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.

Storm Damage Repair in King County: What Every Homeowner Needs to Know

When a Storm Hits Your King County Home — Here’s What to Do

King County averages 37 inches of rain per year, and our fall-winter storm season brings damaging winds that regularly exceed 50 mph. For homeowners in Kirkland, Renton, Kent, and across the county, storm damage isn’t a question of if — it’s a question of when.

At Prolific Design-Build and Restoration, we’ve responded to hundreds of storm damage calls across King County. Here’s what we’ve learned about protecting your home and navigating the recovery process.

The First 24 Hours After Storm Damage

The steps you take immediately after storm damage can significantly affect both your safety and your insurance claim outcome. First, document everything with photos and video before touching anything. Capture damage from multiple angles, including wide shots that show context and close-ups of specific damage points.

Second, prevent further damage. This is actually required by most insurance policies — you have a duty to mitigate. Cover roof breaches with tarps, board up broken windows, and extract standing water. If you can’t do this safely yourself, call a restoration contractor with 24/7 emergency response. Prolific provides emergency board-up and tarping services across King County within 30-60 minutes of your call.

Third, contact your insurance company to file a claim. Don’t wait — most policies have reporting deadlines. Take note of your claim number and adjuster assignment.

Common Storm Damage in the Pacific Northwest

Our region’s storms create specific damage patterns that differ from other parts of the country. Wind damage to roofing is the most common — shingles lift, flashing separates, and ridge caps blow off. Even if your roof looks intact from the ground, high winds can create micro-damage that leads to leaks weeks or months later.

Fallen trees and large branches cause structural damage to roofs, siding, fences, and vehicles. King County’s heavy tree canopy means this risk is especially high in cities like Issaquah, Redmond, and Kirkland where mature evergreens tower over residential properties.

Water intrusion follows wind damage — once the building envelope is compromised, rain enters the structure and causes secondary damage to insulation, drywall, flooring, and electrical systems. This is where mold risk begins, often within 24-48 hours.

Why You Should Choose an Independent Contractor Over a Franchise

After major storms, franchise restoration companies flood the market — literally sending crews from out of state who don’t know local building codes, don’t have relationships with local adjusters, and won’t be around for warranty work. They’re optimized for volume, not quality.

An independent, local contractor like Prolific offers significant advantages. We know King County building codes and permitting requirements. We have established relationships with local insurance adjusters. We’re here for warranty work because we live and work in this community. And most importantly, we don’t just restore — we design and build. That means your repaired home doesn’t just return to its pre-storm condition; it can be improved.

The Insurance Claims Process for Storm Damage

Filing a storm damage insurance claim can be overwhelming, especially if you’ve never done it before. The process typically starts with your initial report, followed by an adjuster visit within 3-7 days. The adjuster will assess visible damage and create an initial estimate using Xactimate software.

Here’s where many homeowners lose money: the initial adjuster estimate often misses hidden damage. Water behind walls, compromised roof decking under intact shingles, and moisture-damaged insulation aren’t always visible during a surface inspection. A knowledgeable contractor will document this hidden damage and file supplements to your claim — potentially adding thousands to your payout.

Prolific handles the entire insurance process: we write detailed Xactimate estimates, meet with adjusters on-site, file supplements with photographic evidence, and negotiate on your behalf. You shouldn’t have to become an insurance expert on top of dealing with a damaged home.

Protect Your Home Before the Next Storm

Prevention is always cheaper than restoration. Consider having your roof inspected annually, trimming trees within striking distance of your home, ensuring gutters and downspouts are clear, and checking that your sump pump is operational before the rainy season. These simple steps can prevent thousands in damage.

If your King County home has been affected by storm damage — or you want a professional assessment of your property’s vulnerability — call Prolific Design-Build and Restoration at (425) 800-4775. We respond 24/7 for emergencies and offer free consultations for preventive assessments.

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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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