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.

How to File an Insurance Claim for Storm Damage in Washington State

A Step-by-Step Guide to Filing Storm Damage Insurance Claims in WA

Washington State gets hit with serious storms every year — from the atmospheric rivers that dump inches of rain to the windstorms that bring down trees and tear off roofing. If your home has been damaged, filing an insurance claim correctly from the start can make the difference between a smooth recovery and months of frustration.

At Prolific Design-Build and Restoration, we’ve guided hundreds of King County homeowners through the claims process. Here’s what we’ve learned about getting it right.

Step 1: Document Everything Before You Touch Anything

Before you move debris, before you clean up, before you make temporary repairs — document. Take photos and video from every angle. Capture both the damage itself and the wider context (the tree that fell, the direction of wind damage, the water line on walls). This documentation becomes the foundation of your claim.

Pro tip: Take photos with your phone’s location and timestamp features enabled. Adjusters pay attention to metadata that confirms when and where documentation was captured.

Step 2: Prevent Further Damage (This Is Required)

Your insurance policy includes a \”duty to mitigate\” clause. This means you’re required to take reasonable steps to prevent additional damage after the initial event. Board up broken windows, tarp damaged roofs, extract standing water, and turn off water supply if pipes have burst.

The cost of these emergency mitigation measures is covered by your insurance policy — separate from your deductible in most cases. Keep all receipts. If you can’t safely perform emergency mitigation yourself, call a professional. Prolific provides 24/7 emergency board-up and water extraction across King County.

Step 3: File Your Claim Immediately

Contact your insurance company as soon as possible. Most policies have reporting requirements, and delays can complicate or even jeopardize your claim. When you call, have your policy number ready and provide a clear, factual description of the damage. Don’t speculate about causes or costs — just describe what happened and what you see.

Write down your claim number, your adjuster’s name and contact information, and any reference numbers provided. You’ll need these throughout the process.

Step 4: Get an Independent Damage Assessment

This is where many homeowners make their biggest mistake: they rely solely on the insurance company’s assessment. Remember, the adjuster works for the insurance company, not for you. Their job is to assess damage fairly, but their estimates often miss hidden damage that a restoration professional would catch.

Having an independent contractor assess damage before or during the adjuster’s visit gives you leverage. They can point out damage the adjuster might miss — water behind walls, compromised structural members, moisture in insulation — and document it properly for your claim.

Step 5: Understand Your Policy and Rights

Washington State has strong consumer protection laws for insurance claims. Key things to know: you have the right to choose your own contractor regardless of what your insurance company recommends. Your insurance company must respond to your claim within specific timeframes. You can dispute claim decisions through your state’s Office of the Insurance Commissioner.

Don’t sign anything from your insurance company that you don’t fully understand. If the initial settlement offer seems low, you have the right to negotiate and provide additional documentation.

Step 6: Work With a Contractor Who Knows Insurance

The ideal restoration contractor does more than just fix your home — they function as your advocate in the claims process. They write detailed estimates using Xactimate (the industry-standard software adjusters use), meet with adjusters on-site to ensure all damage is documented, and file supplements when hidden damage is discovered during restoration.

Prolific Design-Build and Restoration handles the full insurance claims process for King County homeowners. We document, we negotiate, we restore, and we rebuild — all under one roof. Call (425) 800-4775 for a free consultation.

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Dealing with storm damage? We're here — call now or submit your info and we'll call you within the hour.

We Got Your Request

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:

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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