ADOPTS WITH AMENDMENTS:

International Residential Code 2018 (IRC 2018)

Part IV Energy Conservation

Part V Mechanical

Part VI Fuel Gas

Part VII Plumbing

Part VIII Electrical

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).

TABLE R301.2(1)

CLIMATIC AND GEOGRAPHIC DESIGN CRITERIA

GROUND SNOW LOADo WIND DESIGN SEISMIC DESIGN CATEGORYt SUBJECT TO DAMAGE FROM WINTER DESIGN TEMPe ICE BARRIER UNDERLAYMENT REQUIREDh FLOOD HAZARDSg AIR FREEZING INDEXi MEAN ANNUAL TEMPj
Speedd (mph) Topographic effectsk Special wind regionl Windborne 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, f, g

Zone Effective Wind Areas (feet2) Ultimate Design Wind Speed,Vult
90 95 100 105 110 115 120 130 140 150 160 170 180
Pos Neg Pos Neg Pos Neg Pos Neg Pos Neg Pos Neg Pos Neg Pos Neg Pos Neg Pos Neg Pos Neg Pos Neg Pos Neg
Flat and Gable Roof 0 to 7 degrees 1 10 3.6 -13.9 4.0 -15.5 4.4 -17.2 4.8 -19.0 5.3 -20.8 5.8 -22.7 6.3 -24.8 7.4 -29.1 8.6 -33.7 9.9 -38.7 11.2 -44.0 12.7 -49.7 14.2 -55.7
1 20 3.3 -13.0 3.7 -14.5 4.1 -16.0 4.5 -17.7 5.0 -19.4 5.4 -21.2 5.9 -23.1 7.0 -27.1 8.1 -31.4 9.3 -36.1 10.5 -41.1 11.9 -46.4 13.3 -52.0
1 50 3.0 -11.8 3.4 -13.1 3.8 -14.5 4.1 -16.0 4.5 -17.6 5.0 -19.2 5.4 -20.9 6.3 -24.5 7.4 -28.4 8.4 -32.6 9.6 -37.1 10.8 -41.9 12.2 -47.0
1 100 2.8 -10.8 3.1 -12.1 3.5 -13.4 3.8 -14.7 4.2 -16.2 4.6 -17.7 5.0 -19.2 5.9 -22.6 6.8 -26.2 7.8 -30.0 8.9 -34.2 10.1 -38.6 11.3 -43.3
2 10 3.6 -18.4 4.0 -20.5 4.4 -22.7 4.8 -25.0 5.3 -27.4 5.8 -30.0 6.3 -32.7 7.4 -38.3 8.6 -44.5 9.9 -51.0 11.2 -28.1 12.7 -65.6 14.2 -73.5
2 20 3.3 -17.2 3.7 -19.2 4.1 -21.2 4.5 -23.4 5.0 -25.7 5.4 -28.1 5.9 -30.6 7.0 -35.9 8.1 -41.6 9.3 -47.8 10.5 -54.3 11.9 -61.4 13.3 -68.8
2 50 3.0 -15.6 3.4 -17.4 3.8 -19.3 4.1 -21.3 4.5 -23.3 5.0 -25.5 5.4 -27.8 6.3 -32.6 7.4 -37.8 8.4 -43.4 9.6 -49.4 10.8 -55.8 12.2 -62.5
2 100 2.8 -14.4 3.1 -16.1 3.5 -17.8 3.8 -19.7 4.2 -21.6 4.6 -23.6 5.0 -25.7 5.9 -30.1 6.8 -35.0 7.8 -40.1 8.9 -45.7 10.0 -51.5 11.3 -57.8
3 10 3.6 -25.0 4.0 -27.9 4.4 -30.9 4.8 -34.1 5.3 -37.4 5.8 -40.9 6.3 -44.5 7.4 -52.2 8.6 -60.6 9.9 -69.6 11.2 -79.1 12.7 -89.4 14.2 -100.2
3 20 3.3 -22.6 3.7 -25.2 4.1 -28.0 4.5 -30.8 5.0 -33.8 5.4 -37.0 5.9 -40.3 7.0 -47.2 8.1 -54.8 9.3 -62.9 10.5 -71.6 11.9 -80.8 13.3 -90.6
3 50 3.0 -19.4 3.4 -21.7 3.8 -24.0 4.1 -26.5 4.5 -29.0 5.0 -31.7 5.4 -34.6 6.3 -40.6 7.4 -47.0 8.4 -54.0 9.6 -61.4 10.8 -69.4 12.2 -77.8
