ADOPTS WITH AMENDMENTS:

International Residential Code 2015 (IRC 2015)

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.

Chapter 46 Coastal and Flood Plain Construction Standards

AMENDMENT
This section has been amended at the state or city level.

Section R4601 Purpose, Application and Scope

AMENDMENT
This section has been amended at the state or city level.

R4601.1 General

AMENDMENT
This section has been amended at the state or city level.
The requirements set forth in this section shall apply to all construction located within areas identified by governmental agency (state and federal) as coastal high hazard areas, ocean hazard areas, the regulatory flood plain areas, and all areas designated as 150 mph (67 m/s) wind zone. See Table R301.2(1).

Section R4602 Definitions

AMENDMENT
This section has been amended at the state or city level.
BASE FLOOD ELEVATION. The peak water elevation in relation to MSL expected to be reached during a design flood that is established by the North Carolina Building Code Council as a flood having a 1-percent chance of being equaled or exceeded in any given year.

COASTAL HIGH HAZARD AREA. An area subject to coastal flooding and high velocity waters including storm wave wash, as shown by Federal Emergency Management Agency Maps and subject to the approval of the Building Code Council.

FLOOD PLAIN. Land below base flood elevation, which of record has in the past been flooded by storm water-surface runoffs, or tidal influx, and as defined by the Corps of Engineers' maps, the Federal Emergency Management Agency maps or as approved by the Building Code Council.

LOWEST FLOOR. The lowest floor of the lowest enclosed area (including basement). An unfinished or flood-resistant enclosure, usable solely for parking of vehicles, building access or storage in an area other than a basement area is not considered a building's lowest floor provided that:
  1. The walls are substantially impermeable to the passage of water and the structural components have the capability of resisting hydrostatic and hydrodynamic loads and effects of buoyancy; or
  2. Construction shall be designed to automatically equalize hydrostatic flood forces on exterior walls by allowing the entry and exit of flood waters.
MSL. Mean Sea Level as defined by National Geodetic Vertical Datum.

OCEAN HAZARD AREA. An area, as identified by the North Carolina Coastal Resources Commission, and subject to approval by the Building Code Council, near the shoreline of the Atlantic Ocean that has been identified as subject to at least one of the following hazards: (A) historical or predicted future trends of long-term erosion, (B) erosion expected to occur during a coastal storm reaching the base flood elevation, or (C) shoreline fluctuations due to tidal inlets.

Section R4603 Piling Standards

AMENDMENT
This section has been amended at the state or city level.

R4603.1 General

AMENDMENT
This section has been amended at the state or city level.
All one- and two-family dwellings in areas identified as coastal high hazard areas or ocean hazard areas shall be constructed on a pile foundation of wood or concrete.

R4603.2 Concrete Piles

AMENDMENT
This section has been amended at the state or city level.
Concrete piles are permitted to be used if made and installed in accordance with the North Carolina Building Code, Chapter 18.

R4603.3 Size of Wood Piles

AMENDMENT
This section has been amended at the state or city level.
Round timber piles shall not be less than 8 inches (203 mm) in diameter at building level and have a minimum tip diameter of 6 inches (152 mm). Square timber piles shall not be less than 8 inches square (0.005 m2), nominal. Piles supporting uncovered stairs, uncovered walkways and uncovered decks shall be 6 inches × 6 inches (153 mm × 153 mm) minimum, or if round, have a minimum tip diameter of 6 inches (153 mm). Piles supporting uncovered stairs, uncovered walkways and uncovered decks less than 5 feet (1524 mm) above grade are permitted to be 4 inches × 4 inches (102 mm × 102 mm) minimum.

R4603.4 Required Depth of Piles

AMENDMENT
This section has been amended at the state or city level.
Pile tip shall extend to a depth of not less than 8 feet (2438 mm) below the natural grade or finished grade of the lot, whichever is lower. All pilings within the ocean hazard area shall have a tip penetration of at least 5 feet (1524 mm) below mean sea level or 16 feet (4877 mm) below average original grade, whichever is least. Structures within ocean hazard areas that are placed upon the site behind a line 60 times the annual erosion rate away from the most seaward line of stable natural vegetation are exempt from this additional tip penetration requirement.

