ADU and DADU Builders in Bellevue, WA
Bellevue allows two ADUs on a lot, each up to 1,200 square feet, attached to the house or detached in the yard.
- We check slopes, setbacks and parking for your lot before anything is drawn.
- We draw the unit and file the Bellevue permits through MyBuildingPermit.com.
- You approve a written, itemized price before work starts.
By appointment. Limited start dates.
- Over 200 projects
- 4.9 on Google
- 20+ years of experience
- WA license VOLCABI792C6
Four ways to add an ADU to a Bellevue lot
An ADU is a second home on your lot with its own kitchen, bathroom and entrance. In Bellevue it can take four forms.
Attached ADU
A new wing built onto the house, with its own entrance. It counts toward the two ADUs a lot may hold and stays within 1,200 square feet.
ADU inside the house
A basement or lower floor turned into a separate unit. Bellevue treats creating an ADU inside the house as a remodel that needs plan review.
Detached ADU (DADU)
A backyard cottage on its own foundation, up to 24 feet tall, or 28 feet when it is built over an existing accessory structure such as a garage.
Garage conversion
An existing garage can become an ADU even if it sits closer to the lot line than today's setbacks allow.
How an ADU and a DADU differ is on ADU Builders Across the Greater Seattle Area. For the main house, see home remodeling in Bellevue.
Bellevue ADU rules in force today
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The Bellevue rule
Two units per lot, 1,200 square feet each
Any Bellevue lot that allows a single family house can have up to two accessory dwelling units under LUC 20.20.120. Each can have up to 1,200 square feet of floor area, not counting up to 300 square feet of parking or unheated storage. Ordinance 6931, adopted 28 July 2026 and effective from 4 August 2026, amended the section again.
What we doWe measure the house and lot and tell you which mix of units fits before a plan is drawn.
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The Bellevue rule
Detached units since July 2025
Council adopted Ordinance 6851 on 24 June 2025, and detached ADUs have been allowed since it took effect in summer 2025. A detached unit is capped at 24 feet in height, or 28 feet when it sits over an existing accessory structure.
What we doWe draw the DADU to those heights and to the setbacks for your zone.
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The Bellevue rule
Parking only for larger units
An ADU under 1,000 square feet needs no parking space, and neither does one within half a mile of a major transit stop. A larger unit farther from transit needs one space.
What we doWe size the unit with the parking rule in mind, so a space is only planned where the code asks for one.
The owner does not have to live on the property: Bellevue dropped that requirement with Ordinance 6746 on 17 July 2023.
Bellevue ADU permits and timeline
Bellevue Development Services issues every ADU permit, fully paperless.
- Inside the house or in the garage: the single family remodel permit with plan review.
- Detached ADU: permitted like a house, on the one and two family residence permit.
- Filing: applications, plans, fees and inspection requests all go through MyBuildingPermit.com.
- Slopes: a slope of 40 percent or more with 10 feet of rise is a steep slope critical area with a 50 foot buffer, which can move or shrink the unit.
- Timeline: the city publishes median and average processing days for each permit type, and we set your start date from the medians, not the fastest cases.
How we build your Bellevue ADU
One licensed team from the lot check to the final inspection.
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Lot check and written price
We visit, check zoning, slopes, sewer and power, and send a written, itemized estimate.
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Drawings and permits
We draw the unit, show it in 3D and pull the Bellevue permits, then answer any correction the city sends.
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Build and warranty
One project manager runs the build through every inspection. The work carries our 2-year workmanship warranty.
Who builds your ADU
Volcano Builders is a licensed general contractor, WA license VOLCABI792C6, with our main office in Bellevue.
Over 200 projects
Kitchens, bathrooms, basements, additions and whole homes completed across Western Washington.
20+ years
Bar, our founder, has been building for 20+ years, and every job is run by one project manager.
132+ cities
We work across 8 Western Washington counties, from Bellevue and Seattle outward.
4.9 on Google
The rating on our main Google Business Profile.
See the finished jobs in Our Completed Remodeling Projects, and the warranty terms on Remodeling Warranty for the Greater Seattle Area.
Kitchens, bathrooms and concrete we have built
An ADU is built around a kitchen and a bathroom. These are finished kitchen and bath jobs, labelled with what they are and where.
What homeowners say about working with us
Had a great experience working with Volcano Builders on remodeling bathroom and flooring in my condo! Bar and his team were very professional from estimates to timely completion of the job! Highly recommend!
I had an amazing experience with Volcano Builders! Bar was incredibly kind, communicative, and made the whole process smooth. We completely redid the bathroom,new flooring, vanity, tub, and wall tiles, and it turned out fantastic. I'm so happy with their work that I'm already planning my second bathroom and hopefully the kitchen too. Highly recommend them to anyone looking for quality work and great service!
Volcano Builders did a great job on our master bathroom. The tile work and finishing touches were great. Even though they weren't the cheapest quote we got, you can tell they care about quality.
Read more of our Google reviews, word for word, with video reviews from finished homes.
Our workmanship warranty
- 2 years standard. Our installation and labor are covered for 2 years from substantial completion.
- Up to 5 years. You can extend the workmanship coverage up to 5 years for an added charge, set in your contract.
- Not transferable. Coverage stays with the homeowner who signed the contract and does not pass to a new owner.
- Materials. Materials, finish materials included, carry the manufacturer's or supplier's warranty, and we help you file a claim.
Remodeling Warranty for the Greater Seattle Area
Related: Kitchen Remodeling Portfolio Across the Greater Seattle Area, Bathroom Remodeling Portfolio Across the Greater Seattle Area, ADU Builders Across the Greater Seattle Area, Home Remodeling Contractors in Bellevue, WA.
Bellevue ADU questions
Can I build a detached ADU in Bellevue?
Yes. Detached ADUs have been allowed in Bellevue since Ordinance 6851, adopted by Council on 24 June 2025, took effect in summer 2025. A detached unit can be up to 1,200 square feet and 24 feet tall, and it is permitted like a house on the one and two family residence permit.
How many ADUs can I add to my Bellevue lot?
Two. Any lot that allows a single family house can have up to two ADUs, attached, detached or one of each (LUC 20.20.120).
Do I have to live on the property?
No. Bellevue removed the owner occupancy requirement with Ordinance 6746 on 17 July 2023, so you do not have to live in the house or the ADU.
Can I turn my garage into an ADU in Bellevue?
Usually, yes. The code lets an existing garage be converted even when it does not meet today's setbacks. The conversion goes through the single family remodel permit with plan review. More on the work itself in Garage Conversion.
How do I get a price for a Bellevue ADU?
Book a consultation below. We check the lot, talk through who the unit is for and send a written, itemized price before any work starts. For background, read How Much Does It Cost to Build an ADU? and our Remodeling Pricing Guide.
Book your Bellevue ADU consultation
Four quick steps. Tell us about your project and we’ll reach out to discuss it and see if we’re the right fit.