3 100 2.8 -17.4 3.1 -19.0 3.5 -21.0 3.8 -23.2 4.2 -25.5 4.6 -27.8 5.0 -30.3 5.9 -35.6 6.8 -41.2 7.8 -47.3 8.9 -53.9 10.0 -60.8 11.3 -68.2
Gable Roof >7 to 20 degrees 1,2e 10 5.4 -16.2 6.0 -18.0 6.7 -19.9 7.4 -22.0 8.1 -24.1 8.8 -26.4 9.6 -28.7 11.3 -33.7 13.1 -39.1 15.0 -44.9 17.1 -51.0 19.3 -57.6 21.6 -64.6
1,2e 20 4.9 -16.2 5.4 -18.0 6.0 -19.9 6.6 -22.0 7.2 -24.1 7.9 -26.4 8.6 -28.7 10.1 -33.7 11.7 -39.1 13.5 -44.9 15.3 -51.0 17.3 -57.6 19.4 -64.6
1,2e 50 4.1 -9.9 4.6 -11.0 5.1 -12.2 5.6 -13.4 6.1 -14.7 6.7 -16.1 7.3 -17.5 8.6 -20.6 10.0 -23.8 11.4 -27.4 13.0 -31.1 14.7 -35.2 16.4 -39.4
1,2e 100 3.6 -5.0 4.0 -5.6 4.4 -6.2 4.8 -6.9 5.3 -7.5 5.8 -8.2 6.3 -9.0 7.4 -10.5 8.6 -12.2 9.9 -14.0 11.2 -15.9 12.7 -18.0 14.2 -20.2
2n, 2r, 3e 10 5.4 -23.6 6.0 -26.3 6.7 -29.1 7.4 -32.1 8.1 -35.2 8.8 -38.5 9.6 -41.9 11.3 -49.2 13.1 -57.0 15.0 -65.0 17.1 -74.5 19.3 -84.1 21.6 -94.2
2n, 2r, 3e 20 4.9 -20.3 5.4 -22.7 6.0 -25.1 6.6 -27.7 7.2 -30.4 7.9 -33.2 8.6 -36.2 10.1 -42.4 11.7 -49.2 13.5 -56.5 15.3 -64.3 17.3 -72.6 19.4 -81.4
2n, 2r, 3e 50 4.1 -16.0 4.6 -17.9 5.4 -19.8 5.6 -21.8 6.1 -24.0 6.7 -26.2 7.3 -28.5 8.6 -33.5 10.0 -38.8 11.4 -44.6 130 -50.7 14.7 -57.2 16.4 -64.2
2n, 2r, 3e 100 3.6 -12.8 4.0 -14.3 4.4 -15.8 4.8 -17.4 5.3 -19.1 5.8 -20.9 6.3 -22.8 7.4 -26.7 8.6 -31.0 9.9 -35.6 11.2 -40.5 12.7 -45.7 14.2 -51.3
3r 10 5.4 -28.0 6.0 -30.2 6.7 -34.6 7.4 -38.1 8.1 -41.8 8.8 -45.7 9.6 -49.8 11.3 -58.4 13.1 -67.8 15.0 -77.8 17.1 -88.5 19.3 -99.9 21.6 -112.0
3r 20 4.9 -24.0 5.4 -26.7 6.0 -29.6 6.6 -32.7 7.2 -35.9 7.9 -39.2 8.6 -42.7 10.1 -50.1 11.7 -58.1 13.5 -66.7 15.3 -75.9 17.3 -85.6 19.4 -96.1
3r 50 4.1 -18.7 4.6 -20.8 5.1 -23.1 5.6 -25.4 6.1 -27.9 6.7 -30.5 7.3 -33.2 8.6 -39.0 10.0 -45.2 11.4 -51.9 13.0 -59.0 14.7 -66.6 16.4 -74.7
3r 100 3.6 -14.7 4.0 -16.3 4.4 -18.1 4.8 -20.0 5.3 -21.9 5.8 -24.0 6.3 -26.1 7.4 -30.6 8.6 -35.5 9.9 -40.8 11.2 -46.4 12.7 -52.3 14.2 -58.7
Gable Roof >20 to 27 degrees 1, 2e 10 6.5 -12.4 7.3 -13.9 8.0 -15.4 8.9 -16.9 9.7 -18.6 10.6 -20.3 11.6 -22.1 13.6 -26.0 15.8 -30.1 18.1 -34.6 20.6 -39.3 23.3 -44.4 26.1 -49.9
1, 2e 20 5.6 -12.4 6.3 -13.9 7.0 -15.4 7.7 -16.9 8.4 -18.6 9.2 -20.3 10.0 -22.1 11.7 -26.0 13.6 -30.1 15.6 -34.6 17.8 -39.3 20.1 -44.4 22.5 -49.8
1, 2e 50 4.4 -10.6 5.0 -11.8 5.5 -13.1 6.1 -14.4 6.6 -15.8 7.3 -17.3 7.9 -18.8 9.3 -22.1 10.8 -25.6 12.3 -29.4 14.0 -33.5 15.9 -37.8 17.8 -42.4
1, 2e 100 3.6 -9.1 4.0 -10.2 4.4 -11.3 4.8 -12.4 5.3 -13.6 5.8 -14.9 6.3 -16.2 7.4 -19.0 8.6 -22.1 9.9 -25.3 11.2 -28.8 12.7 -32.5 14.2 -36.5
