Deck Specifications

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DECK SPECIFICATIONS - 2015 IRC

1. Required Information To Obtain Permit

  • Submit a plat of survey showing the location of the deck and area of the deck. Indicate all setbacks from the property line.

  • Submit one set of plans.

  • Plans shall include the following information: Deck size, size and spacing of floor joists, size and location of concrete post holes, size and location of support posts, size of all headers and beams, size of ledger board and number and spacing of lag bolts, flashing, guardrail and handrail design and spacing and height. Posts need to be attached to concrete piers. Lag bolts need to be 16” on center and staggered. NOTE: Locating the property lines and irons is the responsibility of homeowner.

2. Building Code Requirements

  • All post holes are to be a minimum of 42” below grade when deck is attached to house; post holes for free-standing decks are to be a minimum of 24" below grade.  Post holes should be a minimum 10" in diameter.  All supporting deck posts are to be a minimum of 4"x4", 4"x6" or 6"x6" sized in accordance with 2015 IRC Table R507.8 and connected using Figure R507.7.1.  Lateral load connections are required on all decks that are not self-supporting and that exceed 30" from grade.

  • All lumber for deck shall be of approved wood, of natural resistance to decay or treated wood. Hot-dipped galvanized or stainless steel fasteners and joist hangers and galvanized or copper flashing are required.

  • Decks greater than 30” above grade shall have a guardrail.

  • Guardrails will be a minimum of 36” in height with 4” maximum spacing between balusters on stairs and decks.

  • Stairways shall be a minimum of 36” wide with a maximum riser of 7 ¾” and a minimum total tread size of 11” (measuring a minimum of 10" nose to nose). The risers need to be consistent, and closed (solid).

  • A grippable handrail is to be provided to all stairways having four or more risers.

  • Grippable handrails shall be placed not less than 34”, no more than 38” above the nosing of the treads with 4” maximum spacing between balusters on stairs and decks. They shall be continuous the full length of the stairs.

  • Floor joist spacing at 24” on center require a minimum of 2x decking and floor joist spacing at 16” requires 1x decking.  Engineered decking products to be installed per manufacturers instructions.

Inspections are required before concrete is poured.  A rough framing inspection is required, and final inspection when deck is complete with guardrails and handrails if applicable.  Revised 09/17/2018