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.

Appendix M Wood Decks

AMENDMENT
This section has been amended at the state or city level.
This appendix is a North Carolina addition and not part of the 2015 International Residential Code.

There will be no underlined text.

(The provisions contained in this appendix are adopted as part of this code.)

Section AM101 General

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

AM101.1 General

AMENDMENT
This section has been amended at the state or city level.
A deck is an exposed exterior wood floor structure that is permitted to be attached to the structure or freestanding. Roofed porches (open or screened-in) are permitted to be constructed using these provisions.

AM101.2 Deck Design

AMENDMENT
This section has been amended at the state or city level.
Computer deck design programs are permitted to be accepted by the code official.

Section AM102 Footings

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

AM102.1 Footings

AMENDMENT
This section has been amended at the state or city level.
Support posts shall be supported by a minimum footing in accordance with Figure AM102.1(1) and Table AM102.1. Minimum footing depth shall be 12 inches (305 mm) below finished grade in accordance with Section R403.1.4. Tributary area is calculated as shown in Figure AM102.1(2).

TABLE AM102.1
FOOTING TABLEa, b, c
SIZE
(inches)
TRIBUTARY AREA
(square feet)
THICKNESS
(inches)
A × A B × C Precast Cast-In-Place
8 × 16 8 × 16 36 4 6
12 × 12 12 × 12 40 4 6
16 × 16 16 × 16 70 8 8
16 × 24 100 8
24 × 24 150 8
For SI: 1 inch = 25.4 mm, 1 square foot = 0.0929 m2.
  1. Footing values are based on single floor and roof loads.
  2. Support post must rest in center one-third of footing.
  3. Top of footing shall be level for full bearing support of post.


FIGURE AM102.1(1)
SUPPORT POST FOOTING


For SI: 1 inch = 25.4 mm, 1 square foot = 0.0929 m2.

Note: Tributary area of shaded section on the free standing deck shown is 5' × 6' = 30 square feet (2.79 m2). Code will require a minimum footing of 8" × 16" (203 mm × 406 mm) in accordance with Table AM102.1.
FIGURE AM102.1(2)
CALCULATED TRIBUTARY AREA

Section AM103 Flashing

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

AM103.1 Flashing

AMENDMENT
This section has been amended at the state or city level.
When attached to a structure, the structure to which it is attached shall have a treated wood band for the length of the deck, or corrosion-resistant flashing shall be used to prevent moisture from coming in contact with the untreated framing of the structure. Aluminum flashing shall not be used in conjunction with deck construction. The deck band and the structure band shall be constructed in contact with each other except on brick veneer structures and where plywood sheathing is required and properly flashed. Siding shall not be installed between the structure and the deck band. If attached to a brick structure, neither the flashing nor a treated band for brick structure is required. In addition, the treated deckband shall be constructed in contact with the brick veneer. Flashing shall be installed in accordance with Figure AM103.1.


For SI: 1 inch = 25.4 mm
FIGURE AM103.1
FLASHING FOR DECK ATTACHED TO STRUCTURE

Section AM104 Deck Attachment

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

AM104.1 Deck Attachment

AMENDMENT
This section has been amended at the state or city level.
When a deck is supported at the structure by attaching the deck to the structure, Tables AM104.1(1) and AM104.1(2) shall apply for attaching the deck band to the structure.

TABLE AM104.1(1)
DECK ATTACHMENT FOR ALL STRUCTURES EXCEPT BRICK VENEER
FASTENERS 8' MAX JOIST SPANa 16' MAX JOIST SPANa
5/8" Hot-dip galvanized bolts with nut and washerb
and
12d Common hot-dip galvanized nailsc
1 @ 3'-6" o.c.
and
2 @ 8" o.c.
1 @ 1'-8" o.c.
and
3 @ 6" o.c.
OR
Self-drilling screw fastenerd 12" o.c. staggered 6" o.c. staggered
For SI: 1 inch = 25.4, 1 foot = 304.8 mm
  1. Attachment interpolation between 8 foot and 16 foot joists span is allowed.
  2. Minimum edge distance for bolts is 21/2 inches.
  3. Nails must penetrate the supporting structure band a minimum of 11/2 inches.
  4. Self-drilling screw fastener having a minimum shank diameter of 0.195 inches and a length long enough to penetrate through the supporting structure band. The structure band shall have a minimum depth of 11/8 inches. Screw shall be evaluated by an approved testing agency for allowable shear load for Southern Pine to Southern Pine lumber of 250 pounds and shall have a corrosion-resistant finish equivalent to hot dip galvanized. Minimum edge distance for screws is 17/16 inches. A maximum of 1/2 inch thick wood structural panel is permitted to be located between the deck ledger and the structure band.
TABLE AM104.1(2)
DECK ATTACHMENT FOR BRICK VENEER STRUCTURES
FASTENERS 8' MAX JOIST SPANa 16' MAX JOIST SPANa
5/8" Hot-dip galvanized bolts with nut and washerb 1 @ 2'-4" o.c. 1 @ 1'-4" o.c.
For SI: 1 inch = 25.4, 1 foot = 304.8 mm.
  1. Attachment interpolation between 8 foot and 16 foot joist span is allowed.
  2. Minimum edge distance for bolts is 21/2 inches.