2n, 2r, 3e 10 6.5 -19.9 7.3 -22.1 8.0 -24.5 8.9 -27.0 9.7 -29.7 10.6 -32.4 11.6 -35.3 13.6 -41.4 15.8 -48.0 18.1 -55.2 20.6 -62.8 23.3 -70.8 26.1 -79.4
2n, 2r, 3e 20 5.6 -17.4 6.3 -19.4 7.0 -21.5 7.7 -23.7 8.4 -26.0 9.2 -28.4 10.0 -31.0 11.7 -36.3 13.6 -42.1 15.6 -48.4 17.8 -55.0 20.1 -62.1 22.5 -69.6
2n, 2r, 3e 50 4.4 -14.2 5.0 -15.8 5.5 -17.5 6.1 -19.3 6.6 -21.1 7.3 -23.1 7.9 -25.2 9.3 -29.5 10.8 -34.2 12.3 -39.3 14.0 -44.7 15.9 -50.5 17.8 -56.6
2n, 2r, 3e 100 3.6 -11.7 4.0 -13.0 4.4 -14.5 4.8 -15.9 5.3 -17.5 5.8 -19.1 6.3 -20.8 7.4 -24.4 8.6 -28.3 9.9 -32.5 11.2 -37.0 12.7 -41.8 14.2 -46.8
3r 10 6.5 -23.6 7.3 -26.3 8.0 -29.1 8.9 -32.1 9.7 -35.2 10.6 -38.5 11.6 -41.9 13.6 -49.2 15.8 -57.0 18.1 -65.4 20.6 -74.5 23.3 -84.1 26.1 -94.2
3r 20 5.6 -19.9 6.3 -22.1 7.0 -24.5 7.7 -27.0 8.4 -29.7 9.2 -32.4 10.0 -35.3 11.7 -41.4 13.6 -48.0 15.6 -55.2 17.8 -62.8 20.1 -70.8 22.5 -79.4
3r 50 4.4 -14.7 5.0 -16.3 5.5 -18.1 6.1 -20.0 6.6 -21.9 7.3 -24.0 7.9 -26.1 9.3 -30.6 10.8 -35.5 12.3 -40.8 14.0 -46.4 15.9 -52.3 17.8 -58.7
3r 100 3.6 -14.7 4.0 -16.3 4.4 -18.1 4.8 -20.0 5.3 -21.9 5.8 -24.0 6.3 -26.1 7.4 -30.6 8.6 -35.5 9.9 -40.8 11.2 -46.4 12.7 -52.3 14.2 -58.7
Gable Roof >27 to 45 degrees 1, 2e, 2r 10 8.0 -14.7 8.9 -16.3 9.9 -18.1 10.9 -20.0 12.0 -21.9 13.1 -24.0 14.2 -26.1 16.7 -30.6 19.4 -35.5 22.2 -40.8 25.3 -46.4 28.5 -52.3 32.0 -58.7
1, 2e, 2r 20 7.1 -12.7 7.9 -13.9 8.8 -15.4 9.7 -16.9 10.6 -18.6 11.6 -20.3 12.6 -22.1 14.8 -26.0 17.2 -30.1 19.8 -34.6 22.5 -39.3 25.4 -44.4 28.5 -49.8
1, 2e, r 50 5.9 -9.5 6.6 -10.6 7.3 -11.7 8.1 -12.9 8.9 -14.2 9.7 -15.5 10.5 -16.9 12.4 -19.8 14.3 -22.9 16.5 -26.3 18.7 -30.0 21.1 -33.8 23.7 -37.9
1, 2e, 2r 100 5.0 -7.3 5.6 -8.1 6.2 -9.0 6.9 -9.9 7.5 -10.8 8.2 -11.9 9.0 -12.9 10.5 -15.1 12.2 -17.6 14.0 -20.2 15.9 -22.9 18.0 -25.9 20.2 -29.0
2n, 3r 10 8.0 -16.2 8.9 -18.0 9.9 -19.9 10.9 -22.0 12.0 -24.1 13.1 -26.4 14.2 -28.7 16.7 -33.7 19.4 -39.1 22.2 -44.9 25.3 -51.0 28.5 -57.6 32.0 -64.6
2n, 3r 20 7.1 -14.4 7.9 -16.1 8.8 -17.8 9.7 -19.7 10.6 -21.6 11.6 -23.6 12.6 -25.7 14.8 -30.1 17.2 -34.9 19.8 -40.1 22.5 -45.6 25.4 -51.5 28.5 -57.8
2n, 3r 50 5.9 -12.2 6.6 -13.5 7.3 -15.0 8.1 -16.5 8.9 -18.2 9.7 -19.9 10.5 -21.6 12.4 -25.4 14.3 -29.4 16.5 -33.8 18.7 -38.4 21.1 -43.4 23.7 -48.6
2n, 3r 100 5.0 -10.4 5.6 -11.6 6.2 -12.9 6.9 -14.2 7.5 -15.6 8.2 -17.1 9.0 -18.6 10.5 -21.8 12.2 -25.3 14.0 -29.0 15.9 -33.0 18.0 -37.3 20.0 -41.8
