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.

About Us

About Prolific Design-Build and Restoration
Prolific Design-Build and Restoration, the forefront of Commercial & Residential Solutions
Welcome to Prolific Design-Build and Restoration, the forefront of Commercial & Residential Solutions in the Greater Seattle area. With a passion for excellence, we are dedicated to transforming spaces through innovative design, impeccable craftsmanship, and a customer-centric approach.At Prolific Design-Build and Restoration, we believe in the power of collaboration and the value of listening to our clients. Understanding your unique vision and requirements, we tailor our solutions to meet your specific needs, delivering results that exceed expectations.Our team of experienced professionals brings a wealth of expertise and a keen eye for detail to every project. From concept to completion, we guide you through the process, ensuring transparency, clear communication, and a seamless experience. With a focus on quality and precision, we take pride in delivering exceptional craftsmanship that stands the test of time. Our commitment to staying at the forefront of industry trends and innovations enables us to bring fresh ideas and cutting-edge solutions to your projects. Whether it’s a commercial construction venture or a residential remodeling project, we approach each undertaking with passion and dedication. We value integrity, honesty, and building long-lasting relationships with our clients.At Prolific Design-Build and Restoration, our mission is to create remarkable environments that inspire, empower, and make a lasting impact. Join us on this transformative journey, where excellence meets innovation and your vision becomes a reality. Experience the Prolific Design-Build and Restoration difference. Contact us today to discuss your project and embark on a partnership that will elevate your spaces to new heights.
Our History

Superior services designed to elevate your spaces

Prolific DBR

At Prolific Design-Build and Restoration, we are a leading provider of high-quality Commercial & Residential Solutions. With a wealth of expertise and a commitment to excellence, we deliver exceptional results that surpass expectations. Choose us for unparalleled craftsmanship and outstanding customer service.

Why Choose Us

Six Reasons For People Choosing Us

Unparalleled Expertise

Our team consists of highly skilled professionals with extensive experience in the industry, ensuring exceptional results for your project.

Customized Solutions

We understand that every client is unique, and we tailor our services to meet your specific needs, preferences, and budget.

Attention to Detail

We take pride in our meticulous approach to every task, leaving no room for errors and delivering flawless outcomes.

Outstanding Customer Service

Our clients are at the heart of everything we do, and we go above and beyond to provide exceptional service and a seamless experience.

Reliable and Timely

With a track record of meeting deadlines and delivering on our promises, you can trust us to complete your project on time and within budget.

Licensed, Bonded, and Insured

As a fully licensed, bonded, and insured company, we prioritize safety and compliance, giving you peace of mind throughout the process.

GET A QUICK FREE QUOTE
Getting in touch with us is easy. Reach out to our team for a consultation or to discuss your project requirements. Find our contact information, including phone number, email address, and a convenient contact form, right here. We look forward to hearing from you and turning your vision into reality.

Call us

(425) 800-4775

Email us

info@prolificsolutionsnw.com

Location

14401 Issaquah Hobart Rd SE Issaquah, WA 98027

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