AM104.1.1 Masonry Ledge Support

AMENDMENT
This section has been amended at the state or city level.
If the deck band is supported by a minimum of 1/2 inch (13 mm) masonry ledge along the foundation wall, 5/8-inch (16 mm) hot-dip galvanized bolts with washers spaced at 48 inches (1219 mm) o.c. are permitted to be used for support.

AM104.1.2 Other Means of Support

AMENDMENT
This section has been amended at the state or city level.
Joist hangers or other means of attachment are permitted to be connected to the house band and shall be properly flashed.

Section AM105 Girder Support and Span

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

AM105.1 General

AMENDMENT
This section has been amended at the state or city level.
Girders shall bear directly on the support post with the post attached at top to prevent lateral displacement or be connected to the side of the posts with one of the methods shown in Table AM105.1. Girder support is permitted to be installed in accordance with Figure AM105.1(1) for top mount; Figure AM105.1(2) for side mount and Figure AM105.1(3) for split girders. See Figure AM105.1(4) for cantilevered girders.


For SI: 1 inch = 25.4 mm.
FIGURE AM105.1(1)
TOP MOUNT/FLUSH GIRDER



For SI: 1 inch = 25.4 mm.
FIGURE AM105.1(2)
SIDE MOUNT DROPPED GIRDER



For SI: 1 inch = 25.4 mm.
FIGURE AM105.1(3)
SPLIT GIRDER



For SI: 1 inch = 25.4 mm.
FIGURE AM105.1(4)
CANTILIEVERED DROPPED GIRDER


Table AM105.1
Girder Connection to Side of Post
Maximum Girder Thickness
Any 3" (Double 2X) 1-1/2" (Single 2X)
Two 5/8" diameter bolts1 Four 6" long screws2 Three 4" long screws2
  1. Bolts shall be hot dip galvanized through bolts with nut and washer
  2. Screws shall be hot dipped galvanized self-drilling screw fastener having a minimum diameter of 0.270", staggered so that the screws are not in a line, and having a minimum edge distance of 1-1/2 inches.
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:

"Girders shall bear directly on the support post with the post attached at top to prevent lateral displacement or be connected to the side of the posts with two 5/8-inch (16 mm) hot-dip galvanized bolts with nut and washer. Girder support is permitted to be installed in accordance with Figure AM105.1(1) for top mount; Figure AM105.1(2) for side mount and Figure AM105.1(3) for split girders. See Figure AM105.1(4) for cantilevered girders."

AM105.2 Girder Span for Uncovered Porches and Decks

AMENDMENT
This section has been amended at the state or city level.
Maximum allowable spans for wood deck girders, as shown in Figure AM105.2, shall be in accordance with Table AM105.2. Girder plies shall be fastened with two rows of 10d (3-inch × 0.128-inch) nails minimum at 16 inches (406 mm) on center along each edge. Girders shall be permitted to cantilever at each end up to one-fourth of the actual beam span. Splices of multispan beams shall be located at interior post locations.