3e 10 8.0 -19.9 8.9 -22.1 9.9 -24.5 10.9 -27.0 12.0 -29.7 13.1 -32.4 14.2 -35.3 16.7 -41.4 19.4 -48.0 22.2 -55.2 25.3 -62.8 28.8 -70.8 32.0 -79.4
3e 20 7.1 -17.6 7.9 -19.6 8.8 -21.8 9.7 -24.0 10.6 -26.3 11.6 -28.8 12.6 -31.3 14.8 -36.8 17.2 -42.7 19.8 -49.0 22.5 -55.7 25.4 -62.9 28.5 -70.5
3e 50 5.9 -14.7 6.6 -16.3 7.3 -18.1 8.1 -20.0 8.9 -21.9 9.7 -24.0 10.5 -26.1 12.4 -30.6 14.3 -35.5 16.5 -40.8 18.7 -46.4 21.1 -52.3 23.7 -58.7
3e 100 5.0 -12.4 5.5 -13.9 6.2 -15.4 6.9 -16.9 7.5 -18.6 8.2 -20.3 9.0 -22.1 10.5 -26.0 12.2 -30.1 14.0 -34.6 15.9 -39.3 18.0 -44.4 20.2 -49.8
Hipped Roof >7 to 20 degrees 1 10 6.5 -14.7 7.3 -16.3 8.0 -18.1 8.9 -20.0 9.7 -21.9 10.6 -24.0 11.6 -26.1 13.6 -30.6 15.8 -35.5 18.1 -40.8 20.6 -46.4 23.3 -52.3 26.1 -58.7
1 20 5.6 -14.7 6.3 -16.3 7.0 -18.1 7.7 -20.0 8.4 -21.9 9.2 -24.0 10.0 -26.1 11.7 -30.6 13.6 -35.5 15.6 -40.8 17.8 -46.4 20.1 -52.3 22.5 -58.7
1 50 4.4 -11.3 5.0 -12.6 5.5 -14.0 6.1 -15.4 6.6 -16.9 7.3 -18.5 7.9 -20.2 9.3 -23.7 10.8 -27.4 12.3 -31.5 14.0 -35.8 15.9 -40.4 17.8 -45.3
1 100 3.6 -8.7 4.0 -9.7 4.4 -10.8 4.8 -11.9 5.3 -13.1 5.8 -14.3 6.3 -15.5 7.4 -18.2 8.6 -21.2 9.9 -24.3 11.2 -27.6 12.7 -31.2 14.2 -35.0
2r 10 6.5 -19.1 7.3 -21.3 8.0 -23.6 8.9 -26.0 9.7 -28.6 10.6 -31.2 11.6 -34.0 13.6 -39.9 15.8 -46.3 18.1 -53.1 20.6 -60.4 23.3 -68.2 26.1 -76.5
2r 20 5.6 -17.2 6.3 -19.2 7.0 -21.3 7.7 -23.4 8.4 -25.7 9.2 -28.1 10.0 -30.6 11.7 -35.9 13.6 -41.7 15.6 -47.9 17.8 -54.4 20.1 -61.5 22.1 -68.9
2r 50 4.4 -14.7 5.0 -16.4 5.5 -18.2 6.1 -20.0 6.6 -22.0 7.3 -24.0 7.9 -26.1 9.3 -30.7 10.8 -35.6 12.3 -40.9 14.0 -46.5 15.9 -52.5 17.8 -58.8
2r 100 3.6 -12.8 4.0 -14.3 4.4 -15.8 4.8 -17.4 5.3 -19.1 5.8 -20.9 6.3 -22.8 7.4 -26.7 8.6 -31.0 9.9 -35.6 11.2 -40.5 12.7 -45.7 14.2 -51.3
2e, 3 10 6.5 -20.6 7.3 -22.9 8.0 -25.4 8.9 -28.0 9.7 -30.8 10.6 -33.6 11.6 -36.6 13.6 -43.0 15.8 -49.8 18.1 -57.2 20.6 -65.1 23.3 -73.5 26.1 -82.4
2e, 3 20 5.6 -18.5 6.3 -20.6 7.0 -22.9 7.7 -25.2 8.4 -27.7 9.2 -30.3 10.0 -32.9 11.7 -38.7 13.6 -44.8 15.6 -51.5 17.8 -58.6 20.1 -66.1 22.5 -74.1
2e, 3 50 4.4 -15.8 5.0 -17.6 5.5 -19.5 6.1 -21.5 6.6 -23.6 7.3 -25.8 7.9 -28.0 9.3 -32.7 10.8 -38.2 12.3 -43.8 14.0 -49.9 15.9 -56.3 17.8 -63.1
2e, 3 100 3.6 -13.7 4.0 -15.3 4.4 -16.9 4.8 -18.7 5.3 -20.5 5.8 -22.4 6.3 -24.4 7.4 -28.6 8.6 -33.2 9.9 -38.1 11.2 -43.3 12.7 -48.9 14.2 -54.8
