seattle backyard cottage blog

Backyard cottages (DADUs) provide opportunities for families, while increasing housing stock density and diversity. Continue reading for more information about Seattle's backyard cottage ordinance or contact us to find out if your lot is eligible for a backyard cottage..

backyard cottages - regs.

Backyard Cottages - Seattle 

Every lot and potential use of a backyard cottage is unique and the cost of building a backyard cottage in Seattle is not insignificant. It is important to consult with experts when beginning the process to best guide the many decisions that make up the design process

Getting Started

Because we design so many backyard cottages we can answer most feasibility questions over the phone.To start the process send us an email with your address and tell us about your goals for your small house or backyard cottage.  We will schedule a follow up phone call where we can discuss the specifics of your project.

Digging Deeper

Our open houses and workshops are a great opportunity to learn about and meet others thinking about building and living in a backyard cottage. We hold these event periodically throughout the year. Refer to our events page for more information or sign up for our open house invitation list. Many of our events are by invitation only.

Common Code Requirements

In 2009 the City of Seattle expanded the their demonstration backyard cottage ordinance to allow backyard cottages in all Seattle neighborhoods.  Fast forward to 2019 and the city is has expanded the ordinance still further.  Follow this blog to lean more about these proposed changes and their implementation.  These are some of the common requirements.

Backyard Cottage Parking 

Backyard cottages (detached ADUs) no longer require one parking space. However the parking space required for the primary residence may not be removed unless replaced elsewhere on the property. Required parking spaces cannot be located in the required front yard.

owner occupancy: Seattle no longer requires owner occupancy either the primary structure or the detached ADU. 

minimum lot size: Detached ADUs are restricted to lots over a specific size. This varies quite a bit as different jurisdictions have different norms. In Seattle, the minimum lot size is 3,200 sq. ft. (Exceptions exist). 

maximum cottage size and height: Detached ADUs are restricted by size and height limitations. In Seattle the maximum size of a backyard cottage is 1,000 sq. ft. excluding storage and garage space. The maximum allowable height depends on the specifics of the lot.

permitting process: In Seattle cottages are allowed outright which means that they will be approved if they meet all of the requirements of the  building and land use codes.  New ADUs and conversions of existing accessory structures must meet the same building codes applicable to houses.

Can I convert my garage to a backyard cottage (detached ADU)?

For a single family lot in a single family zone in Seattle an existing detached accessory structure may be converted to an accessory dwelling unit (DADU) if it meets certain requirements outlined in the Seattle Municipal Code. One of these requirements is meeting minimum side and rear yard setbacks 5 ft (DADUs are not allowed in required front yards). Most detached garages are built on or within 5 ft of the side property line. At the discretion of the director  these to be converted to backyard cottages if the accessory structure was constructed legally prior to December 31, 2017 and the conversion does not increase its non-conformity.

Backyard Cottages - Other Cities 

A number of northwest cities and counties have modified their zoning ordinances to allow detached ADUs. They appeal to families because they provide opportunities to grow or to provide rental income. They appeal to cities because they provide additional housing options and increase density. Contact us for more information about specific cities.

A short list of Washington cities that allow backyard cottages;
Bremerton, Burien,  Kent, Kirkland, Mercer Island, Mill Creek, Mountlake Terrace, North Bend,  Redmond, Sammamish, Spokane, Seattle, Vancouver.
Unincorporated Areas;

                King County, Pierce County

Other northwest cities;
    Portland Oregon, Vancouver British Columbia.
Other cities considering backyard cottages;
    Bellevue, Denver Colorado, Madison, Wisconsin.