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.

Emergency Water Damage Restoration in King County: What to Do in the First 24 Hours

Water Damage Strikes Fast — Your Response Matters

Whether it’s a burst pipe in the middle of winter, a roof leak during a Pacific Northwest rainstorm, or flooding from a failed sump pump, water damage is one of the most common — and most destructive — emergencies homeowners face in King County. What you do in the first 24 hours can mean the difference between a manageable repair and a catastrophic loss.

At Prolific Design-Build and Restoration, we provide emergency water damage restoration across Issaquah, Sammamish, Bellevue, Renton, and the greater King County area. We’ve restored hundreds of water-damaged homes, and we know that fast action saves homes — and saves money.

The First 24 Hours: Your Emergency Checklist

If you’re dealing with water damage right now, here’s what to do immediately:

1. Stop the water source if possible. Shut off the main water supply if the damage is from a plumbing failure. If it’s storm-related or from an external source, focus on containing the spread with towels, buckets, or barriers.

2. Turn off electricity in affected areas. Water and electricity are a dangerous combination. If standing water is near outlets, switches, or your electrical panel, shut off power at the breaker. If you can’t safely reach the panel, call your utility company.

3. Document everything. Before you start cleanup, photograph and video all damage from multiple angles. Document the water source, affected rooms, damaged belongings, and water levels. This documentation is critical for your insurance claim.

4. Call your insurance company. Report the damage as soon as possible. Most homeowner policies require prompt reporting. Ask for a claim number and take notes on everything discussed. Need help navigating the process? We wrote a complete guide to the insurance claims process.

5. Call a professional restoration contractor. Water extraction, structural drying, and mold prevention require professional equipment — industrial dehumidifiers, air movers, moisture meters, and thermal imaging cameras. The sooner extraction begins, the less secondary damage occurs.

Types of Water Damage and Why Classification Matters

Not all water damage is the same. The insurance industry and restoration professionals classify water damage into three categories:

Category 1 — Clean Water: From a broken supply line, faucet, or ice maker. This is the least hazardous but still requires prompt extraction and drying to prevent mold growth.

Category 2 — Gray Water: From dishwashers, washing machines, or toilet overflows (without solid waste). Contains contaminants and requires sanitization in addition to extraction.

Category 3 — Black Water: From sewage backups, river flooding, or storm surge. This water contains bacteria, viruses, and other pathogens. Affected materials often must be removed and replaced entirely. Professional hazmat-grade cleanup is required.

The category of water damage directly affects your restoration plan, your insurance coverage, and the cost of repairs. High-value homes often have more complex water damage scenarios due to finished basements, custom millwork, and premium materials that require specialized restoration techniques.

The Professional Water Damage Restoration Process

Here’s what to expect when Prolific Design-Build and Restoration responds to a water damage emergency:

Emergency Response & Assessment: We arrive on-site, assess the damage, identify the water source and category, and develop a restoration plan. We use moisture meters and thermal imaging to find hidden water in walls, ceilings, and subfloors.

Water Extraction: Using commercial-grade pumps and extractors, we remove standing water as quickly as possible. Every hour water sits increases damage exponentially.

Structural Drying: Industrial dehumidifiers and air movers are strategically placed to dry the structure. We monitor moisture levels daily until the building reaches acceptable dryness standards.

Demolition of Unsalvageable Materials: Saturated drywall, insulation, carpet padding, and other porous materials that can’t be dried effectively are carefully removed and disposed of.

Mold Prevention & Remediation: Water that sits for more than 24–48 hours almost always leads to mold growth. We apply antimicrobial treatments and monitor for mold development. If mold is already present, we handle full mold remediation as part of the restoration.

Reconstruction & Restoration: Once the structure is dry and clean, we rebuild — drywall, flooring, paint, trim, cabinetry, and any other affected components. As a design-build contractor, we handle the full rebuild in-house, so you don’t need to hire a separate construction company.

Common Causes of Water Damage in King County

Our region’s climate and housing stock create specific water damage risks:

Storm damage and roof leaks are the most common cause we see, especially during fall and winter storms. Heavy rain combined with wind can compromise roofing, flashing, and gutters. Read our guide on storm damage restoration on the Eastside.

Frozen and burst pipes occur during cold snaps, particularly in older homes with pipes in exterior walls or unheated crawl spaces.

Appliance failures from water heaters, washing machines, dishwashers, and refrigerators account for a significant portion of water damage claims.

Foundation and drainage issues are common in hillside homes throughout Issaquah and Sammamish, where improper grading or failed drainage systems allow water intrusion.

Insurance Coverage for Water Damage

Most standard homeowner policies cover sudden and accidental water damage — burst pipes, appliance failures, and storm damage to the roof. However, coverage varies significantly by policy and insurer.

Flood damage from rising water (rivers, surface runoff) is typically NOT covered by standard policies and requires separate flood insurance through FEMA’s National Flood Insurance Program or a private flood policy.

Gradual damage — slow leaks, long-term moisture buildup, or maintenance-related issues — is often excluded. This is why prompt action and documentation are so important. We work directly with your insurance adjuster to ensure your claim reflects the full scope of damage and help you maximize your coverage.

Don’t Wait — Call Prolific Now

Water damage gets worse every hour. If your home has been affected by water damage, call Prolific Design-Build and Restoration immediately at (425) 800-4775. We serve Issaquah, Sammamish, Bellevue, Renton, Redmond, Kirkland, and all of King County.

Contact us for emergency service — we’ll get your home dry, safe, and restored.

Related reading: Mold Remediation After Water Damage | Kitchen Remodeling in Issaquah, Sammamish & Bellevue | ADU & DADU Construction Guide

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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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