Hipped Roof >20 to 27 degrees 1 10 6.5 -11.7 7.3 -13.0 8.0 -14.5 8.9 -15.9 9.7 -17.5 10.6 -19.1 11.6 -20.8 13.6 -24.4 15.8 -28.3 18.1 -32.5 20.6 -37.0 23.3 -41.8 26.1 -46.8
1 20 5.6 -10.4 6.3 -11.6 7.0 -12.8 7.7 -14.1 8.4 -15.5 9.2 -16.9 10.0 -18.4 11.7 -21.6 13.6 -25.1 15.6 -28.8 17.8 -32.8 20.1 -37.0 22.5 -41.5
1 50 4.4 -8.6 5.0 -9.6 5.5 -10.6 6.1 -11.7 6.6 -12.8 7.3 -14.0 7.9 -15.3 9.3 -17.9 10.8 -20.8 12.3 -23.9 14.0 -27.2 15.9 -30.7 17.8 -34.4
1 100 3.6 -7.3 4.0 -8.1 4.4 -9.0 4.8 -9.9 5.3 -10.8 5.8 -11.9 6.3 -12.9 7.4 -15.1 8.6 -17.6 9.9 -20.2 11.2 -22.9 12.7 -25.9 14.2 -29.0
2e, 2r, 3 10 6.5 -16.2 7.3 -18.0 8.0 -19.9 8.9 -22.0 9.7 -24.1 10.2 -26.4 11.6 -28.7 13.6 -33.7 15.8 -39.1 18.1 -44.9 20.6 -51.0 23.3 -57.6 26.1 -64.6
2e, 2r, 3 20 5.6 -14.4 6.3 -16.1 7.0 -17.8 7.7 -19.7 8.4 -21.6 8.9 -23.6 10.0 -25.7 11.7 -30.1 13.6 -34.9 15.6 -40.1 17.8 -45.6 20.1 -51.5 22.5 -57.8
2e, 2r, 3 50 4.4 -12.2 5.0 -13.5 5.5 -15.0 6.1 -16.5 6.6 -18.2 7.3 -19.9 7.9 -21.6 9.3 -25.4 10.8 -29.4 12.3 -33.8 14.0 -38.4 15.9 -43.4 17.8 -48.6
2e, 2r, 3 100 3.6 -10.4 4.0 -11.6 4.4 -12.9 4.8 -14.2 5.3 -15.6 5.8 -17.1 6.3 -18.6 7.4 -21.8 8.6 -25.3 9.9 -29.0 11.2 -33.0 12.7 -37.3 14.2 -41.8
Hipped Roof >27 to 45 degrees 1 10 6.2 -12.4 6.9 -13.9 7.7 -15.4 8.5 -16.9 9.3 -18.6 10.2 -20.3 11.1 -22.1 13.0 -26.0 15.1 -30.1 17.3 -34.6 19.7 -39.3 22.2 -44.4 24.9 -49.8
1 20 5.4 -11.0 6.0 -12.3 6.7 -13.6 7.4 -15.0 8.1 -16.5 8.9 -18.0 9.6 -19.6 11.3 -23.0 13.1 -26.7 15.1 -30.7 17.1 -34.9 19.4 -39.4 21.7 -44.2
1 50 4.4 -9.2 4.9 -10.2 5.4 -11.3 5.9 -12.5 6.5 -13.7 7.1 -15.0 7.7 -16.3 9.1 -19.2 10.5 -22.2 12.1 -25.5 13.8 -29.0 15.5 -32.8 17.4 -36.7
1 100 3.6 -7.8 4.0 -8.7 4.4 -9.6 4.8 -10.6 5.3 -11.6 5.8 -12.7 6.3 -13.8 7.4 -16.2 8.6 -18.8 9.9 -21.6 11.2 -24.6 12.7 -27.8 14.2 -31.1
2e 10 6.2 -14.8 6.9 -16.5 7.7 -18.3 8.5 -20.2 9.3 -22.1 10.2 -24.2 11.1 -26.3 13.0 -30.9 15.1 -35.9 17.3 -41.2 19.7 -46.8 22.2 -52.9 24.9 -59.3
2e 20 5.4 -11.7 6.0 -13.0 6.7 -14.5 7.4 -15.9 8.1 -17.5 8.9 -19.1 9.6 -20.8 11.3 -24.4 13.1 -28.3 15.1 -32.5 17.1 -37.0 19.4 -41.8 21.7 -46.8
2e 50 4.4 -7.3 4.9 -8.1 5.4 -9.0 5.9 -9.9 6.5 -10.8 7.1 -11.9 7.7 -12.9 9.1 -15.1 10.5 -17.6 12.1 -20.2 13.8 -22.9 15.5 -25.9 17.4 -29.0
2e 100 3.6 -7.3 4.0 -8.1 4.4 -9.0 4.8 -9.9 5.3 -10.8 5.8 -11.9 6.3 -12.9 7.4 -15.1 8.6 -17.6 9.9 -20.2 11.2 -22.9 12.7 -25.9 14.2 -29.0
2r 10 6.2 -18.7 6.9 -20.9 7.7 -23.1 8.5 -25.5 9.3 -28.0 10.2 -30.6 11.1 -33.3 13.0 -39.1 15.1 -45.4 17.3 -52.1 19.7 -59.2 22.2 -66.9 24.9 -75.0
