If you've been thinking about adding a backyard cottage, a space for your parents, or a little rental to help with the mortgage, we have some really good news. Cities around Snohomish County are rolling out pre-approved ADU plans, and they can take a lot of the waiting (and guesswork) out of building one.
We've been getting a lot of questions about this lately, so we put together a quick, friendly rundown of what pre-approved plans are, which cities have them, and what they actually mean for your project.
First, what's an ADU?
An ADU (accessory dwelling unit) is a second, smaller home on the same lot as your main house. It might be attached to your home or a converted garage, or it might be a separate little house in the backyard. That detached version is often called a DADU, and it's the type most pre-approved plan programs focus on.
Families use them for all kinds of things: a place for aging parents to live close by, a first home for grown kids, a home office or studio, or a rental that helps cover costs.
What does "pre-approved" mean?
Normally, an ADU starts from scratch. You hire a designer, they draw up plans, and then the city reviews every page. That back and forth can take a long time.
With a pre-approved plan, the city has already reviewed the building design itself. You pick a plan from the city's gallery, pay the designer a licensing fee to use it, and then your permit review can focus on the parts that are specific to your property. Seattle has offered pre-approved backyard cottage plans since 2020, and a 2023 city report found those permits moved about 40% faster on average.
Everett: three designs ready to go
Everett launched its pre-approved program in June 2026 with three detached ADU designs that range from about 820 to 1,000 square feet. A few things worth knowing:
The designer's licensing fee is typically around $1,500, and the city caps it at $1,500 for ADU designs.
The city's goal is to approve permits for pre-approved designs within about three months. Designing from scratch can take up to a year before permitting even starts.
Everett allows up to two ADUs on a qualifying lot, and DADUs under 1,200 square feet don't have parking requirements.
You can browse the designs on the City of Everett's Pre-Approved Designs page.
Edmonds, Lynnwood, and Snohomish County are on the way
Edmonds launched its pre-approved DADU program this summer and is building its plan catalog now. Plans will cost no more than $1,000 from the designer, and DADUs there can be up to 1,000 or 1,200 square feet depending on zoning.
Lynnwood is developing its own pre-approved DADU program and has been reviewing submitted designs. Keep an eye on the City of Lynnwood's Pre-Approved DADUs page for updates.
Unincorporated Snohomish County is also working on a pre-approved ADU plan program. Under the county's current rules, urban lots with a detached single-family home can have up to two ADUs.
What pre-approved plans don't cover
This is the part we always want folks to know up front. A pre-approved plan covers the house itself, but every lot is different. You'll still need site-specific permits and work for things like:
Site prep and access
Foundation
Utility connections (water, sewer, power)
Stormwater
And here's a big one: if you change the plan, even something small like moving a window, it goes back through the full review process and you lose the time savings. So it really pays to pick a plan you love as-is.
Where Blade comes in
The site work is where a lot of ADU projects get tricky, and it's exactly what we do. From clearing and grading to utilities, foundations, and the build itself, we can take a pre-approved plan from the city's gallery to a finished home in your backyard. We'll help you figure out what your lot needs, and you won't have to worry about a thing.
Thinking about an ADU in Everett, Edmonds, Lynnwood, or anywhere in Snohomish County? Reach out to us and we'd love to talk it through with you!
Program details are current as of October 2026. City programs can change, so check with your city's permit office for the latest.
