -17.0 18.8 -20.0 21.6 -23.0 24.6 -26.0 27.7 -29.0 31.1 -33.2
1 50 11.2 -11.0 12.2 -12.0 13.3 -13.0 15.6 -16.0 18.1 -18.0 20.8 -21.0 23.6 -24.0 26.7 -27.0 29.9 -30.8
1 100 10.9 -10.0 11.9 -11.0 12.9 -12.0 15.1 -15.0 17.6 -17.0 20.2 -20.0 22.9 -22.0 25.9 -25.0 29.0 -29.0
2 10 11.9 -15.0 13.1 -16.0 14.2 -18.0 16.7 -21.0 19.4 -24.0 22.2 -28.0 25.3 -32.0 28.5 -36.0 32.0 -40.9
2 20 11.6 -14.0 12.7 -16.0 13.8 -17.0 16.2 -20.0 18.8 -23.0 21.6 -27.0 24.6 -30.0 27.7 -34.0 31.1 -39.1
2 50 11.2 -13.0 12.2 -15.0 13.3 -16.0 15.6 -19.0 18.1 -22.0 20.8 -25.0 23.6 -29.0 26.7 -32.0 29.9 -36.8
2 100 10.9 -13.0 11.9 -14.0 12.9 -15.0 15.1 -18.0 17.6 -21.0 20.2 -24.0 22.9 -27.0 25.9 -31.0 29.0 -35.0
3 10 11.9 -15.0 13.1 -16.0 14.2 -18.0 16.7 -21.0 19.4 -24.0 22.2 -28.0 25.3 -32.0 28.5 -36.0 32.0 -40.9
3 20 11.6 -14.0 12.7 -16.0 13.8 -17.0 16.2 -20.0 18.8 -23.0 21.6 -27.0 24.6 -30.0 27.7 -34.0 31.1 -39.1
3 50 11.2 -13.0 12.2 -15.0 13.3 -16.0 15.6 -19.0 18.1 -22.0 20.8 -25.0 23.6 -29.0 26.7 -32.0 29.9 -36.8
3 100 10.9 -13.0 11.9 -14.0 12.9 -15.0 15.1 -18.0 17.6 -21.0 20.2 -24.0 22.9 -27.0 25.9 -31.0 29.0 -35.0
Wall 4 10 13.1 -14.0 14.3 -15.0 15.5 -16.0 18.2 -19.0 21.2 -22.0 24.3 -26.0 27.7 -30.0 31.2 -33.0 35.0 -37.9
4 20 12.5 -13.0 13.6 -14.0 14.8 -16.0 17.4 -19.0 20.2 -22.0 23.2 -25.0 26.4 -28.0 29.7 -32.0 33.4 -36.4
4 50 11.7 -12.0 12.8 -14.0 13.9 -15.0 16.3 -17.0 19.0 -20.0 21.7 -23.0 24.7 -27.0 27.9 -30.0 31.3 -34.3
4 100 11.1 -12.0 12.1 -13.0 13.2 -14.0 15.5 -17.0 18.0 -19.0 20.6 -22.0 23.5 -25.0 26.5 -29.0 29.8 32.7
4 500 10.0 -10.0 10.6 -11.0 11.6 -12.0 13.6 -15.0 15.8 -17.0 18.1 -20.0 20.6 -22.0 23.2 -25.0 26.1 -29.0
5 10 13.1 -17.0 14.3 -19.0 15.5 -20.0 18.2 -24.0 21.2 -28.0 24.3 -32.0 27.7 -37.0 31.2 -41.0 35.0 -46.8
5 20 12.5 -16.0 13.6 -17.0 14.8 -19.0 17.4 -22.0 20.2 -26.0 23.2 -30.0 26.4 -34.0 29.7 -39.0 33.4 -43.7
5 50 11.7 -14.0 12.8 -16.0 13.9 -17.0 16.3 -20.0 19.0 -23.0 21.7 -27.0 24.7 -31.0 27.9 -35.0 31.3 -39.5
5 100 11.1 -13.0 12.1 -14.0 13.2 -16.0 15.5 -19.0 18.0 -22.0 20.6 -25.0 23.5 -28.0 26.5 -32.0 29.8 -36.4
5 500 10.0 -10.0 10.6 -11.0 11.6 -12.0 13.6 -15.0 15.8 -17.0 18.1 -20.0 20.6 -22.0 23.2 -25.0 26.1 -29.0

For SI: 1 foot = 304.8 mm, 1 square foot = 0.0929 m2, 1 mile per hour = 0.447 m/s, 1 pound per square foot = 0.0479 kPa.

  1. The effective wind area shall be equal to the span length multiplied by an effective width. This width shall be permitted to be not less than one-third the span length. For cladding fasteners, the effective wind area shall not be greater than the area that is tributary to an individual fastener.
  2. For effective areas between those given, the load shall be interpolated or the load associated with the lower effective area shall be used.
  3. Table values shall be adjusted for height and exposure by multiplying by the adjustment coefficient in Table R301.2(3).
  4. See Figure R301.2(8) for location of zones.
  5. Plus and minus signs signify pressures acting toward and away from the building surfaces.

TABLE R301.2(3)

HEIGHT AND EXPOSURE ADJUSTMENT COEFFICIENTS FOR TABLE R301.2(2)

MEAN ROOF HEIGHT EXPOSURE
B C D
15 1.00 1.21 1.47
20 1.00 1.29 1.55
25 1.00 1.35 1.61
30 1.00 1.40 1.66
35 1.05 1.45 1.70
40 1.09 1.49 1.74
45 1.12 1.53 1.78
50 1.16 1.56 1.81
55 1.19 1.59 1.84
60 1.22 1.62 1.87

For SI: °C = [(°F)-32]/1.8.

FIGURE R301.2(1)

ISOLINES OF THE 971/2 -PERCENT WINTER (DECEMBER, JANUARY AND FEBRUARY) DESIGN TEMPERATURES (°F)

FIGURE R301.2(2)

SEISMIC DESIGN CATEGORIES

FIGURE R301.2(3)

ALTERNATE SEISMIC DESIGN CATEGORIES

  1. Alaska and Hawaii are classified as severe and negligible, respectively.
  2. Lines defining areas are approximate only. Local conditions may be more or less severe than indicated by region classification. A severe classification is where weather conditions result in significant snowfall combined with extended periods during which there is little or no natural thawing causing deicing salts to be used extensively.

FIGURE R301.2(4)

WEATHERING PROBABILITY MAP FOR CONCRETEa, b

FIGURE R301.2(5)A

ULTIMATE DESIGN WIND SPEEDS

FIGURE R301.2(5)B

REGIONS WHERE WIND DESIGN IS REQUIRED

FIGURE R301.2(6)

GROUND SNOW LOADS, Pg, FOR THE UNITED STATES (lb/ft2)

Note: Lines defining areas are approximate only. Local conditions may be more or less severe than indicated by the region classification.

FIGURE R301.2(7)

TERMITE INFESTATION PROBABILITY MAP

For SI: 1 foot = 304.8 mm, 1 degree = 0.0175 rad.

Note: a = 4 feet in all cases.

FIGURE R301.2(8)

COMPONENT AND CLADDING PRESSURE ZONES

Buildings and portions thereof shall be constructed in accordance with the wind provisions of this code using the ultimate design wind speed in Table R301.2(1) as determined from Figure R301.2(5)A. The structural provisions of this code for wind loads are not permitted where wind design is required as specified in Section R301.2.1.1. Where different construction methods and structural materials are used for various portions of a building, the applicable requirements of this section for each portion shall apply. Where not otherwise specified, the wind loads listed in Table R301.2(2) adjusted for height and exposure using Table R301.2(3) shall be used to determine design load performance requirements for wall coverings, curtain walls, roof coverings, exterior windows, skylights, garage doors and exterior doors. Asphalt shingles shall be designed for wind speeds in accordance with Section R905.2.4. A continuous load path shall be provided to transmit the applicable uplift forces in Section R802.11.1 from the roof assembly to the foundation.

The wind provisions of this code shall not apply to the design of buildings where wind design is required in accordance with Figure R301.2(5)B.

Exceptions:

  1. For concrete construction, the wind provisions of this code shall apply in accordance with the limitations of Sections R404 and R608.
  2. For structural insulated panels, the wind provisions of this code shall apply in accordance with the limitations of Section R610.
  3. For cold-formed steel light-frame construction, the wind provisions of this code shall apply in accordance with the limitations of Sections R505, R603 and R804.

In regions where wind design is required in accordance with Figure R301.2(5)B, the design of buildings for wind loads shall be in accordance with one or more of the following methods:

  1. AWC Wood Frame Construction Manual (WFCM).
  2. ICC Standard for Residential Construction in High-Wind Regions (ICC 600).
  3. ASCE Minimum Design Loads for Buildings and Other Structures (ASCE 7).
  4. AISI Standard for Cold-Formed Steel Framing—Prescriptive Method For One- and Two-Family Dwellings (AISI S230).
  5. International Building Code.

The elements of design not addressed by the methods in Items 1 through 5 shall be in accordance with the provisions of this code.

Where ASCE 7 or the International Building Code is used for the design of the building, the wind speed map and exposure category requirements as specified in ASCE 7 and the International Building Code shall be used.

Sunrooms shall comply with AAMA/NPEA/NSA 2100. For the purpose of applying the criteria of AAMA/NPEA/NSA 2100 based on the intended use, sunrooms shall be identified as one of the following categories by the permit applicant, design professional or the property owner or owner's agent in the construction documents. Component and cladding pressures shall be used for the design of elements that do not qualify as main windforce-resisting systems. Main windforce-resisting system pressures shall be used for the design of elements assigned to provide support and stability for the overall sunroom.

  • Category I: A thermally isolated sunroom with walls that are open or enclosed with insect screening or 0.5 mm (20 mil) maximum thickness plastic film. The space is nonhabitable and unconditioned.
  • Category II: A thermally isolated sunroom with enclosed walls. The openings are enclosed with translucent or transparent plastic or glass. The space is nonhabitable and unconditioned.
  • Category III: A thermally isolated sunroom with enclosed walls. The openings are enclosed with translucent or transparent plastic or glass. The sunroom fenestration complies with additional requirements for air infiltration resistance and water penetration resistance. The space is nonhabitable and unconditioned.
  • Category IV: A thermally isolated sunroom with enclosed walls. The sunroom is designed to be heated or cooled by a separate temperature control or system and is thermally isolated from the primary structure. The sunroom fenestration complies with additional requirements for water penetration resistance, air infiltration resistance and thermal performance. The space is nonhabitable and conditioned.
  • Category V: A sunroom with enclosed walls. The sunroom is designed to be heated or cooled and is open to the main structure. The sunroom fenestration complies with additional requirements for water penetration resistance, air infiltration resistance and thermal performance. The space is habitable and conditioned.

Exterior glazing in buildings located in windborne debris regions shall be protected from windborne debris. Glazed opening protection for windborne debris shall meet the requirements of the Large Missile Test of ASTM E1996 and ASTM E1886 as modified in Section 301.2.1.2.1. Garage door glazed opening protection for windborne debris shall meet the requirements of an approved impact-resisting standard or ANSI/DASMA 115.

Exception: Wood structural panels with a thickness of not less than 7/16 inch (11 mm) and a span of not more than 8 feet (2438 mm) shall be permitted for opening protection. Panels shall be precut and attached to the framing surrounding the opening containing the product with the glazed opening. Panels shall be predrilled as required for the anchorage method and shall be secured with the attachment hardware provided. Attachments shall be designed to resist the component and cladding loads determined in accordance with either Table R301.2(2) or ASCE 7, with the permanent corrosion-resistant attachment hardware provided and anchors permanently installed on the building. Attachment in accordance with Table R301.2.1.2 is permitted for buildings with a mean roof height of 45 feet (13 728 mm) or less where the ultimate design wind speed, Vult, is 180 mph (290 kph) or less.

TABLE R301.2.1.2

WINDBORNE DEBRIS PROTECTION FASTENING SCHEDULE FOR WOOD STRUCTURAL PANELSa, b, c, d

FASTENER TYPE FASTENER SPACING (inches)a, b
Panel
span ≤
4 feet
4 feet <
panel span
≤ 6 feet
6 feet <
panel span
≤ 8 feet
No. 8 wood-screw-based
anchor with 2-inch embedment
length
16 10 8
No. 10 wood-screw-based
anchor with 2-inch embedment
length
16 12 9
1/4-inch lag-screw-based
anchor with 2-inch embedment
length
16 16 16

For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound = 4.448 N, 1 mile per hour = 0.447 m/s.

  1. This table is based on 180 mph ultimate design wind speeds, Vult, and a 45-foot mean roof height.
  2. Fasteners shall be installed at opposing ends of the wood structural panel. Fasteners shall be located not less than 1 inch from the edge of the panel.
  3. Anchors shall penetrate through the exterior wall covering with an embedment length of not less than 2 inches into the building frame. Fasteners shall be located not less than 21/2 inches from the edge of concrete block or concrete.
  4. Panels attached to masonry or masonry/stucco shall be attached using vibration-resistant anchors having an ultimate withdrawal capacity of not less than 1,500 pounds.

The text of Section 2.2 of ASTM E1996 shall be substituted as follows:

2.2 ASCE Standard:

ASCE 7-10 American Society of Civil Engineers Minimum Design Loads for Buildings and Other Structures

The text of Section 6.2.2 of ASTM E1996 shall be substituted as follows:

6.2.2 Unless otherwise specified, select the wind zone based on the ultimate design wind speed, Vult, as follows:

6.2.2.1 Wind Zone 1—130 mph ≤ ultimate design wind speed, Vult < 140 mph.

6.2.2.2 Wind Zone 2—140 mph ≤ ultimate design wind speed, Vult < 150 mph at greater than 1 mile (1.6 km) from the coastline. The coastline shall be measured from the mean high-water mark.

