Are you looking to expand your living space, build a rental unit, or create a guest house? BB-Builders Pro specializes in high-quality Detached Accessory Dwelling Units (D-ADUs), Accessory Dwelling Units (ADUs), and home extensions tailored to your needs. Whether you need a standalone backyard cottage, an attached ADU, a garage conversion, or a full home addition, our experienced team delivers custom solutions that enhance both the functionality and value of your property.
Trusted Family Owned Remodeling Service
Our licensed ADU construction team has completed numerous projects across King County, ensuring top-tier craftsmanship.
We create tailor-made ADU floor plans and home layouts that blend seamlessly with your existing property and lot size.
Navigating zoning laws and permits can feel overwhelming. We handle every step, so your ADU construction meets all code requirements.
We use durable, high-performance materials built to last longer, reduce maintenance costs, and help lower your monthly energy bills.
From initial consultation and 3D renderings to final walkthrough, we manage every step of your ADU construction project closely.
BB-Builders Pro offers a wide range of services to cover every aspect of your expansion project. Our comprehensive services include:
Create a standalone, fully functional living space in your backyard, ideal for rental income, aging parents, or guest accommodations.
Convert your garage or repurpose underused space into a fully livable attached ADU, with no separate building footprint required.
Planning ahead? We design yard additions and outbuildings built to support a future detached ADU on your property.
We create tailor-made ADU floor plans and layouts designed to fit your lot, your budget, and your long-term goals.
We handle all permits, zoning approvals, and municipal requirements, ensuring a smooth and legal ADU construction process.
Already have an existing ADU or home extension? We offer renovations, interior upgrades, and energy-efficient improvements.
Testimonials
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We assess your property, discuss your goals, and offer expert advice on the best ADU or home expansion options for your needs.
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Our architects create detailed blueprints and 3D models, allowing you to visualize your ADU or home addition before construction begins.
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We take care of all permits, zoning regulations, and compliance requirements, so you don’t have to worry about legal issues.
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Our skilled builders begin the construction process, ensuring quality, efficiency, and minimal disruption to your property.
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Once complete, we conduct a thorough inspection and walkthrough, ensuring everything meets safety and quality standards.
An ADU is a secondary housing unit on a single-family lot in Bellevue, either attached to the home or in a separate detached structure. Bellevue allows up to two ADUs per qualifying lot. As of June 2025, both attached and detached ADUs are permitted under updated city code. This makes Bellevue more flexible for homeowners than it was just a year ago.
An ADU adds rental income, housing for family, or extra living space without buying a new property. Since 2023, Bellevue ADUs can be sold separately from the main home, adding flexibility for resale. They also support multigenerational living, letting aging parents or adult children stay close while keeping privacy. Many homeowners use an ADU to offset their mortgage with steady rental income.
Yes. Bellevue requires a building permit and a complete site plan for both attached and detached ADUs. Standard residential permits typically take two to four weeks for first review. Projects that trigger critical area or stormwater review can take six to twelve weeks or longer. Submitting a complete application up front is the best way to avoid delays.
A new detached ADU in Bellevue typically costs $450,000 to $650,000 all-in, including design, permits, and construction. Attached ADUs tend to run somewhat lower since they share an existing foundation and walls with the main home. Garage conversions are the most affordable option, often costing under $250,000 depending on the garage’s condition. Permit fees alone can run from several hundred to a few thousand dollars, based on your project’s construction valuation.
Most standard Bellevue ADU permits take two to four weeks for the first round of review. Projects near wetlands, steep slopes, or other critical areas can take six to twelve weeks or more due to additional review. Total construction time depends on the size and complexity of the ADU itself. Most homeowners should plan for several months from permit submission to move-in.
Yes. Bellevue removed its owner-occupancy requirement, so you are no longer required to live in either unit. This means you can rent out your ADU, your main home, or both at the same time. Rental income can help offset mortgage or construction costs significantly. Just be sure to follow any applicable landlord-tenant regulations in Washington state.
Bellevue allows ADUs up to 1,200 square feet in floor area, whether attached or detached. Detached ADUs are limited to 24 feet in height, or 28 feet if built above an existing accessory structure. Attached ADUs follow the same height and setback rules as the main home. These limits give homeowners meaningful flexibility for a full living space.
Utility requirements depend on your specific site and the size of the ADU. Many attached ADUs share utility connections with the main home, which can simplify the project. Detached units sometimes need separate connections, especially for water and sewer. Your contractor or the city’s Development Services team can confirm what your specific lot requires.
Yes. Bellevue allows garage conversions into ADUs, even if the existing garage does not meet current setback requirements. This makes garage conversions one of the more cost-effective ways to add an ADU. The structure still needs to meet building, electrical, and plumbing code standards. A permit and site plan are required just as with new construction.
Adding an ADU typically increases your home’s assessed value, which can raise your property taxes. The exact increase depends on the size, finishes, and overall value the ADU adds to your property. King County handles property tax assessments, not the City of Bellevue directly. Contacting the King County assessor’s office is the best way to get a specific estimate.
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.