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PRISMGENERAL CONTRACTORS Get an Estimate

Price your ADU. Then check it fits.

An itemized planning range for your ADU, and a quick check of which ADU types your lot can take — tuned to each Puget Sound city.

02 — ADU TYPE
300 SF1,000 SF · STATE FLOOR1,200 SF
04 — FINISH LEVEL
05 — DESIGN
06 — UTILITY CONNECTIONS
Roof trusses of a house under construction
Carpenter framing a wall
Finished compact kitchen
§HOW THE NUMBERS ARE BUILT
Cost per square foot, by type New construction, conversions and modular units each carry their own base rate, adjusted for local labor and permitting in your city.
Fixed costs, itemized Design, permit fees and utility connections don’t scale with size, so they are shown as their own lines.
Ranges, not a single number Every line is a low–high band. Soil, access and finish choices move a real project inside it. Methodology & sources →