ADU & DADU Contractor — King County, WA

Add a Legal Dwelling Unit
to Your King County Property

From permit application to final walkthrough — Prolific handles design-build ADU and DADU projects across Federal Way, Issaquah, Renton, Kent, and greater King County.

$180KAverage ADU Cost (King County)
6–12moTypical Timeline Permit to Move-In
$1,800+Monthly Rental Income Potential
3–5yrAverage ROI Payback Period

What We Build

Every ADU project is custom-designed for your lot, your goals, and King County code.

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Detached ADU (DADU)

A standalone dwelling in your backyard. Most flexible for rental or multigenerational living. Requires setback compliance and separate utility connections.

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Attached ADU

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.

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Junior ADU (JADU)

Converted from existing interior space — garage, basement, or bonus room. Lowest cost entry point. Limited to 500 sq ft per King County code.

The King County Permitting Process

Prolific handles every step. Most homeowners have never pulled a permit — we've done hundreds.

1

Site & Zoning Review

We verify your parcel's zoning, setbacks, lot coverage, and utility capacity before design starts. Catches 80% of project-killers on day one.

2

Design & Engineering

Architectural plans drawn to King County standards. Structural engineering included where required. Typical design phase: 3–6 weeks.

3

Permit Submission

We submit to King County DPER or the applicable city (Federal Way, Renton, Issaquah, Kent). Electronic submission with full plan set.

4

Review & Corrections

County review typically takes 6–12 weeks. We respond to all correction requests and manage the back-and-forth until permit issuance.

5

Build & Final Inspection

Construction with milestone inspections. Final inspection and certificate of occupancy required before the unit can be rented or occupied.

Cost Ranges for King County ADUs

Rough estimates — every project varies by site, size, and finish level. Free estimate available after a site visit.

ADU TypeSize RangeTypical Cost Range
Junior ADU (JADU)Up to 500 sq ft$60,000 – $120,000
Attached ADU400–800 sq ft$120,000 – $200,000
Detached ADU (DADU)400–1,200 sq ft$160,000 – $320,000

Ready to Add a Unit to Your Property?

Free site consultation. We'll tell you what's possible on your lot before you spend a dollar.

Get Your Free ADU Estimate

Prolific's Differentiator

While We're Restoring Your Home, Let's Make It Better Than Before

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.

Storm + Remodel

Federal Way — Hail Damage + Kitchen Upgrade

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.

Water + Addition

Renton — Burst Pipe + Primary Bath Expansion

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.

Fire + Rebuild

Issaquah — Garage Fire + ADU Conversion

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.

Insurance Claim? We Handle Everything.

Your Insurance Company Has Adjusters.
Now You Have Us.

STORM DAMAGE RESPONSEthousands more for homeowners just like you.

Can I Choose My Own Contractor for an Insurance Claim?

Yes — absolutely. In Washington State, you have the legal right to choose any licensed contractor to perform your insurance restoration work. Your insurance company cannot force you to use a specific contractor, and they cannot deny or reduce your claim based on your contractor choice.

This is one of the most important rights homeowners have during the insurance claims process, and it’s one that many people don’t know about. Insurance companies often recommend “preferred vendors” or “program contractors,” and while these suggestions may seem helpful, understanding your options can save you thousands of dollars and result in significantly better work.

Your Right to Choose Is Protected by Washington State Law

Washington State insurance regulations are clear: the policyholder selects the contractor. Your insurance company pays for the covered repairs regardless of which licensed contractor performs the work. They cannot steer you toward a specific company, penalize you for choosing your own, or offer a lower payout because you didn’t use their preferred vendor.

This right exists because insurance is a contract between you and your insurer to cover the cost of repairs — not to dictate who performs them. The same way you choose your own doctor for medical care, you choose your own contractor for property restoration.

Why Insurance Companies Recommend “Preferred” Contractors

When you file a claim, your insurer may suggest contractors from their “preferred vendor” or “managed repair” network. Understanding why helps you make a better decision:

Volume discounts. Preferred contractors often agree to reduced rates in exchange for a steady stream of referrals from the insurance company. This means the contractor may be working on thinner margins — which can affect material quality, crew experience, and attention to detail.