R4603.5 Spacing of Wood Piles

AMENDMENT
This section has been amended at the state or city level.
The maximum center-to-center spacing of wood piles shall not be more than 8 feet (2438 mm) on center under load-bearing sills, beams, or girders. For dwellings having more than two stories above piles or where the piling spacing exceeds 8 feet (2438 mm) on center, the pile foundation shall be designed by a registered design professional. Pile spacing in the nonload-bearing direction are permitted to be 12 feet (305 mm).

R4603.6 Tying and Bracing of Wood Piles

AMENDMENT
This section has been amended at the state or city level.
Beams and girders shall fully bear on pilings and butt joints shall occur over pilings. Sills, beams or girders shall be attached to the piling using either bolts or screws at each piling connection in accordance with Table R4603.6 and Figure R4603.6(a). When the piling is notched so that the cross-section is reduced below 50 percent or the girder is top bearing, sills, beams or girders shall be attached using 3/16 × 4 × 18-inch (5 × 102 × 467 mm) hot dip galvanized straps, one each side, fastened top and bottom with either bolts or screws in accordance with Table R4603.6 and Figure R4603.6(b) and Figure R4603.6(c). Where butt joints occur over the piling and screws are used, there shall be two straps on each side of the piling, having a minimum size of 3/16 × 2 × 18 inches (5 × 51 × 467 mm), with four self-drilling screws as described below in each end. At corners, girders shall be connected to the pile with a minimum 3/16 × 4 × 18-inch (5 × 102 × 467 mm) hot dip galvanized strap bolted with two 5/8 inch (15.9 mm) galvanized through bolts on the exterior and a minimum L4 × 3/16 × 18 inches (102 × 5 × 467 mm) galvanized steel angle bolted with two 5/8 inch (15.9 mm) galvanized through bolts on the interior in accordance with Figure R4603.6(d).

     Bracing of pile foundations is required where the clear height from ground to sill, beam or girder exceeds 10 feet (3048 mm) or the dwelling is more than one story above piles. A line of X-bracing is defined as a row of piles with X-bracing provided in at least two bays. A line of X-bracing shall be provided at all exterior pile lines. Where the perimeter lines of Xbracing exceed 40 feet (12 192 mm), an additional line of Xbracing shall be provided near the center of the building. See Figure R4603.6(e). X-bracing shall be with 2 × 10s through bolted with two 3/4-inch (19.1 mm) bolts at each end. The code official is permitted to accept alternative bracing designs if they bear the seal of a registered design professional.

FIGURE R4603.6(a)
PILING NOTCHED LESS THAN 50%


FIGURE R4603.6(b)
TOP MOUNTED GIRDER


FIGURE R4603.6(c)
PILING NOTCHED MORE THAN 50%


FIGURE R4603.6(d)
CORNER PILE CONNECTION


FIGURE R4603.6(e)
ELEVATIONS (SHOWING POSSIBLE ARRANGEMENT OF X-BRACING IN LINE) (G AND H SIMILAR)
UpCodes note: The 2017-2021 Approved Amendments 201309-Residential Code has an update to this section. Existing figure R4603.6(e) has been renamed to Figure 4603.6(f) and a new Figure R4603.6(e) has been added.

FIGURE R4603.6(e)
CORNER PILE CONNECTION
FIGURE R4603.6(f)
ELEVATIONS
(SHOWING POSSIBLE ARRANGEMENT OF X-BRACING IN LINE) (G AND H SIMILAR)


The delayed effective date of this Rule is January 1, 2022.
The Statutory authority for Rule-making is G. S. 143-136; 143-138.


