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.

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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.

Deck Coating, Stain & Sealant Guide — Seattle / King County

URL slug: /cost-guides/deck-coating-stain-seattle/ Target keywords: deck stain Seattle | deck coating Pacific Northwest | best deck sealant rain | deck refinishing cost Seattle


Western Washington’s climate is one of the hardest on wood decks in the country — long wet winters, UV-intense summers, and rapid mold growth in shaded areas. Choosing the right coating and applying it correctly can add 5–10 years to a wood deck’s life. Here’s what works in the Puget Sound.

The Three Coating Categories

Penetrating Sealers (Clear or Semi-Transparent) Penetrating sealers soak into the wood fibers rather than forming a surface film. They preserve the natural look of the wood and are easier to maintain — you apply a new coat without stripping the old one.

Best for: New cedar, pressure-treated, or redwood decks where you want a natural look.

Top products for PNW: Armstrong Clark Semi-Transparent, Defy Extreme Wood Stain, TWP (Total Wood Preservative).

Solid Stains and Paints Solid stains form a pigmented film over the wood. They hide grain and color variation — useful for older, weathered decks. They provide more UV protection than penetrating stains.

Downside: They peel. In a wet climate, a solid stain applied over a deck with any trapped moisture will peel within 1–2 seasons. They also require stripping before recoating.

Deck Resurfacers Products like Rust-Oleum Deck Restore or Behr Advanced Deck Resurfacer fill cracks and gouges with a thick, textured coating. They can make an old deck look significantly better.

Best for: Older decks with surface damage that aren’t ready for full replacement. Not a substitute for structural repair — if boards are soft or posts are rotted, resurface won’t save the deck.

Cost to Refinish a Deck in Seattle

ServiceCost (400 SF deck)
Pressure wash + clean$300–$600
Strip old coating (if needed)$400–$800
Apply penetrating stain (1 coat)$600–$1,200
Apply solid stain / paint (2 coats)$900–$1,800
Full refinish (clean + strip + 2 coats)$1,200–$2,500

When to Recoat vs. When to Replace

Signs it’s time to refinish (not replace): – Surface graying and slight checking – Peeling or flaking coating – Water no longer beads on the surface

Signs it’s time to replace: – Soft, spongy boards (probe with a screwdriver — if it penetrates easily, the board is rotted) – Structural framing showing rot or insect damage – Boards over 20 years old with widespread cracking

Get a deck refinishing or replacement estimate from Prolific →


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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

📋 Get a Free Estimate