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.

How to Get a Building Permit in Shoreline, WA

Target keywords: Shoreline WA building permit | deck permit Shoreline WA | Shoreline Planning Development | permit cost Shoreline


Shoreline was incorporated in 1995 and has developed one of the more homeowner-friendly building departments in the north King County area. The city is undergoing significant growth around its light rail stations, but the residential permitting process for single-family homes remains accessible.

Does My Project Need a Permit in Shoreline?

Decks Attached decks require a permit. Freestanding platforms under 200 SF and less than 30 inches above grade are typically exempt.

Fences Fences up to 6 feet are generally exempt in rear and side yards. Front yard fences are subject to the city’s setback and height standards.

ADUs Shoreline has embraced ADU development, particularly around its two light rail stations (145th St and 185th St). Both attached ADUs and detached backyard cottages are allowed with a building permit.

Interior Remodels Structural, electrical, plumbing, and HVAC work requires permits.

Shoreline Permitting Department

City of Shoreline Planning and Development Services – Website: shorelinewa.gov/planning – Phone: (206) 801-2500 – Address: 17500 Midvale Ave N, Shoreline, WA 98133

Permit Fees in Shoreline

ProjectEstimated Fee
Deck (200–400 SF)$400–$800
Fence (if required)$150–$325
ADU$2,000–$5,000+
Kitchen remodel (with mechanical)$600–$1,400
Room addition$1,200–$3,000

How Long Does Permitting Take in Shoreline?

  • Simple projects: 2–4 weeks
  • Standard residential: 5–12 weeks
  • ADU near light rail overlay: Add 2–4 weeks for urban design review

What Shoreline Inspectors Check

Standard structural and code inspections. Projects in the 145th or 185th Street Station Subareas may be subject to additional design review standards. Tree retention is regulated — Shoreline has a significant canopy protection program.

Let Prolific Handle the Permits

We work in Shoreline regularly and know the city’s ADU incentive program. Get an estimate →


Schema: Shoreline Permitting Guide

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  "@context": "https://schema.org",
  "@type": "FAQPage",
  "mainEntity": [
    {
      "@type": "Question",
      "name": "Does Shoreline WA allow ADUs?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Yes, Shoreline allows both attached ADUs and detached backyard cottages on single-family lots. The city has been actively promoting ADU development near its light rail stations."
      }
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    {
      "@type": "Question",
      "name": "How long does it take to get a permit in Shoreline?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Standard residential permits in Shoreline take 5–12 weeks. ADU projects near the light rail station overlay areas may require additional urban design review."
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      "@type": "Question",
      "name": "How much does a deck permit cost in Shoreline?",
      "acceptedAnswer": {
        "@type": "Answer",
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WordPress Deployment Notes

Each guide above = one WordPress page. Recommended setup:

  1. Page URL slugs:
  2. /permits/seattle/
  3. /permits/king-county/
  4. /permits/seatac/
  5. /permits/bellevue/
  6. /permits/renton/
  7. /permits/kirkland/
  8. /permits/redmond/
  9. /permits/shoreline/

  10. Parent page: Create a /permits/ parent page with a brief intro and links to all 8 guides. This creates a hub that gets internal link equity from all 8 child pages.

  11. Schema injection: Paste each guide’s JSON-LD block into a Custom HTML block at the bottom of the page, or use RankMath’s Schema module.

  12. Internal linking: Every guide should link to:

  13. The discovery survey (/free-estimate/)
  14. At least one related cost guide page (e.g. Seattle deck permit guide → deck cost guide)
  15. The /permits/ hub page

  16. LocalBusiness schema on parent page:

{
  "@context": "https://schema.org",
  "@type": "LocalBusiness",
  "name": "Prolific Design-Build & Restoration",
  "telephone": "+14258004775",
  "email": "info@prolificsolutionsnw.com",
  "url": "https://prolificsolutionsnw.com",
  "areaServed": [
    "Seattle, WA", "King County, WA", "SeaTac, WA",
    "Bellevue, WA", "Renton, WA", "Kirkland, WA",
    "Redmond, WA", "Shoreline, WA"
  ],
  "serviceArea": {
    "@type": "GeoCircle",
    "geoMidpoint": {
      "@type": "GeoCoordinates",
      "latitude": 47.6062,
      "longitude": -122.3321
    },
    "geoRadius": "50000"
  }
}

All 8 guides — REQ-189 | Authored 2026-04-28

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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