6.2.2.3 Wind Zone 3—150 mph (58 m/s) ≤ ultimate design wind speed, Vult ≤ 170 mph (76 m/s), or 140 mph (54 m/s) ≤ ultimate design wind speed, Vult ≤ 170 mph (76 m/s) and within 1 mile (1.6 km) of the coastline. The coastline shall be measured from the mean high-water mark.

6.2.2.4 Wind Zone 4—ultimate design wind speed, Vult > 170 mph (76 m/s).

Where referenced documents are based on nominal design wind speeds and do not provide the means for conversion between ultimate design wind speeds and nominal design wind speeds, the ultimate design wind speeds, Vult, of Figure R301.2(5)A shall be converted to nominal design wind speeds, Vasd, using Table R301.2.1.3.

TABLE R301.2.1.3

WIND SPEED CONVERSIONSa

Vult 110 115 120 130 140 150 160 170 180 190 200
Vasd 85 89 93 101 108 116 124 132 139 147 155

For SI: 1 mile per hour = 0.447 m/s.

  1. Linear interpolation is permitted.

For each wind direction considered, an exposure category that adequately reflects the characteristics of ground surface irregularities shall be determined for the site at which the building or structure is to be constructed. For a site located in the transition zone between categories, the category resulting in the largest wind forces shall apply. Account shall be taken of variations in ground surface roughness that arise from natural topography and vegetation as well as from constructed features. For a site where multiple detached one- and two-family dwellings, townhouses or other structures are to be constructed as part of a subdivision or master-planned community, or are otherwise designated as a developed area by the authority having jurisdiction, the exposure category for an individual structure shall be based on the site conditions that will exist at the time when all adjacent structures on the site have been constructed, provided that their construction is expected to begin within 1 year of the start of construction for the structure for which the exposure category is determined. For any given wind direction, the exposure in which a specific building or other structure is sited shall be assessed as being one of the following categories:

  1. Exposure B. Urban and suburban areas, wooded areas or other terrain with numerous closely spaced obstructions having the size of single-family dwellings or larger. Exposure B shall be assumed unless the site meets the definition of another type exposure.
  2. Exposure C. Open terrain with scattered obstructions, including surface undulations or other irregularities, having heights generally less than 30 feet (9144 mm) extending more than 1,500 feet (457 m) from the building site in any quadrant. This exposure shall apply to any building located within Exposure B type terrain where the building is directly adjacent to open areas of Exposure C type terrain in any quadrant for a distance of more than 600 feet (183 m). This category includes flat, open country and grasslands.
  3. Exposure D. Flat, unobstructed areas exposed to wind flowing over open water, smooth mud flats, salt flats and unbroken ice for a distance of not less than 5,000 feet (1524 m). This exposure shall apply only to those buildings and other structures exposed to the wind coming from over the unobstructed area. Exposure D extends downwind from the edge of the unobstructed area a distance of 600 feet (183 m) or 20 times the height of the building or structure, whichever is greater.

In areas designated in Table R301.2(1) as having local historical data documenting structural damage to buildings caused by wind speed-up at isolated hills, ridges and escarpments that are abrupt changes from the general topography of the area, topographic wind effects shall be considered in the design of the building in accordance with Section R301.2.1.5.1 or in accordance with the provisions of ASCE 7. See Figure R301.2.1.5.1(1) for topographic features for wind speed-up effect.

In these designated areas, topographic wind effects shall apply only to buildings sited on the top half of an isolated hill, ridge or escarpment where all of the following conditions exist:

  1. The average slope of the top half of the hill, ridge or escarpment is 10 percent or greater.
  2. The hill, ridge or escarpment is 60 feet (18 288 mm) or greater in height for Exposure B, 30 feet (9144 mm) or greater in height for Exposure C, and 15 feet (4572 mm) or greater in height for Exposure D.
  3. The hill, ridge or escarpment is isolated or unobstructed by other topographic features of similar height in the upwind direction for a distance measured from its high point of 100 times its height or 2 miles (3.2 km), whichever is less. See Figure R301.2.1.5.1(3) for upwind obstruction.
  4. The hill, ridge or escarpment protrudes by a factor of two or more above the height of other upwind topographic features located in any quadrant within a radius of 2 miles (3.2 km) measured from its high point.

As an alternative to the ASCE 7 topographic wind provisions, the provisions of Section R301.2.1.5.1 shall be permitted to be used to design for wind speed-up effects, where required by Section R301.2.1.5.

Structures located on the top half of isolated hills, ridges or escarpments meeting the conditions of Section R301.2.1.5 shall be designed for an increased basic wind speed as determined by Table R301.2.1.5.1. On the high side of an escarpment, the increased basic wind speed shall extend horizontally downwind from the edge of the escarpment 1.5 times the horizontal length of the upwind slope (1.5L) or 6 times the height of the escarpment (6H), whichever is greater. See Figure R301.2.1.5.1(2) for where wind speed increase is applied.

TABLE R301.2.1.5.1

ULTIMATE DESIGN WIND SPEED MODIFICATION FOR TOPOGRAPHIC WIND EFFECTa, b

ULTIMATE DESIGN
WIND SPEED FROM
FIGURE R301.2(5)A
(mph)
AVERAGE SLOPE OF THE TOP HALF OF HILL, RIDGE OR ESCARPMENT (percent)
0.10 0.125 0.15 0.175 0.20 0.23 0.25
Required ultimate design wind speed-up, modified for topographic wind speed-up (mph)
110 132 137 142 147 152 158 162
115 138 143 148 154 159 165 169
120 144 149 155 160 166 172 176
130 156 162 168 174 179 NA NA
140 168 174 181 NA NA NA NA
150 180 NA NA NA NA NA NA

For SI: 1 mile per hour = 0.447 m/s, 1 foot = 304.8 mm.

NA = Not Applicable.

  1. Table applies to a feature height of 500 feet or less and dwellings sited a distance equal or greater than half the feature height.
  2. Where the ultimate design wind speed as modified by Table R301.2.1.5.1 equals or exceeds 140 miles per hour, the building shall be considered as "wind design required" in accordance with Section R301.2.1.1.

Note: H/2 determines the measurement point for Lh. L is twice Lh.

FIGURE R301.2.1.5.1(1)

TOPOGRAPHIC FEATURES FOR WIND SPEED-UP EFFECT

FIGURE R301.2.1.5.1(2)

ILLUSTRATION OF WHERE ON A TOPOGRAPHIC FEATURE, WIND SPEED INCREASE IS APPLIED

FIGURE R301.2.1.5.1(3)

UPWIND OBSTRUCTION

Buildings in Seismic Design Categories C, D0, D1, and D2 shall be constructed in accordance with the requirements of this section and other seismic requirements of this code. The seismic provisions of this code shall apply as follows:

  1. Townhouses in Seismic Design Categories C, D0, D1 and D2.
  2. Detached one- and two-family dwellings in Seismic Design Categories, D0, D1 and D2.

Buildings in Seismic Design Category E shall be designed to resist seismic loads in accordance with the International Building Code, except where the seismic design category is reclassified to a lower seismic design category in accordance with Section R301.2.2.1. Components of buildings not required to be designed to resist seismic loads shall be constructed in accordance with the provisions of this code.

The seismic design categories and corresponding short-period design spectral response accelerations, SDS, shown in Figure R301.2(2), are based on soil Site Class D, used as an assumed default, as defined in Section 1613.2.2 of the International Building Code. If soil conditions are determined by the building official to be Site Class A, B, or D, the seismic design category and short-period design spectral response accelerations, SDS, for a site shall be allowed to be determined in accordance with Figure R301.2(3), or Section 1613.2 of the International Building Code. The value of SDS determined in accordance with Section 1613.2 of the International Building Code is permitted to be used to set the seismic design category in accordance with Table R301.2.2.1.1, and to interpolate between values in Tables R602.10.3(3), R603.9.2(1) and other seismic design requirements of this code.

TABLE R301.2.2.1.1

SEISMIC DESIGN CATEGORY DETERMINATION

CALCULATED SDS SEISMIC DESIGN CATEGORY
SDS ≤ 0.17g A
0.17g < SDS ≤ 0.33g B
0.33g < SDS ≤ 0.50g C
0.50g < SDS ≤ 0.67g D0
0.67g < SDS ≤ 0.83g D1
0.83g < SDS ≤ 1.25g D2
1.25g < SDS E

Buildings located in Seismic Design Category E in accordance with Figure R301.2(2), or Figure R301.2(3) where applicable, are permitted to be reclassified as being in Seismic Design Category D2 provided that one of the following is done:

  1. A more detailed evaluation of the seismic design category is made in accordance with the provisions and maps of the International Building Code. Buildings located in Seismic Design Category E in accordance with Table R301.2.2.1.1, but located in Seismic Design Category D in accordance with the International Building Code, shall be permitted to be designed using the Seismic Design Category D2 requirements of this code.
  2. Buildings located in Seismic Design Category E that conform to the following additional restrictions are permitted to be constructed in accordance with the provisions for Seismic Design Category D2 of this code:

    1. 2.1. All exterior shear wall lines or braced wall panels are in one plane vertically from the foundation to the uppermost story.
    2. 2.2. Floors shall not cantilever past the exterior walls.
    3. 2.3. The building is within the requirements of Section R301.2.2.6 for being considered as regular.

Average dead loads shall not exceed 15 pounds per square foot (720 Pa) for the combined roof and ceiling assemblies (on a horizontal projection) or 10 pounds per square foot (480 Pa) for floor assemblies, except as further limited by Section R301.2.2. Dead loads for walls above grade shall not exceed:

  1. Fifteen pounds per square foot (720 Pa) for exterior light-frame wood walls.
  2. Fourteen pounds per square foot (670 Pa) for exterior light-frame cold-formed steel walls.
  3. Ten pounds per square foot (480 Pa) for interior light-frame wood walls.
  4. Five pounds per square foot (240 Pa) for interior light-frame cold-formed steel walls.
  5. Eighty pounds per square foot (3830 Pa) for 8-inch-thick (203 mm) masonry walls.
  6. Eighty-five pounds per square foot (4070 Pa) for 6-inch-thick (152 mm) concrete walls.
  7. Ten pounds per square foot (480 Pa) for SIP walls.

Exceptions:

  1. Roof and ceiling dead loads not exceeding 25 pounds per square foot (1190 Pa) shall be permitted provided that the wall bracing amounts in Section R602.10.3 are increased in accordance with Table R602.10.3(4).
  2. Light-frame walls with stone or masonry veneer shall be permitted in accordance with the provisions of Sections R702.1 and R703.
  3. Fireplaces and chimneys shall be permitted in accordance with Chapter 10.
Anchored stone and masonry veneer shall comply with the requirements of Sections R702.1 and R703.
Masonry construction in Seismic Design Categories D0 and D1 shall comply with the requirements of Section R606.12.1. Masonry construction in Seismic Design Category D2 shall comply with the requirements of Section R606.12.4.

Buildings with exterior above-grade concrete walls shall comply with PCA 100 or shall be designed in accordance with ACI 318.

Exception: Detached one- and two-family dwellings in Seismic Design Category C with exterior above-grade concrete walls are allowed to comply with the requirements of Section R608.

The seismic provisions of this code shall not be used for structures, or portions thereof, located in Seismic Design Categories C, D0, D1 and D2 and considered to be irregular in accordance with this section. A building or portion of a building shall be considered to be irregular where one or more of the conditions defined in Items 1 through 7 occur. Irregular structures, or irregular portions of structures, shall be designed in accordance with accepted engineering practice to the extent the irregular features affect the performance of the remaining structural system. Where the forces associated with the irregularity are resisted by a structural system designed in accordance with accepted engineering practice, the remainder of the building shall be permitted to be designed using the provisions of this code.


  1. Shear wall or braced wall offsets out of plane. Conditions where exterior shear wall lines or braced wall panels are not in one plane vertically from the foundation to the uppermost story in which they are required.

    Exception: For wood light-frame construction, floors with cantilevers or setbacks not exceeding four times the nominal depth of the wood floor joists are permitted to support braced wall panels that are out of plane with braced wall panels below provided that all of the following are satisfied:

    1. Floor joists are nominal 2 inches by 10 inches (51 mm by 254 mm) or larger and spaced not more than 16 inches (406 mm) on center.
    2. The ratio of the back span to the cantilever is not less than 2 to 1.
    3. Floor joists at ends of braced wall panels are doubled.
    4. For wood-frame construction, a continuous rim joist is connected to ends of cantilever joists. Where spliced, the rim joists shall be spliced using a galvanized metal tie not less than 0.058 inch (1.5 mm) (16 gage) and 11/2 inches (38 mm) wide fastened with six 16d nails on each side of the splice; or a block of the same size as the rim joist and of sufficient length to fit securely between the joist space at which the splice occurs, fastened with eight 16d nails on each side of the splice.
    5. Gravity loads carried at the end of cantilevered joists are limited to uniform wall and roof loads and the reactions from headers having a span of 8 feet (2438 mm) or less.
  2. Lateral support of roofs and floors. Conditions where a section of floor or roof is not laterally supported by shear walls or braced wall lines on all edges.

    Exception: Portions of floors that do not support shear walls, braced wall panels above, or roofs shall be permitted to extend not more than 6 feet (1829 mm) beyond a shear wall or braced wall line.

  3. Shear wall or braced wall offsets in plane. Conditions where the end of a braced wall panel occurs over an opening in the wall below and extends more than 1 foot (305 mm) horizontally past the edge of the opening. This provision is applicable to shear walls and braced wall panels offset in plane and to braced wall panels offset out of plane in accordance with the exception to Item 1.

