Seattle DADUs & Backyard Cottages

A detached accessory dwelling unit (a “legal” DADU) in Seattle typically costs between $500,000 and $750,000, depending on the size, design complexity, and site conditions.

A smaller backyard studio/office (not a “legal” DADU) will be less expensive as it does not feature a kitchenette and may not include a bathroom.

Site preparation costs can vary significantly based on your lot—slope, access for construction equipment, utility connections, and tree preservation requirements all factor in. Our free Backyard Cottage + DADU Pricing Guide (crddesignbuild.com/content-offer/backyard-cottage-dadu-pricing-guide/) provides detailed cost ranges based on real Seattle projects.

A DADU project with CRD typically takes twelve to fourteen months from design through construction completion. The design phase runs four to six months, followed by permitting, which in Seattle usually takes six to ten weeks for new detached structures.

Construction typically takes six to nine months depending on the size and complexity of the build, plus site conditions like slope and access. Your Project Manager will provide a detailed schedule before construction begins.

Seattle allows most single-family lots to have both an attached ADU and a detached ADU (DADU). Key requirements change year-to-year and often include maximum size limits, setback requirements from property lines, height restrictions, and lot coverage limits that vary by zone.

There is no owner-occupancy requirement, which means you can rent out both your main home and the DADU if you choose. Our team stays current on Seattle’s evolving ADU regulations and can assess what’s feasible on your specific lot during the initial consultation.

CRD warrants its work for 24 months starting from the time we sign the construction agreement. As the warranty comes to an end we always reach out to clients to let them know in advance in case any last minute fixes need to be made.

Design build is a full-service approach to home remodeling that includes both the design and construction. The design-build approach tends to offer homeowners better efficiency, accountability, communication, and convenience for their home remodeling project.

Our design process is divided into three steps: Schematic Design, Design Development and Construction Agreement.

Your design journey with CRD will begin with the Schematic Design phase in which we learn more about your goals, take measurements of your home, and gather ideas. During a series of meetings, your designer and architect will get your feedback on initial floor plans and design direction. As we develop an ideal scope of work, you will then have the opportunity to review preliminary pricing at the Schematic Estimate Meeting. Open and honest conversation about budget tracking is the foundation of CRD’s proven process and will give you the confidence and clarity to move forward.

This is followed by a series of Design Development meetings, where you will further refine your design. At the Letter of Intent Meeting, you will review updated pricing and make the decision to move forward with construction.

Finally, at the Construction Agreement meeting, you will have the opportunity to review your final pricing and construction documents before signing a fixed-price construction agreement. From there, construction begins, and soon you will be enjoying your remodeled space.

The design process timeline will differ depending on the size of the project.

See Also: The CRD Design Build Process

Prices vary widely depending on the area of the house being remodeled, how old the house is, and if any major structural alterations need to be done to the existing home to achieve the design goal.

See also: Pricing Guides