Deck building
in Olathe

Usually, yes. Olathe enforces the 2018 International Residential Code, adopted by Ordinance 19-28 with the city's own amendments, and those amendments set out which decks are exempt. Under Olathe Municipal Code 15.04.080.2, a deck needs no permit only if it covers no more than 200 square feet, is no more than 30 inches above grade at any point, isn't attached to a dwelling and doesn't serve the exit door the code requires. The same section adds that exempt decks still have to meet the city's setback requirements, so skipping the permit doesn't mean a deck can go anywhere on the lot.

Olathe's height test is measured at any point on the deck. On a sloping yard, a deck that sits a step off the ground near the house can be well over 30 inches at its outer edge, and that alone puts it outside the exemption.

The Johnson County deck guideline that Olathe points builders to states that builders and homeowners must obtain a permit before constructing, altering or replacing a deck. That wording matters for projects that change an existing deck. Adding square footage, a second level or a new stair is an alteration, and it goes through the permit process even when the original deck stays in place.

A newer house doesn't change that. The Census Bureau's 2024 American Community Survey estimates a median year built of 1997 for the city's housing units, with about 44 percent built in 2000 or later and about 23 percent built before 1980. A deck on a house that is only a few decades old is still reviewed against the code Olathe enforces today whenever it is enlarged, altered or replaced.

The Johnson County guideline, a 2018-code document published by the Johnson County Building Officials Association and the county's Contractor Licensing Program, describes the drawings in detail. The site plan is drawn to scale and shows all lot dimensions, the deck's location relative to the house, the distance to each property line, and any easements and building lines. The deck plan, also drawn to scale, shows the joists, beams, posts, piers and the connection to the house. Under the guideline, neither drawing has to be sealed by a design professional, and either one can be drawn by deck builders in Olathe or by the homeowner.

The deck plan also has to name the decking material, its size and the direction it runs. The guideline asks for this because the decking sets the joist spacing. Composite boards run perpendicular to the joists typically require joists at 16 inches on center, and boards run diagonally typically require 12 inches.

The guideline's limits shape the plan as well. Its tables assume a floor load of 40 pounds per square foot live load and 10 pounds dead load. Multi-level decks, decks that support roofs, hot tubs, spas or sunrooms, and cantilevers beyond what the code allows fall outside it, so those designs need further direction from the city and may need an architect or engineer.

Olathe's amended climate table sets the frost line at 36 inches, rates weathering as severe and marks the area as subject to termite damage. The county guideline applies the frost line directly: every pier is at least 36 inches deep, with its top at least 1 inch above grade. Pier diameter depends on how much deck area each post supports, and each post has to be fastened to its pier with a column anchor that resists sideways movement and uplift. A drift pin drilled into the bottom of the post isn't enough.

Two rules in the guideline decide whether a deck attaches to the house at all. A ledger can't be attached to or through brick, masonry, stone or stucco veneer, because veneer isn't structural, so on those walls the deck is built freestanding. A freestanding deck more than 2 feet above grade then has to resist sideways movement, either with diagonal bracing between the posts and beams or by attaching to the house wall.

The guideline also requires the deck to be built of naturally decay-resistant or preservative-treated lumber, a requirement that carries extra weight in a city whose design table marks termite damage as a local risk.

KC Deck Builds is a locally owned, licensed and insured deck builder in Olathe, and we serve the wider Kansas City metro as well. New deck construction builds a deck to the county guideline from the piers up. Deck expansion adds size or a level to an existing deck, which Olathe reviews as an alteration. Covered deck construction adds a roof, a design the county guideline doesn't cover on its own. Deck replacement rebuilds a deck whose frame, footings or house connection has failed. Deck repair fixes specific damage on a deck worth keeping. Wood deck construction covers treated lumber and cedar decks and their upkeep.