    Exception: For wood light-frame wall construction, one end of a braced wall panel shall be permitted to extend more than 1 foot (305 mm) over an opening not more than 8 feet (2438 mm) in width in the wall below provided that the opening includes a header in accordance with all of the following:

    1. The building width, loading condition and framing member species limitations of Table R602.7(1) shall apply.
    2. The header is composed of:

      1. 2.1. Not less than one 2 × 12 or two 2 × 10 for an opening not more than 4 feet (1219 mm) wide.
      2. 2.2. Not less than two 2 × 12 or three 2 × 10 for an opening not more than 6 feet (1829 mm) in width.
      3. 2.3. Not less than three 2 × 12 or four 2 × 10 for an opening not more than 8 feet (2438 mm) in width.
    3. The entire length of the braced wall panel does not occur over an opening in the wall below.
  4. Floor and roof opening. Conditions where an opening in a floor or roof exceeds the lesser of 12 feet (3658 mm) or 50 percent of the least floor or roof dimension.
  5. Floor level offset. Conditions where portions of a floor level are vertically offset.

    Exceptions:

    1. Framing supported directly by continuous foundations at the perimeter of the building.
    2. For wood light-frame construction, floors shall be permitted to be vertically offset where the floor framing is lapped or tied together as required by Section R502.6.1.
  6. Perpendicular shear wall and wall bracing. Conditions where shear walls and braced wall lines do not occur in two perpendicular directions.
  7. Wall bracing in stories containing masonry or concrete construction. Conditions where stories above grade plane are partially or completely braced by wood wall framing in accordance with Section R602 or cold-formed steel wall framing in accordance with Section R603 include masonry or concrete construction. Where this irregularity applies, the entire story shall be designed in accordance with accepted engineering practice.

    Exceptions: Fireplaces, chimneys and masonry veneer in accordance with this code.

Wood-framed buildings shall be limited to three stories above grade plane or the limits given in Table R602.10.3(3). Cold-formed steel-framed buildings shall be limited to less than or equal to three stories above grade plane in accordance with AISI S230. Mezzanines as defined in Section R202 that comply with Section R325 shall not be considered as stories. Structural insulated panel buildings shall be limited to two stories above grade plane.
In Seismic Design Categories D0, D1 and D2 in addition to the requirements of this code, cold-formed steel framing shall comply with the requirements of AISI S230.
In Seismic Design Categories D0, D1 and D2, masonry chimneys shall be reinforced and anchored to the building in accordance with Sections R1003.3 and R1003.4.

In Seismic Design Categories D0, D1 and D2, water heaters shall be anchored against movement and overturning in accordance with Section M1307.2.

Wood-framed construction, cold-formed, steel-framed construction and masonry and concrete construction, and structural insulated panel construction in regions with ground snow loads 70 pounds per square foot (3.35 kPa) or less, shall be in accordance with Chapters 5, 6 and 8. Buildings in regions with ground snow loads greater than 70 pounds per square foot (3.35 kPa) shall be designed in accordance with accepted engineering practice.
Buildings and structures constructed in whole or in part in flood hazard areas (including A or V Zones) as established in Table R301.2(1), and substantial improvement and repair of substantial damage of buildings and structures in flood hazard areas, shall be designed and constructed in accordance with Section R322. Buildings and structures that are located in more than one flood hazard area shall comply with the provisions associated with the most restrictive flood hazard area. Buildings and structures located in whole or in part in identified floodways shall be designed and constructed in accordance with ASCE 24.
As an alternative to the requirements in Section R322, ASCE 24 is permitted subject to the limitations of this code and the limitations therein.

The wind and seismic provisions of this code shall apply to buildings with story heights not exceeding the following:

  1. For wood wall framing, the story height shall not exceed 11 feet 7 inches (3531 mm) and the laterally unsupported bearing wall stud height permitted by Table R602.3(5).
  2. For cold-formed steel wall framing, the story height shall be not more than 11 feet 7 inches (3531 mm) and the unsupported bearing wall stud height shall be not more than 10 feet (3048 mm).
  3. For masonry walls, the story height shall be not more than 13 feet 7 inches (4140 mm) and the bearing wall clear height shall be not more than 12 feet (3658 mm).

    Exception: An additional 8 feet (2438 mm) of bearing wall clear height is permitted for gable end walls.

  4. For insulating concrete form walls, the maximum story height shall not exceed 11 feet 7 inches (3531 mm) and the maximum unsupported wall height per story as permitted by Section R608 tables shall not exceed 10 feet (3048 mm).
  5. For structural insulated panel (SIP) walls, the story height shall be not more than 11 feet 7 inches (3531 mm) and the bearing wall height per story as permitted by Section R610 tables shall not exceed 10 feet (3048 mm).

Individual walls or wall studs shall be permitted to exceed these limits as permitted by Chapter 6 provisions, provided that story heights are not exceeded. An engineered design shall be provided for the wall or wall framing members where the limits of Chapter 6 are exceeded. Where the story height limits of this section are exceeded, the design of the building, or the noncompliant portions thereof, to resist wind and seismic loads shall be in accordance with the International Building Code.

R301.4 Dead Load

ILLUSTRATION
The actual weights of materials and construction shall be used for determining dead load with consideration for the dead load of fixed service equipment.

The minimum uniformly distributed live load shall be as provided in Table R301.5.

TABLE R301.5

MINIMUM UNIFORMLY DISTRIBUTED LIVE LOADS (in pounds per square foot)

USE LIVE LOAD
Uninhabitable attics without storageb 10
Uninhabitable attics with limited storageb, g 20
Habitable attics and attics served with fixed stairs 30
Balconies (exterior) and deckse 60i
Fire escapes 40
Guards and handrailsd 200h
Guard in-fill componentsf 50h
Passenger vehicle garagesa 50a
Rooms other than sleeping rooms 40
Sleeping rooms 30
Stairs 40c

For SI: 1 pound per square foot = 0.0479 kPa, 1 square inch = 645 mm2, 1 pound = 4.45 N.

  1. Elevated garage floors shall be capable of supporting a 2,000-pound load applied over a 20-square-inch area.
  2. Uninhabitable attics without storage are those where the clear height between joists and rafters is not more than 42 inches, or where there are not two or more adjacent trusses with web configurations capable of accommodating an assumed rectangle 42 inches in height by 24 inches in width, or greater, within the plane of the trusses. This live load need not be assumed to act concurrently with any other live load requirements.
  3. Individual stair treads shall be designed for the uniformly distributed live load or a 300-pound concentrated load acting over an area of 4 square inches, whichever produces the greater stresses.
  4. A single concentrated load applied in any direction at any point along the top.
  5. See Section R507.1 for decks attached to exterior walls.
  6. Guard in-fill components (all those except the handrail), balusters and panel fillers shall be designed to withstand a horizontally applied normal load of 50 pounds on an area equal to 1 square foot. This load need not be assumed to act concurrently with any other live load requirement.
  7. Uninhabitable attics with limited storage are those where the clear height between joists and rafters is 42 inches or greater, or where there are two or more adjacent trusses with web configurations capable of accommodating an assumed rectangle 42 inches in height by 24 inches in width, or greater, within the plane of the trusses.

    The live load need only be applied to those portions of the joists or truss bottom chords where all of the following conditions are met:

    1. The attic area is accessed from an opening not less than 20 inches in width by 30 inches in length that is located where the clear height in the attic is not less than 30 inches.
    2. The slopes of the joists or truss bottom chords are not greater than 2 inches vertical to 12 units horizontal.
    3. Required insulation depth is less than the joist or truss bottom chord member depth.

    The remaining portions of the joists or truss bottom chords shall be designed for a uniformly distributed concurrent live load of not less than 10 pounds per square foot.

  8. Glazing used in handrail assemblies and guards shall be designed with a safety factor of 4. The safety factor shall be applied to each of the concentrated loads applied to the top of the rail, and to the load on the in-fill components. These loads shall be determined independent of one another, and loads are assumed not to occur with any other live load.
  9. Where structural tables in Section R507 only specify snow loads, the values corresponding to 70 psf snow loads shall be used.

The roof shall be designed for the live load indicated in Table R301.6 or the snow load indicated in Table R301.2(1), whichever is greater.

TABLE R301.6

MINIMUM ROOF LIVE LOADS IN POUNDS-FORCE PER SQUARE FOOT OF HORIZONTAL PROJECTION

ROOF SLOPE TRIBUTARY LOADED AREA IN
SQUARE FEET FOR ANY
STRUCTURAL MEMBER
0 to 200 201 to 600 Over 600
Flat or rise less than 4 inches per
foot (1:3)
20 16 12
Rise 4 inches per foot (1:3) to
less than 12 inches per foot (1:1)
16 14 12
Rise 12 inches per foot (1:1)
and greater
12 12 12

For SI: 1 square foot = 0.0929 m2, 1 pound per square foot = 0.0479 kPa, 1 inch per foot = 83.3 mm/m.

The allowable deflection of any structural member under the live load listed in Sections R301.5 and R301.6 or wind loads determined by Section R301.2.1 shall not exceed the values in Table R301.7.

TABLE R301.7

ALLOWABLE DEFLECTION OF STRUCTURAL MEMBERSb, c

STRUCTURAL MEMBER ALLOWABLE
DEFLECTION
Rafters having slopes greater than 3:12 with
finished ceiling not attached to rafters
L/180
Interior walls and partitions H/180
Floors L/360
Ceilings with brittle finishes (including plaster
and stucco)
L/360
Ceilings with flexible finishes (including gypsum
board)
L/240
All other structural members L/240
Exterior walls—wind loadsa with plaster or
stucco finish
H/360
Exterior walls—wind loadsa with other brittle
finishes
H/240
Exterior walls—wind loadsa with flexible finishes H/120d
Lintels supporting masonry veneer wallse L/600

Note: L = span length, H = span height.

  1. For the purpose of the determining deflection limits herein, the wind load shall be permitted to be taken as 0.7 times the component and cladding (ASD) loads obtained from Table R301.2(2).
  2. For cantilever members, L shall be taken as twice the length of the cantilever.
  3. For aluminum structural members or panels used in roofs or walls of sunroom additions or patio covers, not supporting edge of glass or sandwich panels, the total load deflection shall not exceed L/60. For continuous aluminum structural members supporting edge of glass, the total load deflection shall not exceed L/175 for each glass lite or L/60 for the entire length of the member, whichever is more stringent. For sandwich panels used in roofs or walls of sunroom additions or patio covers, the total load deflection shall not exceed L/120.
  4. Deflection for exterior walls with interior gypsum board finish shall be limited to an allowable deflection of H/180.
  5. Refer to Section R703.8.2.
For the purposes of this code, dimensions of lumber specified shall be deemed to be nominal dimensions unless specifically designated as actual dimensions.

R302.1 Exterior Walls

ILLUSTRATION

Construction, projections, openings and penetrations of exterior walls of dwellings and accessory buildings shall comply with Table R302.1(1); or dwellings equipped throughout with an automatic sprinkler system installed in accordance with Section P2904 shall comply with Table R302.1(2).

Exceptions:

  1. Walls, projections, openings or penetrations in walls perpendicular to the line used to determine the fire separation distance.
  2. Walls of individual dwelling units and their accessory structures located on the same lot.
  3. Detached tool sheds and storage sheds, playhouses and similar structures exempted from permits are not required to provide wall protection based on location on the lot. Projections beyond the exterior wall shall not extend over the lot line.
  4. Detached garages accessory to a dwelling located within 2 feet (610 mm) of a lot line are permitted to have roof eave projections not exceeding 4 inches (102 mm).
  5. Foundation vents installed in compliance with this code are permitted.

TABLE R302.1(1)

EXTERIOR WALLS

EXTERIOR WALL ELEMENT MINIMUM
FIRE-RESISTANCE RATING
MINIMUM FIRE
SEPARATION DISTANCE
Walls Fire-resistance rated 1 hour—tested in accordance with ASTM E119,
UL 263 or Section 703.3 of the International Building Code
with exposure from both sides
0 feet
Not fire-resistance rated 0 hours ≥ 5 feet
Projections Not allowed NA < 2 feet
Fire-resistance rated 1 hour on the underside, or heavy timber, or fire-
retardant-treated wooda, b
≥ 2 feet to < 5 feet
Not fire-resistance rated 0 hours ≥ 5 feet
Openings in walls Not allowed NA < 3 feet
25% maximum of wall area 0 hours 3 feet
Unlimited 0 hours 5 feet
Penetrations All Comply with Section R302.4 < 3 feet
None required 3 feet

For SI: 1 foot = 304.8 mm.

NA = Not Applicable.

  1. The fire-resistance rating shall be permitted to be reduced to 0 hours on the underside of the eave overhang if fireblocking is provided from the wall top plate to the underside of the roof sheathing.
  2. The fire-resistance rating shall be permitted to be reduced to 0 hours on the underside of the rake overhang where ventilation openings are not installed in the rake overhang or in walls that are common to attic areas.

TABLE R302.1(2)

EXTERIOR WALLSDWELLINGS WITH FIRE SPRINKLERS

EXTERIOR WALL ELEMENT MINIMUM
FIRE-RESISTANCE RATING
MINIMUM FIRE
SEPARATION DISTANCE
Walls Fire-resistance rated 1 hour—tested in accordance with ASTM E119,
UL 263 or Section 703.3 of the International Building Code
with exposure from the outside
0 feet
Not fire-resistance rated 0 hours 3 feeta
Projections Not allowed NA < 2 feet
Fire-resistance rated 1 hour on the underside, or heavy timber, or fire-
retardant-treated woodb, c
2 feeta
Not fire-resistance rated 0 hours 3 feet
Openings in walls Not allowed NA < 3 feet
Unlimited 0 hours 3 feeta
Penetrations All Comply with Section R302.4 < 3 feet
None required 3 feeta

For SI: 1 foot = 304.8 mm.

NA = Not Applicable.