Table R4603.6
Minimum Fastening of Beams and Girders to Pilings
Amount Piling is
Notched
Beam/Girder Continuous Beam/Girder Butt Joint
Bolts Screws Bolts Screws
≤ 50% two 5/8" bolts2 four screws3 four 5/8" bolts2 eight screws3
> 50%1 two 5/8" bolts2 four screws3 four 5/8" bolts3 eight screws
  1. Where piling is notched over 50%, use strap as required in Section 4603.6. Install the specified number of bolts or screws in each end of the strap.
  2. Bolts shall be 5/8" diameter hot dipped galvanized through bolts with nuts and washers.
  3. Screws shall be 0.270" (6.9 mm) minimum in diameter, hot dipped galvanized to a minimum of A153, Class C, and having a minimum length of 4", and also shall be long enough to penetrate at least one inch through the remaining pile and into the girder.
The delayed effective date of this Rule is January 1, 2020.
The Statutory authority for Rule-making is G. S. 143-136; 143-138.
UpCodes note: Prior to January 1, 2020, this section was:

"If sills, beams or girders are attached to the piling, a minimum of two 5/8-inch (16 mm) galvanized steel bolts per beam member shall be through bolted at each piling connection in accordance with Figure R4503.6(a). When piling is notched so that the crosssection is reduced below 50 percent or is top bearing, sills, beams or girders shall be attached using 3/16 × 4 × 18-inch (5 × 102 × 467 mm) hot dip galvanized straps, one each side, bolted with two 5/8 inch (15.9 mm) galvanized through bolts in accordance with Figure R4603.6(b) and Figure R4603.6(c). At corners, girders shall be connected to the pile with a minimum 3/16 × 4 × 18-inch (5 × 102 × 467 mm) hot dip galvanized strap bolted with two 5/8 inch (15.9 mm) galvanized through bolts on the exterior and a minimum L4 × 3/16 × 18 inches (102 × 5 × 467 mm) galvanized steel angle bolted with two 5/8 inch (15.9 mm) galvanized through bolts on the interior in accordance with Figure R4603.6(d).

     Bracing of pile foundations is required where the clear height from ground to sill, beam or girder exceeds 10 feet (3048 mm) or the dwelling is more than one story above piles. A line of X-bracing is defined as a row of piles with X-bracing provided in at least two bays. A line of X-bracing shall be provided at all exterior pile lines. Where the perimeter lines of Xbracing exceed 40 feet (12 192 mm), an additional line of Xbracing shall be provided near the center of the building. See Figure R4603.6(e). X-bracing shall be with 2 × 10s through bolted with two 3/4-inch (19.1 mm) bolts at each end. The code official is permitted to accept alternative bracing designs if they bear the seal of a registered design professional."

R4603.6.1 Tying at Corners

AMENDMENT
This section has been amended at the state or city level.
At corners, girders shall be connected to the pile with a minimum 3/16 × 4 × 18-inch (5 × 102 × 467 mm) hot dip galvanized strap bolted with two 5/8 inch (15.9 mm) galvanized through bolts on the exterior and a minimum L4 x 3/16 x 1'-6" (102 × 5 × 467 mm) galvanized steel angle bolted with two 5/8 inch (15.9 mm) galvanized through bolts on the interior in accordance with Figure R4603.6(d).

The delayed effective date of this Rule is January 1, 2020.
The Statutory authority for Rule-making is G. S. 143-136; 143-138.
UpCodes note:The 2017-2021 Approved Amendments 201309-Residential Code has an update to this section:

At corners, girders shall be connected to the pile with a minimum 3/16 × 4 × 18-inch (5 × 102 × 467 mm) hot dip galvanized strap bolted with two 5/8 inch (15.9 mm) galvanized through bolts on the exterior and a minimum L4 x 4 x 3/16 x 1'-6" (102 × 5 × 467 mm) galvanized steel angle bolted with two 5/8 inch (15.9 mm) galvanized through bolts on the interior in accordance with Figure R4603.6(d), or with a minimum of (2) 3/16" x 4" x 18" (5x102x467 mm) hot dip galvanized straps installed on the outside of the girders with fasteners per Table R4603.6.1 and in accordance with Figure R4603.6 (e).
Table R4603.6.1
Minimum Fastening of Corner Beams and Girder to Pilings

Amount Piling is Notched

Associated 
Figure

Hardware

Fasteners

> 50%1

R4603.6(d)

one 3/16" x 4" x 18" 

six 5/8" bolts2

one L4 x 4 x 3/16 x 18"

R4603.6 (e) 

two 3/16" x 4" x 18"

eight 0.27"x4" each strap3

  1. Where piling is notched over 50%, use strap as required in Section 4603.6. Install the specified number of bolts or screws in each end of the strap.
  2. Bolts shall be 5/8" diameter hot dipped galvanized through bolts with nuts and washers.
  3. Screws shall be 0.270" (6.9 mm) minimum in diameter, hot dipped galvanized to a minimum of A153, Class C, and have a minimum length of 4" or shall be long enough to penetrate through the girder and a minimum of one inch into the remaining pile, whichever is greater.
The delayed effective date of this Rule is January 1, 2022.
The Statutory authority for Rule-making is G. S. 143-136; 143-138.

