ADU Parking Rules in Seattle: What You Need to Know
By Eric Dexter, Owner & Builder ·
One of the first worries homeowners have about building an ADU is parking: do I have to add a spot? For a lot of Seattle-area lots, the answer is now no — the rules loosened significantly. Here's where things stand.
The short answer
In many cases you no longer have to add off-street parking to build an ADU or DADU — especially on lots near frequent transit. That change removed one of the biggest obstacles to backyard homes.
What changed
As part of Washington's broader ADU reforms, cities can no longer require added parking for ADUs within a set distance of major transit, and overall parking mandates were rolled back — alongside the removal of owner-occupancy requirements. The goal was to stop small, arbitrary rules from blocking new housing.
When parking might still apply
This is where it gets local: outside transit-rich areas, some cities in King and Snohomish County may still ask for a space, and design or access standards vary by jurisdiction. The only way to know your exact requirement is to check your specific lot and city.
Why it matters for your build
No parking requirement means more of your lot is available for the actual home — and one less cost and design constraint. It can be the difference between a DADU fitting comfortably or not. See whether your lot works in can I build an ADU on my lot?
Confirm the rules for your lot
We sort out parking, setbacks and every other requirement as part of a feasibility study. Check the ADU & DADU FAQ, or send us your address and we'll tell you what applies.