  1. For residential subdivisions where all dwellings are equipped throughout with an automatic sprinkler system installed in accordance with Section P2904, the fire separation distance for exterior walls not fire-resistance rated and for fire-resistance-rated projections shall be permitted to be reduced to 0 feet, and unlimited unprotected openings and penetrations shall be permitted, where the adjoining lot provides an open setback yard that is 6 feet or more in width on the opposite side of the property line.
  2. The fire-resistance rating shall be permitted to be reduced to 0 hours on the underside of the eave overhang if fireblocking is provided from the wall top plate to the underside of the roof sheathing.
  3. The fire-resistance rating shall be permitted to be reduced to 0 hours on the underside of the rake overhang where ventilation openings are not installed in the rake overhang or in walls that are common to attic areas.

Walls separating townhouse units shall be constructed in accordance with Section R302.2.1 or R302.2.2.

FIGURE R302.2(1)

EXTENDED TOWNHOUSE SEPARATION WALL

For SI: 1 foot = 304.8 mm.

FIGURE R302.2(2)

TOWNHOUSE SEPARATION OVERHANG PROTECTION

When used, each townhouse unit shall be separated from other townhouse units by two 1-hour fire-resistance-rated wall assemblies tested in accordance with ASTM E119, UL 263 or Section 703.3 of the International Building Code.

R302.2.2 Common Walls

ILLUSTRATION

Common walls separating townhouse units shall be assigned a fire-resistance rating in accordance with Item 1 or 2. The common wall shared by two townhouse units shall be constructed without plumbing or mechanical equipment, ducts or vents in the cavity of the common wall. The wall shall be rated for fire exposure from both sides and shall extend to and be tight against exterior walls and the underside of the roof sheathing. Electrical installations shall be in accordance with WAC 296-46B Electrical Safety Standards, Administration, and Installation. Penetrations of the membrane of common walls for electrical outlet boxes shall be in accordance with Section R302.4.

  1. Where a fire sprinkler system in accordance with Section P2904 is provided, the common wall shall be not less than a 1-hour fire-resistance-rated wall assembly tested in accordance with ASTM E119, UL 263 or Section 703.3 of the International Building Code.
  2. Where a fire sprinkler system in accordance with Section P2904 is not provided, the common wall shall be not less than a 2-hour fire-resistance-rated wall assembly tested in accordance with ASTM E119, UL 263 or Section 703.3 of the International Building Code.

Exception: Common walls are permitted to extend to and be tight against the interior side of the exterior walls where voids in the exterior wall at the end of the common wall are fireblocked.

The fire-resistance-rated wall or assembly separating townhouse units shall be continuous from the foundation to the underside of the roof sheathing, deck or slab. The fire-resistance rating shall extend the full length of the wall or assembly, including wall extensions through and separating attached enclosed accessory structures.

Where a story extends beyond the exterior wall of a story below:

  1. The fire-resistance-rated wall or assembly shall extend to the outside edge of the upper story [see Figure R302.2(1)]; or
  2. The underside of the exposed floor-ceiling assembly shall be protected as required for projections in Section R302 [see Figure R302.2(2)].

Parapets constructed in accordance with Section R302.2.5 shall be constructed for townhouses as an extension of exterior walls or common walls separating townhouse units in accordance with the following:

  1. Where roof surfaces adjacent to the wall or walls are at the same elevation, the parapet shall extend not less than 30 inches (762 mm) above the roof surfaces.
  2. Where roof surfaces adjacent to the wall or walls are at different elevations and the higher roof is not more than 30 inches (762 mm) above the lower roof, the parapet shall extend not less than 30 inches (762 mm) above the lower roof surface.

    Exception: A parapet is not required in the preceding two cases where the roof covering complies with a minimum Class C rating as tested in accordance with ASTM E108 or UL 790 and the roof decking or sheathing is of noncombustible materials or fire-retardant-treated wood for a distance of 4 feet (1219 mm) on each side of the wall or walls, or one layer of 5/8-inch (15.9 mm) Type X gypsum board is installed directly beneath the roof decking or sheathing, supported by not less than nominal 2-inch (51 mm) ledgers attached to the sides of the roof framing members, for a distance of not less than 4 feet (1219 mm) on each side of the wall or walls and any openings or penetrations in the roof are not within 4 feet (1219 mm) of the common walls. Fire-retardant-treated wood shall meet the requirements of Sections R802.1.5 and R803.2.1.2.

  3. A parapet is not required where roof surfaces adjacent to the wall or walls are at different elevations and the higher roof is more than 30 inches (762 mm) above the lower roof. The common wall construction from the lower roof to the underside of the higher roof deck shall have not less than a 1-hour fire-resistance rating. The wall shall be rated for exposure from both sides.
Parapets shall have the same fire-resistance rating as that required for the supporting wall or walls. On any side adjacent to a roof surface, the parapet shall have noncombustible faces for the uppermost 18 inches (457 mm), to include counterflashing and coping materials. Where the roof slopes toward a parapet at slopes greater than 2 units vertical in 12 units horizontal (16.7-percent slope), the parapet shall extend to the same height as any portion of the roof within a distance of 3 feet (914 mm), and the height shall be not less than 30 inches (762 mm).

Each individual townhouse shall be structurally independent.

Exceptions:

  1. Foundations supporting exterior walls or common walls.
  2. Structural roof and wall sheathing from each unit fastened to the common wall framing.
  3. Nonstructural wall and roof coverings.
  4. Flashing at termination of roof covering over common wall.
  5. Townhouses separated by a common wall as provided in Section R302.2.2, Item 1 or 2.
Wall and floor/ceiling assemblies separating dwelling units in two-family dwellings shall be constructed in accordance with Section R302.3.1 or R302.3.3. One accessory dwelling unit constructed within an existing dwelling unit need not be considered a separated dwelling unit in a two-family dwelling where all required smoke alarms, in the accessory dwelling unit and the primary dwelling unit, are interconnected in such a manner that the actuation of one alarm will activate all alarms in both the primary dwelling unit and the accessory dwelling unit.

Dwelling units in two-family dwellings shall be separated from each other by wall and floor assemblies having not less than a 1-hour fire-resistance rating where tested in accordance with ASTM E119, UL 263 or Section 703.3 of the International Building Code.

Exception: A fire-resistance rating of 1/2 hour shall be permitted in buildings equipped throughout with an automatic sprinkler system installed in accordance with NFPA 13D.

Fire-resistance-rated floor/ceiling and wall assemblies shall extend to and be tight against the exterior wall, and wall assemblies shall extend from the foundation to the underside of the roof sheathing.

Exception: Wall assemblies need not extend through attic spaces where the ceiling is protected by not less than 5/8-inch (15.9 mm) Type X gypsum board, an attic draft stop constructed as specified in Section R302.12.1 is provided above and along the wall assembly separating the dwellings and the structural framing supporting the ceiling is protected by not less than 1/2-inch (12.7 mm) gypsum board or equivalent.

Where floor/ceiling assemblies are required to be fire-resistance rated by Section R302.3, the supporting construction of such assemblies shall have an equal or greater fire-resistance rating.
Penetrations of wall or floor-ceiling assemblies required to be fire-resistance rated in accordance with Section R302.2 or R302.3 shall be protected in accordance with this section.

Through penetrations of fire-resistance-rated wall or floor assemblies shall comply with Section R302.4.1.1 or R302.4.1.2.

Exception: Where the penetrating items are steel, ferrous or copper pipes, tubes or conduits, or fire sprinkler piping, the annular space shall be protected as follows:

  1. In concrete or masonry wall or floor assemblies, concrete, grout or mortar shall be permitted where installed to the full thickness of the wall or floor assembly or the thickness required to maintain the fire-resistance rating, provided that both of the following are complied with:

    1. 1.1. The nominal diameter of the penetrating item is not more than 6 inches (152 mm).
    2. 1.2. The area of the opening through the wall does not exceed 144 square inches (92 900 mm2).
  2. The material used to fill the annular space shall prevent the passage of flame and hot gases sufficient to ignite cotton waste where subjected to ASTM E119 or UL 263 time temperature fire conditions under a positive pressure differential of not less than 0.01 inch of water (3 Pa) at the location of the penetration for the time period equivalent to the fire-resistance rating of the construction penetrated.
Penetrations shall be installed as tested in the approved fire-resistance-rated assembly.
Penetrations shall be protected by an approved penetration firestop system installed as tested in accordance with ASTM E814 or UL 1479, with a positive pressure differential of not less than 0.01 inch of water (3 Pa) and shall have an F rating of not less than the required fire-resistance rating of the wall or floor-ceiling assembly penetrated.

Membrane penetrations shall comply with Section R302.4.1. Where walls are required to have a fire-resistance rating, recessed fixtures shall be installed so that the required fire-resistance rating will not be reduced.

Exceptions:

  1. Membrane penetrations of not more than 2-hour fire-resistance-rated walls and partitions by steel electrical boxes that do not exceed 16 square inches (0.0103 m2) in area provided that the aggregate area of the openings through the membrane does not exceed 100 square inches (0.0645 m2) in any 100 square feet (9.29 m2) of wall area. The annular space between the wall membrane and the box shall not exceed 1/8 inch (3.1 mm). Such boxes on opposite sides of the wall shall be separated by one of the following:

    1. 1.1. By a horizontal distance of not less than 24 inches (610 mm) where the wall or partition is constructed with individual noncommunicating stud cavities.
    2. 1.2. By a horizontal distance of not less than the depth of the wall cavity where the wall cavity is filled with cellulose loose-fill, rockwool or slag mineral wool insulation.
    3. 1.3. By solid fireblocking in accordance with Section R302.11.
    4. 1.4. By protecting both boxes with listed putty pads.
    5. 1.5. By other listed materials and methods.
  2. Membrane penetrations by listed electrical boxes of any materials provided that the boxes have been tested for use in fire-resistance-rated assemblies and are installed in accordance with the instructions included in the listing. The annular space between the wall membrane and the box shall not exceed 1/8 inch (3.1 mm) unless listed otherwise. Such boxes on opposite sides of the wall shall be separated by one of the following:

    1. 2.1. By the horizontal distance specified in the listing of the electrical boxes.
    2. 2.2. By solid fireblocking in accordance with Section R302.11.
    3. 2.3. By protecting both boxes with listed putty pads.
    4. 2.4. By other listed materials and methods.
  3. The annular space created by the penetration of a fire sprinkler provided that it is covered by a metal escutcheon plate.
  4. Ceiling membrane penetrations by listed luminaires or by luminaires protected with listed materials that have been tested for use in fire-resistance-rated assemblies and are installed in accordance with the instructions included in the listing.
Openings and penetrations through the walls or ceilings separating the dwelling from the garage shall be in accordance with Sections R302.5.1 through R302.5.3.
Openings from a private garage directly into a room used for sleeping purposes shall not be permitted. Other openings between the garage and residence shall be equipped with solid wood doors not less than 13/8 inches (35 mm) in thickness, solid or honeycombcore steel doors not less than 13/8 inches (35 mm) thick, or 20-minute fire-rated doors, equipped with a self-closing or automatic-closing device.
Ducts in the garage and ducts penetrating the walls or ceilings separating the dwelling from the garage shall be constructed of a minimum No. 26 gage (0.48 mm) sheet steel or other approved material and shall not have openings into the garage.
Penetrations through the separation required in Section R302.6 shall be protected as required by Section R302.11, Item 4.

The garage shall be separated as required by Table R302.6. Openings in garage walls shall comply with Section R302.5. Attachment of gypsum board shall comply with Table R702.3.5. The wall separation provisions of Table R302.6 shall not apply to garage walls that are perpendicular to the adjacent dwelling unit wall.

TABLE R302.6

DWELLING-GARAGE SEPARATION

SEPARATION MATERIAL
From the residence and attics Not less than 1/2-inch gypsum board or equivalent applied to the
garage side
From habitable rooms above the garage Not less than 5/8-inch Type X gypsum board or equivalent
Structure(s) supporting floor/ceiling assemblies used for separation
required by this section
Not less than 1/2-inch gypsum board or equivalent
Garages located less than 3 feet from a dwelling unit on the same lot Not less than 1/2-inch gypsum board or equivalent applied to the interior
side of exterior walls that are within this area

For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm.

Enclosed space under stairs that is accessed by a door or access panel shall have walls, under-stair surface and any soffits protected on the enclosed side with 1/2-inch (12.7 mm) gypsum board.
For requirements for foam plastics, see Section R316.

Wall and ceiling finishes shall have a flame spread index of not greater than 200.

Exception: Flame spread index requirements for finishes shall not apply to trim defined as picture molds, chair rails, baseboards and handrails; to doors and windows or their frames; or to materials that are less than 1/28 inch (0.91 mm) in thickness cemented to the surface of walls or ceilings if these materials exhibit flame spread index values not greater than those of paper of this thickness cemented to a noncombustible backing.

Wall and ceiling finishes shall have a smoke-developed index of not greater than 450.
Tests shall be made in accordance with ASTM E84 or UL 723.

As an alternative to having a flame spread index of not greater than 200 and a smoke-developed index of not greater than 450 where tested in accordance with ASTM E84 or UL 723, wall and ceiling finishes shall be permitted to be tested in accordance with NFPA 286. Materials tested in accordance with NFPA 286 shall meet the following criteria:

The interior finish shall comply with the following:

  1. During the 40 kW exposure, flames shall not spread to the ceiling.
  2. The flame shall not spread to the outer extremity of the sample on any wall or ceiling.
  3. Flashover, as defined in NFPA 286, shall not occur.
  4. The peak heat release rate throughout the test shall not exceed 800 kW.
  5. The total smoke released throughout the test shall not exceed 1,000 m2.

Insulating materials installed within floor-ceiling assemblies, roof-ceiling assemblies, wall assemblies, crawl spaces and attics shall comply with the requirements of this section. They shall exhibit a flame spread index not to exceed 25 and a smoke-developed index not to exceed 450 where tested in accordance with ASTM E84 or UL 723. Insulating materials, where tested in accordance with the requirements of this section, shall include facings, where used, such as vapor retarders, vapor permeable membranes and similar coverings.

