Deck building
in Kansas City

Both conditions have to be met. "At any point" means the deck is measured where it sits highest above the ground, not at the back door. On a lot that falls away from the house, a deck that steps out level from the door can be 20 inches up at the house and well past 30 inches at its outer edge, and that deck needs a permit. A low deck built over a walkout basement or a lower story doesn't qualify at any height. Unlike the small-deck exemptions in some suburban codes, Kansas City's has no size limit and doesn't require the deck to be detached from the house.

The exemption covers only the permit. The same section states that an exemption doesn't authorize work that violates the code or any other city ordinance, so a low deck still has to meet the residential code and the zoning setbacks described below.

Repairs follow a separate rule. Sec. 18-4(b) lets ordinary repairs go ahead without an application, but it excludes the removal or cutting of any structural beam or load-bearing support. Swapping out deck boards or a stair tread is an ordinary repair. Replacing joists, beams or posts is structural work, and tearing out a deck taller than 30 inches to build a new one is construction that needs a permit, the same as a first deck.

Kansas City, Missouri spans parts of Jackson, Clay, Platte and Cass counties and borders separate cities such as North Kansas City, Gladstone, Raytown, Grandview and Independence, each with its own building department. A Kansas City mailing address doesn't always place a house inside KCMO's city limits. For a deck builder in Kansas City, the lot's jurisdiction settles the permit office, the code edition and the setbacks, and this page covers property inside KCMO's limits.

Kansas City enforces the 2018 International Residential Code, adopted with local amendments in Sec. 18-57 of the Code of Ordinances. The city's amended climate table sets the frost line depth at 36 inches, so footings for a permitted deck bear below that depth, where freezing and thawing soil can't lift them. The same table rates weathering as Severe, sets the air freezing index at 1,000 degree-days and rates termite risk as Moderate to Heavy.

The administrative chapter sets out what a permitted deck goes through:

Construction documents

Sec. 18-18 requires drawings to scale that show the location, nature and extent of the work, plus a site plan showing the new construction, existing structures, distances from lot lines, and existing and proposed grades, drawn from an accurate boundary survey. The building official can waive the site plan for an alteration or repair.

Footing inspection

under Sec. 18-21, footings are inspected after the excavation is complete and before concrete is placed.

Framing and final

framing gets a rough-in inspection before anything covers it, work can't continue past an inspection point without approval, and every permitted structure gets a final inspection.

Erosion control

the permit holder has to keep erosion and sediment controls in place, and the building official can refuse inspections until they are.

Historic properties. For a designated landmark, or a property inside a historic district or historic overlay district, Sec. 88-585 requires a certificate of appropriateness for exterior alterations visible from any public place or right-of-way. Construction and reconstruction both count as exterior alterations, and no building permit can be issued until the certificate is approved. City planning staff can approve insubstantial changes to features that aren't historically significant, while other applications go to the Historic Preservation Commission.

Floodplains. Sec. 18-4 requires the city's floodplain management chapter to be met for any alteration, encroachment or substantial improvement in a regulatory floodplain, and permit applications there have to include floor elevations and floodproofing details where required. That review follows the location rather than the deck's height.

Much of Kansas City's housing predates current deck rules. Census Bureau American Community Survey estimates for 2024 put the median year built at 1969, with about 39 percent of housing units built before 1960 and about 20 percent built in 1939 or earlier.

On a house that age, the existing deck was built to an earlier code. Footings may be shallower than 36 inches, guards may be lower than current rules allow, and the house connection may predate flashing requirements. A deck that's rebuilt is reviewed under the 2018 code, so those details are corrected rather than carried over.

The wall itself often decides how a new deck attaches. The 2018 code doesn't allow a deck ledger to be supported on stone or masonry veneer, so where brick or stone covers the back of the house, the deck is built freestanding, with its own beam and posts along the wall. On older frame houses, the rim board behind the siding has to be sound enough for a bolted ledger. Our deck replacement page explains how that connection is built and flashed. For a deck builder in Kansas City, the age of the house is often the first thing that shapes the frame.