TABLE AM105.2
DECK GIRDER SPAN LENGTHSa, b (feet — inches)
SPECIESc SIZEd DECK JOIST SPAN LESS THAN OR EQUAL TO:
(feet)
6 8 10 12 14 16 18
Southern pine 2 — 2 × 6 6-11 5-11 5-4 4-10 4-6 4-3 4-0
2 — 2 × 8 8-9 7-7 6-9 6-2 5-9 5-4 5-0
2 — 2 × 10 10-4 9-0 8-0 7-4 6-9 6-4 6-0
2 — 2 × 12 12-2 10-7 9-5 8-7 8-0 7-6 7-0
3 — 2 × 6 8-2 7-5 6-8 6-1 5-8 5-3 5-0
3 — 2 × 8 10-10 9-6 8-6 7-9 7-2 6-8 6-4
3 — 2 × 10 13-0 11-3 10-0 9-2 8-6 7-11 7-6
3 — 2 × 12 15-3 13-3 11-10 10-9 10-0 9-4 8-10
Douglas fir-larche, hem-fire, spruce-pine-fire, redwood, western cedars, ponderosa pinef, red pinef 3 × 6 or 2 — 2 × 6 5-5 4-8 4-2 3-10 3-6 3-1 2-9
3 × 8 or 2 — 2 × 8 6-10 5-11 5-4 4-10 4-6 4-1 3-8
3 × 10 or 2 — 2 × 10 8-4 7-3 6-6 5-11 5-6 5-1 4-8
3 × 12 or 2 — 2 × 12 9-8 8-5 7-6 6-10 6-4 5-11 5-7
4 × 6 6-5 5-6 4-11 4-6 4-2 3-11 3-8
4 × 8 8-5 7-3 6-6 5-11 5-6 5-2 4-10
4 × 10 9-11 8-7 7-8 7-0 6-6 6-1 5-8
4 × 12 11-5 9-11 8-10 8-1 7-6 7-0 6-7
3 — 2 × 6 7-4 6-8 6-0 5-6 5-1 4-9 4-6
3 — 2 × 8 9-8 8-6 7-7 6-11 6-5 6-0 5-8
3 — 2 × 10 12-0 10-5 9-4 8-6 7-10 7-4 6-11
3 — 2 × 12 13-11 12-1 10-9 9-10 9-1 8-6 8-1
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square foot = 0.0479 kPa, 1 pound = 0.454 kg.
  1. Ground snow load, live load = 40 psf, dead load = 10 psf, L/Δ = 360 at main span, L/Δ = 180 at cantilever with a 220-pound point load applied at the end.
  2. Girders supporting deck joists from one side only.
  3. No. 2 grade, wet service factor.
  4. Girder depth shall be greater than or equal to depth of joists with a flush beam condition.
  5. Includes incising factor.
  6. Northern species. Incising factor not included.
FIGURE AM105.2
TYPICAL DECK GIRDER SPANS

AM105.3 Girder Span for Roofed Porches and Decks

AMENDMENT
This section has been amended at the state or city level.
Girder spans for covered decks shall be in accordance with Tables R602.7(1) and (2).

Section AM106 Joist Spans and Cantilevers

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

AM106.1 Joist Spans for Uncovered Porches and Decks

AMENDMENT
This section has been amended at the state or city level.
Maximum allowable spans for wood deck joists, as shown in Figure AM106.1, shall be in accordance with Table AM106.1. Deck joists shall be permitted to cantilever not greater than one-fourth of the actual, adjacent joist span.

TABLE AM106.1
DECK JOIST SPANS FOR COMMON LUMBER SPECIESf (feet — inches)
SPECIESa SIZE SPACING OF DECK JOISTS WITH NO CANTILEVERb (inches) SPACING OF DECK JOISTS WITH CANTILEVERSc (inches)
12 16 24 12 16 24
Southern pine 2 × 6 9-11 9-0 7-7 6-8 6-8 6-8
2 × 8 13-1 11-10 9-8 10-1 10-1 9-8
2 × 10 16-2 14-0 11-5 14-6 14-0 11-5
2 × 12 18-0 16-6 13-6 18-0 16-6 13-6
Douglas fir-larchd, hem-fird, spruce-pine-fird 2 × 6 9-6 8-8 7-2 6-3 6-3 6-3
2 × 8 12-6 11-1 9-1 9-5 9-5 9-1
2 × 10 15-8 13-7 11-1 13-7 13-7 11-1
2 × 12 18-0 15-9 12-10 18-0 15-9 12-10
Redwood, western cedars, ponderosa pinee, red pinee 2 × 6 8-10 8-0 7-0 5-7 5-7 5-7
2 × 8 11-8 10-7 8-8 8-6 8-6 8-6
2 × 10 14-11 13-0 10-7 12-3 12-3 10-7
2 × 12 17-5 15-1 12-4 16-5 15-1 12-4
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square foot = 0.0479 kPa, 1 pound = 0.454 kg.
  1. No. 2 grade with wet service factor.
  2. Ground snow load, live load = 40 psf, dead load = 10 psf, L/Δ = 360.
  3. Ground snow load, live load = 40 psf, dead load = 10 psf, L/Δ = 360 at main span, L/Δ = 180 at cantilever with a 220-pound point load applied to end.
  4. Includes incising factor.
  5. Northern species with no incising factor.
  6. Cantilevered spans not exceeding the nominal depth of the joist are permitted.
FIGURE AM106.1
TYPICAL DECK JOIST SPANS

AM106.1.1 Lateral Restraint at Supports

AMENDMENT
This section has been amended at the state or city level.
Joist ends and bearing locations shall be provided with lateral restraint to prevent rotation. Where lateral restraint is provided by joist hangers or blocking between joists, their depth shall equal not less than 60 percent of the joist depth. Where lateral restraint is provided by rim joists, they shall be secured to the end of each joist with not less than (3) 10d (3-inch × 0.128-inch) nails or (3) No. 10 × 3-inch (76 mm) long wood screws.