2r 20 5.4 -15.7 6.0 -17.5 6.7 -19.4 7.4 -21.4 8.1 -23.5 8.9 -25.7 9.6 -28.0 11.3 -32.8 13.1 -38.1 15.1 -43.7 17.1 -49.8 19.4 -56.2 21.7 -63.0
2r 50 4.4 -11.7 4.9 -13.1 5.4 -14.5 5.9 -16.0 6.5 -17.5 7.1 -19.2 7.7 -20.9 9.1 -24.5 10.5 -28.4 12.1 -32.6 13.8 -37.1 15.5 -41.9 17.4 -47.0
2r 100 3.6 -8.7 4.0 -9.7 4.4 -10.8 4.8 -11.9 5.3 -13.1 5.8 -14.3 6.3 -15.5 7.4 -18.2 8.6 -21.2 9.9 -24.3 11.2 -27.6 12.7 -31.2 14.2 -35.0
3 10 6.2 -20.0 6.9 -22.3 7.7 -24.7 8.5 -27.2 9.3 -29.9 10.2 -32.7 11.1 -35.6 13.0 -41.7 15.1 -48.4 17.3 -55.6 19.7 -63.2 22.2 -71.4 24.9 -80.0
3 20 5.4 -15.0 6.0 -16.8 6.7 -18.6 7.4 -20.5 8.1 -22.5 8.9 -24.6 9.6 -26.7 11.3 -31.4 13.1 -36.4 15.1 -41.8 17.1 -47.5 19.4 -53.8 21.7 -60.2
3 50 4.4 -8.7 4.9 -9.7 5.4 -10.8 5.9 -11.9 6.5 -13.1 7.1 -14.3 7.7 -15.5 9.1 -18.2 10.5 -21.2 12.1 -24.3 13.8 -27.6 15.5 -31.2 17.4 -35.0
3 100 3.6 -8.7 4.0 -9.7 4.4 -10.8 4.8 -11.9 5.3 -13.1 5.8 -14.3 6.3 -15.5 7.4 -18.2 8.6 -21.2 9.9 -24.3 11.2 -27.6 12.7 -31.2 14.2 -35.0
Wall 4 10 8.7 -9.5 9.7 -10.6 10.8 -11.7 11.9 -12.9 13.1 -14.2 14.3 -15.5 15.5 -16.9 18.2 -19.8 21.2 -22.9 24.3 -26.3 27.6 -30.0 31.2 -33.8 35.0 -37.9
4 20 8.3 -9.1 9.3 -10.1 10.3 -11.2 11.4 -12.4 12.5 -13.6 13.6 -14.8 14.8 -16.2 17.4 -19.0 20.2 -22.0 23.2 -25.3 26.4 -28.7 29.8 -32.4 33.4 -36.4
4 50 7.8 -8.6 8.7 -9.5 9.7 -10.6 10.7 -11.7 11.7 -12.8 12.8 -14.0 13.9 -15.2 16.3 -17.9 18.9 -20.7 21.7 -23.8 24.7 -27.1 27.9 -30.6 31.3 -34.3
4 100 7.4 -8.2 8.3 -9.1 9.2 -10.1 10.1 -11.1 11.1 -12.2 12.1 -13.3 13.2 -14.5 15.5 -17.1 18.0 -19.8 20.6 -22.7 23.5 -25.8 26.5 -29.2 29.7 -32.7
4 500 6.5 -7.3 7.3 -8.1 8.0 -9.0 8.9 -9.9 9.7 -10.8 10.6 -11.9 11.6 -12.9 13.5 -15.1 15.8 -17.6 18.1 -20.2 20.6 -22.9 23.3 -25.9 26.1 -29.0
5 10 8.7 -11.8 9.7 -13.0 10.8 -14.5 11.9 -15.9 13.1 -17.5 14.3 -19.1 15.5 -20.8 18.2 -24.4 21.2 -28.3 24.3 -32.5 27.6 -37.0 31.2 -41.8 35.0 -46.8
5 20 8.3 -10.9 9.3 -12.2 10.3 -13.5 11.4 -14.9 12.5 -16.3 13.6 -17.8 14.8 -19.4 17.4 -22.8 20.2 -26.4 23.2 -30.3 26.4 -34.5 29.8 -39.0 33.4 -43.7
5 50 7.8 -9.9 8.7 -11.0 9.7 -12.2 10.7 -13.4 11.7 -14.7 12.8 -16.1 13.9 -17.5 16.3 -20.6 18.9 -23.9 21.7 -27.4 24.7 -31.2 27.9 -35.2 31.3 -39.5
5 100 7.4 -9.1 8.3 -10.1 9.2 -11.2 10.1 -12.4 11.1 -13.6 12.1 -14.8 13.2 -16.1 15.5 -19.0 18.0 -22.0 20.6 -25.2 23.5 -28.7 26.5 -32.4 29.7 -36.3
5 500 6.5 -7.3 7.3 -8.1 8.0 -9.0 8.9 -9.9 9.7 -10.8 10.6 -11.9 11.6 -12.9 13.6 -15.1 15.8 -17.6 18.1 -20.2 20.6 -22.9 23.3 -25.9 26.1 -29.0

