Window Replacement Seattle: $5,735 to $23,555 + L&I Check

Seattle rows are local figures from Angi; the national row is labeled.

Do you need a permit to replace windows in Seattle?

Usually not for a like-for-like swap: Angi (August 2026) says neither the City of Seattle nor King County requires a permit to replace windows in existing openings, and that changing a window's style or cutting a new opening does need one. We could not load the City's own permit page to confirm, so for anything beyond a same-size swap, call the Seattle Department of Construction and Inspections at (206) 684-8600. SDCI's energy code guidance on windows (Tip 428) is written for commercial buildings, not single-family houses.

Seattle's eight historic districts need a Certificate of Approval

Seattle has eight historic districts, and work on designated landmarks or inside those districts needs a Certificate of Approval, a written authorization the City must issue before certain changes are made. The districts are Ballard Avenue, Columbia City, Fort Lawton, Harvard-Belmont, the International Special Review District, Pike Place Market, Pioneer Square and Sand Point Naval Air Station. If your house is in Harvard-Belmont, Columbia City or another district, check with the Department of Neighborhoods before you order windows.

Washington's own lead rule: 53% of Seattle homes predate 1980

The Census Bureau counts 207,857 of 393,918 Seattle housing units (52.8%) built before 1980, with a median year built of 1976. Washington runs its own lead renovation rule, WAC 365-230, which applies to all renovations done for pay in target housing (homes built before 1978) and requires renovation firms to be certified (WAC 365-230-360). The EPA's rule sets the same baseline nationally, and window replacement is not covered by its minor repair exemption. Ask every bidder for its lead-safe firm certificate before old sashes are cut out.

Seattle's mild, damp winters and what to look for in a window

Sea-Tac averages 25.2 nights a year at or below 32 F and just 3.8 days at or above 90 F in NOAA's 1991 to 2020 normals, so in Seattle the U-factor (how well a window holds heat) matters more than solar heat gain. Angi notes Seattle prices run high because the cost of living is 46% above the national average, and that spring and fall are the busy seasons. ENERGY STAR says certified windows lower energy bills by an average of up to 13% when replacing single-pane windows. The federal window credit ended for anything placed in service after 2025, the IRS says. National frame prices: window replacement cost.

How to hire a window installer in Seattle

Washington requires contractors to register with the Department of Labor and Industries, and L&I's Verify tool shows the registration, bond and any lawsuits against the bond. Look up the company before you sign, and ask: insert or full-frame replacement, the U-factor on each NFRC label, the firm's lead-safe certificate for a pre-1978 house, whether your address is in a historic district, and proof of insurance. Angi adds that Seattle's combined sales tax is 10.35%, so ask whether the quote includes it. Calls go to an independent company that serves your area and takes this kind of job (how calls work).

Rules, programs and conditions for window work in Seattle, from official city, state, Census and NOAA pages unless marked.

More Seattle home repair guides

Heating: furnace repair in Seattle and HVAC repair in Seattle. Damp: mold removal in Seattle and roof repair in Seattle. Pipes: plumber in Seattle. Compare window replacement in Portland and window replacement in Salt Lake City. Siding around windows: siding repair. All prices: home repair costs.