Do I need a permit for deck construction or replacement in Lacey?

Most likely yes. Deck construction or replacement usually requires a permit in Washington. Confirm the specifics with Lacey.

The state-adopted 2021 IRC exempts only decks that are not over 200 square feet, not more than 30 inches above grade, not attached to the house, and not serving the required exit door; cities and counties may amend this administrative exemption. Washington amends the IRC deck tables for footings, posts, beams, and joists to cover ground snow loads up to 70 psf, so deck sizing depends on the local snow load (WAC 51-51-0507). A permit exemption does not waive zoning setbacks, critical-area rules, or lot coverage limits set by the city or county. This deck is attached to the house or will have a roof. Where a small deck exemption exists at all, it covers only small, low, freestanding decks that do not serve the home's required exit door, so an attached deck falls outside it. A ledger bolted to the house is the most common point of deck failure, which is why departments inspect the footings, framing and ledger connection before the decking goes on. Adding a roof makes the deck a covered structure that is reviewed like a patio cover or addition, including roof framing and, in high wind areas, uplift connections.