For SI:1 foot = 304.8mm, 1 square foot = 0.0929m2, 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 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 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.
  6. Positive and negative design wind pressures shall be not less than 10 psf.
  7. Where the ratio of the building mean roof height to the building length or width is less than 0.8, uplift loads shall be permitted to be calculated in accordance with ASCE 7.

TABLE R301.2(3)

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

MEAN ROOF HEIGHT EXPOSURE
B C D
15 0.82 1.21 1.47
20 0.89 1.29 1.55
25 0.94 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

Note: Crosshatching on map indicates special wind region.

FIGURE R301.2(5)A

 ULTIMATE DESIGN WIND SPEEDS

Notes:

  1. Values are nominal design 3-second gust wind speeds in miles per hour (m/s) at 33 ft (10m) above ground for Exposure C category.
  2. Linear interpolation between contours is permitted.
  3. Islands and coastal areas outside the last contour shall use the last wind speed contour of the coastal area.
  4. Mountainous terrain, gorges, ocean promontories, and special wind regions shall be examined for unusual wind conditions.
  5. Wind speeds correspond to approximately a 7% probability of exceedance in 50 years (Annual Exceedance Probability = 0.00143, MRI = 700 Years).

FIGURE R301.2(5)B

 REGIONS WHERE WIND DESIGN IS REQUIRED

For SI: 1 foot = 304.8 mm, 1 pound per square foot = 0.0479 kPa, 1 mile = 1.61 km.

  1. In CS areas, site-specific Case Studies are required to establish ground snow loads. Extreme local variations in ground snow loads in these areas preclude mapping at this scale.
  2. Numbers in parentheses represent the upper elevation limits in feet for the ground snow load values presented below. Site-specific case studies are required to establish ground snow loads at elevations not covered.

