Residential permit rules in Washington
Representative cities: Seattle, Spokane. Covers 16 common home projects.
| Project | Permit? | Authority | Typical fee | Timeline | Go / No-Go | Key notes |
|---|---|---|---|---|---|---|
| 🏠 Accessory Dwelling Unit (ADU) | Permit required | city | Valuation-based; Seattle SDCI issue fees scale with project value (no flat state fee). | Seattle pre-approved DADU plans ~2–6 weeks; custom plans longer. | Generally allowed | Washington HB 1337 (2025) mandates ADUs; Seattle also allows two ADUs per lot. Owner-occupancy and extra parking are not required in Seattle. Exempt: Statewide HB 1337 (eff. 2025) allows ≥1 ADU per lot; Seattle allows up to 2 ADUs. |
| 🪵 Deck / Porch | Conditional | city | Valuation-based; fee set by the issuing city. | Simple decks may be Subject-to-Field-Inspection; standard review 4–8 weeks. | Generally allowed | Attached decks and decks over 30 in above grade always require a permit. Exempt: Freestanding decks ≤30 in above grade and ≤200 sq ft are commonly exempt. |
| 🧱 Fence / Wall | Conditional | city | Often no building-permit fee when under the height threshold; zoning rules still apply. | Typically no building permit below threshold; review only if over height. | Generally allowed | Corner lots have sight-triangle limits; Environmentally Critical Area (ECA) lots need a pre-application site visit. Exempt: Seattle: no building permit for fences < 8 ft; Spokane generally requires a permit for new/replacement fences. |
| 🛖 Shed / Outbuilding | Conditional | city | Valuation-based when a permit is required; many small sheds are exempt. | Exempt sheds need no review; others often Subject-to-Field-Inspection. | Generally allowed | Lot-coverage and stormwater rules still apply even when a permit is not required. Exempt: Seattle: one-story detached accessory building <120 sq ft roof area on slab-on-grade exempt; Spokane <200 sq ft exempt. |
| 🪜 Basement Finish | Permit required | city | Valuation-based; includes trade permits (electrical, plumbing). | Standard review 4–8 weeks. | Generally allowed | Bedrooms must have an emergency egress window (≥5.7 sq ft opening). Exempt: Cosmetic-only finishing (paint, flooring) is exempt. |
| 🚗 Garage / Carport | Permit required | city | Valuation-based; includes trade permits. | New structure review; complex projects 8–16 weeks. | Generally allowed | Attached and detached garages require a full building permit and plan review. Exempt: No exemption — a new garage is a new structure. |
| ☀️ Rooftop Solar PV | Permit required | city | Building + electrical permits; Seattle combined fees typically a few hundred dollars. | Seattle Solar Express: same-day for standard residential PV <30 kW (RCW 64.40 / HB 1117). | Generally allowed | Washington HB 1117 requires expedited solar permitting; HOA solar restrictions are limited by RCW 64.38.055. Exempt: No size exemption; systems >30 kW use the standard path. |
| 🌡️ HVAC Replacement | Permit required | city | Mechanical (trade) permit; fee set by city. | Trade permits often issued quickly; same-day in many cases. | Generally allowed | New equipment must meet the Washington State Energy Code (WSEC-R). Exempt: No exemption for equipment replacement. |
| 🍳 Kitchen Remodel | Conditional | city | Valuation-based when structural/plumbing/electrical work is included. | Standard review 4–8 weeks for permitted scopes. | Generally allowed | Verify whether walls are load-bearing before any layout change. Exempt: Cabinet/countertop swap in the same layout is exempt. |
| 🛁 Bathroom Remodel | Conditional | city | Valuation-based when plumbing is relocated. | Standard review for permitted scopes. | Generally allowed | Ventilation must meet code; exhaust to the exterior is required. Exempt: Fixture-for-fixture swap in place is often exempt. |
| 🏗️ Room Addition | Permit required | city | Valuation-based; includes trade permits. | Complex review 8–16 weeks. | Generally allowed | Middle-housing reforms (HB 1110) may allow more units by right; check zoning. Exempt: No exemption — any new conditioned footprint requires a permit. |
| 🪟 Window / Door Replacement | Conditional | city | Usually no fee for in-kind swap; permit needed if opening is enlarged. | In-kind swaps typically need no review. | Generally allowed | Replacement windows should meet U-factor requirements when the energy code is triggered. Exempt: Same-size, in-kind replacement is generally exempt. |
| 🏘️ Roof Replacement | Conditional | city | Often Subject-to-Field-Inspection or exempt for same-footprint re-roof. | STFI re-roofs can be approved same-day. | Generally allowed | Snow-load and seismic detailing apply in eastern WA (Spokane). Exempt: Same-material, same-slope re-roof often exempt/STFI. |
| 🅿️ Driveway / Parking Pad | Conditional | city | Building permit often not required; curb-cut/right-of-way work is separate. | Right-of-way permits reviewed by the city/utility. | Generally allowed | A separate right-of-way or utility permit is usually needed to cut the curb. Exempt: Seattle: driveways <18 in above grade exempt from building permit; Spokane <30 in exempt. |
| 🏊 Swimming Pool / Spa | Permit required | city | Valuation-based; includes barrier/fencing review. | Standard review; varies by city. | Generally allowed | Washington adopts the International Swimming Pool & Spa Code (WAC 51-50-3109); barrier fencing is mandatory. Exempt: No exemption — pools/spas require a permit (incl. most above-ground). |
| 🧱 Retaining Wall | Conditional | city | Valuation-based when over the height threshold. | Over-threshold walls need plan review. | Generally allowed | Walls in Environmentally Critical Areas need a pre-application site visit. Exempt: Walls <4 ft from bottom of footing are generally exempt. |