WOOD DECKS

Transcript

WOOD DECKS Page 1 APPENDIX M WOOD DECKS This appendix is a North Carolina addition to the 2009 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 AM101.1 General. A deck is an exposed exterior wood floor structure which may be attached to the structure or freestanding. Roofed porches (open or screened-in) may be constructed using these provisions. AM101.2 Deck design. Computer deck design programs may be accepted by the code enforcement official. SECTION AM102 FOOTERS AM102.1 Footers. Support post shall be supported by a min- imum footing per Figure AM102 and Table AM102. l. Mini~ mum footing depth shall be 12-inches below finished grade per Section R403.1.4. Tributary area is calculated per Figure AM 1 O2. 1 . an SECTION AM103 FLASHING AM103.1 Flashing. When attached to a structure, the struc~ ture to which 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 per Figure AM103. FIGURE AM102 TABLE AM102.1 FOOTING TABLE“-c SIZE (Inches) TRIBUTARY AREA THICKNESS (inches) A x A B x C (sq. ft.) Precast Cast-in-Place 8 X 16 8 X 16 36 4 6 l2 X l2 12 X 12 40 4 6 16 X 16 16 X 16 70 8 8 — 16 X 24 100 — 8 — 24 X 24 150 — 8 For SI: 1 inch = 25.4 mm, 1 square foot = 0.0929 m2. a. Footing values are based on single floor and roof loads b. Support post must rest in center ‘/3 of footer 0. Top of footer shall be level for full bearing support of post 2012 NORTH CAROLINA RESIDENTIAL CODE 911 Page 2 APPENDIX M Note: Tributary area of shaded section on free standing deck shown is 5’ X 6’ = 30 sq. ft. Code will require a minimum footer of 8'’ X 16" per Table AM102.1. FIGURE AM102.1 SECTION AM104 DECK ATTACHMENT AM104.1 Deck attachment. When a deck is supported at the structure by attaching the deck to the structure, the following attachment schedules shall apply for attaching the deck band to the structure. AM104.1.1 All structures except brick veneer structures. 8’ MAX JOIST 16’ MAX JOIST FASTENERS SPANa SPANEl 5/3" Hot dipped galv. bolts with nut and washerb 1 @ 3’-6" o.c. 1 @ 1'-8" o.c. and and and 12d Common hot dipped galv. nails° 2 @ 8" o.c. 3 @ 6" o.c. a. Attachment interpolation between 8 foot and 16 footjoists span is allowed. b. Minimum edge distance for bolts is 21/2 inches. c. Nails must penetrate the supporting structureband a minimum of 1 1/2 inches. I AM104.1.2 Brick veneer structures. FASTENERS ‘ 8’ MAX JOIST SPANE 16’ MAX JOIST SPANa 5/3" Hot dipped galv. bolts , ,, with nut and washerb 1@ 1 '4 0'6‘ a. Attachment interpolation between 8 foot and 16 foot joist span is allowed. b. Minimum edge distance for bolts is 21/2 inches. I I Treated bands on both the house and deck can be in contact with v"IV K I 1 no flashing. A I K /\ DECK \ I In _ ‘. A . A \_>'*'''- HOUSE NO FLASHING-TREATED AM104.1.3 Masonry ledge support. If the deck band is supported by a minimum of 1/2 inch masonry ledge along the foundation wall, 5/8 inch hot dipped galvanized bolts with washers spaced at 48 inches o.c. may be used for support. AM104.1.4 Other means of support. Joist hangers or other means of attachment may be connected to house band and shall be properly flashed. SECTION AM105 GIRDER SUPPORT AND SPAN AM105.1 Girder support and span. Girders shall bear directly on support post with post attached at top to prevent lat- eral displacement or be connected to the side of posts with two 5/3 inch hot dipped galvanized bolts with nut and washer. Girder spans are per Tables R502.5(1) and (2). Girder support may be installed per Figure AM105 for top mount; Figure AM105.1 for side mount and Figure AM105.2 for split girder detail. Girders may also be cantilevered off ends of support post no more than 1 joist spacing or 16 inches, whichever is greater per Figure AM105.3. SECTION AM106 JOIST SPANS AND CANTILEVERS AM106.1 Joist spans and cantilevers. Joists spans shall be based upon Table R502.3. 