Faster claims processing. Network contractors are familiar with the insurer’s process and paperwork, which can speed things up. However, speed isn’t always in the homeowner’s best interest if it means less thorough damage documentation.

Lower claim costs for the insurer. Preferred contractors are incentivized to keep costs within the insurer’s initial estimate. An independent contractor who works for you is incentivized to ensure every dollar of legitimate damage is captured in the claim.

Advantages of Choosing Your Own Contractor

They work for you, not the insurance company. This is the fundamental difference. An independent contractor’s loyalty is to the homeowner. They document every item of damage, file supplements for anything the adjuster missed, and advocate for the full scope of repairs your policy covers.

Better documentation and higher claim payouts. Contractors experienced in insurance restoration know how to document damage in ways that maximize your claim. They identify hidden damage, file supplements, and ensure code-required upgrades are included — items that preferred vendors may not push for.

Higher quality materials and workmanship. When your contractor isn’t locked into discounted pricing, they can use premium materials and take the time needed to do the job right. You get the quality your insurance policy is paying for.

Accountability to you. If something goes wrong, your contractor answers to you directly. With a preferred vendor, complaints often go through the insurance company — adding layers of complexity and reducing your leverage.

What to Look for When Choosing Your Contractor

Not every contractor is equipped to handle insurance restoration work. The insurance claims process requires specific expertise that general contractors may not have. Here’s what to look for:

Insurance restoration experience. Choose a contractor who specializes in insurance work, not one who occasionally handles a claim. They should understand Xactimate estimating, supplement procedures, adjuster coordination, and the documentation requirements that different insurers expect.

Willingness to attend adjuster meetings. Your contractor should be present during the adjuster’s inspection. This is when the scope of work is established, and having your contractor there ensures nothing is missed.

Supplement filing capability. If the initial insurance estimate misses damage or underestimates repair costs, your contractor should know how to file a professional supplement with supporting documentation.

Licensed, bonded, and insured in Washington State. This is non-negotiable. Verify your contractor’s license through the Washington State Department of Labor and Industries.

Local reputation and reviews. Check Google reviews, ask for references, and look for a track record of completed insurance restoration projects in your area.

What If My Insurance Company Pushes Back?

Some adjusters or claims representatives may subtly pressure you to use their preferred contractor — by implying the process will be easier, faster, or that they “can’t guarantee” coverage with an outside contractor. Know your rights:

Your insurer cannot deny your claim because you chose your own contractor. They cannot reduce your payout because your contractor charges more than their preferred vendor. And they cannot delay your claim as a tactic to pressure you into using their network.

If you experience pushback, document the conversation, reiterate your right to choose your own contractor, and proceed with your chosen professional. If the issue persists, you can file a complaint with the Washington State Office of the Insurance Commissioner.

Why King County Homeowners Choose Prolific Design-Build and Restoration

We’re an independent insurance restoration contractor — not part of any insurance company’s preferred vendor network. That means our only client is you. We document every dollar of legitimate damage, file supplements when the initial estimate falls short, attend every adjuster meeting, and complete every repair with premium materials and expert craftsmanship.

With 500+ completed insurance restoration projects across King County, we know how to navigate the claims process and maximize your payout. You pay only your deductible — we handle everything else.

Need an independent contractor for your insurance claim? Call (425) 800-4775 for a free inspection. We’ll assess the damage, explain your options, and handle the entire insurance process. Serving Issaquah, Bellevue, Renton, Sammamish, Kirkland, Redmond, Kent, Auburn, Federal Way, Maple Valley, and all of King County.

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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:

What to Have Ready

  • Photos of the damage or area of concern (phone photos are fine)
  • Your insurance carrier name and claim number (if applicable)
  • Best time and number to reach you
  • A rough idea of when the damage occurred or project timeline
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Prolific Design-Build & Restoration — Federal Way, WA

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