Giant Builders SeattleGiant Builders(425) 757-7872
5.0 Rating · 1,000+ Happy Clients · 15+ Years

Seattle's Stress-Free DADU Builders

We handle design, permits & construction — so you can add $200K–$350K in property value and earn $1,500–$3,500/month in rental income without the headaches.

Licensed (GIANTBS78RZ) · Bonded · Insured · 5-Year Warranty

Get My Free Feasibility Check (425) 757-7872

No obligation · No pressure · 100% free

Google ReviewsYelp ReviewsBBB AccreditedHouzz ReviewsAngi Reviews
1,000+
Happy Clients
500+
Projects Completed
15+
Years in Business
Licensed & Insured

Why Seattle Homeowners Are Building DADUs

Seattle's updated zoning laws make building a DADU more accessible — and more profitable — than ever before.

$1,500–$3,500
Monthly Rental Income

Generate consistent passive income in one of the nation's hottest rental markets.

$200K–$350K
Added Property Value

A DADU typically increases your property value by 10–30%, building long-term equity.

Family Flexibility
Multigenerational Living

Keep aging parents close while giving them independence, or provide a private space for adult children.

Sell Separately
New Subdivision Option

Under WA's HB 1337, DADUs can now be subdivided and sold as independent properties.

See What You Can Build — Free

From Idea to Move-In — Our Simple Process

Building a DADU can feel overwhelming. We make it straightforward and stress-free.

Step 01

Free Feasibility Check

We visit your property, review zoning, setbacks, and utilities to determine exactly what you can build.

Step 02

Custom Design

Our in-house designer creates plans tailored to your needs — with 3D renderings so you can see your DADU before it's built.

Step 03

Permits & Approvals

We handle Seattle's entire permitting process. No paperwork headaches for you.

Step 04

Build & Enjoy

Our licensed crew builds your DADU with premium materials. Your project manager oversees every detail until move-in.

Get My Free DADU Feasibility Check

Fill out the form and we'll contact you within 24 hours to schedule your free property assessment.

Limited availability — book your free consultation this week!

No obligationNo hidden feesLicensed & insuredResponse within 24 hrs

Seattle's DADU Rules Have Never Been Better

Recent zoning updates removed major barriers — more properties qualify than ever before.

No Owner-Occupancy Required
Build it as a pure investment — you don't need to live on-site
Lots as Small as 3,500 sq ft
Reduced minimum lot size means more properties qualify
Up to 2 ADUs Per Lot
Build two detached units on a single property
No Parking Required
No off-street parking mandate for your DADU
Heights Up to 32 Feet
Build a full two-story DADU in qualifying zones
Streamlined Permitting
HB 1337 makes the approval process faster than ever

What Our Clients Say

Don't take our word for it — hear from Seattle homeowners who built their DADU with us.

Google Verified

“Giant Builders handled everything — permits, design, construction. Our DADU in Capitol Hill is now renting for $2,800/month. Best investment we've made.”

Michael & Lisa T.
Custom DADU, Capitol Hill
Google Verified

“We built a DADU for my mother-in-law. The team was incredibly professional, and the final result exceeded our expectations. It blends perfectly with our home.”

David & Karen R.
Multigenerational DADU, Bellevue
Houzz Verified

“From design to final walkthrough, the experience was seamless. Our project manager kept us informed daily, and the craftsmanship is outstanding.”

Sarah M.
Backyard Cottage, Ballard

You're Protected by Our Quadruple Guarantee

We stand behind every project with four ironclad promises.

Best Value Guarantee

Transparent, competitive pricing. Your written quote is your final price — no surprise change orders.

Best Quality Guarantee

Premium materials, expert craftsmanship, and rigorous quality inspections at every stage.

Best Crew Guarantee

Licensed, certified professionals. Every team member is background-checked and fully insured.

5-Year Warranty

Our industry-leading workmanship warranty protects your investment long after move-in.

Why Homeowners Choose Giant Builders

We handle every detail so you can enjoy the results — not the stress.