R4603.6.2 Bracing of Pilings

AMENDMENT
This section has been amended at the state or city level.
Bracing of pile foundations is required where the clear height from ground to sill, beam or girder exceeds 10 feet (3048 mm) or the dwelling is more than one story above piles. A line of X-bracing is defined as a row of piles with X-bracing provided in at least two bays. A line of X-bracing shall be provided at all exterior pile lines. Where the perimeter lines of X-bracing exceed 40 feet (12 192 mm), an additional line of X-bracing shall be provided near the center of the building. See Figure R4603.6(e). X-bracing shall be with 2 × 10s through bolted with two 3/4-inch (19.1 mm) bolts at each end. The code official is permitted to accept alternate bracing designs if they bear the seal of a registered design professional.

The delayed effective date of this Rule is January 1, 2020.
The Statutory authority for Rule-making is G. S. 143-136; 143-138.
UpCodes note:The 2017-2021 Approved Amendments 201309-Residential Code has an update to this section:

Bracing of pile foundations is required where the clear height from ground to sill, beam or girder exceeds 10 feet (3048 mm) or the dwelling is more than one story above piles. A line of X-bracing is defined as a row of piles with X-bracing provided in at least two bays. A line of X-bracing shall be provided at all exterior pile lines. Where the perimeter lines of X-bracing exceed 40 feet (12 192 mm), an additional line of X-bracing shall be provided near the center of the building. See Figure R4603.6(f). X-bracing shall be with 2 × 10s through bolted with two 3/4-inch (19.1 mm) bolts at each end. The code official is permitted to accept alternate bracing designs if they bear the seal of a registered design professional.

The delayed effective date of this Rule is January 1, 2022.
The Statutory authority for Rule-making is G. S. 143-136; 143-138.

R4603.7 Protection Against Decay

AMENDMENT
This section has been amended at the state or city level.
The minimum net retention of preservatives shall be in accordance with AWPA U1.

R4603.8 Piling May Be Placed by Auger, Jetting or Drop Hammer

AMENDMENT
This section has been amended at the state or city level.
Piling shall receive a final set by drop hammer or other approved methods, acceptable to the code official to ensure compaction of material at end bearing.

Section R4604 Elevation Standards

AMENDMENT
This section has been amended at the state or city level.

R4604.1 Lowest Structural Member

AMENDMENT
This section has been amended at the state or city level.
The lowest structural member, excluding pilings and bracing supporting the lowest habitable floor in the coastal high hazard area and ocean hazard area, shall be elevated above the base flood elevation.

R4604.2 First Habitable Floor

AMENDMENT
This section has been amended at the state or city level.
The elevation of the first habitable floor of all structures in the regulatory flood plain except in the coastal high hazard areas shall be above the base flood elevation.

Exception: This requirement does not apply to the addition, renovation or reconstruction to any building that was constructed prior to the initial Flood Insurance Study for that area if the addition, renovation or reconstruction does not exceed 50 percent of the present market value of the structure.

R4604.3 Walls Below Flood Elevation

AMENDMENT
This section has been amended at the state or city level.
Where walls are constructed below flood elevation in coastal high hazard area and ocean hazard area, they shall be constructed in a manner to eliminate wave forces on the piling.

Section R4605 Construction Materials and Methods Standards

AMENDMENT
This section has been amended at the state or city level.

R4605.1 General

AMENDMENT
This section has been amended at the state or city level.
The requirements of Sections R4605.2 through R4605.8 are applicable in the coastal high-hazard area, the ocean hazard area, and all areas defined as 150 mph (67 m/s) wind zone.

