Whether your deck needs a permit depends mostly on three things: how high it is, whether it's attached to the house, and whether it has a roof. Who may build it depends on where you live, because Colorado licenses contractors locally.
Live inside a city? Cities such as Aurora, Centennial, Lakewood, Arvada, Boulder, Longmont, Thornton, Castle Rock and Parker run their own permits and licenses. The county rules below apply outside city limits; Denver is both a city and a county.
Who may build: Denver contractor license required; other jurisdictions' licenses aren't accepted.
Who may build: County license, 3-year term; ICC exam or another Colorado license.
Who may build: Free registration; any Colorado municipal license or ICC certification.
Who may build: County license for general contractors.
Who may build: Registration with insurance and workers' comp; no exam.
Who may build: County license with insurance and ICC exam.
Summarized from each county's published pages in November 2026. Rules change and every lot is different, so confirm with your building department before you build. This isn't legal advice.
Most DeckMarket builders handle permits themselves. Every bid says who pulls the permit and whether fees are included, so you're not surprised later.
At 30 in or more above the ground, most places require a permit and a guardrail. Denver starts zoning review at 12 in.
A deck fastened to your house usually needs one, whatever its height, because the ledger connection carries the load.
A filled tub can weigh several tons. Expect stamped drawings.