ADU Builders Seattle

With more than 15 years of experience and over 1,000 completed projects across Washington, Renovate Builders specializes in designing and building high-quality ADUs that provide homeowners with functional, code-compliant living spaces built to last.

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Premier ADU Contractor Seattle

Seattle’s housing crisis isn’t slowing down. ADUs or Accessory Dwelling Units help ease the pressure by adding more living space to your existing home. With 15+ years in business and over 1000+ in successful projects across Washington, Renovate Builders knows how to design and construct ADUs that create space and facilities for homeowners, both functionally and legally. Our in-house team of 25+ local professionals takes care of planning, custom design, permits with the City of Seattle, coordination with utility companies, and building your project.

All of our ADU construction Seattle balances cost, quality and speed. We use durable, high-quality materials that endure the city’s weather and wear, providing value for rental income, multigenerational living, and future resale. From backyard cottages to detached garages and basement units, every build is code-compliant and optimized for ROI.

Different Types of ADUs Seattle

Detached ADUs (DADUs):

Detached ADUs are small, independent units built separately from the main home and are also called “backyard cottages”. Have an underused backyard space? You can make it useful through long-term rentals or multigenerational living with the help of detached ADUs. Call us for site planning, custom design, permitting, and full build.

Attached ADUs or Garage ADUs:

Attached ADUs share at least one wall or structural component with the main home. We also call them home extensions or garage ADUs, as they are usually built over garages or as side additions. Need a space for in-law suites or flexible rental space with shared utilities? This option is for you that adds luxury and comfort to your lifestyle.

Conversion ADUs:

Conversion ADUs are garage or basement conversions. We use existing square footage, like basements, attics, or garages, and transform them into livable units. This option is best for fast turnaround and lower cost-per-square-foot, making it ideal for short-term rental or guest suites.

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Benefits of Investing in an ADU or Cottage

Income Without Relocation

ADUs generate consistent passive income through short- or long-term rentals. It’s one of the lowest-barrier ways to invest in real estate without buying a second property or moving out.

Higher Resale & Appraisal Value:

And if you do relocate, it’s known that Seattle homes with ADUs consistently sell for more. Buyers value extra rentable space, which means your property stands out in listings.

Built-In Futureproofing:

Adding an ADU gives your property long-term flexibility. Enjoy a livable space for aging parents, adult kids, or a future home office. It adapts to your lifestyle while preserving privacy and personal space.

Our Process: How We Build Your ADU or DADU

Site Assessment:

We evaluate your lot for zoning, access, and size constraints before beginning any design or permitting process.

Concept & Pre-Approved Plans:

Choose from Seattle’s pre-approved and popular ADU/DADU plans, or work with us to develop a custom layout.

Custom Design & Engineering:

Our in-house team develops detailed drawings optimized for layout, light, and utility performance before submitting permit applications.

Permitting & Approvals:

We handle all city submissions, revisions, and responses. Since Seattle permits can take several months to a year, our proactive process helps prevent costly rejections.

Full Build & Final Delivery:

Once approved, our crew begins excavation, foundation, framing, and finishes. You’ll get a fully permitted, move-in-ready ADU or DADU.

Why Choose Renovate Builders?

Renovate Builders is one of the top Seattle ADU contractors, and we’re the backbone behind over 1,000 successful custom ADU and DADU builds. With 25+ in-house experts, we deliver custom ADUs that meet the city’s strict codes, maximize rental ROI, and match your home’s architecture. Our goal is to make sure that the ADU fits in or out of your home without sticking out.

Local Experts: Unlike most firms, we build with our in-house crew for faster timelines and better control. You’ll get a Seattle-based crew of 25+ pros delivering fully managed ADU and DADU projects.
Pre-Approved or Fully Custom Options: Choose from fast-track, permit-ready plans or build a high-end custom ADU with luxury design features tailored to your needs.

