Adu services — Seattle, WA | AccessoryDwellingUnit Solutions

Looking for adu services in Seattle, WA? Call AccessoryDwellingUnit Solutions for a contact a provider — no obligation. Licensed adu builders serve Seattle and the surrounding area, and you'll get straight answers on timing and what affects the price.

Last updated: September 24, 2026

What affects the price

Building an ADU involves several moving parts that shape your total budget. The biggest factor is whether you choose a prefabricated unit or a custom build on-site. Site preparation is also significant; if your land requires extensive grading, utility trenching, or foundation work, costs will climb. Your choice of finishes—like kitchen cabinetry, flooring, and siding materials—also shifts the bottom line. We help you navigate these variables to find a setup that fits your property. Exact pricing confirmed free on the call.

About this service

ADU services manage the technical and creative side of building a secondary unit on your lot. Whether you are converting a garage or building a new structure from the ground up, you need these services to bridge the gap between architectural plans and physical construction. They help manage site preparation, utility connections, and structural integrity, ensuring your project is ready for occupancy without you having to coordinate multiple subcontractors independently.

Frequently asked in Seattle

What are the disadvantages of ADUs in Seattle?

How much does an ADU cost in Washington?

The cost of an ADU in Washington State, including Seattle, varies based on size, design, and materials used. Factors like foundation type, utility connections, and interior finishes all contribute to the final price. Site preparation can also be a significant cost. For an accurate estimate tailored to your Seattle property, a professional quote is essential.

What are the rules for ADUs in Washington?

Washington State has statewide ADU regulations, but cities like Seattle also have their own specific local ordinances. These rules often cover aspects such as minimum lot size, setbacks, and parking requirements. Understanding both state and city regulations is crucial for a successful ADU project. A professional can clarify the specific rules for your Seattle location.

Is ADU allowed in Maryland?

This service is focused on ADU projects within Washington State, specifically serving the Seattle area. Regulations for Accessory Dwelling Units differ significantly by state and municipality. If you have a property in Maryland, you will need to seek out local ADU services and information specific to that region. We specialize in Seattle ADU solutions.

How does an ADU affect my utilities in Seattle?

Adding an ADU will increase your overall utility usage (water, electricity, gas). Depending on your setup, the ADU might be on its own meter or share with the main house. Professionals can advise on the most efficient systems and how to manage utility costs. This is a key consideration for any ADU project in Seattle.

Also serving nearby: Kirkland · Bellevue · Renton · Kent · Federal Way

All cities in Washington →

More on this: HUD ADU resources — ADU policy and financing research.

Service area details

755,078residents

8,989per sq mile

8ZIP codes served

Serving all of Seattle — population 755,078; about 8,989 residents per square mile across 84.0 sq mi. ZIP codes covered include 98101, 98102, 98103, 98104, 98105, 98106, 98107, 98108.

Neighborhoods served in Seattle: Ballard, Fremont, Capitol Hill, Queen Anne, Green Lake, West Seattle — and every surrounding area.