Detached backyard cottage
A separate small house in the backyard, with its own entry, kitchen and bath.
Good at
- Most privacy for a parent, a grown kid or a tenant
- Plans from a studio up to two bedrooms
- Its own address for mail and utilities, where allowed
What we check first
- How far the sewer runs to the street or alley
- Trees with protected root zones
- Slope and drainage at the back of the lot
Fits: Lots with a usable rear yard, ideally with alley access or a clear path for the sewer line.
Plans that start here
Owner slot From-prices set by the builder. Example only; quoted after a site visit. What moves the price
Questions
Current rules: Seattle SDCI ADU page.
How big can a backyard cottage be?
Size, height and setback limits are set by the City and have changed several times. We confirm the current limits for your lot at the feasibility call and point you to the SDCI page, rather than quoting a number here that could be out of date.
Does a cottage need its own sewer line?
Usually it ties into your existing side sewer. The distance and the fall to that line drive a large part of the cost, which is why the lot check asks which side your sewer leaves the house.
Start with the lot.