AM106.2 Roofed Porches and Decks

AMENDMENT
This section has been amended at the state or city level.
Joists spans shall be in accordance with Table R502.3.1(2) with 40-pounds persquare-foot live load and 10-pounds per-square-foot dead load. Cantilevered floor joists shall be in accordance with Table R502.3.3(1).

Section AM107 Floor Decking

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

AM107.1 Floor Decking

AMENDMENT
This section has been amended at the state or city level.
Floor decking shall be No. 2 grade treated Southern Pine or equivalent. The minimum floor decking thickness shall be in accordance with Table AM107.1.

TABLE AM107.1
FLOOR DECKING THICKNESS
SPACING DECKING
(nominal)
12" o.c. 1" S4S
16" o.c. 1" T&G
19.2" o.c. 1/4" S4S
24"-36" o.c. 2" S4S
For SI: 1 inch = 25.4, 1 foot = 304.8 mm.

Section AM108 Post Height

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

AM108.1 Post Height

AMENDMENT
This section has been amended at the state or city level.
Maximum height of deck support posts shall be in accordance with Table AM108.1.

TABLE AM108.1
DECK SUPPORT POST HEIGHT
POST SIZEa MAXIMUM POST HEIGHTb, c
4" × 4" 8'-0"
6" × 6" 20'-0"
For SI: 1 inch = 25.4, 1 foot = 304.8 mm.
  1. This table is based on No. 2 Southern Pine posts.
  2. From top of footing to bottom of girder.
  3. Decks with post heights exceeding these requirements shall be designed by a registered design professional.

Section AM109 Deck Bracing

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

AM109.1 Deck Bracing

AMENDMENT
This section has been amended at the state or city level.
Decks shall be braced to provide lateral stability. Lateral stability shall be provided in accordance with one of the methods in Sections AM109.1.1 through AM109.1.5.




For SI: 1 inch = 25.4, 1 foot = 304.8 mm.
FIGURE AM109.1(1)
NO LATERAL BRACING



For SI: 1 inch = 25.4, 1 foot = 304.8 mm.
FIGURE AM109.1(2)
KNEE BRACING



For SI: 1 inch = 25.4, 1 foot = 304.8 mm.
FIGURE AM109.1(3)
POST EMBEDMENT


FIGURE AM109.1(4)
CROSS BRACING
UpCodes note: From January 1, 2020 to December 31, 2020, FIGURE AM109.1(4) was:


For SI: 1 inch = 25.4, 1 foot = 304.8 mm.
FIGURE AM109.1(4)
CROSS BRACING


The delayed effective date of this Rule is January 1, 2021.
The Statutory authority for Rule-making is G. S. 143-136; 143-138.

AM109.1.1 Lateral Bracing Not Required

AMENDMENT
This section has been amended at the state or city level.
When the deck floor height is less than 4 feet (1219 mm) above finished grade as shown in Figure AM109.1(1) and the deck is attached to the structure in accordance with Section AM104, lateral bracing is not required. Lateral bracing is not required for freestanding decks with a deck floor height 30 inches (762 mm) or less above finished grade.

AM109.1.2 Knee Bracing

AMENDMENT
This section has been amended at the state or city level.
4 × 4 wood knee braces are permitted to be provided on each column in both directions for freestanding decks or parallel to the structure at the exterior column line for attached decks per Figure AM109.1(2). The knee braces shall attach to each post at a point not less than 1/3 of the post length from the top of the post, and the braces shall be angled between 45 degrees (0.79 rad) and 60 degrees (1.05 rad) from the horizontal. Knee braces shall be fastened to the post and the girder/double band in accordance with one of the methods shown in Table AM109.1.

TABLE AM109.1
FASTENING OF BRACE TO POST AND GIRDER/BAND (CHOOSE ONE)
Fastener Installation Minimum Distances
One 5/8" diameter hot dipped galvanized through
bolt with nut and washer
Perpendicular to
post or
girder/band
2-3/16" end distance
Two hot dipped galvanized (ASTM A153, Class C,
minimum) screws having minimum diameter of
0.270" and long enough to achieve 3" penetration
into the post or girder/band.
Perpendicular to
post or
girder/band
1" edge distance, 1-1/2"
horizontal spacing, minimum 3"
end distance

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:

"4 × 4 wood knee braces are permitted to be provided on each column in both directions. The knee braces shall attach to each post at a point not less than 1/3 of the post length from the top of the post, and the braces shall be angled between 45 degrees (0.79 rad) and 60 degrees (1.05 rad) from the horizontal. Knee braces shall be bolted to the post and the girder/double band with one 5/8-inch (16 mm) hot-dip galvanized bolt with nut and washer at both ends of the brace as shown in Figure AM109.1(2)."

