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.

🏡

Detached ADU (DADU)

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

🏗

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.

🏠

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 Mitigation vs Water Restoration: What’s the Difference?

When water damages your home — whether from a burst pipe, storm intrusion, or appliance failure — you’ll hear two terms thrown around: water mitigation and water restoration. They sound similar, and many people use them interchangeably. But they’re actually two distinct phases of the recovery process, and understanding the difference matters for your insurance claim, your timeline, and the health of your home.

Water Mitigation: Stop the Damage

Water mitigation is the emergency phase. It happens first and its goal is simple: stop the water damage from getting worse. Every minute counts — water spreads fast, soaking into drywall, subfloors, insulation, and framing. Within 24-48 hours, mold can start growing. Mitigation is about speed.

What water mitigation includes:

Water extraction — Industrial pumps and truck-mounted extractors remove standing water from your home. This is the first priority and happens within hours of the call.

Structural drying — Commercial-grade dehumidifiers and air movers are placed throughout affected areas to pull moisture out of building materials. This process typically takes 3-5 days and is monitored with moisture meters to confirm materials reach acceptable dryness levels.

Moisture mapping — Technicians use thermal imaging cameras and moisture meters to identify exactly where water has traveled — often behind walls, under flooring, and into areas you can’t see. This creates a complete picture of the affected area.

Antimicrobial treatment — Affected surfaces are treated to prevent mold growth during the drying period.

Content protection — Furniture, electronics, and personal items are moved, elevated, or removed from wet areas to prevent further damage.

Mitigation companies are typically IICRC-certified (Institute of Inspection, Cleaning and Restoration Certification) and follow the S500 Standard for water damage restoration. This certification matters because insurance companies expect mitigation work to follow these standards.

Water Restoration: Rebuild and Repair

Water restoration is the reconstruction phase. It begins after mitigation is complete and the structure is dry. The goal is to return your home to its pre-damage condition — or better.

What water restoration includes:

Demolition of damaged materials — Waterlogged drywall, saturated insulation, warped flooring, and damaged trim are removed. Materials that can’t be saved are documented for the insurance claim before disposal.

Mold remediation — If mold has developed (common when water damage isn’t addressed within 24-48 hours), professional remediation includes containment, removal, cleaning, and HEPA air filtration.

Structural repairs — Damaged framing, subfloors, and structural elements are repaired or replaced.

Drywall replacement — New drywall is hung, taped, textured, and painted to match existing finishes.

Flooring installation — New carpet, hardwood, laminate, or tile is installed to replace water-damaged flooring.

Painting and finishing — Walls, trim, and ceilings are painted to match pre-damage condition.

Final inspection — A walkthrough ensures all repairs meet quality standards and match the approved insurance scope.

Why the Distinction Matters for Your Insurance Claim

On your insurance estimate, mitigation and restoration are typically listed as separate line items with different category codes in Xactimate. Water mitigation costs appear under WTR (water mitigation) categories, while restoration costs appear under construction categories like DRY (drywall), FLR (flooring), PNT (painting), etc.

This matters because some insurance companies try to combine or overlap these costs, or argue that mitigation costs were excessive. Having a contractor who understands both phases — and how they’re documented separately in Xactimate — ensures your claim accurately reflects all necessary work.

The Problem with Using Two Separate Companies

Many homeowners end up using one company for mitigation and a different company for restoration. This happens because mitigation companies often show up first (they’re the emergency responders), but many only do the drying — they don’t do construction. So you end up hiring a second contractor for repairs.

This creates several problems:

Communication gaps. The mitigation company documents the water damage one way; the restoration contractor interprets it differently. Information gets lost in the handoff.

Finger-pointing. If mold develops after drying, who’s responsible — the mitigation company that dried it or the restoration contractor who rebuilt it? With two companies, accountability is unclear.

Two insurance scopes. Your insurance claim now involves two separate companies submitting two separate invoices, which can create confusion and delays in payment.

Longer timelines. Waiting to find and schedule a second contractor after mitigation adds days or weeks to your recovery.

The Advantage of One Company Handling Both

A full-service restoration contractor that handles both mitigation and restoration eliminates all of these problems. One company, one insurance scope, one point of contact from the moment water enters your home to the moment the last coat of paint dries.

At Prolific Design-Build and Restoration, we handle the entire water damage process: emergency water extraction, structural drying, moisture monitoring, mold remediation, demolition, reconstruction, and finishing — all coordinated through a single insurance claim. We document the mitigation phase, transition seamlessly into restoration, and ensure your insurance claim covers both phases completely.

How Fast Should You Act?

The speed of mitigation directly affects the cost and scope of restoration. Here’s the general timeline:

Within 1 hour: Water spreads rapidly. Drywall begins wicking moisture upward. Furniture stains floors. Metal surfaces begin tarnishing.

Within 24 hours: Drywall begins to swell and break down. Mold spores activate. Wood starts to warp. Musty odors develop.

Within 48-72 hours: Mold colonies become visible. Drywall may need replacement rather than drying. Wood framing can begin to swell and compromise structural integrity.

After one week: Extensive mold growth. Structural damage. Significantly higher restoration costs. Insurance companies may question delayed mitigation.

The takeaway: call immediately. The faster mitigation begins, the less restoration you’ll need — which means lower costs, faster recovery, and a cleaner insurance claim.

Dealing with water damage? Call (425) 800-4775 for immediate 24/7 emergency response. We handle both water mitigation and water restoration under one roof — one call, one company, one insurance claim. Serving all of King County, WA.

Related Articles

Leave a Comment

Your email address will not be published. Required fields are marked *

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
Back to Home

Prolific Design-Build & Restoration — Federal Way, WA

📋 Get a Free Estimate