A: The ADU process typically follows design → permit application → construction → inspection → final approval. We help you at every step, from preparing site plans to navigating reviews.

A: In Seattle, ADU costs commonly range from $200 to $400 per square foot, depending on finishes, utility upgrades, site complexity, and compliance costs.

A: Seattle limits ADUs to 1,000 square feet in most zones, with setbacks and height rules that now match primary home standards under the new consolidated ADU code.

A: Yes. If your lot is in a Neighborhood Residential zone and has no critical area issues, you may use a pre-approved standard plan for a detached ADU (DADU) to fast-track permit review.

A: Yes. When adding an ADU, Seattle submits your project to King County for a sewer treatment capacity charge, often billed quarterly over up to 15 years.

A: Using a standard plan, you can often get permit approval in 2 to 6 weeks, though full design and review can take several months depending on complexity.

A: Under Seattle’s new 2025 code update, yes — you may now build up to two ADUs on a single lot (in addition to the primary home) in many zones.

A: No. ADUs in Seattle are exempt from off-street parking requirements, and you cannot remove existing required parking unless replaced elsewhere on the lot.

A: Yes. ADUs may be rented under Seattle law with no owner-occupancy requirement under current rules.
(Seattle ADU policy)