Exceptions:

  1. Where such materials are installed in concealed spaces, the flame spread index and smoke-developed index limitations do not apply to the facings, provided that the facing is installed in substantial contact with the unexposed surface of the ceiling, floor or wall finish.
  2. Cellulose fiber loose-fill insulation that is not spray applied and that complies with the requirements of Section R302.10.3 shall not be required to meet the flame spread index requirements but shall be required to meet a smoke-developed index of not more than 450 where tested in accordance with CAN/ULC S102.2.
  3. Foam plastic insulation shall comply with Section R316.

Loose-fill insulation materials that cannot be mounted in the ASTM E84 or UL 723 apparatus without a screen or artificial supports shall comply with the flame spread and smoke-developed limits of Section R302.10.1 where tested in accordance with CAN/ULC S102.2.

Exception: Cellulosic fiber loose-fill insulation shall not be required to be tested in accordance with CAN/ULC S102.2, provided that such insulation complies with the requirements of Sections R302.10.1 and R302.10.3.

Cellulosic fiber loose-fill insulation shall comply with CPSC 16 CFR, Parts 1209 and 1404. Each package of such insulating material shall be clearly labeled in accordance with CPSC 16 CFR, Parts 1209 and 1404.
Exposed insulation materials installed on attic floors shall have a critical radiant flux of not less than 0.12 watt per square centimeter.
Tests for critical radiant flux shall be made in accordance with ASTM E970.

R302.11 Fireblocking

ILLUSTRATION

In combustible construction, fireblocking shall be provided to cut off both vertical and horizontal concealed draft openings and to form an effective fire barrier between stories, and between a top story and the roof space.

Fireblocking shall be provided in wood-framed construction in the following locations:

  1. In concealed spaces of stud walls and partitions, including furred spaces and parallel rows of studs or staggered studs, as follows:

    1. 1.1. Vertically at the ceiling and floor levels.
    2. 1.2. Horizontally at intervals not exceeding 10 feet (3048 mm).
  2. At interconnections between concealed vertical and horizontal spaces such as occur at soffits, drop ceilings and cove ceilings.
  3. In concealed spaces between stair stringers at the top and bottom of the run. Enclosed spaces under stairs shall comply with Section R302.7.
  4. At openings around vents, pipes, ducts, cables and wires at ceiling and floor level, with an approved material to resist the free passage of flame and products of combustion. The material filling this annular space shall not be required to meet the ASTM E136 requirements.
  5. For the fireblocking of chimneys and fireplaces, see Section R1003.19.
  6. Fireblocking of cornices of a two-family dwelling is required at the line of dwelling unit separation.

Except as provided in Section R302.11, Item 4, fireblocking shall consist of the following materials.

  1. Two-inch (51 mm) nominal lumber.
  2. Two thicknesses of 1-inch (25.4 mm) nominal lumber with broken lap joints.
  3. One thickness of 23/32-inch (18.3 mm) wood structural panels with joints backed by 23/32-inch (18.3 mm) wood structural panels.
  4. One thickness of 3/4-inch (19.1 mm) particleboard with joints backed by 3/4-inch (19.1 mm) particleboard.
  5. One-half-inch (12.7 mm) gypsum board.
  6. One-quarter-inch (6.4 mm) cement-based millboard.
  7. Batts or blankets of mineral wool or glass fiber or other approved materials installed in such a manner as to be securely retained in place.
  8. Cellulose insulation installed as tested in accordance with ASTM E119 or UL 263, for the specific application.
Batts or blankets of mineral or glass fiber or other approved nonrigid materials shall be permitted for compliance with the 10-foot (3048 mm) horizontal fireblocking in walls constructed using parallel rows of studs or staggered studs.
Unfaced fiberglass batt insulation used as fireblocking shall fill the entire cross section of the wall cavity to a height of not less than 16 inches (406 mm) measured vertically. Where piping, conduit or similar obstructions are encountered, the insulation shall be packed tightly around the obstruction.
Loose-fill insulation material shall not be used as a fireblock unless specifically tested in the form and manner intended for use to demonstrate its ability to remain in place and to retard the spread of fire and hot gases.
The integrity of fireblocks shall be maintained.

R302.12 Draftstopping

ILLUSTRATION

In combustible construction where there is usable space both above and below the concealed space of a floor-ceiling assembly, draftstops shall be installed so that the area of the concealed space does not exceed 1,000 square feet (92.9 m2). Draftstopping shall divide the concealed space into approximately equal areas. Where the assembly is enclosed by a floor membrane above and a ceiling membrane below, draftstopping shall be provided in floor-ceiling assemblies under the following circumstances:

  1. Ceiling is suspended under the floor framing.
  2. Floor framing is constructed of truss-type open-web or perforated members.

R302.12.1 Materials

ILLUSTRATION
Draftstopping materials shall be not less than 1/2-inch (12.7 mm) gypsum board, 3/8-inch (9.5 mm) wood structural panels or other approved materials adequately supported. Draftstopping shall be installed parallel to the floor framing members unless otherwise approved by the building official. The integrity of the draftstops shall be maintained.

Floor assemblies that are not required elsewhere in this code to be fire-resistance rated, shall be provided with a 1/2-inch (12.7 mm) gypsum wallboard membrane, 5/8-inch (16 mm) wood structural panel membrane, or equivalent on the underside of the floor framing member. Penetrations or openings for ducts, vents, electrical outlets, lighting, devices, luminaires, wires, speakers, drainage, piping and similar openings or penetrations shall be permitted.

Exceptions:

  1. Floor assemblies located directly over a space protected by an automatic sprinkler system in accordance with Appendix U, NFPA 13D, or other approved equivalent sprinkler system.
  2. Floor assemblies located directly over a crawl space not intended for storage or fuel-fired appliances.
  3. Portions of floor assemblies shall be permitted to be unprotected where complying with the following:

    1. 3.1. The aggregate area of the unprotected portions does not exceed 80 square feet (7.4 m2) per story.
    2. 3.2. Fireblocking in accordance with Section R302.11.1 is installed along the perimeter of the unprotected portion to separate the unprotected portion from the remainder of the floor assembly.
  4. Wood floor assemblies using dimensional lumber or structural composite lumber with a cross-sectional area equal to or greater than 2-inch by 10-inch (50.8 mm by 254 mm) nominal dimensional, or other approved floor assemblies demonstrating equivalent fire performance.

Combustible insulation shall be separated not less than 3 inches (76 mm) from recessed luminaires, fan motors and other heat-producing devices.

Exception: Where heat-producing devices are listed for lesser clearances, combustible insulation complying with the listing requirements shall be separated in accordance with the conditions stipulated in the listing.

Recessed luminaires installed in the building thermal envelope shall meet the requirements of Section N1102.4.5 of this code.

All habitable rooms shall have an aggregate glazing area of not less than 8 percent of the floor area of such rooms.

Exception: The glazed areas need not be installed in rooms where artificial light is provided capable of producing an average illumination of 6 footcandles (65 lux) over the area of the room at a height of 30 inches (762 mm) above the floor level.

R303.2 Adjoining Rooms

ILLUSTRATION

For the purpose of determining light requirements, any room shall be considered to be a portion of an adjoining room where at least one-half of the area of the common wall is open and unobstructed and provides an opening of not less than one-tenth of the floor area of the interior room and not less than 25 square feet (2.3 m2).

Exception: Openings required for light shall be permitted to open into a sunroom with thermal isolation or a patio cover, provided that there is an openable area between the adjoining room and the sunroom or patio cover of not less than one-tenth of the floor area of the interior room and not less than 20 square feet (2 m2).

This section is not adopted.

Dwelling units shall be equipped with local exhaust and whole-house ventilation systems designed and installed as specified in Section M1505.

Exception: Additions with less than 500 square feet (46 m2) of conditioned floor area are exempt from the requirements in this code for whole-house ventilation systems.

Outdoor intake and exhaust openings shall be located in accordance with Sections R303.5.1 and R303.5.2.

Mechanical and gravity outdoor air intake openings shall be located a minimum of 10 feet (3048 mm) from any hazardous or noxious contaminant, such as vents, chimneys, plumbing vents, streets, alleys, parking lots and loading docks, except as otherwise specified in this code.

For the purpose of this section, the exhaust from dwelling unit toilet rooms, bathrooms and kitchens shall not be considered as hazardous or noxious.


Exceptions:

  1. The 10-foot (3048 mm) separation is not required where the intake opening is located 3 feet (914 mm) or greater below the contaminant source.
  2. Vents and chimneys serving fuel-burning appliances shall be terminated in accordance with the applicable provisions of Chapters 18 and 24.
  3. Clothes dryer exhaust ducts shall be terminated in accordance with Section M1502.3.
Exhaust air shall not be directed onto walkways. All exhaust ducts shall terminate outside the building. Terminal elements shall have at least the equivalent net free area of the duct work.
Exhaust ducts shall be equipped with back-draft dampers. All exhaust ducts in unconditioned spaces shall be insulated to a minimum of R-4.
Air exhaust and intake openings that terminate outdoors shall be protected with corrosion-resistant screens, louvers or grilles having an opening size of not less than 1/4 inch (6 mm) and a maximum opening size of 1/2 inch (13 mm), in any dimension. Openings shall be protected against local weather conditions. Outdoor air exhaust and intake openings shall meet the provisions for exterior wall opening protectives in accordance with this code.

Interior stairways shall be provided with an artificial light source to illuminate the landings and treads. Stairway illumination shall receive primary power from the building wiring. The light source shall be capable of illuminating treads and landings to levels not less than 1 foot-candle (11 lux) measured at the center of treads and landings. There shall be a wall switch at each floor level to control the light source where the stairway has six or more risers.

Exception: A switch is not required where remote, central or automatic control of lighting is provided.

Exterior stairways shall be provided with an artificial light source located at the top landing of the stairway. Stairway illumination shall receive primary power from the building wiring. Exterior stairways providing access to a basement from the outdoor grade level shall be provided with an artificial light source located at the bottom landing of the stairway.

Required glazed openings shall open directly onto a street or public alley, or a yard or court located on the same lot as the building.

Exceptions:

  1. Required glazed openings that face into a roofed porch where the porch abuts a street, yard or court are permitted where the longer side of the porch is not less than 65 percent unobstructed and the ceiling height is not less than 7 feet (2134 mm).
  2. Eave projections shall not be considered as obstructing the clear open space of a yard or court.
  3. Required glazed openings that face into the area under a deck, balcony, bay or floor cantilever are permitted where an unobstructed pathway of not less than 36 inches (914 mm) in height, 36 inches (914 mm) in width, and no greater than 60 inches (1524 mm) in length is provided and opens to a yard or court. The pathway shall be measured from the exterior face of the glazed opening, or if the glazed opening is in a window well, at the window well wall furthest from the exterior face of the glazed opening.
Required glazed openings shall be permitted to open into sunroom additions or patio covers that abut a street, yard or court if in excess of 40 percent of the exterior sunroom walls are open, or are enclosed only by insect screening, and the ceiling height of the sunroom is not less than 7 feet (2134 mm).

When the winter design temperature in Table R301.2(1) is below 60°F (16°C), every dwelling unit shall be provided with heating facilities capable of maintaining a minimum room temperature of 68°F (20°C) at a point 3 feet (914 mm) above the floor and 2 feet (610 mm) from exterior walls in all habitable rooms at design temperature. The installation of one or more portable heaters shall not be used to achieve compliance with this section.

Exception: Unheated recreational tents or yurts not exceeding 500 square feet provided it is not occupied as a permanent dwelling.

For the purposes of this section only, the following definitions apply.


DESIGNATED AREAS are those areas designated by a county to be an urban growth area in Chapter 36.70A RCW and those areas designated by the U.S. Environmental Protection Agency as being in nonattainment for particulate matter.

SUBSTANTIALLY REMODELED means any alteration or restoration of a building exceeding 60 percent of the appraised value of such building within a 12 month period. For the purpose of this section, the appraised value is the estimated cost to replace the building and structure in kind, based on current replacement costs.

Primary heating sources in all new and substantially remodeled buildings in designated areas shall not be dependent upon wood stoves.

No new or used solid fuel burning device shall be installed in new or existing buildings unless such device is U.S. Environmental Protection Agency certified or exempt from certification by the United States Environmental Protection Agency and conforms with RCW 70.94.011, 70.94.450, 70.94.453, and 70.94.457.

Exceptions:

  1. Wood cook stoves.
  2. Antique wood heaters manufactured prior to 1940.

Habitable rooms shall have a floor area of not less than 70 square feet (6.5 m2).

Exception: Kitchens.

Habitable rooms shall be not less than 7 feet (2134 mm) in any horizontal dimension.

Exception: Kitchens.

Portions of a room with a sloping ceiling measuring less than 5 feet (1524 mm) or a furred ceiling measuring less than 7 feet (2134 mm) from the finished floor to the finished ceiling shall not be considered as contributing to the minimum required habitable area for that room.

R305.1 Minimum Height

ILLUSTRATION

Habitable space, hallways and portions of basements containing these spaces shall have a ceiling height of not less than 7 feet (2134 mm). Bathrooms, toilet rooms and laundry rooms shall have a ceiling height of not less than 6 feet 8 inches (2032 mm).

Exceptions:

  1. For rooms with sloped ceilings, the required floor area of the room shall have a ceiling height of not less than 5 feet (1524 mm) and not less than 50 percent of the required floor area shall have a ceiling height of not less than 7 feet (2134 mm).
  2. The ceiling height above bathroom and toilet room fixtures shall be such that the fixture is capable of being used for its intended purpose. A shower or tub equipped with a showerhead shall have a ceiling height of not less than 6 feet 8 inches (2032 mm) above an area of not less than 30 inches (762 mm) by 30 inches (762 mm) at the showerhead.
  3. Beams, girders, ducts or other obstructions in basements containing habitable space shall be permitted to project to within 6 feet 4 inches (1931 mm) of the finished floor.

