ADU & DADU Contractor — King County, WA
From permit application to final walkthrough — Prolific handles design-build ADU and DADU projects across Federal Way, Issaquah, Renton, Kent, and greater King County.
Every ADU project is custom-designed for your lot, your goals, and King County code.
A standalone dwelling in your backyard. Most flexible for rental or multigenerational living. Requires setback compliance and separate utility connections.
Connected to the primary home via a shared wall. Lower cost than detached, faster permitting. Ideal for in-law suites or long-term rental income.
Converted from existing interior space — garage, basement, or bonus room. Lowest cost entry point. Limited to 500 sq ft per King County code.
Prolific handles every step. Most homeowners have never pulled a permit — we've done hundreds.
We verify your parcel's zoning, setbacks, lot coverage, and utility capacity before design starts. Catches 80% of project-killers on day one.
Architectural plans drawn to King County standards. Structural engineering included where required. Typical design phase: 3–6 weeks.
We submit to King County DPER or the applicable city (Federal Way, Renton, Issaquah, Kent). Electronic submission with full plan set.
County review typically takes 6–12 weeks. We respond to all correction requests and manage the back-and-forth until permit issuance.
Construction with milestone inspections. Final inspection and certificate of occupancy required before the unit can be rented or occupied.
Rough estimates — every project varies by site, size, and finish level. Free estimate available after a site visit.
| ADU Type | Size Range | Typical Cost Range |
|---|---|---|
| Junior ADU (JADU) | Up to 500 sq ft | $60,000 – $120,000 |
| Attached ADU | 400–800 sq ft | $120,000 – $200,000 |
| Detached ADU (DADU) | 400–1,200 sq ft | $160,000 – $320,000 |
Free site consultation. We'll tell you what's possible on your lot before you spend a dollar.
Get Your Free ADU EstimateProlific's Differentiator
Most contractors patch the damage and leave. We use the restoration as a launchpad — pairing insurance coverage with a remodel that upgrades what you had.
Insurance covered the roof and siding. While we had the crew on-site, the homeowners financed a kitchen remodel they'd been putting off for years. One mobilization, two wins.
A burst pipe triggered an insurance claim for the subfloor and drywall. We rebuilt the bathroom larger than it was — same timeline, carrier paid the base, owner paid the delta.
Garage total loss became a permitted two-car garage with a studio ADU above. Insurance rebuilt what burned. The ADU now generates rental income to offset the mortgage.
7 questions to ask before hiring any contractor in King County — takes 2 minutes to read.
Check your inbox in the next few minutes.
STORM DAMAGE RESPONSEthousands more for homeowners just like you.
Step-by-step guide to filing a water damage insurance claim in Washington State. Learn your rights, avoid common mistakes, and get the full settlement you deserve from your insurance company.
How to File a Water Damage Insurance Claim in Washington State Read More »
One of the first questions homeowners ask us about a bathroom remodel is “how long will this take?” It’s a fair question — nobody wants to be without a functional bathroom longer than necessary. Here’s what a realistic timeline looks like based on our experience remodeling bathrooms across Issaquah, Bellevue, Redmond, Kirkland, and the rest
Bathroom Remodel Timeline: How Long Does It Really Take in the Seattle Eastside? Read More »
Accessory dwelling units have become one of the hottest topics in King County real estate. Whether you call them ADUs, DADUs, backyard cottages, or in-law suites, these secondary living spaces are transforming how Eastside homeowners use their property. At Prolific Design-Build and Restoration, we’ve been building ADUs and DADUs across Issaquah, Bellevue, Sammamish, Redmond, and
ADU and DADU Construction in King County: Rules, Costs, and What to Expect in 2026 Read More »
If you’re a homeowner in Bellevue, Issaquah, Sammamish, or elsewhere on the Eastside, you’ve probably wondered what a kitchen remodel actually costs in this market. The short answer: it depends on scope. The real answer takes a bit more nuance. At Prolific Design-Build and Restoration, we handle kitchen remodels across King County every month. Here’s
When you file an insurance claim for storm damage, water damage, or fire damage, your insurance company may recommend a contractor from their “preferred vendor” or “managed repair” network. Names like Servpro, Paul Davis, and ServiceMaster often come up. These are large franchise operations with nationwide footprints and long-standing relationships with insurance carriers. But you’re
Your insurance adjuster inspected the damage, wrote an estimate, and your insurance company sent a check. But when your contractor starts the repair work, they discover additional damage that wasn’t in the original estimate — water damage behind the walls, compromised roof decking hidden under the shingles, or code upgrades required by current building standards.
What Is an Insurance Supplement and Why Your Contractor Should File One Read More »
When water damages your home — whether from a burst pipe, storm intrusion, or appliance failure — you’ll hear two terms thrown around: water mitigation and water restoration. They sound similar, and many people use them interchangeably. But they’re actually two distinct phases of the recovery process, and understanding the difference matters for your insurance
Water Mitigation vs Water Restoration: What’s the Difference? Read More »
You filed your insurance claim, the adjuster approved the repairs, and you received a check — but it’s for less than the full estimate. What happened? In most cases, your insurance company withheld the recoverable depreciation, and that missing money is yours to claim once the repairs are complete. Recoverable depreciation is one of the
What Is Recoverable Depreciation on an Insurance Claim? Read More »
When you’re dealing with significant property damage — a storm tears off your roof, a pipe floods your basement, a fire damages your kitchen — you’ll quickly encounter two types of professionals who can help with the insurance side: public adjusters and restoration contractors. Both work on your behalf, but they do very different things.
Public Adjuster vs Restoration Contractor: Which Do You Need? Read More »
After you file an insurance claim for storm damage, water damage, or fire damage, your insurance adjuster will produce an estimate using a software program called Xactimate. This estimate determines how much your insurance company will pay for repairs — and understanding it is one of the most important things you can do to protect
How to Read an Xactimate Estimate: A Homeowner’s Guide Read More »
We respond within 2 business hours — same day for emergencies.
A member of our team will reach out shortly to schedule your free estimate or inspection. Here's what to have ready when we call:
Prolific Design-Build & Restoration — Federal Way, WA