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.

Water Damage Restoration Cost in Seattle: What to Expect in 2026

How Much Does Water Damage Restoration Cost in the Seattle Area?

If you’re dealing with water damage in your Seattle-area home, one of your first questions is probably about cost. The answer depends on several factors, but here’s a realistic breakdown based on our experience restoring hundreds of King County properties.

Average Water Damage Restoration Costs

Water damage restoration in the Seattle metro area typically ranges from $2,500 for minor incidents (a small pipe leak affecting one room) to $25,000+ for major events (sewage backup, flood damage, or multi-room water intrusion). The national average sits around $3,500-$5,000, but Seattle-area costs tend to run 15-20% higher due to our cost of living and specialized labor market.

The primary cost drivers are the volume of water, the category of water (clean, gray, or black), the materials affected, and how long the water sat before mitigation began. A burst supply line caught within hours is a fundamentally different job than a slow leak that’s been soaking subfloor and framing for weeks.

Cost Breakdown by Service

Water extraction and structural drying typically runs $1,500-$5,000 depending on the affected area. This includes industrial pumps, dehumidifiers, air movers, and daily monitoring with moisture meters. Most drying cycles take 3-5 days.

Mold remediation, if needed, adds $1,500-$6,000 depending on extent. In the Pacific Northwest, mold risk is elevated due to our ambient humidity — if water damage goes unaddressed for more than 48 hours, mold remediation is almost always necessary.

Structural repair and rebuild is the variable that swings costs most dramatically. Replacing drywall and baseboards in a single room might run $2,000-$4,000. Rebuilding a kitchen or bathroom with water-damaged cabinets, flooring, and fixtures can easily reach $15,000-$30,000.

What Insurance Covers

Most homeowner insurance policies cover sudden and accidental water damage — burst pipes, appliance failures, storm-driven water intrusion. They typically don’t cover gradual damage from maintenance neglect, flooding from external sources (that requires separate flood insurance), or sewer backup unless you have a specific rider.

When insurance does cover the damage, your out-of-pocket cost is usually limited to your deductible. Prolific works directly with insurance companies to document damage thoroughly and ensure claims reflect the true scope of work needed. We’ve seen too many homeowners accept underpaid claims because they didn’t have a knowledgeable contractor advocating for them.

How to Minimize Costs

Speed is everything. The single most important factor in controlling water damage restoration cost is response time. Water that’s extracted within hours causes dramatically less damage than water that sits for days. That’s why Prolific offers 24/7 emergency response across King County — because every hour of delay means exponentially more damage and cost.

If you’re facing water damage in your Seattle-area home, call Prolific Design-Build and Restoration at (425) 800-4775 for immediate response and a free damage assessment. We’ll give you an honest scope and work with your insurance to minimize your out-of-pocket expense.

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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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