how big? - a look at Seattle's backyard cottage rules

The first question we typically answer is what can we build? As the cost of building a backyard cottage is not insignificant, it makes sense to make a careful analysis of both the governing regulations and the potential for each site. It seems obvious that an erroneous or incomplete knowledge of land use and building codes can lead to expensive mistakes and delays.  What might be less obvious is that lack of informed planning may also lead to a failure to realize the full potential of a particular site and use. 


FAQ: backyard cottage allowable size - in Seattle backyard cottages are limited to 800 sq. ft. in size -- referred to in the land use code as Gross Square Footage

  This 3 bedroom cottage has a footprint of 800 sq. ft. and a full basement

This 3 bedroom cottage has a footprint of 800 sq. ft. and a full basement

This Columbia City property is shared by two sisters who are planning to build a family compound with separate houses. They were worried that an 800 sq. ft. cottage would not be adequate for a growing family. They felt that it was important for the cottage to have a kitchen, living, full bath, and 2 bedrooms on the main level in addition to a separate family room, office and 1/2 bath.  A tall order for 800 sq. ft..

For them, the solution was to add a basement level -- as below grade basements are not counted towards the allowable area. This also reduced the height and bulk of the cottage which is another consideration when adding a DADU to a typical Seattle lot. Fortunately, the owners have a couple of things working in their favor. One is that they have a relatively large lot which allowed them to build 800 sq. ft. on one level. The other is that the owner's father is a contractor and who built them a scaled mock-up that we could use to help model the visual impacts to on their yard. In this case, the cottage was designed to be just large enough to block the view of a series of new apartment buildings, but not so large as to adversely shade their yard. 

FAQ: backyard cottage allowable size - storage areas, attics, garages, and carports are included in the allowable area.

It is important, but not always easy, to get a handle on how a cottage will feel in the backyard. We often start by pacing out the dimensions of typical cottages with our clients. We think of 400 sq. ft. as being the minimum footprint for a single level 1 bedroom cottage. However most cottages we design have a 2nd floor to maximize living area while keeping the footprint to a minimum. 

    This one bedroom backyard cottage has a footprint of 336 sq. ft.

 

This one bedroom backyard cottage has a footprint of 336 sq. ft.

Just getting started? We recommend attending one of our backyard cottage tours, which happen periodically throughout the year. They provide an opportunity to get a sense for the size of DADU's both inside and out. You can use the widget at the top of the page to sign up for our open house invite list.  

 

Looking for backyard cottage ideas? Please visit our work tab.