This information assumes all lumber to be pressure-treated Southern Pine.
1. General:
- All wood should be pressure-treated or an approved alternative.
- Metal connectors should be galvanized or an approved alternative.
- Deck structures shall be designed for a minimum 40 lb. sq. ft. live load.
2. Plans:
- 2 sets of plans drawn to scale showing all proposed levels are required. Framing plans need to clearly show each level. Computerized plans from Home Centers/Lumber Yards with separate material list will not be accepted unless framing plans have the structural elements clearly labeled on the drawings themselves.
3. Footings:
- Poured concrete footings should be a minimum of 8" wider than the posts (4"X4" post - 12" min. width, 6"x6" post - 14" min. width), a two level deck or deck with roof - 24"x24".
- The bottom of the footings must be a minimum of 36" below finish grade level.
- Footings must be a min. of 8" thick below post bottom.
- Suggest footings be placed at least 48" away from the house foundation to avoid a back-filled area.
- Pre-cast footings on a gravel base are allowed.
4. Posts:
- Post can be set directly on the footing with tamped back-fill or on top of a pier at grade with an approved post anchor.
- Posts should be a minimum 4"x4" lumber size. Recommend using 6"x6" lumber size for posts over 8'0" tall.
- For posts over 10'0" tall, recommend cross bracing.
5. Beams:
- Beams must be solidly connected to the posts and joists. Please specify beam size on plans for review when you get a permit.
6. Joists:
- Joists can be set in hangers on the face of the beam or cantilevered over the top of the beam (See Table 1) or set on a 2"x2" ledger attached to the band board.
- For best strength the maximum cantilever distance should not exceed: at 16" o.c. 2"x8"'s: 2' max.; 2"x10"'s: 3'; 2"x12"'s: 4'
7. Band Boards:
- Band boards should be the same size lumber as the joists or larger and shall be properly bolted to solid structure material of the house (not sheathing). Decks or a portion of a deck may be required to be self-supporting when attaching to an existing house cantilever. Also, if the house band board cannot be verified as being structurally adequate, then the deck must be free standing.
- Bolt size and spacing: (use 1/2" bolts up to 8' - 23" OC; 8' to 10' - 18" OC; 10' to 12' - 18" OC; 12' to 14' - 13" OC; 14' to 16' - 11" OC; 16' to 18' - 10" OC)
8. Decking:
- When using different species of lumber or composite material, follow the manufacturer's recommendations.
- Suggestion: To strengthen the deck structure, the decking may be set at a 45 degree angle across the joists.
9. Rails:
- Guardrails on decks shall be a minimum of 36" in height above the deck surface and are required on decks over 30" above ground level. Railing systems shall be able to resist a concentrated load of 200 lbs. on or against the top rail at any point and direction.
- Guardrail in-fill shall be designed to withstand a horizontally applied normal load of 50 lbs. per sq. ft.
- Guardrails on stairs must be 34" minimum height above the tread nosing, if the stairs are 30" above grade.
- Balusters/pickets shall have no more than a 4" space between them.
- Continuous graspable handrails on stairs shall be between 34" and 38" above the tread nosing and are required on stairs of 4 or more risers.
10. Stairs:
- Minimum stair width is 3'.
- Maximum riser is 8 1/4".
- Minimum tread is 9" from nosing to nosing. If tread depth is a minimum of 11" no nosing is required.
- The greatest riser height/tread depth within any flight of stairs shall not exceed the smallest height/depth by more than 3/8".
- 2"x12" stringers on stairs are required to be a maximum of 24" OC.
- All interior and exterior stairways shall be provided with a means to illuminate the stairs, including the landings and treads.
