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ADU / DADU Packages & Pricing in the Greater Seattle Area

Free in-home design consultation

Find out what fits on your lot — free feasibility study.

We check zoning, utilities and what fits on your lot, then give you a realistic range. Before construction, you sign a fixed-price contract.

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Discover the Benefits of ADUs & DADUs

ADUs and DADus offer many benefits, including

Bonus Space

They provide additional square footage versatile enough to be created into an office, home gym, entertainment center, playroom, studio, or anything in between

Additional Rental Income

You can generate extra income by renting out your ADUs or DADU, maximizing the value of your property, and recouping back your investment.

Multigenerational Living

ADUs and DADUs are ideal for accommodating grandparents, extended family who are visiting, or college-aged children. Everyone is able to have their own space and privacy.

Explore our
customize packages

Compact

Space-efficient ADUs for singles, couples, or starter rentals.

OFFERINGS

Priced as a package

Standard

Mid-size ADUs with a balance of comfort and value — great for guests or a small office + bedroom.

OFFERINGS

Priced as a package

Family

Two-bedroom ADUs with full living areas for families, roommates, or extended stays.

OFFERINGS

Priced as a package

Spacious

Large ADUs with open layouts, bonus rooms, or home offices. Perfect for multi-gen living or long-term rentals.

OFFERINGS

Priced as a package

Compact

Space-efficient ADUs for singles, couples, or starter rentals.

OFFERINGS

Priced as a package

Standard

Mid-size ADUs with a balance of comfort and value — great for guests or a small office + bedroom.

OFFERINGS

Priced as a package

Family

Two-bedroom ADUs with full living areas for families, roommates, or extended stays.

OFFERINGS

Priced as a package

Spacious

Large ADUs with open layouts, bonus rooms, or home offices. Perfect for multi-gen living or long-term rentals.

OFFERINGS

Priced as a package

See why you should
consider to building an ADU

Affordable financing available – check your eligibility today!

What’s Included in our ADU construction services

Design
Consultation

You’ll work with our expert team of designers and builders to craft custom design plans for your ADU or DADU.

Professional Workmanship

Our ADU construction process is meticulously executed by seasoned professionals to ensure flawless results.

Genuine
Materials

We prioritize both durability and aesthetics by selecting only the finest genuine materials from top vendors and manufacturers.

Project Management

Efficient project management is at the heart of our approach. This allows us to complete your ADU project on time and within budget.

Customer Satisfaction

Your satisfaction is our top priority. We are committed to providing ongoing support throughout every phase of the project.

Permitting and Compliance

We handle all aspects of permitting and regulatory compliance.

Calculate the cost of
your ADU or DADU Instantly!

Curious about the cost of your ADU project? Use our easy-to-navigate cost calculator to get a detailed estimate tailored to your needs.

Our ADU / DADU plans

Signature Modern – 1,205 sq ft

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Project type	Family
Size	Spacious ADU (1,205 sq ft)
No. of rooms	2
No. of baths	2.25 BA
ADU type	Modern/Luxury
Notable	Two levels
Location (state)	Seattle, WA

The Atlas – 1,213 sq ft with garage

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Project type	Spacious
Size	Large ADU (1,213 sq ft)
No. of rooms	2
No. of baths	1.5 BA
ADU type	Luxury
Notable	Over a 2-car garage / shop
Location (state)	Washington

Cedar Groove – 800 SF (with garage)

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Project type	Family
Size	Standard ADU (800 sq ft)
No. of rooms	2
No. of baths	1 BA
ADU type	Modern
Notable	Attached garage
Location (state)	Washington

Cedar Groove – 800 SF

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Project type	Family
Size	Standard ADU (800 sq ft)
No. of rooms	2
No. of baths	1 BA
ADU type	Luxury
Notable	Single level
Location (state)	Washington

The Ridge G – 994 sq ft.

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Project type	Family
Size	Large ADU (994 sq ft)
No. of rooms	2
No. of baths	0.75 BA + 2 Car Garage
ADU type	Contemporary
Notable	Over a 2-car garage
Location (state)	Washington

The Country Cottage – 785 sq ft.

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Project type	Standard
Size	Standard ADU (785 sq ft)
No. of rooms	2
No. of baths	1 BA
ADU type	Luxury
Notable	Single level
Location (state)	Washington

The Horizon – 981 sq ft.

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Project type	Standard
Size	Large ADU (981 sq ft)
No. of rooms	1
No. of baths	1 BA
ADU type	Contemporary
Notable	Over a garage
Location (state)	Washington

Main St ADU 550 Sf

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Project type	Compact
Size	Compact ADU (550 sq ft)
No. of rooms	1
No. of baths	0.75 BA
ADU type	Compact
Notable	Single level
Location (state)	Washington

What people say about us

United Signature handled a large and complex kitchen reconstruction and remodel after a leak was discovered in the wall and under the floorboards. They were great communicators and helped me handle insurance and the HOA.

We had a bathroom and kitchen remodel done by Oleg (senior project manager), Natasha (lead designer) and Sergei (project manager). Excellent, high quality work. Always available and professional.

Exceptional service! I recently had my kitchen renovated by United Signature Design and Build and I couldn’t be happier with the results. From the initial consultation to the final details, everything went so smooth.

Oleg, Anna, and their team made all of our kitchen dreams come true! This review is long overdue but they were the absolute best team to work with. We will absolutely be using their services again when we decide to renovate our master bathroom!

It was a pleasure to work with United Signatu. Company perform best quality of services and products. Friendly approach, time efficiency. If you are looking for a project well done I strongly recommend United Signature .

Awesome kitchen remodeler company. Got the job done quick and on time. Will definitely use them again when I have remodel needs. I recommend to everyone looking for a good kitchen remodeler. Also shoutout to Nina for doing a great job with her work.

Frequently Asked Questions About ADU Construction

How much does it cost to build an ADU?

Our backyard homes are priced as five packages, from $297,049 in 2026. Each price includes construction, the builder’s fee and design & engineering; permits, utility and connection fees, and sales tax are extra. A fixed price comes after a site visit and design. See the packages and prices →

What is ADU?

An accessory dwelling unit (ADU) is a second, smaller home on a single-family lot, with its own kitchen, bath and entrance. A detached ADU (DADU), or backyard home, stands on its own; an attached ADU is part of the house, such as a basement unit, a garage conversion or an addition.

What kind of ADUs are there?

Detached backyard homes (DADUs), garage conversions, basement or attic units, and attached additions. Washington’s 2023 law (HB 1337) requires cities and counties to allow two ADUs on most lots inside urban growth areas.

Where on my property can I build an ADU?

It depends on your lot: setbacks, lot coverage, utilities, trees, slope and easements decide where a backyard home can go. A free feasibility report checks your lot’s zoning and mapped constraints and shows where one may fit.

How big can an ADU be in Washington state?

Under Washington’s HB 1337 (RCW 36.70A.681), cities and counties inside urban growth areas can’t cap an ADU below 1,000 sq ft. Some allow more — unincorporated Snohomish County allows 1,200 sq ft. Your city’s code sets the exact limit, and the feasibility report names it.

Where do I start if I want to consider building an ADU?

Start with a free feasibility report on your address. It shows what your lot may allow within a few hours. Then we visit, design, and give you a fixed price. Get my free report →