Backyard homes are the smartest square feet in Washington
ADUs are the fastest-growing way Puget Sound families add rental income, house parents or adult kids, and build equity — and new state law makes them easier than ever. ABM designs, permits and builds them start to finish.
Washington said yes — the window is open
For decades, zoning kept backyard cottages rare. HB 1337 changed that: cities across Washington must now allow ADUs on most residential lots, owner-occupancy requirements are gone, and parking mandates are limited. Everett, Seattle, Lynnwood, Edmonds, Mill Creek and Marysville all permit ADUs today.
The result: a once-in-a-generation chance to add a legal second home to property you already own.
A stand-alone small home in your backyard — maximum privacy, maximum rent.
Learn more →02Garage & Attached ConversionsTurn existing square footage into a legal, rentable dwelling.
Learn more →03ADU Cost Guide 2026Real per-sq-ft numbers for every ADU type in our region.
Learn more →04ADU Rules & HB 1337What’s allowed on your lot, in plain English.
Learn more →
One backyard, three payoffs
- Rental income — Puget Sound one-bedrooms rent $1,500–$2,200/mo; an ADU often covers its own financing
- Family flexibility — aging parents nearby, adult kids launched, a real home office or guest house
- Equity — a permitted ADU adds lasting appraised value to your property
Financing options: ADU financing guide → · Building in Everett? Everett ADU page →
A backyard cottage, frame to finish
A recent detached ADU (DADU) — dark board-and-batten siding, covered craftsman porch, heat-pump heating and its own wooded setting. Tap any photo to view it full-screen.
Your lot to your tenant’s keys
We confirm what your lot allows: size, setbacks, utilities, parking.
A design matched to your lot and goals, priced honestly.
Full permit package — we handle the city, you watch the progress.
8–12 months for a DADU; conversions are faster.
Final inspection, certificate, keys — and a warranty in writing.
What is an ADU?
An ADU (accessory dwelling unit) is a complete second home on your lot — with its own kitchen, bathroom and entrance. It can be attached to your house, converted from a garage, or built detached in the backyard (a DADU).
Are ADUs legal in Everett and Seattle?
Yes. Washington’s HB 1337 (2023) requires cities to allow ADUs, and both Everett and Seattle now permit them broadly on residential lots. Our ADU rules guide covers the current local requirements.
How much does an ADU cost in 2026?
In the Puget Sound region: garage/attached conversions $150–$300/sq ft, detached backyard cottages (DADUs) $300–$500/sq ft. A typical 750 sq ft DADU runs roughly $225,000–$375,000 all-in.
How long does it take?
Conversions: about 4–7 months including permits. Detached DADUs: 8–12 months design-to-keys.
Can I rent out my ADU?
Yes — long-term rental is allowed in all our service cities. Short-term rental rules vary by city; Everett and Seattle both regulate STRs separately.