Portions of basements that do not contain habitable space or hallways shall have a ceiling height of not less than 6 feet 8 inches (2032 mm).

Exception: At beams, girders, ducts or other obstructions, the ceiling height shall be not less than 6 feet 4 inches (1931 mm) from the finished floor.

Every dwelling unit shall be provided with a water closet, lavatory, and a bathtub or shower.
Each dwelling unit shall be provided with a kitchen area and every kitchen area shall be provided with a sink.
Plumbing fixtures shall be connected to a sanitary sewer or to an approved private sewage disposal system.
Plumbing fixtures shall be connected to an approved water supply. Kitchen sinks, lavatories, bathtubs, showers, bidets, laundry tubs and washing machine outlets shall be provided with hot and cold water.

R307.1 Space Required

ILLUSTRATION

Fixtures shall be spaced in accordance with Figure R307.1, and in accordance with the requirements of the state plumbing code Section 402.5.

For SI: 1 inch = 25.4 mm.

FIGURE R307.1

MINIMUM FIXTURE CLEARANCES

Bathtub and shower floors and walls above bathtubs with installed shower heads and in shower compartments shall be finished with a nonabsorbent surface. Such wall surfaces shall extend to a height of not less than 6 feet (1829 mm) above the floor.

Except as indicated in Section R308.1.1 each pane of glazing installed in hazardous locations as defined in Section R308.4 shall be provided with a manufacturer's designation specifying who applied the designation, the type of glass and the safety glazing standard with which it complies, and that is visible in the final installation. The designation shall be acid etched, sandblasted, ceramic-fired, laser etched, embossed, or be of a type that once applied cannot be removed without being destroyed. A label shall be permitted in lieu of the manufacturer's designation.

Exceptions:

  1. For other than tempered glass, manufacturer's designations are not required provided that the building official approves the use of a certificate, affidavit or other evidence confirming compliance with this code.
  2. Tempered spandrel glass is permitted to be identified by the manufacturer with a removable paper designation.
Multipane assemblies having individual panes not exceeding 1 square foot (0.09 m2) in exposed area shall have not less than one pane in the assembly identified in accordance with Section R308.1. Other panes in the assembly shall be labeled "CPSC 16 CFR 1201" or "ANSI Z97.1" as appropriate.
Regular, float, wired or patterned glass in jalousies and louvered windows shall be not less than nominal 3/16 inch (5 mm) thick and not more than 48 inches (1219 mm) in length. Exposed glass edges shall be smooth.
Wired glass with wire exposed on longitudinal edges shall not be used in jalousies or louvered windows.

Individual glazed areas, including glass mirrors in hazardous locations such as those indicated as defined in Section R308.4, shall pass the test requirements of Section R308.3.1.

Exceptions:

  1. Louvered windows and jalousies shall comply with Section R308.2.
  2. Mirrors and other glass panels mounted or hung on a surface that provides a continuous backing support.
  3. Glass unit masonry complying with Section R607.

Where required by other sections of the code, glazing shall be tested in accordance with CPSC 16 CFR 1201. Glazing shall comply with the test criteria for Category II unless otherwise indicated in Table R308.3.1(1).

Exception: Glazing not in doors or enclosures for hot tubs, whirlpools, saunas, steam rooms, bathtubs and showers shall be permitted to be tested in accordance with ANSI Z97.1. Glazing shall comply with the test criteria for Class A unless otherwise indicated in Table R308.3.1(2).

TABLE R308.3.1(1)

MINIMUM CATEGORY CLASSIFICATION OF GLAZING USING CPSC 16 CFR 1201

EXPOSED SURFACE
AREA OF ONE SIDE
OF ONE LITE
GLAZING IN
STORM OR
COMBINATION
DOORS
(Category Class)
GLAZING IN
DOORS
(Category Class)
GLAZED PANELS
REGULATED BY
SECTION R308.4.3
(Category Class)
GLAZED PANELS
REGULATED BY
SECTION R308.4.2
(Category Class)
GLAZING IN
DOORS AND
ENCLOSURES
REGULATED BY
SECTION 308.4.5
(Category Class)
SLIDING GLASS
DOORS PATIO
TYPE
(Category Class)
9 square feet or less I I NR I II II
More than 9 square feet II II II II II II

For SI: 1 square foot = 0.0929 m2.

NR = No Requirement.

TABLE R308.3.1(2)

MINIMUM CATEGORY CLASSIFICATION OF GLAZING USING ANSI Z97.1

EXPOSED SURFACE AREA
OF ONE SIDE OF ONE LITE
GLAZED PANELS REGULATED BY
(Category Class)
GLAZED PANELS REGULATED BY
(Category Class)
DOORS AND ENCLOSURES REGULATED
(Category Class)
9 square feet or less No requirement B A
More than 9 square feet A A A

For SI: 1 square foot = 0.0929 m2.

  1. Use is permitted only by the exception to Section R308.3.1.
The locations specified in Sections R308.4.1 through R308.4.7 shall be considered to be specific hazardous locations for the purposes of glazing.

Glazing in fixed and operable panels of swinging, sliding and bifold doors shall be considered to be a hazardous location.

Exceptions:

  1. Glazed openings of a size through which a 3-inch-diameter (76 mm) sphere is unable to pass.
  2. Decorative glazing.

Glazing in an individual fixed or operable panel adjacent to a door shall be considered to be a hazardous location where the bottom exposed edge of the glazing is less than 60 inches (1524 mm) above the floor or walking surface and it meets either of the following conditions:

  1. Where the glazing is within 24 inches (610 mm) of either side of the door in the plane of the door in a closed position.
  2. Where the glazing is on a wall less than 180 degrees (3.14 rad) from the plane of the door in a closed position and within 24 inches (610 mm) of the hinge side of an in-swinging door.

Exceptions:

  1. Decorative glazing.
  2. Where there is an intervening wall or other permanent barrier between the door and the glazing.
  3. Where access through the door is to a closet or storage area 3 feet (914 mm) or less in depth. Glazing in this application shall comply with Section R308.4.3.
  4. Glazing that is adjacent to the fixed panel of patio doors.

Glazing in an individual fixed or operable panel that meets all of the following conditions shall be considered to be a hazardous location:

  1. The exposed area of an individual pane is larger than 9 square feet (0.836 m2).
  2. The bottom edge of the glazing is less than 18 inches (457 mm) above the floor.
  3. The top edge of the glazing is more than 36 inches (914 mm) above the floor.
  4. One or more walking surfaces are within 36 inches (914 mm), measured horizontally and in a straight line, of the glazing.

    Exceptions:

    1. Decorative glazing.
    2. Where glazing is adjacent to a walking surface and a horizontal rail is installed 34 to 38 inches (864 to 965 mm) above the walking surface. The rail shall be capable of withstanding a horizontal load of 50 pounds per linear foot (730 N/m) without contacting the glass and have a cross-sectional height of not less than 11/2 inches (38 mm).
    3. Outboard panes in insulating glass units and other multiple glazed panels where the bottom edge of the glass is 25 feet (7620 mm) or more above grade, a roof, walking surfaces or other horizontal [within 45 degrees (0.79 rad) of horizontal] surface adjacent to the glass exterior.
Glazing in guards and railings, including structural baluster panels and nonstructural in-fill panels, regardless of area or height above a walking surface shall be considered to be a hazardous location.

Guards with structural glass baluster panels shall be installed with an attached top rail or handrail. The top rail or handrail shall be supported by not less than three glass baluster panels, or shall be otherwise supported to remain in place should one glass baluster panel fail.

Exception: An attached top rail or handrail is not required where the glass baluster panels are laminated glass with two or more glass plies of equal thickness and of the same glass type.

Glazing in walls, enclosures or fences containing or facing hot tubs, spas, whirlpools, saunas, steam rooms, bathtubs, showers and indoor or outdoor swimming pools where the bottom exposed edge of the glazing is less than 60 inches (1524 mm) measured vertically above any standing or walking surface shall be considered to be a hazardous location. This shall apply to single glazing and each pane in multiple glazing.

Exception: Glazing that is more than 60 inches (1524 mm), measured horizontally and in a straight line, from the water's edge of a bathtub, hot tub, spa, whirlpool or swimming pool or from the edge of a shower, sauna or steam room.

Glazing where the bottom exposed edge of the glazing is less than 36 inches (914 mm) above the plane of the adjacent walking surface of stairways, landings between flights of stairs and ramps shall be considered to be a hazardous location.

Exceptions:

  1. Where glazing is adjacent to a walking surface and a horizontal rail is installed at 34 to 38 inches (864 to 965 mm) above the walking surface. The rail shall be capable of withstanding a horizontal load of 50 pounds per linear foot (730 N/m) without contacting the glass and have a cross-sectional height of not less than 11/2 inches (38 mm).
  2. Glazing 36 inches (914 mm) or more measured horizontally from the walking surface.

Glazing adjacent to the landing at the bottom of a stairway where the glazing is less than 36 inches (914 mm) above the landing and within a 60-inch (1524 mm) horizontal arc less than 180 degrees (3.14 rad) from the bottom tread nosing shall be considered to be a hazardous location. (See Figure R308.4.7.)

Exception: Where the glazing is protected by a guard complying with Section R312 and the plane of the glass is more than 18 inches (457 mm) from the guard.

For SI: 1 inch = 25.4 mm.

FIGURE R308.4.7

HAZARDOUS GLAZING LOCATIONS AT BOTTOM STAIR LANDINGS

Site-built windows shall comply with Section 2404 of the International Building Code.
Skylights and sloped glazing shall comply with the following sections.

Glazing materials shall be limited to the following:

  1. Laminated glass with not less than a 0.015-inch (0.38 mm) polyvinyl butyral interlayer for glass panes 16 square feet (1.5 m2) or less in area located such that the highest point of the glass is not more than 12 feet (3658 mm) above a walking surface; for higher or larger sizes, the interlayer thickness shall be not less than 0.030 inch (0.76 mm).
  2. Fully tempered glass.
  3. Heat-strengthened glass.
  4. Wired glass.
  5. Approved rigid plastics.
For fully tempered or heat-strengthened glass, a retaining screen meeting the requirements of Section R308.6.7 shall be installed below the glass, except for fully tempered glass that meets either condition listed in Section R308.6.5.
Where the inboard pane is fully tempered, heat-strengthened or wired glass, a retaining screen meeting the requirements of Section R308.6.7 shall be installed below the glass, except for either condition listed in Section R308.6.5. Other panes in the multiple glazing shall be of any type listed in Section R308.6.2.

Screens shall not be required where fully tempered glass is used as single glazing or the inboard pane in multiple glazing and either of the following conditions is met:

  1. The glass area is 16 square feet (1.49 m2) or less; the highest point of glass is not more than 12 feet (3658 mm) above a walking surface; the nominal glass thickness is not more than 3/16 inch (4.8 mm); and (for multiple glazing only) the other pane or panes are fully tempered, laminated or wired glass.
  2. The glass area is greater than 16 square feet (1.49 m2); the glass is sloped 30 degrees (0.52 rad) or less from vertical; and the highest point of glass is not more than 10 feet (3048 mm) above a walking surface.
Any glazing material is permitted to be installed without screening in the sloped areas of greenhouses, provided that the greenhouse height at the ridge does not exceed 20 feet (6096 mm) above grade.
The screen and its fastenings shall be capable of supporting twice the weight of the glazing, be firmly and substantially fastened to the framing members, and have a mesh opening of not more than 1 inch by 1 inch (25 mm by 25 mm).
Unit skylights installed in a roof with a pitch of less than three units vertical in 12 units horizontal (25-percent slope) shall be mounted on a curb extending not less than 4 inches (102 mm) above the plane of the roof, unless otherwise specified in the manufacturer's installation instructions.
Unit skylights and tubular daylighting devices shall be tested by an approved independent laboratory, and bear a label identifying manufacturer, performance grade rating and approved inspection agency to indicate compliance with the requirements of AAMA/WDMA/CSA 101/I.S.2/A440.

Structural wind load design pressures for glass-glazed unit skylights different than the size tested in accordance with Section R308.6.9 shall be permitted to be different than the design value of the tested unit where determined in accordance with one of the following comparative analysis methods:

  1. Structural wind load design pressures for glass-glazed unit skylights smaller than the size tested in accordance with Section R308.6.9 shall be permitted to be higher than the design value of the tested unit provided that such higher pressures are determined by accepted engineering analysis. Components of the smaller unit shall be the same as those of the tested unit. Such calculated design pressures shall be validated by an additional test of the glass-glazed unit skylight having the highest allowable design pressure.
  2. In accordance with WDMA I.S. 11.

Garage floor surfaces shall be of approved noncombustible material.

The area of floor used for parking of automobiles or other vehicles shall be sloped to facilitate the movement of liquids to a drain or toward the main vehicle entry doorway.

R309.2 Carports

ILLUSTRATION

Carports shall be open on not less than two sides. Carport floor surfaces shall be of approved noncombustible material. Carports not open on two or more sides shall be considered to be a garage and shall comply with the provisions of this section for garages.

The area of floor used for parking of automobiles or other vehicles shall be sloped to facilitate the movement of liquids to a drain or toward the main vehicle entry doorway.

Exception: Asphalt surfaces shall be permitted at ground level in carports.

For buildings located in flood hazard areas as established by Table R301.2(1), garage floors shall be one of the following:

  1. Elevated to or above the design flood elevation as determined in accordance with Section R322.
  2. Located below the design flood elevation provided that the floors are at or above grade on not less than one side, are used solely for parking, building access or storage, meet the requirements of Section R322 and are otherwise constructed in accordance with this code.
Automatic garage door openers, if provided, shall be listed and labeled in accordance with UL 325.
Private garages shall be protected by fire sprinklers where the garage wall has been designed based on Table R302.1(2), Note a. Sprinklers in garages shall be connected to an automatic sprinkler system that complies with Section P2904. Garage sprinklers shall be residential sprinklers or quick-response sprinklers, designed to provide a density of 0.05 gpm/ft2. Garage doors shall not be considered obstructions with respect to sprinkler placement.