We Handle All Permits

Seattle's permitting process is complex. We manage it end-to-end — design review, structural engineering, utility coordination, and inspections.

In-House Design Team

Every DADU is custom-designed to complement your home and neighborhood. 3D renderings included so you see it before we build it.

Transparent Fixed Pricing

Detailed line-item estimates. Your written quote is your final price — no hidden fees, no surprise change orders.

Dedicated Project Manager

One point of contact from design through move-in. Daily progress updates keep you informed at every step.

5-Year Workmanship Warranty

Our industry-leading warranty protects your investment long after construction is complete.

On-Time Completion

We respect your timeline. Detailed scheduling and proactive communication keep your project on track.

988
DADUs Permitted in Seattle in 2022 — 4x Growth Since 2018
10–30%
Average Property Value Increase with a DADU
6–12 Mo
Typical Timeline from Consultation to Move-In

Questions? Answers.

Everything you need to know about building a DADU in Seattle.

How much does it cost to build a DADU in Seattle?
A standard one-story DADU typically costs $250,000–$400,000, while two-story units range from $400,000–$600,000. We provide a detailed, transparent estimate during your free feasibility check so there are no surprises. Financing options are available.
What is a DADU?
A DADU (Detached Accessory Dwelling Unit) is a small, self-contained residential structure on the same lot as your main house — also called a backyard cottage, granny flat, or carriage house. It includes living, sleeping, kitchen, and bathroom facilities with its own entrance. DADUs are separate from the main house, unlike attached ADUs.
Is my lot big enough for a DADU?
Under current Seattle regulations, lots as small as 3,200 square feet can qualify for a DADU in single-family zones. You can build up to two ADUs on a single lot. Our free feasibility check will confirm what's possible on your specific property, including setback and height limits.
Do I need to live on the property to build a DADU?
No. Seattle removed the owner-occupancy requirement, meaning you can build a DADU and rent out both the main house and the DADU, or use it purely as an investment property. You must own at least 50% of the property to build.
How long does the whole process take?
From initial consultation to move-in, most DADU projects take 6–12 months. Permitting typically takes 2–4 months (or 2–6 weeks with Seattle's pre-approved DADU plans), and construction runs 4–8 months depending on the design complexity.
Do you handle all the permits?
Yes. We manage Seattle's entire permitting process — design review, structural engineering, utility coordination, and inspections. You don't have to deal with any of the paperwork. We're familiar with SDCI requirements and pre-approved plan options that can speed up approval.
Can I use Seattle's pre-approved DADU plans?
Yes. Seattle offers pre-approved DADU designs through ADUniverse that can streamline permitting to just 2–6 weeks instead of 2–4 months. We can build from these plans or create custom designs. Pre-approved plans work well for standard lots and can save time and money.
Can I sell my DADU separately from my main home?
Yes. Under Washington's HB 1337, DADUs can now be subdivided into separate legal lots and sold independently — giving you even more flexibility with your investment. This is a significant change from previous regulations.
What's included in the free feasibility check?
We assess your lot size, zoning classification, setback requirements, utility connections, and allowable building footprint. You'll know exactly what you can build — and what it will cost — before you commit to anything. No obligation.
Do you offer financing options?
While we don't provide financing directly, we work with homeowners who use home equity loans, construction loans, HELOCs, and refinancing. We can also connect you with lenders experienced in ADU/DADU construction financing.

Don't see your question? Call us at (425) 757-7872 — we're happy to help.

Serving Seattle & the Greater Puget Sound Area

Seattle·Bellevue·Kirkland·Redmond·Renton·Kent·Tacoma·Federal Way·Bothell·Woodinville·Issaquah·Sammamish·Mercer Island·Burien·Shoreline·Lynnwood·Edmonds·Auburn·Tukwila·SeaTac

Ready to Unlock Your Property's Potential?

Seattle's DADU regulations have never been more favorable. Let us show you what's possible on your lot.

Free feasibility check · No obligation · Response within 24 hours

Prefer to talk? Call us directly:

(425) 757-7872