AM109.1.3 Post Embedment

AMENDMENT
This section has been amended at the state or city level.
For free standing decks without knee braces or diagonal bracing, lateral stability is permitted to be provided by embedding the post in accordance with Figure AM109.1(3) and Table AM109.2.

TABLE AM109.2
POST EMBEDMENT FOR FREE STANDING DECKS
POST SIZE MAXIMUM
TRIBUTARY
AREA
MAXIMUM
POST
HEIGHT
EMBEDMENT
DEPTH
CONCRETE
DIAMETER
4" × 4" 48 SF 4'-0" 2'-6" 1'-0"
6" × 6" 120 SF 6'-0" 3'-6" 1'-8"
For SI: 1 inch = 25.4 mm, 1 square foot = 0.0929 m2.

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:

"For free standing decks without knee braces or diagonal bracing, lateral stability is permitted to be provided by embedding the post in accordance with Figure AM109.1(3) and Table AM109.1."

Furtheremore, TABLE AM109.2 was referenced as TABLE AM109.1.

AM109.1.4 Cross Bracing

AMENDMENT
This section has been amended at the state or city level.
2x6 diagonal vertical cross bracing is permitted to be provided in two perpendicular directions for free standing decks or parallel to the structure at the exterior column line for attached decks. The 2x6 bracing shall be attached to the posts with one of the methods in Table AM109.1.4 at each end of each bracing member in accordance with Figure AM109.1(4)

Table AM109.1.4
FASTENING OF BRACE (CHOOSE ONE)
Fastener Type Diameter (inches) QTY Length
Bolt 5/8a 1 As required
Screws 0.27b 2 Long enough to achieve a 1 1/2" thread
penetration of structural member opposite head of screw
  1. Bolts shall be hot dip galvanized through bolts with nut and washer
  2. Screws shall be hot dip galvanized (ASTM A153, Class C, minimum) self drilling screw fastener having a minimum diameter of 0.27", and installed in the center of the post with a minimum of 1" space between screws.

AM109.1.5 Piles in Coastal Regions

AMENDMENT
This section has been amended at the state or city level.
For embedment of piles in coastal regions, see Chapter 46.

Section AM110 Stairs

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

AM110.1 Stair Construction

AMENDMENT
This section has been amended at the state or city level.
Stringer spans shall be no greater than 7 feet (2134 mm) between supports. Spacing between stringers shall be based upon decking material used in accordance with AM107.1. Each stringer shall have a minimum of 31/2 inches (89 mm) between step cut and back of stringer. If used, suspended headers shall be attached with 3/8-inch (9.5 mm) galvanized bolts with nuts and washers to securely support stringers at the top. See Figure AM 110.1.


For SI: 1 inch = 25.4, 1 foot = 304.8 mm.
FIGURE AM110.1
STAIR STRINGER

Section AM111 Handrails, Guards and General

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

AM111.1 Handrails, Guards and General

AMENDMENT
This section has been amended at the state or city level.
Deck handrails, guards and general construction shall be as shown in Figure AM111.1.


For SI: 1 inch = 25.4, 1 foot = 304.8 mm.
FIGURE AM111.1
DECK CONSTRUCTION

Section AM112 Walkways in Ocean Hazard Areas

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

AM112.1 Walkways Over Dunes

AMENDMENT
This section has been amended at the state or city level.
Walkways over dunes in ocean hazard areas shall be constructed as shown in Figure AM112.1.


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

* Posts for walkways over dunes or berms shall be embedded a minimum depth of 4' - 0" and post heights shall be limited to 5'- 0" above grade for 4 × 4 and 10' - 0" above grade for 6 × 6.Walkways or portions of walkways over 4' 0" in width shall comply with the requirements of Chapters 45 and 46. Maximum walkway surface height is 30" above grade without guard rails.

** Walkway stair runs are permitted to be greater than 12' without a landing.

*** Open risers permitted on ocean shoreline stair.

**** Horizontal guards permitted to have maximum 18 inch opening on cross-over walkway and ocean shoreline stair.
FIGURE AM112.1
WALKWAYS OVER DUNES OR BERMS IN OCEAN HAZARD AREAS
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