Trusted Seattle ADU Builders for Detached and Attached Units
Want a rental unit, guest house, or more room for family? BB-Builders Pro is a team of ADU builders serving Seattle. We design, permit, and build detached backyard cottages and accessory dwelling unit additions. State law now allows up to two ADUs per lot, so there is more room to add value than ever. We handle the full build, from site evaluation to final walkthrough, on your schedule.
Trusted Family Owned Remodeling Service
Our licensed crew has built detached and attached ADUs across Seattle and King County with careful, lasting craft.
We draw detached backyard cottages and attached accessory units around your lot and how you want to live day to day.
SDCI review and the two-ADU law can feel like a maze. We walk each permit step so your build clears every code check.
We pick rugged, energy-smart materials that lower upkeep, hold for decades, and keep your monthly utility costs down.
From the first consult and 3D renderings through to final sign-off, we steer every phase of your ADU build with care.
BB-Builders Pro handles every part of your ADU project, from first sketch to final sign-off in Seattle. Our full services include:
Set a freestanding backyard cottage on your Seattle lot, an ideal fit for rental income, family, or a private guest retreat.
Convert underused interior space into a fully livable attached ADU, adding a second home inside your current footprint.
Building later? We put up yard additions and outbuildings set up to become a future detached ADU whenever you choose.
We shape bespoke ADU floor plans and layouts around your Seattle lot, your budget, and exactly how you plan to use it.
We manage each SDCI permit, zoning sign-off, and code check, keeping your ADU project moving along smoothly and legally.
Already own an aging ADU or home extension? We take on renovations, interior updates, and energy-efficient upgrades too.
Testimonials
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We come to your Seattle property, listen to your goals, and offer clear guidance on the right ADU or home plan for the lot.
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Our design team creates full blueprints and 3D renderings, so you can see your ADU or addition in true detail well before we ever dig.
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We handle each SDCI permit, zoning rule, and code check, so the legal paperwork never turns into your problem to solve.
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Our crew clears and preps the ground, then builds with real care, keeping the site clean, orderly, and easy on your routine.
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Once we wrap up, a thorough inspection and walkthrough confirm that every last detail meets our safety and quality marks.
An ADU is a secondary home on a single-family lot, either attached to the main house or built as a separate detached structure. Seattle allows at least two ADUs per lot, and recent zoning changes let some lots hold even more homes. Both attached and detached units are permitted, giving homeowners more flexibility than ever.
An ADU adds rental income, housing for family, or a private guest space. Seattle also offers a limited-time property tax exemption on new ADUs, which improves the return. Strong citywide rental demand makes a second unit a dependable long-term investment.
Yes. Seattle’s ADUniverse program offers a gallery of pre-approved detached ADU designs from local architects. Building from one can shorten permit review to as little as two to six weeks. We build from an ADUniverse plan or design a fully custom unit, whichever suits your lot.
Yes. Every ADU in Seattle needs a permit through SDCI, plus zoning and code review under the city’s updated rules. Detached units and conversions each carry their own requirements. We prepare the full application and manage it through the Seattle Services Portal for you.
Cost depends on size, type, and finishes. A conversion of existing space runs the least, while a large detached cottage costs the most. SDCI permit fees, a King County sewer charge, and site work add to the total. We give one written estimate after a free on-site visit.
Most ADUs take four to ten months of construction after permits clear. A custom DADU adds four to eight weeks of SDCI review up front, while a pre-approved plan trims that to a few weeks. We map the full schedule before work begins.
Yes. Seattle removed its owner-occupancy rule back in 2019, so you can rent both the main home and the ADU without living on-site. That makes a second unit a strong income option. Short-term rentals follow separate city rules, which we can point you to.
Seattle caps an ADU at 1,000 square feet, or 60 percent of the primary home, whichever is smaller. Detached units also gain generous lot-coverage allowances. Height limits rose sharply under the new code. We design to the largest unit your lot allows.
Yes. Seattle’s tree protection rules and critical-area limits on steep slopes, wetlands, and shorelines can shape where a detached ADU sits. These are easy to miss and costly to fix late. We check your lot for these constraints before we finalize the design.
Not always. Some ADUs share water and power with the main house, while others need separate connections depending on size and layout. Seattle also applies a King County sewer capacity charge. We assess your utilities during the site evaluation.
Usually yes, though Seattle offers a limited-term exemption that can soften the impact for several years. Adding livable square footage raises your assessed value over time. The King County assessor sets the exact change after the build.
Simple Financing Options
Discover the perfect financing solution for your remodeling project. We provide tailored options to suit your budget and ensure your dream home becomes a reality.
Contact us today for a free consultation, and let’s begin transforming your house into the home you’ve always wanted.
Contact us today for a free consultation, and let’s begin transforming your house into the home you’ve always wanted.