Giant Builders SeattleGiant Builders(425) 757-7872
Beautiful granny flat in a lush Pacific Northwest backyard with a family visiting
5.0 Rating
1,000+ Happy Clients15+ Years

Keep Your Family Close Build a Granny Flat

Custom granny flats & backyard apartments designed for multigenerational living. Give your parents independence just steps from your door — or earn $1,800–$2,500/mo in rental income.

Licensed (GIANTBS78RZ) · Bonded · Insured · 5-Year Warranty · King & Snohomish County, WA

Get My Free Consultation (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 Families Build Granny Flats

84% of seniors want to age in place. A granny flat gives your family the “close but not too close” arrangement everyone wants.

84%
Of Seniors Want to Age in Place

A granny flat lets your parents live independently — just steps from your door. No nursing home. No guilt. Just family.

$54K/yr
Average Assisted Living Cost

A granny flat costs a fraction of assisted living — and you keep the equity. Build once, use for decades.

25–35%
Property Value Increase

A backyard apartment adds significant equity to your home — the highest value-add of any accessory dwelling type.

$1,800–$2,500
Monthly Rental Income

Not ready for family use? Rent your backyard apartment and earn $21K–$30K/year in passive income in King County.

See What You Can Build — Free

A Backyard Apartment for Every Family

Whether it's for aging parents, adult children, or rental income — your granny flat is built around your life.

Aging Parents

Keep Mom and Dad close without sharing walls. Accessible design with wide doorways, walk-in showers, and single-level living — so they can age safely in your backyard.

Adult Children

Give your grown kids privacy and independence while they save for their own place. 25% of adults aged 25–34 now live in multigenerational households.

Rental Income

Turn your backyard into a $1,800–$2,500/month income stream. No owner-occupancy requirement means you can rent it out from day one.

Home Office or Studio

A dedicated workspace just steps from your house. No commute, no distractions, no shared walls — the ultimate work-from-home upgrade.

Guest Cottage

Host family and friends in comfort without sacrificing your own space. A backyard apartment is the guest room your visitors actually enjoy.

Long-Term Investment

Build equity now, flexibility later. Use it for family today, rent it tomorrow, or sell it separately under Washington's HB 1337.

From Idea to Move-In — Our Simple Process

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

Step 01

Free Consultation

We visit your property, assess your lot, review zoning, and discuss your family's needs. You'll know exactly what you can build — for free.

Step 02

Custom Design

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

Step 03

Permits & Approvals

We handle Washington's entire permitting process. No paperwork headaches for you — just updates from your project manager.

Step 04

Build & Move In

Our licensed crew builds your backyard apartment with premium materials. Your project manager oversees every detail until your family moves in.

Get My Free Granny Flat Consultation

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
Aerial view of a Washington state neighborhood with granny flats and backyard apartments

Washington's Granny Flat Rules Have Never Been Better

HB 1337 removed major barriers — more properties in King & Snohomish County qualify for a backyard apartment than ever before.

No Owner-Occupancy Required
Build a granny flat as a pure investment — you don't need to live on-site
Up to 2 Units Per Lot
Build two backyard apartments on a single property for maximum flexibility
Reduced Lot Minimums
Lots as small as 3,200 sq ft can qualify — more homes than ever are eligible
No Parking Required
No off-street parking mandate near transit stops — saves space and money
Heights Up to 32 Feet
Build a full two-story granny flat in qualifying zones
Sell Independently
HB 1337 allows you to subdivide and sell your granny flat as a separate lot

What Our Clients Say

Hear from King & Snohomish County families who built granny flats and backyard apartments with us.

Google

“We built a granny flat for my mother so she could age close to family instead of going into assisted living. She's steps away but still has her independence. Giant Builders made the whole process stress-free.”

Linda & Robert H.
Granny Flat, Bellevue
Google

“Our backyard apartment pays for itself — we're earning $2,200/month in rent. But we built it knowing we can move my parents in someday. The fixed pricing meant zero surprises.”

James & Patricia W.
Backyard Apartment, Kirkland
Houzz

“Our adult son moved into the granny flat while saving for his first home. It gave him privacy and us peace of mind. The accessibility features mean my mother can use it when she visits, too.”

Maria G.
Granny Flat, Redmond
Google

“We compared four contractors. Giant Builders was the only one who truly listened to what our family needed. The granny flat blends perfectly with our home — guests think it was always there.”

Steve & Diane C.
Backyard Apartment, Everett

You're Protected by Our Quadruple Guarantee

We stand behind every granny flat 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 of your granny flat build.

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 backyard apartment investment long after move-in.

Why Families Choose Giant Builders

Your local granny flat experts in King & Snohomish County.