Basements, habitable attics and every sleeping room shall have not less than one operable emergency escape and rescue opening. Where basements contain one or more sleeping rooms, an emergency escape and rescue opening shall be required in each sleeping room. Emergency escape and rescue openings shall open directly into a public way, or to a yard or court providing an unobstructed path with a width of not less than 36 inches (914 mm) that opens to a public way.

Exceptions:

  1. Storm shelters and basements used only to house mechanical equipment not exceeding a total floor area of 200 square feet (18.58 m2).
  2. Where the dwelling unit or townhouse unit is equipped with an automatic sprinkler system installed in accordance with Section P2904, sleeping rooms in basements shall not be required to have emergency escape and rescue openings provided that the basement has one of the following:

    1. 2.1. One means of egress complying with Section R311 and one emergency escape and rescue opening.
    2. 2.2. Two means of egress complying with Section R311.
Emergency escape and rescue openings shall be operational from the inside of the room without the use of keys, tools, or special knowledge. Window opening control devices on windows serving as a required emergency escape and rescue opening shall be not more than 70 inches (177.8 cm) above the finished floor and shall comply with ASTM F2090.
Emergency escape and rescue openings shall have minimum dimensions as specified in this section.

Emergency escape and rescue openings shall have a net clear opening of not less than 5.7 square feet (0.530 m2). The net clear opening dimensions required by this section shall be obtained by the normal operation of the emergency escape and rescue opening from the inside. The net clear height of the opening shall be not less than 24 inches (610 mm) and the net clear width shall be not less than 20 inches (508 mm).

Exception: Grade floor openings or below-grade openings shall have a net clear opening area of not less than 5 square feet (0.465 m2).

Where a window is provided as the emergency escape and rescue opening, it shall have a sill height of not more than 44 inches (1118 mm) above the floor; where the sill height is below grade, it shall be provided with a window well in accordance with Section R310.2.3.

R310.2.3 Window Wells

ILLUSTRATION

The horizontal area of the window well shall be not less than 9 square feet (0.9 m2), with a horizontal projection and width of not less than 36 inches (914 mm). The area of the window well shall allow the emergency escape and rescue opening to be fully opened.

Exception: The ladder or steps required by Section R310.2.3.1 shall be permitted to encroach not more than 6 inches (152 mm) into the required dimensions of the window well.

Window wells with a vertical depth greater than 44 inches (1118 mm) shall be equipped with a permanently affixed ladder or steps usable with the window in the fully open position. Ladders or steps required by this section shall not be required to comply with Section R311.7. Ladders or rungs shall have an inside width of not less than 12 inches (305 mm), shall project not less than 3 inches (76 mm) from the wall and shall be spaced not more than 18 inches (457 mm) on center vertically for the full height of the window well.

Window wells shall be designed for proper drainage by connecting to the building's foundation drainage system required by Section R405.1 or by an approved alternative method.

Exception: A drainage system for window wells is not required where the foundation is on well-drained soil or sand-gravel mixture soils in accordance with the United Soil Classification System, Group I Soils, as detailed in Table R405.1.

Emergency escape and rescue openings installed under decks and porches shall be fully openable and provided with an unobstructed pathway of not less than 36 inches (914 mm) in height, 36 inches (914 mm) in width, and no greater than 60 inches (1524 mm) in length that opens to a yard or court. The pathway shall be measured from the exterior face of the glazed opening, or if the glazed opening is in a window well, at the window well wall furthest from the exterior face of the glazed opening.

Replacement windows installed in buildings meeting the scope of this code shall be exempt from the maximum sill height requirements of Section R310.2.2 and the requirements of Section R310.2.1, provided that the replacement window meets the following conditions:

  1. The replacement window is the manufacturer's largest standard size window that will fit within the existing frame or existing rough opening. The replacement window is of the same operating style as the existing window or a style that provides for an equal or greater window opening area than the existing window.
  2. The replacement window is not part of a change of occupancy.
Where a door is provided as the required emergency escape and rescue opening, it shall be a side-hinged door or a slider. Where the opening is below the adjacent grade, it shall be provided with an area well.
The minimum net clear height opening for any door that serves as an emergency and escape rescue opening shall be in accordance with Section R310.2.1.

R310.3.2 Area Wells

ILLUSTRATION
Area wells shall have a width of not less than 36 inches (914 mm). The area well shall be sized to allow the emergency escape and rescue door to be fully opened.
Area wells with a vertical depth greater than 44 inches (1118 mm) shall be equipped with a permanently affixed ladder or steps usable with the door in the fully open position. Ladders or steps required by this section shall not be required to comply with Section R311.7. Ladders or rungs shall have an inside width of not less than 12 inches (305 mm), shall project not less than 3 inches (76 mm) from the wall and shall be spaced not more than 18 inches (457 mm) on center vertically for the full height of the exterior stairwell.

Area wells shall be designed for proper drainage by connecting to the building's foundation drainage system required by Section R405.1 or by an approved alternative method.

Exception: A drainage system for area wells is not required where the foundation is on well-drained soil or sand-gravel mixture soils in accordance with the United Soil Classification System, Group I Soils, as detailed in Table R405.1.

Where bars, grilles, covers, screens or similar devices are placed over emergency escape and rescue openings, area wells, or window wells, the minimum net clear opening size shall comply with Sections R310.2.1 through R310.2.3, and such devices shall be releasable or removable from the inside without the use of a key, tool, special knowledge or force greater than that required for the normal operation of the escape and rescue opening.

Where dwelling additions contain sleeping rooms, an emergency escape and rescue opening shall be provided in each new sleeping room. Where dwelling additions have basements, an emergency escape and rescue opening shall be provided in the new basement.

Exceptions:

  1. An emergency escape and rescue opening is not required in a new basement that contains a sleeping room with an emergency escape and rescue opening.
  2. An emergency escape and rescue opening is not required in a new basement where there is an emergency escape and rescue opening in an existing basement that is accessed from the new basement.

An emergency escape and rescue opening is not required where existing basements undergo alterations or repairs.

Exception: New sleeping rooms created in an existing basement shall be provided with emergency escape and rescue openings in accordance with Section R310.1.

Dwellings shall be provided with a means of egress in accordance with this section. The means of egress shall provide a continuous and unobstructed path of vertical and horizontal egress travel from all portions of the dwelling to the required egress door without requiring travel through a garage. The required egress door shall open directly into a public way or to a yard or court that opens to a public way.

R311.2 Egress Door

ILLUSTRATION
Not less than one egress door shall be provided for each dwelling unit. The egress door shall be side-hinged, and shall provide a clear width of not less than 32 inches (813 mm) where measured between the face of the door and the stop, with the door open 90 degrees (1.57 rad). The clear height of the door opening shall be not less than 78 inches (1981 mm) in height measured from the top of the threshold to the bottom of the stop. Other doors shall not be required to comply with these minimum dimensions. Egress doors shall be readily openable from inside the dwelling without the use of a key or special knowledge or effort.

There shall be a landing or floor on each side of each exterior door. The width of each landing shall be not less than the door served. Landings shall have a dimension of not less than 36 inches (914 mm) measured in the direction of travel. The slope at exterior landings shall not exceed 1/4 unit vertical in 12 units horizontal (2 percent).

Exception: Exterior balconies less than 60 square feet (5.6 m2) and only accessed from a door are permitted to have a landing that is less than 36 inches (914 mm) measured in the direction of travel.

Landings or finished floors at the required egress door shall be not more than 11/2 inches (38 mm) lower than the top of the threshold.

Exception: The landing or floor on the exterior side shall be not more than 73/4 inches (196 mm) below the top of the threshold provided that the door does not swing over the landing or floor.

Where exterior landings or floors serving the required egress door are not at grade, they shall be provided with access to grade by means of a ramp in accordance with Section R311.8 or a stairway in accordance with Section R311.7.

Doors other than the required egress door shall be provided with landings or floors not more than 73/4 inches (196 mm) below the top of the threshold.

Exception: A top landing is not required where a stairway of not more than two risers is located on the exterior side of the door, provided that the door does not swing over the stairway.

Storm and screen doors shall be permitted to swing over exterior stairs and landings.

Egress from habitable levels including habitable attics and basements not provided with an egress door in accordance with Section R311.2 shall be by ramp in accordance with Section R311.8 or a stairway in accordance with Section R311.7.

Exception: Stairs or ladders within an individual dwelling unit used for access to areas of 200 square feet (18.6 m2) or less, and not containing the primary bathroom or kitchen.

Exterior landings, decks, balconies, stairs and similar facilities shall be positively anchored to the primary structure to resist both vertical and lateral forces or shall be designed to be self-supporting. Attachment shall not be accomplished by use of toenails or nails subject to withdrawal.
The width of a hallway shall be not less than 3 feet (914 mm).

R311.7.1 Width

ILLUSTRATION

Stairways shall be not less than 36 inches (914 mm) in clear width at all points above the permitted handrail height and below the required headroom height. The clear width of stairways at and below the handrail height, including treads and landings, shall be not less than 311/2 inches (787 mm) where a handrail is installed on one side and 27 inches (698 mm) where handrails are installed on both sides.

Exception: The width of spiral stairways shall be in accordance with Section R311.7.10.1.

The headroom in stairways shall be not less than 6 feet 8 inches (2032 mm) measured vertically from the sloped line adjoining the tread nosing or from the floor surface of the landing or platform on that portion of the stairway.

Exceptions:

  1. Where the nosings of treads at the side of a flight extend under the edge of a floor opening through which the stair passes, the floor opening shall not project horizontally into the required headroom more than 43/4 inches (121 mm).
  2. The headroom for spiral stairways shall be in accordance with Section R311.7.10.1.
A flight of stairs shall not have a vertical rise larger than 12 feet 7 inches (3835 mm) between floor levels or landings.

R311.7.4 Walkline

ILLUSTRATION
The walkline across winder treads and landings shall be concentric to the turn and parallel to the direction of travel entering and exiting the turn. The walkline shall be located 12 inches (305 mm) from the inside of the turn. The 12-inch (305 mm) dimension shall be measured from the widest point of the clear stair width at the walking surface. Where winders are adjacent within a flight, the point of the widest clear stair width of the adjacent winders shall be used.
Stair treads and risers shall meet the requirements of this section. For the purposes of this section, dimensions and dimensioned surfaces shall be exclusive of carpets, rugs or runners.

The riser height shall be not more than 73/4 inches (196 mm). The riser shall be measured vertically between leading edges of the adjacent treads. The greatest riser height within any flight of stairs shall not exceed the smallest by more than 3/8 inch (9.5 mm). Risers shall be vertical or sloped from the underside of the nosing of the tread above at an angle not more than 30 degrees (0.51 rad) from the vertical. At open risers, openings located more than 30 inches (762 mm), as measured vertically, to the floor or grade below shall not permit the passage of a 4-inch-diameter (102 mm) sphere.

Exceptions:

  1. The opening between adjacent treads is not limited on spiral stairways.
  2. The riser height of spiral stairways shall be in accordance with Section R311.7.10.1.
The tread depth shall be not less than 10 inches (254 mm). The tread depth shall be measured horizontally between the vertical planes of the foremost projection of adjacent treads and at a right angle to the tread's leading edge. The greatest tread depth within any flight of stairs shall not exceed the smallest by more than 3/8 inch (9.5 mm).

Winder treads shall have a tread depth of not less than 10 inches (254 mm) measured between the vertical planes of the foremost projection of adjacent treads at the intersections with the walkline. Winder treads shall have a tread depth of not less than 6 inches (152 mm) at any point within the clear width of the stair. Within any flight of stairs, the largest winder tread depth at the walkline shall not exceed the smallest winder tread by more than 3/8 inch (9.5 mm). Consistently shaped winders at the walkline shall be allowed within the same flight of stairs as rectangular treads and shall not be required to be within 3/8 inch (9.5 mm) of the rectangular tread depth.

Exception: The tread depth at spiral stairways shall be in accordance with Section R311.7.10.1.

Nosings at treads, landings and floors of stairways shall have a radius of curvature at the nosing not greater than 9/16 inch (14 mm) or a bevel not greater than 1/2 inch (12.7 mm). A nosing projection not less than 3/4 inch (19 mm) and not more than 11/4 inches (32 mm) shall be provided on stairways. The greatest nosing projection shall not exceed the smallest nosing projection by more than 3/8 inch (9.5 mm) within a stairway.

Exception: A nosing projection is not required where the tread depth is not less than 11 inches (279 mm).

Plastic composite exterior stair treads shall comply with the provisions of this section and Section R507.2.2.

There shall be a floor or landing at the top and bottom of each stairway. The width perpendicular to the direction of travel shall be not less than the width of the flight served. For landings of shapes other than square or rectangular, the depth at the walk line and the total area shall be not less than that of a quarter circle with a radius equal to the required landing width. Where the stairway has a straight run, the depth in the direction of travel shall be not less than 36 inches (914 mm).

Exception: A floor or landing is not required at the top of an interior flight of stairs, including stairs in an enclosed garage, provided that a door does not swing over the stairs.

The walking surface of treads and landings of stairways shall be sloped not steeper than one unit vertical in 48 inches horizontal (2-percent slope).

R311.7.8 Handrails

ILLUSTRATION
Handrails shall be provided on not less than one side of each flight of stairs with four or more risers.

Handrail height, measured vertically from the sloped plane adjoining the tread nosing, or finish surface of ramp slope, shall be not less than 34 inches (864 mm) and not more than 38 inches (965 mm).

Exceptions:

  1. The use of a volute, turnout or starting easing shall be allowed over the lowest tread.
  2. Where handrail fittings or bendings are used to provide continuous transition between flights, transitions at winder treads, the transition from handrail to guard, or used at the start of a flight, the handrail height at the fittings or bendings shall be permitted to exceed 38 inches (965 mm).