Whether you want premium finishes or need a cheap, affordable option, we offer scalable design-build solutions without sacrificing quality. From zoning headaches to DADU footings, we solve it, manage it, and finish it, because that’s what the best ADU builders Seattle should do.

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Frequently Asked Questions

How much does a custom Seattle ADU cost to build?

ADU costs range from $100,000 to $350,000+, but the exact price depends on the size, layout, location, and type (like garage conversion or detached unit). Call us for a custom quote!

Can I rent out an ADU legally in Seattle?

Yes. Seattle allows long-term and short-term ADU rentals with some occupancy and licensing rules.

How long does it take to build a home addition or ADU?

Most ADUs or home additions take about 3 to 6 months to finish. We give you a timeline upfront.

Do you handle utilities and foundations for detached ADUs?

Absolutely. We manage trenching, utility hookups, foundation pouring, and all required inspections.

How can I get started building my cottage or ADU?

Most online DIY advice won’t work, since ADUs/DADUs involve permits in Seattle. The best option is working with a licensed contractor, so start by reaching out to us.

Read What Our Clients Say About Us on Google

      EXCELLENT  
   Based on 37 reviews 
    
 
 
 
   
 
 
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   Luxe Cabinet 
 
 
 
 Trustindex verifies that the original source of the review is Google. good customers, purchase cabinets and floors, happy to pick up, generous, 5 stars customers
  
 
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   Rajsekhar Das 
 
 
 
 Trustindex verifies that the original source of the review is Google. Renovate builders rebuilt two external staircases, with new composites.
Really happy with the outcome, and the level of engagement with Project Manager Adi, during the whole process.
Would use them again in future.
  
 
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   Kristin Pezall 
 
 
 
 Trustindex verifies that the original source of the review is Google. Called to get a quote and they scheduled it for the next day! Eddie came out to give the quote and did a great job! Arrived in the allotted time window and was extremely thorough and very personable. I appreciate how quick and painless they made this experience.
  
 
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   Destiny Jayson 
 
 
 
 Trustindex verifies that the original source of the review is Google. We had old wood siding that was starting to rot and peel. I contacted a few companies, but this team stood out right away. They walked me through different siding options and helped me pick something that matched the style of the house. The install was quick, clean, and the results are stunning. Couldn’t be happier with Renovate Builders in Seattle.
  
 
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   Dallas Maverick 
 
 
 
 Trustindex verifies that the original source of the review is Google. We needed a retaining wall for both support and aesthetics. The team helped design a stone wall that blends beautifully with our landscaping. The crew worked hard, finished on schedule, and left everything clean. Excellent craftsmanship from Renovate Builders in Seattle.
  
 
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   Aubrey Brenton 
 
 
 
 Trustindex verifies that the original source of the review is Google. The bathroom was small and dark, and I wasn’t sure how much could really be done with the space. But they worked wonders—added better lighting, smart storage, and even made room for a double vanity. The transformation was beyond my expectations. Big thanks to Renovate Builders in Seattle.
  
 
      Posted on Google  
   
   William Graham 
 
 
 
 Trustindex verifies that the original source of the review is Google. Renovate Builders did an amazing job on our home renovation. The team was professional, efficient, and paid attention to every detail. Highly recommend their services!
  
 
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   AMG JUNK REMOVAL 
 
 
 
 Trustindex verifies that the original source of the review is Google. These guys are the real deal if you're looking for a crew that's on time affordable and professional I highly recommend choosing them.
  
 
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   Sophie Conor 
 
 
 
 Trustindex verifies that the original source of the review is Google. They helped renovate my living room and dining area, and I couldn’t be happier with the outcome. The team was respectful of my space, worked efficiently, and left everything spotless. The transformation is incredible—would definitely hire them again!
  
 
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   Elyse Gwen 
 
 
 
 Trustindex verifies that the original source of the review is Google. We hired Renovate Builders to build a custom deck, and they exceeded all our expectations. The craftsmanship is top-notch, and the team was incredibly easy to work with. Our new outdoor space is perfect for summer gatherings—highly recommended!