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Washington ADU Builders
Washington's HB 1337 (2023) requires most cities to allow at least two ADUs per lot, opening the Seattle metro and beyond to backyard cottages at scale. The state's scene includes design-led firms creating timber-frame and SIPs prefab ADU plans.
1 verified builders
Every listing is an ADU-focused business verified against its own website. Featured partners are license-checked.
Prefab & Design
FA
Boutique architecture/design firm; timber-frame + SIPs prefab ADU designs; est. 2011.
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