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.

How to Choose the Right Restoration Contractor in King County: A 2026 Homeowner’s Guide

If your King County home has been hit by a windstorm, a burst pipe, a kitchen fire, or a slow water leak that finally showed itself as a brown ceiling stain, the next decision you make matters more than almost anything else: which restoration contractor do you hire? Pick well and the work gets done correctly, your insurance claim runs smoothly, and your home comes back better than before. Pick poorly and you can spend months fighting your carrier, paying out of pocket for repairs that should have been covered, or living with hidden moisture that quietly grows into mold a year later.

At Prolific Design-Build and Restoration, we sit on both sides of this equation every week. We’re a licensed, insured, Black-owned and Latino-owned restoration and design-build contractor based in Issaquah, serving Sammamish, Bellevue, Redmond, Kirkland, Renton, Mercer Island, and the rest of King County. We get called in to clean up after other contractors as often as we get called in for original loss. This guide is the same one we share with friends, neighbors, and clients who ask the question every King County homeowner eventually asks: how do I choose the right restoration contractor?

Why Choosing the Right Restoration Contractor Matters More Than Choosing a Remodeler

A restoration project is not the same as a remodel. A remodel happens on your timeline, with your design choices, and within a fixed scope that you approved on paper before anyone swung a hammer. A restoration happens on the loss’s timeline — water keeps spreading, smoke residue keeps etching surfaces, mold keeps colonizing — and the scope is dictated by what the damage actually did, not what you wished it did.

That difference makes the contractor’s experience, judgment, and integrity far more consequential. Your restoration contractor decides what gets demolished and what stays, how much drying equipment runs and for how long, which materials get replaced with like-kind-and-quality, and how the final invoice gets justified to your insurance carrier. Most King County homeowners only file a major property loss once or twice in a lifetime, so they have no benchmark for whether what’s being proposed is right, generous, or sketchy.

The right contractor protects your home, your insurance claim, and your sanity in that order. The wrong one creates problems on all three fronts that can take years to undo.

Step 1: Verify Licensing, Bonding, and Insurance — Every Time

Washington is a registered-contractor state, not a strict licensing state, which catches a lot of out-of-state homeowners off guard. Every contractor doing structural work on your King County home must be registered with the Washington State Department of Labor & Industries (L&I), carry a contractor bond, and maintain general liability insurance. You can verify all three in about ninety seconds using L&I’s “Verify a Contractor” lookup.

What you want to see:

An active registration number with no recent suspensions, with the business name matching the company on the truck and the proposal. A current bond on file (typically $12,000 for general contractors). General liability insurance with at least $1 million in coverage. Workers’ comp coverage through L&I — if a worker gets hurt on your property and the contractor isn’t covered, you can become the deep pocket.

For mold remediation, water restoration, and fire restoration specifically, ask whether the firm and its on-site technicians hold IICRC certifications (the industry’s main credentialing body for water restoration, applied structural drying, fire and smoke restoration, and mold remediation). A general contractor without IICRC-certified techs on a water loss is a yellow flag — not disqualifying, but worth a longer conversation.

Step 2: Look for Local Experience in King County, Not Just Years in Business

Twenty years of restoration experience in Phoenix translates poorly to a Sammamish split-level with a wet crawl space and a cedar-shingle roof that’s been through fifteen Pacific Northwest winters. Our region has its own building stock, its own moisture problems, its own permitting authorities, and its own insurance carriers. You want a contractor who knows all of it.

Ask specifically: How many losses have you handled in King County in the last twelve months? Have you worked with my carrier before? Do you know the permitting process in Issaquah, Bellevue, Sammamish, Redmond, Kirkland, or wherever your home sits? Are you familiar with our common housing types — 1980s split-levels, 1990s tract neighborhoods, mid-century rambler stock, contemporary new builds with sealed envelopes that trap moisture differently than older homes?

A truly local contractor will answer those questions with specifics: street names, neighborhood quirks, the inspector who’s tough about vapor barriers, the carrier that pays Xactimate line items quickly versus the one that fights every invoice. That granularity is what you’re paying for.

