ADU Construction in Seattle, WA

Yes, Seattle allows detached ADUs on residential lots across all Neighborhood Residential zones. A detached ADU can be up to 1,000 square feet, and setbacks, height limits, and lot coverage rules apply based on your specific parcel.

Seattle allows up to two ADUs on a single lot, one attached and one detached, alongside the primary residence. Rules vary by zone, so your lot's zoning designation determines exactly what is allowed.

No, Seattle eliminated the owner-occupancy requirement in 2019. You can build and rent an ADU without living on the property.

We build both attached ADUs, such as basement or garage conversions, and detached ADUs, such as backyard cottages. We serve homeowners across Seattle, Kirkland, Redmond, Sammamish, and surrounding areas.

Adding an ADU creates an additional livable or rentable unit, which increases the functional value and market appeal of your property. Buyers in the Seattle area increasingly look for lots with existing or potential ADU capacity.

An ADU involves structural framing, roofing, siding, windows, mechanical rough-ins, and finish work all in a compact footprint. A contractor with experience across those trades can plan and coordinate each phase without gaps or rework.