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.

Our Insurance Claims Process — From Inspection to Restoration

Our Insurance Claims Process — How We Handle Your Claim From Start to Finish

Filing an insurance claim after storm damage, water damage, or fire damage can feel overwhelming. That’s why Prolific Design-Build and Restoration handles the entire process for you. We’ve managed hundreds of insurance claims for King County homeowners, and we know exactly how to document damage, communicate with adjusters, and ensure you receive the full payout your policy provides.

Step 1: Free Damage Inspection

It starts with a phone call. When you contact us, we schedule a thorough inspection of your property — usually within 24 hours, or immediately for emergencies. Our inspector examines your roof, siding, gutters, windows, and interior for all storm-related or water-related damage.

Many homeowners are surprised by what we find. Hail damage to shingles, hidden water intrusion behind walls, compromised flashing that looks fine from the ground — these are issues that an untrained eye misses but that qualify for insurance coverage.

Step 2: Detailed Documentation & Damage Report

Insurance companies approve or deny claims based on documentation. We create a professional damage report that includes high-resolution photographs of every damaged area, precise measurements, a description of the damage and its cause, an itemized scope of work needed for repair, and current material and labor pricing.

This report is formatted to match insurance industry standards. Adjusters review hundreds of claims — when yours arrives with clear, complete documentation, it moves faster and gets approved for more.

Step 3: Claim Filing Assistance

We help you file your claim with your insurance company. We can walk you through the process over the phone, or we can submit documentation directly to your insurer on your behalf. Either way, we make sure your claim includes everything needed for approval.

Step 4: Adjuster Meeting & On-Site Inspection

Your insurance company will send an adjuster to inspect the damage in person. We attend this meeting with you. This is critical — adjusters are trained to assess damage, but they’re also representing the insurance company’s interests. Having your contractor present ensures that all damage is properly identified and documented during the inspection.

If the adjuster misses damage or undervalues repairs, we advocate on your behalf with additional documentation, photos, and industry-standard pricing.

Step 5: Scope Approval & Supplements

Once the adjuster submits their report, your insurance company issues an approved scope of work and payment. We review this carefully. If the approved scope doesn’t cover all necessary repairs — which happens more often than you’d think — we file a supplement with additional documentation to request full coverage.

Supplements are a normal part of the insurance claims process, and we handle them at no additional cost to you.

Step 6: Professional Restoration

With your claim approved, we schedule and complete all repairs. We use premium materials from trusted manufacturers, follow Washington State building codes, and ensure every repair meets or exceeds pre-damage condition. Our work is backed by both our workmanship warranty and manufacturer material warranties.

Step 7: Final Walkthrough & Completion

When repairs are complete, we walk through every item with you. We don’t consider a project done until you’re completely satisfied. We also provide you with final documentation including before and after photos, warranty information, and completion certificates for your records.

What You Pay

You pay only your deductible. Your insurance company pays us directly for the approved scope of work. We never ask for payment beyond your deductible, and we never inflate costs or recommend unnecessary repairs. Our reputation depends on honest, quality work.

Frequently Asked Questions

How long does the insurance claims process take?
Most claims are approved within 2-4 weeks. Emergency repairs can begin immediately, with insurance reimbursement following. The full restoration timeline depends on the scope of work — from a few days for minor repairs to several weeks for major projects.

What if my claim is denied?
We help you appeal. Many initial denials are overturned with additional documentation, a re-inspection, or a supplement filing. Our experience with King County insurance claims gives us insight into what adjusters need to see for approval.

Do you work with all insurance companies?
Yes. We’ve successfully processed claims with every major insurance carrier in Washington State including State Farm, Allstate, USAA, Farmers, Liberty Mutual, Pemco, Safeco, American Family, and many others.

Start Your Claim Today

Call (425) 800-4775 for a free inspection and claims consultation. We’ll assess your damage, explain your coverage options, and handle the entire process from inspection to restoration.

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

📋 Get a Free Estimate