Step 3: Understand the Difference Between a Restoration Contractor and a General Contractor

Not every general contractor is a restoration contractor, and not every restoration company can handle the rebuild side of your project. The distinction matters because most losses involve both mitigation (stopping the damage, drying, demo, debris removal) and reconstruction (rebuilding what was destroyed).

A pure mitigation company can dry your floors and tear out wet drywall, but they’ll hand you off to a separate rebuild contractor who didn’t see what was behind the walls. A pure remodeling contractor can rebuild your kitchen, but they may not know how to scope dry-out, write supplements to your adjuster, or document moisture readings the way an insurance carrier expects.

The smoothest experience comes from a full-service design-build restoration firm that handles both phases under one roof. You don’t lose information between handoffs. The same project manager who saw the original damage signs off on the final paint. The supplement requests are written by the same team that’s actually doing the work, not a third-party estimator. For a deeper breakdown of how this integrated model compares to the traditional fragmented approach, see our guide on design-build versus traditional contracting in King County.

Step 4: Watch Out for Storm Chasers and Door-Knockers

After every major windstorm, hailstorm, or wildfire in the Pacific Northwest, out-of-state contractors flood the region looking for quick claim work. They knock on doors, offer “free inspections,” promise to handle your entire insurance claim, and frequently disappear before warranty issues surface. Some don’t even register with L&I.

Red flags include: unsolicited door-knocks within days of a storm, especially from someone who can’t produce a current L&I registration on the spot; high-pressure tactics that ask you to sign an “Assignment of Benefits” or contingency agreement before you’ve even read it; promises to “waive your deductible” (this is insurance fraud in Washington and exposes you legally); vehicles with out-of-state plates and magnet-stuck logos; and a refusal to give you a physical local office address you can visit.

A legitimate restoration contractor in King County has a real address, real reviews accumulated over years (not weeks), a real phone number that’s answered by a real human, and zero interest in pressuring you into a same-day signature. If someone shows up uninvited claiming “your neighbor sent us,” verify with the neighbor by phone before any conversation continues.

Step 5: Read Reviews — But Read Them Critically

Google, Yelp, Houzz, and the BBB all carry restoration-contractor reviews, and they’re worth reading. But read them like a detective, not a tourist. Five-star reviews stacked in a single week are usually purchased or pressured. A pattern of one-star reviews citing the same complaint — disappearing after deposit, billing surprises, unfinished punch lists, mold returning — matters more than the overall star average.

Look for reviews that mention specific King County cities, specific carriers, and specific loss types similar to yours. A glowing review of a kitchen remodel doesn’t tell you much about how a contractor handles a Category 3 water loss. Ask the contractor directly for two or three references from recent restoration jobs in your area, and actually call those references. The questions worth asking: Did the timeline match the original estimate? Were there supplements, and how were they communicated? Would you hire them again for a different kind of work?

Step 6: Pay Close Attention to How They Handle the Insurance Side

This is where most homeowners get burned. Restoration work in Washington is largely insurance-funded, and the contractor’s relationship with your carrier shapes the entire project. The wrong dynamic looks like this: the contractor demands a non-refundable deposit before the adjuster has even visited, refuses to share the scope of work, writes a number on a napkin and tells you the carrier will pay it, and then bills supplements you never approved.

The right dynamic looks like this: the contractor writes a formal scope in Xactimate (the same software your carrier’s adjuster uses), shares that scope with you and the adjuster, agrees to negotiate line-by-line with the carrier, and only invoices what the carrier has approved or what you’ve authorized in writing. If you’d like to understand what those Xactimate estimates actually mean, our guide on how to read an Xactimate estimate is a good starting point.

Other questions worth asking: Will you bill my carrier directly, or do I pay you and seek reimbursement? Who writes supplements, and how are they communicated to me before they’re submitted? What happens if the carrier denies a line item — do I owe you the difference? You also have the legal right to choose your own contractor in Washington, regardless of what your carrier’s “preferred vendor” representative tells you. We cover that in can I choose my own contractor on an insurance claim.

Step 7: Understand Pricing, Deposits, and Payment Schedules

Restoration pricing in 2026 is mostly market-rate Xactimate plus regional adjustments. A reputable King County contractor’s invoice should align reasonably with the Xactimate price list for our zip codes. Wild deviations — either way too cheap or way too expensive — deserve scrutiny.