1(2) with 40 lbs per sq. ft. live load and 10 lbs per sq. ft. dead load. Floor joists for exterior decks may be cantilevered per Table R502.3.3 (1). SPACING 2X6 w 2X8‘ 2x10 ' 2x172. 12 inches 10-9 14-2 18-0 21-9 16 inches 9-9 12-10 16-1 18-10 19.2 inches 9-2 12-1 14-8 17-2 24 inches 8-6 11-0 13-1 15-5 Partial reprint of Table R502.3.1(2), #2 SYP only joist spans (ft-in) HOUSE ( Flashing shall be between bands for full depth and kick out underneath it siding below. Flashing shall extend underneath siding above a min. 2". FLASHING BETWEEN FIGURE AM103 912 2012 NORTH CAROLINA RESIDENTIAL CODE Page 3 Top of post --—> JDIS t mounted girder _\ \ 2x2 ledger strip orjoist hanger required Decks less than 48" from grade can use 3-16d toenailed for attachment of wood post. Decks 48" or greater from grade requiring lateral bracing shall be anchored at top of wood posts with approve strap or post brackets Footer TOP MOUNT/FLUSH FIGURE AM105 Floor joist max o.c. spacing 16" Connector block at each joist nailed to side of joist with 3-8d nails and face nailed through each girder ply with 2-16d nails. Block must fill gap between girder ply’s 2-5/E" bolts with nuts and washers Split girder limited to floor loads only and cantilever girder ends allowed per AM105.3 SPLIT GIRDER DETAIL FIGURE AM105.2 SECTION AM107 FLOOR DECKING AM107.1 Floor decking. Floor decking shall be N o. 2 grade treated Southern Pine or equivalent. The minimum floor deck- ing thickness shall be as follows: SPACINC‘-I ‘ DECKING (nominal) 12" O.C 1" S45 16" o.c. 1" T&G l9.2" O.C. lI/4" S45 24"—36" O.C. 2" S45 2012 NORTH CAROLINA RESIDENTIAL CODE APPENDIX M Jolsts % :> 2-7;’ Galv. through bolts with nuts and washers SIDE MOUNT DROPPED GIRDER FIGURE AM105.1 Max. 16" girder cantilever at ends or 1 rim/band joist whichever is less ._I_. n ll I DPOPPPOI GIWOIQV‘ Girder can have Floorjoists Cantilevered girder is limited Cetjigorigtli/Z Zigeed to floor loads only, roof loads D/4. D=depth of prohibited on cantilevered member /4 girder application CANTILEVERED DROPPED GIRDER DETAIL FIGURE AM105.3 SECTION AM108 POST HEIGHT AM108.1 Post height. Maximum height of deck support posts as follows: a. This table is based on No. 2 Southern Pine posts. b. From top of footing to bottom of girder. c. Decks with post heights exceeding these requirements shall be designed by a registered design professional. 913 Page 4 APPENDIX M SECTION AM109 DECK BRACING AM109.1 Deck bracing. Decks shall be braced to provide lat- eral stability. The following are acceptable means to provide lateral stability. AM109.1.1. When the deck floor height is less than 4’—O” above finished grade per Figure AM109 and the deck is attached to the structure in accordance with Section AMl04, lateral bracing is not required. AM109.1.2. 4X4 wood knee braces may 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 and 60 degrees from the horizontal. Knee braces shall be bolted to the post and the girder/double band with one 5/8 inch hot dipped galvanized bolt with nut and washer at both ends of the brace per Figure AMl09.l AM109.1.3. For freestanding decks without knee braces or diagonal bracing, lateral stability may be provided by embedding the post in accordance with Figure AMl09.2 and the following: // MAXIMUM MAXIMUM ‘ TRIBUTARY POST EMBEDMENT CONCRETE POST SIZE I AREA HEIGHT DEPTH DIAMETER 4x4 48 SF 4‘-0" 2'-6" l'-0" 6x6 120 SF 6‘-O" 3‘-6" l‘—8" /1 Q Less than 4' (decking to grade) and attached to structure no bracing required Grade FIGURE AM109 AM109.1.4. 2x6 diagonal vertical cross bracing may be provided in two perpendicular directions for freestanding decks or parallel to the structure at the exterior column line for attached decks. The 2X6’s shall be attached to the posts with one 5/8 inch hot dipped galvanized bolt with nut and washer at each end of each bracing member per Figure AMl09l3. AM109.1.5. For embedment of piles in Coastal Regions, see Chapter 45. 