Trusted Tukwila 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 Tukwila. 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 Tukwila and King County with careful, lasting craft.
We map detached backyard cottages and attached accessory units around your lot and the way you want to live each day.
City zoning and the two-ADU law can feel like a maze. We walk each permit step so your build clears every code check.
We select rugged, energy-smart materials that trim upkeep, last for decades, and keep your monthly utility costs down.
From the first consult and 3D renderings right through to final sign-off, we steer each 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 Tukwila. Our full services include:
Add a freestanding backyard cottage on your Tukwila lot, a smart fit for rental income, family, or a quiet guest space.
Rework underused interior space into a fully livable attached ADU, adding a second home within your current footprint.
Building down the line? We raise yard additions and outbuildings set up to become a future detached ADU when you choose.
We shape bespoke ADU floor plans and layouts around your Tukwila lot, your budget, and just how you plan to use it.
We manage each city 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
01
We visit your Tukwila property, listen to your goals, and give clear guidance on the right ADU or home plan for the lot.
02
Our design team delivers full blueprints and 3D renderings, so you can see your ADU or addition in true detail long before we dig.
03
We handle each city permit, zoning rule, and code check, so the legal paperwork never turns into your problem to solve.
04
Our crew clears and preps the ground, then builds with true care, keeping the site neat, orderly, and easy on your routine.
05
Once we wrap up, a careful inspection and walkthrough confirm that every last detail meets our own safety and quality marks.
An accessory dwelling unit is a self-contained second home on a single-family lot, either attached to the house or a detached backyard cottage. Under Tukwila Municipal Code 18.50.220, you can build up to two ADUs on a lot with a principal home. Attached in-law suites and detached DADUs are both allowed, opening more housing options than before.
An accessory dwelling unit turns unused yard or interior space into rental income, multigenerational housing, or a private guest suite. It adds living space and resale value without buying more land. With Tukwila’s central location near light rail and Southcenter, a backyard cottage or in-law suite draws steady long-term tenants.
Yes. Every attached or detached ADU needs a building permit through the Tukwila Permit Center, along with zoning, land-use, and construction review under the Tukwila Municipal Code. Detached backyard cottages and interior conversions each follow their own standards. We prepare the plan set and manage the full application for you.
Cost tracks with size, unit type, and finish level. An interior conversion of existing space is the most affordable route, while a full detached DADU with its own foundation costs the most. Utility hookups and site prep add to the total. We give one written estimate after a free on-site consultation.
Most accessory dwelling units take a few months from permit issuance to move-in. Design, engineering, and city plan review add time before construction starts. A detached backyard cottage usually runs longer than an attached conversion. We hand you a full timeline before any ground is broken.
Yes. Washington’s HB 1337 removed owner-occupancy rules, so you can rent both the main house and the ADU without living on-site. That makes a second unit a strong long-term rental and income property. Short-term rentals follow separate city regulations, which we can walk you through.
Tukwila allows an attached ADU up to 40 percent of the principal home’s floor area or 1,000 square feet, whichever applies. State law bars any city from capping an ADU below 1,000 square feet, so detached backyard cottages have real room. We design to the largest unit your lot and setbacks permit.
Much of Tukwila sits in the Green River valley floodplain, and a low-lying lot adds flood-hazard requirements to an ADU build. Elevated foundations or extra engineering may apply. We check FEMA and city flood maps for your parcel before finalizing any design, so there are no costly surprises.
It depends on the unit. A detached DADU often needs its own water, sewer, and electrical connections, while an attached ADU can share systems with the main house. Separate meters help if you plan to rent. We assess utility capacity and connection costs during the site evaluation.
Usually yes. Adding permitted living space increases your home’s assessed value, so property taxes typically rise. The rental income or added equity from an accessory dwelling unit often outweighs the bump. The King County assessor sets the exact figure after final inspection.
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.