Deck Installation or Repair

Whether or not a building permit is required for installing, repairing or replacing a deck depends on what kind of structure the deck is related to and how high the deck is.

Code requirements come from the 2015 International Building Code (IBC), 2015 International Residential Code (IRC) and the current Kirkland Municipal Code (KMC).

STEP 1 - Determine what kind of structure the deck is related to

There is a difference in requirements, depending on whether the deck is related to an IRC or IBC structure.

IRC Structure = Single Family Residence, Duplex, or Townhouse 

IBC Structure = Structure other than those listed above (such as office, condominium, restaurant, etc.)

STEP 2 - Determine if a building permit is required

For a deck related to an IRC or IBC structure: 

KMC 21.06.215: A building permit is not required for a deck that is not more than 30" above grade and not over any basement or story below and which is not part of an accessible route. 

NOTE: Even when a building permit is not required, it is the responsibility of the person building the deck to ensure it meets related code requirements. Skip to Step 4.

A building permit is required when the deck is more than 30" above grade, located over a basement or story below, or part of an accessible route.

STEP 3 - Apply for a building permit

When applying for a permit:

  • A Site Plan shall be provided to show the location of the deck in relation to other structures and property lines. Lot coverage calculations and required setbacks shall be shown. Any slope, wetland, or other environmentally sensitive area shall be identified on plans. The extent of work to be done shall be defined.
  • Elevations shall be provided to show the deck, including height, related stairs, access, guards, handrails, etc.
  • Floor Plans shall be provided to show the deck and what room(s), window(s) and door(s) are located adjacent to the deck. Indicate if the deck is drip-through or waterproof.
  • Notes and details showing compliance with the deck code requirements identified in Step 4 shall be provided.
  • Structural notes and framing plans shall be provided to identify how the deck is constructed. Framing plans shall have dimensions, showing joist layout, beam size and location, post size and location, footing size, guard post spacing, connections, fasteners, bracing, etc. It shall be clear whether the design is prescriptive per Construction Tip Sheet 5 or engineered. If engineered, structural calculations shall also be provided.
  • Other building permit application requirements can be found on the Building Permit Checklist.

STEP 4 - Deck related code requirements

Note: For IBC structures, consult the IBC for specific code requirements.

For IRC structures, the following code requirements shall be met:

  • Where structurally supported by attachment to an exterior wall, the deck shall be positively anchored to the primary structure and designed for both vertical and lateral loads. The deck and deck ledger connection shall be engineered or shall follow the prescriptive design of Construction Tip Sheet 5.
  • Where the deck walking surface is located more than 30" above grade, guards shall be provided. Guard attachments shall be able to withstand a minimum of 200 lbs per square foot. The guard connection shall be engineered or shall follow the prescriptive design of Construction Tip Sheet 5.
  • Where located outdoors or exposed to the weather, the deck framing members shall be of naturally durable wood or wood that is preservative-treated.
  • Where stairs are provided to or from the deck, they shall have handrails and guards as required. Handrail attachments shall be able to withstand a minimum of 200 lbs per square foot.
  • A deck that is more than 30" above grade is not allowed to be located in a required setback.
  • For a deck that is to remain as a drip-through deck, the area counts at 50% impervious surface.
  • For a deck that is to have a waterproof surface, the area counts at 100% impervious, and drainage from the deck shall be provided.
  • If a covered deck or a waterproof deck is being added to an existing dwelling unit, and its square footage combined with existing square footage results in over 5,000 square feet of gross floor area, fire sprinklers may need to be installed throughout the dwelling unit.