Deck Permit requirements across Washington
By Mario Bailey Last verified 2026-06-17
Requirements and size thresholds for deck permits vary by locality. The table below compares what each Washington county or city requires. Always confirm with the local office before starting.
| Locality | Permit required? | Typical threshold |
|---|---|---|
| Bellevue | Conditional | decks where the highest walking surface is 30 inches or less above grade do not require a permit; decks over 30 inches above grade require a permit with plan review |
| King County | Conditional | uncovered decks 30 inches or less above ground do not require a building permit in unincorporated King County; decks over 30 inches above grade require a permit |
| Seattle | Conditional | decks more than 18 inches above grade require a permit; decks 18 inches or less above grade and not over a basement do not require a permit |
| Tacoma | Conditional | freestanding decks not exceeding 200 sq ft and not more than 30 inches above grade are exempt; decks over 200 sq ft, over 30 inches above grade, or attached to the dwelling require a permit |