914 Freestanding decks requiring bracing shall be installed in onal bracing only at both directions off outside girder line each post parallel with structure Decks attached to t stmcture require diag- Attached not less than I/1 of post length Braces shall be between 45 and 60 degrees LQ FIGURE AM109.1 1f span between post is greater than 7' center blocking and l‘/,,'‘ bolt with nut and washer required Decks attached to structure can also be braced on exterior girder line with embedn1ent option Max post height for 4X4 is 4' from top of footer, 6‘ for 6x6 77 % FIGURE AM109.2 One 7 " bolt 4/ top anii bottom end with nut and washer FIGURE AM109.3 2012 NORTH CAROLINA RESIDENTIAL CODE Page 5 APPENDIX M SECTION AM110 STAIRS AM110.1 Stairs shall be constructed per Figure AM110. Stringer spans shall be no greater than 7 foot span between su - Max. spacing between stringers 36". ports. Spacing between stringers shall be based upon decking material used per AM1 O7. 1. Each Stringer shall have minimum 31/2 inches between step out and back of stringer. If used, sus- pended headers shall shall be attached with 3/8 inch galvinize d bolts with nuts and washers to securely support stringers at the top. SECTION AM111 HANDRAILS, GUARDS AND GENERAL AM111.1 Handrails, guards and general guards and general construct . Deck handrails, Fi 7' Max. stringer span between supports ion shall be per gure AMlll. FIGURE AM11O per Table AMl02.l. Minimum base of footers 12" below grade. - Fnoters Decking per AMIO7 for #2 SYP and attached with 2-8d galv nails at each joist or installation based upon joists o.c. spacing. Altemate material attached per mfg installa- tion instructions. Attachment to structure based upon all cladding types but brick veneerper AMlO4.l.1, Brick ,approved screws Other materials per mfg veneer per AMl04. 1.2, Masonry ledge per AMlO4.l.3 or other per AMl04.l .4. s at a Minimum 36" required per R3l2,l with 30" drop and opening limits per R3I2.2 & R3l2.3 (4“ on ver- tical pickets. 6" on horizontal and ornamental guard Guard 1 rails), top rail and post to support 200 lbs with infill to meet 50 lbs per Table R30l.5 and footnotes. *Partial reproduction of Table R5025(l) at 30 ground snow load and roof ceiling and 1 clear span floor. Deck width is 20' or less measured in the direction ofjoists span. Splices in plys must break over bearing suppor1s. Floor ‘oist cantilevers allowed per Table R502.3.3(l ) Riser openings‘. Stairs with a 30" or more vertical rise must have solid risers or opening restricted to prevent a 4" sphere from passing per R31 1.7.4.3. Rail pasts cannot exceed 8' o.c. spacing and shall be attached with 2’/," Galv bolts with nut & washer to outer bands. Stair handrail/Guard. Height between 34"-38" per R31l.7.l 8: R312.2. Open- ings on side of stairs requir- ing guards shall not allow a sphere 4’/,'‘ to pass per R3 12.3 exception #2. I Stairs treads and risers per R3ll.7.4.l (8'/“‘ Max riser) & R31 l.7.4i2 (9“ minimum tread depth). Stairways min 36" width per R31 l.5.l (rail projections allowed). Lateral Bracing per AM lO9. AMlO9.l.l height required; AMl09.l.2 knee bracing; AMlO9.l.3 freestanding embedment; AMlO9.l.4 diagonal brac- ing; AMl09.l.5 Coastal embedment. FIGURE AM111 915 2012 NORTH CAROLINA RESIDENTIAL CODE Page 6 APPENDIX M BARRIER SAND DUNES/BERMS OCEAN SHORELINE FIGURE AM112 WALKWAYS OVER DUNES OR BERMS IN OCEAN HAZARD AREAS 304.8 mm. For SI: 1 inch = 25.4, 1 foot: * Posts for walkways over dunes or berms shall be embedded a minimum depth of 4I — 0" and postheights shall be limited to 5'» 0" above grade f0r4 X 4 and l0’ - 0" above grade for 6 X 6. Walkways or portions of walkways over 4’ 0" in width shall comply with the requirements of Chapters 45 an height is 30" above grade without guard rails. **Walkway stair runs can be greater than l2’ without a landing. d 46. Maximum walkway surface 2012 NORTH CAROLINA RESIDENTIAL CODE 916

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