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. Where ultimate design wind speeds in Figure R301.2(5)A are less than the lowest wind speed indicated in the prescriptive provisions of this code, the lowest wind speed indicated in the prescriptive provisions of this code shall be used. Wind speeds for localities in special wind regions, near mountainous terrain, and near gorges shall be based on elevation. Areas at 4,000 feet (1219 m) in elevation or higher shall use the nominal design wind speed of 140 mph (62.6 m/s) and areas under 4,000 feet (1219 m) in elevation shall use nominal design wind speed of 110 mph (49.2 m/s). Gorge areas shall be based on the highest recorded speed per locality or in accordance with local jurisdiction requirements determined in accordance with Section 26.5.2 of ASCE 7.

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 or where the ultimate design wind speed, Vult in Figure R301.2(5)A equals or exceeds 140 mph (62.6 m/s) in a special wind region.

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 or where the ultimate design wind speed Vult in Figure R301.2(5)A equals or exceeds 140 mph (62.6 m/s) in a special wind region, 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 non-habitable 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: 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

CALCULATEDSDS 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:

    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.   Floors shall not cantilever past the exterior walls.

    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:

      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.   Not less than two 2 × 12 or three 2 × 10 for an opening not more than 6 feet (1829 mm) in width.

      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 40
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 infill components. These loads shall be determined independent of one another, and loads are assumed not to occur with any other live load.

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.
  6. Decks and open porches.
  7. Walls of dwellings and accessory structures located on lots in subdivisions or zoning districts where building setbacks established by local ordinance prohibit the walls of the structures on adjacent lots from being closer than 10 feet (3048 mm) to each other at any point along the exterior walls.

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 Fire-resistance rated 1 hour on the underside, or heavy timber, or fire-retardant-treated wooda, b < 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 gable vent openings are not installed.

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 gable vent openings are not installed.
Walls separating townhouse units shall be constructed in accordance with Section R302.2.1 or R302.2.2, and shall comply with Sections 302.2.3 through 302.2.5.
Each townhouse shall be separated 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 townhouses shall be assigned a fire-resistance rating in accordance with Item 1 or 2. The common wall shared by two townhouses shall be constructed without plumbing or mechanical equipment, ducts or vents, other than water-filled fire sprinkler piping, 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 Chapters 34 through 43. 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 in accordance with ASTM E119, UL 263 or Section 703.3 of the International Building Code.
The fire-resistance-rated wall or assembly separating townhouses 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.

Parapets constructed in accordance with Section R302.2.5 shall be constructed for townhouses as an extension of exterior walls or common walls 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.
  6. Townhouses protected by a fire sprinkler system complying with Section P2904, NFPA 13, NFPA 13R, or NFPA 13D.

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. 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. Dwelling unit separation wall assemblies that are constructed on a lot line shall be constructed as required in Section R302.2 for townhouses.

Exceptions:

  1. 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 13, NFPA 13R or Section P2904.
  2. 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.
  3. Fire-resistant-rated assemblies are not required to separate a dwelling unit and accessory dwelling unit where both units are located on the same lot and comply with Sections R314.7 and R315.5.
Where floor 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.

Exceptions:

  1. Where the penetrating items are steel, ferrous or copper pipes, tubes or conduits, the annular space shall be protected as follows:

    1.1  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).

    1.1.2.  The area of the opening through the wall does not exceed 144 square inches (92 900 mm2).

    1.2.  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.

  2. The annular space created by the penetration of water-filled fire sprinkler piping, provided that the annular space is filled using a material complying with Exception 1.2 above.
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.   By a horizontal distance of not less than 24 inches (610 mm) where the wall or partition is constructed with individual noncommunicating stud cavities.

    1.2.   By a horizontal distance of not less than the depth of the wall cavity where the wall cavity is filled with cellulose loosefill, rockwool or slag mineral wool insulation.

    1.3.   By solid fireblocking in accordance with Section R302.11.

    1.4.   By protecting both boxes with listed putty pads.

    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:

    2.1.   By the horizontal distance specified in the listing of the electrical boxes.

    2.2.   By solid fireblocking in accordance with Section R302.11.

    2.3.   By protecting both boxes with listed putty pads.

    2.4.   By other listed materials and methods.

  3. The annular space created by the penetration of a fire sprinkler or water-filled fire sprinkler piping, provided that the annular space 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) thick, solid or honeycomb-core steel doors not less than 13/8 inches (35 mm) thick, or 20-minute fire-rated doors.
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.