Handrails shall not project more than 41/2 inches (114 mm) on either side of the stairway.

Exception: Where nosings of landings, floors or passing flights project into the stairway reducing the clearance at passing handrails, handrails shall project not more than 61/2 inches (165 mm) into the stairway, provided that the stair width and handrail clearance are not reduced to less than that required.

Handrails adjacent to a wall shall have a space of not less than 11/2 inches (38 mm) between the wall and the handrails.

Handrails shall be continuous for the full length of the flight, from a point directly above the top riser of the flight to a point directly above the lowest riser of the flight. Handrail ends shall be returned or shall terminate in newel posts or safety terminals.

Exceptions:

  1. Handrail continuity shall be permitted to be interrupted by a newel post at a turn in a flight with winders, at a landing, or over the lowest tread.
  2. A volute, turnout or starting easing shall be allowed to terminate over the lowest tread.

Required handrails shall be of one of the following types or provide equivalent graspability.

  1. Type I. Handrails with a circular cross section shall have an outside diameter of not less than 11/4 inches (32 mm) and not greater than 2 inches (51 mm). If the handrail is not circular, it shall have a perimeter of not less than 4 inches (102 mm) and not greater than 61/4 inches (160 mm) and a cross section of not more than 21/4 inches (57 mm). Edges shall have a radius of not less than 0.01 inch (0.25 mm).
  2. Type II. Handrails with a perimeter greater than 61/4 inches (160 mm) shall have a graspable finger recess area on both sides of the profile. The finger recess shall begin within 3/4 inch (19 mm) measured vertically from the tallest portion of the profile and have a depth of not less than 5/16 inch (8 mm) within 7/8 inch (22 mm) below the widest portion of the profile. This required depth shall continue for not less than 3/8 inch (10 mm) to a level that is not less than 13/4 inches (45 mm) below the tallest portion of the profile. The width of the handrail above the recess shall be not less than 11/4 inches (32 mm) and not more than 23/4 inches (70 mm). Edges shall have a radius of not less than 0.01 inch (0.25 mm).
Stairways shall be provided with illumination in accordance with Sections R303.7 and R303.8.
Spiral stairways and bulkhead enclosure stairways shall comply with the requirements of Section R311.7 except as specified in Sections R311.7.10.1 and R311.7.10.2.
The clear width at and below the handrails at spiral stairways shall be not less than 26 inches (660 mm) and the walkline radius shall be not greater than 241/2 inches (622 mm). Each tread shall have a depth of not less than 63/4 inches (171 mm) at the walkline. Treads shall be identical, and the rise shall be not more than 91/2 inches (241 mm). Headroom shall be not less than 6 feet 6 inches (1982 mm).
Stairways serving bulkhead enclosures, not part of the required building egress, providing access from the outside grade level to the basement shall be exempt from the requirements of Sections R311.3 and R311.7 where the height from the basement finished floor level to grade adjacent to the stairway is not more than 8 feet (2438 mm) and the grade level opening to the stairway is covered by a bulkhead enclosure with hinged doors or other approved means.

Alternating tread devices shall not be used as an element of a means of egress. Alternating tread devices shall be permitted provided that a required means of egress stairway or ramp serves the same space at each adjoining level or where a means of egress is not required. The clear width at and below the handrails shall be not less than 20 inches (508 mm).

Exception: Alternating tread devices are allowed to be used as an element of a means of egress for lofts, mezzanines and similar areas of 200 gross square feet (18.6 m2) or less where such devices do not provide exclusive access to a kitchen or bathroom.

Alternating tread devices shall have a tread depth of not less than 5 inches (127 mm), a projected tread depth of not less than 81/2 inches (216 mm), a tread width of not less than 7 inches (178 mm) and a riser height of not more than 91/2 inches (241 mm). The tread depth shall be measured horizontally between the vertical planes of the foremost projections of adjacent treads. The riser height shall be measured vertically between the leading edges of adjacent treads. The riser height and tread depth provided shall result in an angle of ascent from the horizontal of between 50 and 70 degrees (0.87 and 1.22 rad). The initial tread of the device shall begin at the same elevation as the platform, landing or floor surface.
Handrails shall be provided on both sides of alternating tread devices and shall comply with Sections R311.7.8.2 to R311.7.8.6. Handrail height shall be uniform, not less than 30 inches (762 mm) and not more than 34 inches (864 mm).

Ship's ladders shall not be used as an element of a means of egress. Ship's ladders shall be permitted provided that a required means of egress stairway or ramp serves the same space at each adjoining level or where a means of egress is not required. The clear width at and below the handrails shall be not less than 20 inches.

Exception: Ship's ladders are allowed to be used as an element of a means of egress for lofts, mezzanines and similar areas of 200 gross square feet (18.6 m2) or less that do not provide exclusive access to a kitchen or bathroom.

Treads shall have a depth of not less than 5 inches (127 mm). The tread shall be projected such that the total of the tread depth plus the nosing projection is not less than 81/2 inches (216 mm). The riser height shall be not more than 91/2 inches (241 mm).
Handrails shall be provided on both sides of ship's ladders and shall comply with Sections R311.7.8.2 to R311.7.8.6. Handrail height shall be uniform, not less than 30 inches (762 mm) and not more than 34 inches (864 mm).

R311.8 Ramps

ILLUSTRATION

Ramps serving the egress door required by Section R311.2 shall have a slope of not more than 1 unit vertical in 12 units horizontal (8.3-percent slope). Other ramps shall have a maximum slope of 1 unit vertical in 8 units horizontal (12.5 percent).

Exception: Where it is technically infeasible to comply because of site constraints, ramps shall have a slope of not more than 1 unit vertical in 8 units horizontal (12.5 percent).

There shall be a floor or landing at the top and bottom of each ramp, where doors open onto ramps, and where ramps change directions. The width of the landing perpendicular to the ramp slope shall be not less than 36 inches (914 mm).
Handrails shall be provided on not less than one side of ramps exceeding a slope of one unit vertical in 12 units horizontal (8.33-percent slope).
Handrail height, measured above the finished surface of the ramp slope, shall be not less than 34 inches (864 mm) and not more than 38 inches (965 mm).
Handrails where required on ramps shall be continuous for the full length of the ramp. Handrail ends shall be returned or shall terminate in newel posts or safety terminals. Handrails adjacent to a wall shall have a space of not less than 11/2 inches (38 mm) between the wall and the handrails.
Guards shall be provided in accordance with Sections R312.1.1 through R312.1.4.
Guards shall be provided for those portions of open-sided walking surfaces, including stairs, ramps and landings, that are located more than 30 inches (762 mm) measured vertically to the floor or grade below at any point within 36 inches (914 mm) horizontally to the edge of the open side. Insect screening shall not be considered as a guard.

Required guards at open-sided walking surfaces, including stairs, porches, balconies or landings, shall be not less than 36 inches (914 mm) in height as measured vertically above the adjacent walking surface or the line connecting the nosings.

Exceptions:

  1. Guards on the open sides of stairs shall have a height of not less than 34 inches (864 mm) measured vertically from a line connecting the nosings.
  2. Where the top of the guard serves as a handrail on the open sides of stairs, the top of the guard shall be not less than 34 inches (864 mm) and not more than 38 inches (965 mm) as measured vertically from a line connecting the nosings.

Required guards shall not have openings from the walking surface to the required guard height that allow passage of a sphere 4 inches (102 mm) in diameter.

Exceptions:

  1. The triangular openings at the open side of stair, formed by the riser, tread and bottom rail of a guard, shall not allow passage of a sphere 6 inches (153 mm) in diameter.
  2. Guards on the open side of stairs shall not have openings that allow passage of a sphere 43/8 inches (111 mm) in diameter.
Plastic composite exterior guards shall comply with the requirements of Section R317.4.
Window fall protection shall be provided in accordance with Sections R312.2.1 and R312.2.2.

In dwelling units, where the top of the sill of an operable window opening is located less than 24 inches (610 mm) above the finished floor and greater than 72 inches (1829 mm) above the finished grade or other surface below on the exterior of the building, the operable window shall comply with one of the following:

  1. Operable window openings will not allow a 4-inch-diameter (102 mm) sphere to pass through where the openings are in their largest opened position.
  2. Operable windows are provided with window fall prevention devices that comply with ASTM F2090.
  3. Operable windows are provided with window opening control devices that comply with Section R312.2.2.
Window opening control devices shall comply with ASTM F2090. The window opening control device, after operation to release the control device allowing the window to fully open, shall not reduce the net clear opening area of the window unit to less than the area required by Section R310.2.1.

An automatic residential fire sprinkler system shall be installed in a townhouse unit.

Exceptions:

  1. An automatic residential fire sprinkler system shall not be required where additions or alterations are made to an existing townhouse unit that does not have an automatic residential fire sprinkler system installed.
  2. Townhouse buildings containing no more than four townhouse units.
Automatic residential fire sprinkler systems for a townhouse unit shall be designed and installed in accordance with Section P2904 or NFPA 13D.
Smoke alarms, heat detectors, and heat alarms shall comply with NFPA 72 and Section R314.
Smoke alarms shall be listed in accordance with UL 217. Heat detectors and heat alarms shall be listed for the intended application. Combination smoke and carbon monoxide alarms shall be listed in accordance with UL 217 and UL 2034.
Smoke alarms, heat detectors, and heat alarms shall be provided in accordance with this section.
Smoke alarms shall be provided in dwelling units. A heat detector or heat alarm shall be provided in new attached garages.

Where alterations, repairs or additions requiring a permit occur, or where one or more sleeping rooms are added or created in existing dwellings, or where an accessory dwelling unit is created within an existing dwelling unit, each dwelling unit shall be equipped with smoke alarms as required for new dwellings.

Exceptions:

  1. Work involving the exterior surfaces of dwellings, such as the replacement of roofing or siding, the addition or replacement of windows or doors, or the addition of a porch or deck are exempt from the requirements of this section.
  2. Installation, alteration or repairs of plumbing, electrical or mechanical systems are exempt from the requirements of this section.

A heat detector or heat alarm rated for the ambient outdoor temperatures and humidity shall be installed in new garages that are attached to or located under new and existing dwellings. Heat detectors and heat alarms shall be installed in a central location and in accordance with the manufacturer's instructions.

Exception: Heat detectors and heat alarms shall not be required in dwellings without commercial power.

Smoke alarms shall be installed in the following locations:

  1. In each sleeping room or sleeping loft.
  2. Outside each separate sleeping area in the immediate vicinity of the bedrooms.
  3. On each additional story of the dwelling, including basements and habitable attics and not including crawl spaces and uninhabitable attics. In dwellings or dwelling units with split levels and without an intervening door between the adjacent levels, a smoke alarm installed on the upper level shall suffice for the adjacent lower level provided that the lower level is less than one full story below the upper level.
  4. Smoke alarms shall be installed not less than 3 feet (914 mm) horizontally from the door or opening of a bathroom that contains a bathtub or shower unless this would prevent placement of a smoke alarm required by this section.
  5. In napping areas in a family home child care.
Smoke alarms shall not be installed in the following locations unless this would prevent placement of a smoke alarm in a location required by Section R314.3.
  1. Ionization smoke alarms shall not be installed less than 20 feet (6096 mm) horizontally from a permanently installed cooking appliance.
  2. Ionization smoke alarms with an alarm-silencing switch shall not be installed less than 10 feet (3048 mm) horizontally from a permanently installed cooking appliance.
  3. Photoelectric smoke alarms shall not be installed less than 6 feet (1828 mm) horizontally from a permanently installed cooking appliance.

Where more than one smoke alarm is required to be installed within an individual dwelling unit in accordance with Section R314.3, the alarm devices shall be interconnected in such a manner that the actuation of one alarm will activate all of the alarms in the individual dwelling unit. Where an accessory dwelling unit is created within an existing dwelling unit all required smoke alarms, in the accessory dwelling unit and the primary dwelling unit, shall be interconnected in such a manner that the actuation of one alarm will activate all alarms in both the primary dwelling unit and the accessory dwelling unit. Physical interconnection of smoke alarms shall not be required where listed wireless alarms are installed and all alarms sound upon activation of one alarm.

Exception: Smoke alarms and alarms installed to satisfy Section R314.4.1 shall not be required to be interconnected to existing smoke alarms where such existing smoke alarms are not interconnected or where such new smoke alarm or alarm is not capable of being interconnected to the existing smoke alarms.

Heat detectors and heat alarms shall be connected to an alarm or a smoke alarm that is installed in the dwelling. Alarms and smoke alarms that are installed for this purpose shall be located in a hallway, room, or other location that will provide occupant notification.
Combination smoke and carbon monoxide alarms shall be permitted to be used in lieu of smoke alarms.

Smoke alarms, heat alarms, and heat detectors shall receive their primary power from the building wiring where such wiring is served from a commercial source and, where primary power is interrupted, shall receive power from a battery. Wiring shall be permanent and without a disconnecting switch other than those required for overcurrent protection.

Exceptions:

  1. Smoke alarms shall be permitted to be battery operated where installed in buildings without commercial power.
  2. Smoke alarms installed in accordance with Section R314.2.2 shall be permitted to be battery powered.
Fire alarm systems shall be permitted to be used in lieu of smoke alarms and shall comply with Sections R314.7.1 through R314.7.4.
Fire alarm systems shall comply with the provisions of this code and the household fire warning equipment provisions of NFPA 72. Smoke detectors shall be listed in accordance with UL 268.
Smoke detectors shall be installed in the locations specified in Section R314.3.
Where a household fire alarm system is installed, it shall become a permanent fixture of the occupancy, owned by the homeowner.
Combination smoke and carbon monoxide detectors shall be permitted to be installed in fire alarm systems in lieu of smoke detectors, provided that they are listed in accordance with UL 268 and UL 2075.