Federal Way, WA · DADU
DETACHED ADU Builder in Federal Way, WA
A detached accessory dwelling unit (DADU) is a fully independent residence on your existing single-family lot. We design and build DADUs that meet rental code, hold long-term value, and look like they belong — not like a kit dropped in the yard. Every project starts with a feasibility study and ends with a turn-key handover.
Build timeline
6–8 months
Typical sqft
400–1,000 sqft
Federal Way cost
$286K – $462K
Permit window
10–14 wk
What detached adu looks like in Federal Way
DETACHED ADU projects in Federal Way are shaped by local zoning (RS-7.2 / RS-9.6 / RS-15.0), a lot minimum of 7,200 sqft, and the kinds of sites we see day-to-day: West Campus, Twin Lakes, Mirror Lake. Below is what every Federal Way DADU project from Golden State includes — fixed-price, one contract, one warranty.
- ✓Stamped architectural set
- ✓Structural + MEP engineering
- ✓Permit submittal & city liaison
- ✓Foundation, framing, weather envelope
- ✓Finish carpentry, cabinetry, fixtures
- ✓Final inspection + warranty package
Other services in Federal Way
More from Golden State ADU in Federal Way
AADU
ATTACHED ADU in Federal Way
Seamlessly integrated additions — basement, ground-floor, or wing conversions that maintain the architectural integrity of your existing home.
Garage
GARAGE CONV. in Federal Way
Convert an under-used garage into a high-end studio, office, or rental quarter without surrendering your driveway.
Additions
MODERN ADDITIONS in Federal Way
Structural expansions for growing families — second stories, primary suites, kitchen extensions. Steel, glass, and Pacific Northwest materials.
GC
GENERAL CONTRACTING in Federal Way
Full-service general contracting for remodels, renovations, and ground-up custom homes throughout the Puget Sound region.
Feasibility
FEASIBILITY STUDIES in Federal Way
Before you commit, we analyze zoning, lot coverage, setbacks, utilities, and ROI so you have a real number — not a guess.
DETACHED ADU across the Puget Sound
DETACHED ADU builders in nearby cities
Start your Federal Way DADU feasibility
$1,500 buys lot analysis, Federal Way zoning verification, and a fixed price you can build a budget on.
Request Federal Way feasibilityFrequently asked
What is included in DETACHED ADU in Federal Way?
Our DETACHED ADU in Federal Way scope includes design through completion: feasibility, schematic design, construction documents, permit submittal and review management, construction with one self-performed framing crew plus L&I-licensed MEP subcontractors, all required WA inspections, certificate of occupancy, and warranty. One contract, one license number, one warranty — not a coordination headache across five vendors.
How is DETACHED ADU in Federal Way different from a generic remodel?
DETACHED ADU in Federal Way carries code, permit, and construction details that a one-off remodeler hasn't repeated enough times to optimize. Examples: IECC R406 envelope path selection, fire separation when units are within 5 ft, side-sewer slope requirements, IRC Appendix AQ when permitted as a tiny house, separate utility metering rules. We do this scope every month — repetition is what makes our first-cycle approval rate and our schedule reliability stand out.
What is the typical price range for DETACHED ADU in Federal Way?
DETACHED ADU in Federal Way pricing in 2026 lands in the $295–$465/sqft all-in range depending on size, lot conditions, finish tier, and AHJ. The wide range is real — small lots with difficult access, soils requiring pier-and-beam, or service upgrades push the upper end; flat lots with good access and a catalog plan land at the lower end. Our feasibility report gives you a ±15% number tailored to your specific lot in two weeks.