We Handle All Permits

Washington's permitting process can feel overwhelming. We manage it end-to-end — design review, structural engineering, utility coordination, and inspections.

In-House Design Team

Every granny flat is custom-designed to complement your home and yard. 3D renderings included so you see the finished backyard apartment before we break ground.

Transparent Fixed Pricing

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

Dedicated Project Manager

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

5-Year Workmanship Warranty

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

Accessibility Built In

We design granny flats with aging in place in mind — wider doorways, walk-in showers, single-level layouts, and grab-bar blocking included.

Grandmother and grandchildren walking toward a charming granny flat in a lush Washington backyard at golden hour

Imagine Your Family Just Steps Away

Start Your Granny Flat Project
84%
Of Seniors Prefer Aging in Place Over Facilities
25–35%
Average Property Value Increase with a Granny Flat
$54K
Average Annual Cost of Assisted Living — Build Instead
6–12 Mo
Typical Timeline from Consultation to Move-In

Granny Flat & Backyard Apartment Questions? Answers.

Everything you need to know about building a granny flat or backyard apartment in King & Snohomish County.

How much does it cost to build a granny flat in King County or Snohomish County?
A typical granny flat (detached backyard apartment) in King or Snohomish County costs between $250,000 and $500,000 depending on size, finishes, and site conditions. One-story units are on the lower end; two-story or premium-finish builds are on the higher end. We provide a detailed, transparent estimate during your free consultation — no surprises. Financing options are available.
What is the difference between a granny flat and a backyard apartment?
They're the same thing — a self-contained dwelling unit on your property, separate from the main house. 'Granny flat' is the traditional term (often implying a family member will live there), while 'backyard apartment' emphasizes that it's a fully independent living space that can also be rented. Both include a kitchen, bathroom, bedroom, and private entrance.
Do I need a permit to build a granny flat in Washington state?
Yes, a building permit is required. But Washington's HB 1337 has dramatically simplified the process — cities can no longer require owner-occupancy, parking minimums near transit have been eliminated, and up to two accessory dwelling units are allowed per lot. We handle the entire permit process for you.
Is my lot big enough for a granny flat?
Under current Washington regulations, many residential lots qualify for a granny flat. Minimum lot sizes have been reduced significantly — in Seattle, lots as small as 3,200 sq ft can qualify. Our free consultation will confirm what's possible on your specific property, including setback and height limits.
Can I build a granny flat for my aging parents?
Absolutely — this is the most popular reason homeowners build granny flats. We specialize in accessible designs with features like single-level layouts, wide doorways, walk-in showers, and grab-bar blocking. It's a fraction of the cost of assisted living ($54,000/year) and keeps your family together.
How long does it take to build a granny flat?
From initial consultation to move-in, most granny flat projects take 6–12 months. Permitting typically takes 2–4 months, and construction runs 4–8 months depending on design complexity. Your dedicated project manager will provide a detailed timeline before we begin.
Can I rent out my granny flat or backyard apartment?
Yes. Washington's HB 1337 eliminated the owner-occupancy requirement, so you can rent out your granny flat even if you don't live on the property. Backyard apartments in King County typically rent for $1,800–$2,500/month, generating $21,000–$30,000/year in passive income.
Will a granny flat increase my property value?
Yes — significantly. A detached granny flat typically adds 25–35% to your property value. On a $750,000 home, that's $187,000–$262,000 in added equity. Detached units (granny flats / backyard apartments) deliver the highest value increase of any accessory dwelling type.
Can I sell my granny flat separately from my main home?
Yes. Under Washington's HB 1337, granny flats and backyard apartments can now be subdivided into separate legal lots and sold independently — giving you maximum flexibility with your investment.
What's included in the free consultation?
We assess your lot size, zoning classification, setback requirements, utility connections, and allowable building footprint. We also discuss your family's specific needs — aging-in-place features, rental goals, or guest use. You'll know exactly what you can build and what it will cost before you commit to anything. No obligation.

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

Granny Flat & Backyard Apartment Builders Serving King County & Snohomish County, WA

Your local granny flat builders — we know the codes, the lots, and the neighborhoods.

Seattle·Bellevue·Kirkland·Redmond·Everett·Bothell·Woodinville·Lynnwood·Edmonds·Shoreline·Kenmore·Mountlake Terrace·Renton·Kent·Sammamish·Issaquah·Mercer Island·Burien·Snohomish·Lake Stevens·Marysville·Mill Creek·Mukilteo·Lake Forest Park
Beautifully lit granny flat at dusk in a Washington state backyard

Ready to Build a Granny Flat Your Family Will Love?

Washington's regulations have never been more favorable. Let us show you what's possible in your backyard.

Free consultation · No obligation · Response within 24 hours

Prefer to talk? Call us directly:

(425) 757-7872