On deposits: Washington law caps contractor deposits at a percentage of the contract for many types of work, but restoration jobs are often structured around insurance milestones rather than upfront cash. A modest mobilization fee for emergency mitigation work is reasonable. A demand for thirty or fifty percent down before any work has started, on a claim that hasn’t been adjusted yet, is not.

Reasonable payment schedules are tied to completed milestones: dry-out complete, demo complete, framing complete, mechanical rough-in, drywall, finishes, final punch. Each draw should correspond to inspectable progress. Get this in writing before you sign anything. For typical project pacing, our King County restoration timeline guide walks through what each phase looks like in real days, not marketing days.

Step 8: Get the Contract — All of It — in Writing

A handshake and a one-page proposal is not a restoration contract. The document you sign should include the full scope of work (ideally an Xactimate scope), the schedule of values, the payment schedule, change-order procedures, warranty terms, lien-waiver language, and a clear definition of what triggers project completion. It should name the project manager, list emergency contact numbers, and reference your insurance claim number.

If a contractor balks at a written scope or insists on “we’ll figure it out as we go,” walk away. The reason restoration projects spiral out of control is almost always documentation that wasn’t tight at the start. Solid documentation also protects you when your adjuster requests proof of work — see our piece on documenting property damage for an insurance claim.

Step 9: Trust Your Gut on Communication

Restoration projects are stressful. You’re dealing with displaced living conditions, an unfamiliar insurance process, and decisions that affect your largest asset. Your contractor’s communication style during the first two interactions is a strong predictor of how the next sixty to one hundred and twenty days will feel.

Do they answer the phone? Do they call back when they say they will? Do they explain things in plain English, or do they hide behind jargon? Do they push back honestly when you suggest something that won’t work, or do they just say yes to close the deal? Do they treat your spouse, your roommate, or your elderly parent with the same respect they treat you? Those small signals add up. A technically competent contractor with poor communication will still produce a frustrating project. A merely competent contractor with excellent communication often produces a great one.

Step 10: Consider the Long Arc — Restoration That Becomes Renovation

Many King County restoration projects naturally evolve into improvement projects. You’re already opening walls, replacing flooring, and pulling cabinets. With a design-build firm on your side, that disruption can be leveraged into the kitchen layout you actually wanted, a brighter primary suite, or a more functional laundry room — at a fraction of the cost compared to doing the work as a separate project later. Insurance pays for the like-kind-and-quality replacement; you pay the marginal upgrade cost. We’ve helped many Eastside homeowners turn a frustrating loss into a real upgrade, and we wrote about the approach in from damage to dream home: turning restoration into remodel.

You don’t have to take this path. If you simply want the home back the way it was, a good restoration contractor will execute that cleanly. But knowing the option exists, and choosing a contractor who can deliver either outcome, gives you more leverage and more value from a difficult moment.

Why King County Homeowners Choose Prolific Design-Build and Restoration

Prolific Design-Build and Restoration is licensed, bonded, and insured in Washington, with active L&I registration and full general liability coverage. We’re a Black-owned and Latino-owned firm based in Issaquah, with hands-on experience across Sammamish, Bellevue, Redmond, Kirkland, Renton, Mercer Island, and surrounding King County communities. We handle both sides of the work — emergency mitigation and rebuild — under one roof, with the same project manager from first call to final walkthrough.

We write scopes in Xactimate, negotiate with carriers professionally, communicate with homeowners in plain English, and document every phase of the work. Whether you’re staring at storm damage, a water loss, a fire, a mold issue, or just trying to vet a contractor before a future emergency hits, we’d rather have an honest conversation with you than win a job that isn’t a fit.

If you’re navigating a current loss — or you want a name on file before the next one — call (425) 800-4775 or reach us through our contact page. We respond quickly, show up on time, and treat your home like it’s our own.

Related: How to Find the Best Restoration Company in King County · Public Adjuster vs. Restoration Contractor: What’s the Difference? · What to Expect from an Insurance Adjuster Visit

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Prolific Design-Build & Restoration — Federal Way, WA

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