R4605.2 Roof Anchorage

AMENDMENT
This section has been amended at the state or city level.
Every rafter or roof truss shall be anchored to the bearing wall as required by Section R4508. At the ridges, rafters shall have a minimum 1 × 6 or 2 × 4 collar or wind beam. Every third rafter not to exceed 4 feet (1219 mm) on center shall be anchored vertically with minimum 1 × 6 or 2 × 4 from its midpoint to ceiling joists below.

R4605.3 Wood Frame Wall Construction

AMENDMENT
This section has been amended at the state or city level.
Maximum stud spacing shall be 16 inches o.c. (406 mm) for 2 × 4s and 24 inches (610 mm) for 2 × 6s. See Section R4505 for wall construction requirements. See Section R4508 for uplift anchorage requirements.

R4605.4 Design by Registered Design Professional

AMENDMENT
This section has been amended at the state or city level.
Equal or better methods of tying structures together and to foundations designed for a specific building by a registered design professional shall be accepted by the code official.

R4605.5 Fastener Corrosion Resistance

AMENDMENT
This section has been amended at the state or city level.
In the coastal hazard area and the ocean hazard area, all metal connectors and fasteners outside of conditioned spaces shall be hot-dip galvanized steel after fabrication and meet ASTM A153. Exposed metal connectors, such as tie-down straps on porches, decks, and areas under the structure, shall be a minimum 3/16 -inch (5 mm) thick, and shall be hot-dip galvanized after fabrication and meet ASTM A123 or ASTM A153. Stainless steel light-gage metal connectors shall be permitted in exposed or partially exposed locations. Metal connectors of approved equivalent corrosion-resistant material are permitted to be accepted. See Table R4605.5.

TABLE R4605.5a
CORROSION RESISTANCE
OPEN
(exterior, porches, under house)
EXPOSURE LEVEL
VENTED/ENCLOSED
(attic, floor trusses, enclosed crawl spaces and stud cavity)
CONDITIONED
(heated/cooled living areas)
Nails, staples, screws Hot-dip galvanized Hot-dip galvanized
Nuts, bolts, washers, tie rods Hot-dip galvanized Hot-dip galvanized
Steel connection plates & straps (3/16 " minimum thickness) Hot-dip galvanized after fabrication Hot-dip galvanized
Sheet metal connectors, wind anchors, joists hangers, steel joists and beams Stainless steel or hot-dipped galvanized after fabrication Hot-dip galvanized after plate fabrication or triple galvanizedb Hot-dip galvanized or triple galvanizedb
Truss plates Stainless steel or hot-dipped galvanized after fabrication Hot-dip galvanized after fabrication, stainless steel, triple galvanizedb or in accordance with TPI-1 of the Truss Plate Institute within 6'-0" of a gable louver, ridge or soffit vent. Otherwise, standard galvanizedb Standard galvanized
  1. Applies only to structures located in coastal high-hazard area and ocean high hazard area.
  2. Triple galvanizing—G185, standard galvanizing—G60, both per ASTM A653/A653M.

R4605.6 Building Anchorage

AMENDMENT
This section has been amended at the state or city level.
  1. For masonry buildings, the roof structure, including rafters and joists, shall be anchored to the wall in accordance with Section R606.11. All mortar used for masonry walls shall be Type M or S.
  2. For masonry or wood frame buildings, all sills, beams or girders that resist uplift (including interior sills, beams, girders, and joists where the perimeter is unenclosed) shall be anchored to the footing in accordance with Section R4504. Footing dowel bars shall have an 8-inch (203 mm) hook.
  3. Where wood partitions and masonry walls join, the stud abutting the masonry shall be double and bolted to the masonry with three 1/2-inch (13 mm) galvanized bolts.
  4. Steel and wooden columns and posts, including porch columns, shall be anchored with metal ties and bolts to their foundations and to the members that they support.

R4605.7 Insulation

AMENDMENT
This section has been amended at the state or city level.
Insulation installed in floors in exposed areas under buildings elevated on pilings shall be held in place with plywood with exterior glue or other material approved by the code official.

R4605.8 Accessory Structures

AMENDMENT
This section has been amended at the state or city level.
Detached accessory structures and out buildings shall be bolted to their foundation or otherwise constructed so as to prevent overturning.
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