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..

Thursday, May 10

ADU Draft Environmental Impact Statement (EIS)

Today the Seattle City Council released a ADU Draft Environmental Impact Statement (EIS). The public is invited to review and comment on this Draft EIS, which examines potential environmental impacts of proposed Land Use Code changes related to ADUs in single-family zones.


The City of Seattle proposes to remove regulatory barriers and make it easier for property owners to create accessory dwelling units (ADUs) and increase the number and variety of housing choices in single-family zones. The proposal involves Land Use Code changes that would allow two ADUs on one lot, modify existing off-street parking and owner-occupancy requirements, change development standards that regulate the size and location of detached ADUs, and that regulate the maximum size of single-family dwellings. Based on a decision from the City’s Hearing Examiner in December 2016, the city has prepared an Environmental Impact Statement (EIS) that analyzes three alternatives and identify the impacts of each alternative.

The public comment period for this Draft EIS extends through June 25, 2018. You can learn more about this proposal and provide feedback at Following the Draft EIS comment period, the city will prepare a Final EIS that includes responses to all substantive Draft EIS comments that address the environmental analysis. Comments on the Draft EIS stimulate discussion about how to change or modify the proposal to further protect the environment.

* ADUs include backyard cottages, known as detached accessory dwelling units (DADUs), and in-law apartments, known as attached accessory dwelling units (AADUs)

Saturday, April 28

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 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. 

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 web page at the following link.


Wednesday, April 4

backyard cottage rule changes

This morning SDCI staff briefed the city council on proposed changes to the land use code affecting backyard cottages. The changes are part of omnibus code update, a collection of amendments that are relatively small in scale, and have a limited scope of impact, into an “omnibus” bill. 

If you were hoping, as we were, that clarification on gross square footage or parking or other hot topic items you will be disappointed. However, if you live in a shoreline area you can now build a backyard cottage. The original legislation concerning backyard cottages prohibited DADUs on lots if any portion of the lot was within a shoreline district.  It is not clear what the intent of the original legislation was. Now that it is proposed to be eliminated, should we expect an explosion in the number of beach cabanas in Seattle?  Unlikely, since 2009 we have only spoken with two potential DADU builders who were impacted by this restriction. Of course, they will be quite happy.

Meanwhile, the more significant proposed DADU code changes, those that are part of the ongoing EIS process, are scheduled to go before Seattle City Council this summer.

Sunday, March 11

backyard cottage - would you move into your own backyard?

The owner built this backyard cottage as a rental but fell in love (with the cottage) during the design process and decided to rent out his house instead.  

This backyard cottage features an open floor plan on the ground floor with a kitchen, living and powder rooms that open with accordion doors onto a patio with a gas fireplace.  Upstairs is a master bedroom complete with a kitchenette, and a bath with laundry room.  The overall strategy with this backyard cottage, as it is with most of our designs, is to keep the structure simple allowing a larger percentage of the budget to be spent on finishes. The height and size of DADUs is limited based on the size of the lot. This lot was particularly small limiting the allowable footprint to 294 sq. ft. 

Ceramic tile accentuates the entry area.  The view from the entry towards the kitchen and patio beyond.

The kitchen is located along one wall is both compact and simple.

Accordion doors open up the cottage to the new patio with gas fireplace.

A movable kitchen island is the perfect accessory to the compact kitchen.  Exposed wood joists add warmth and texture in contrast with the concrete floors.  The joists were spaced to accommodate the owner's weight lifting rack.

Where some houses may come with a man cave this DADU features a "man wall" with big screen tv, electric fireplace, weight rack and the ultimate amenity, beer taps.  A keg fridge is located behind the wall in the under stair space.  

A door located at the bottom of the stairs allows for the two floors to be used independently.

The city of Seattle limits both the eave and ridge height of cottages allowing greater height for a gable roof which we took advantage of to good effect. 

The master suite features vaulted ceilings and abundant light. A kitchenette allows this room to be used separately from the first floor.

The shower is tucked into an under eave space. 

The master bath features vaulted ceilings and skylight.  A laundry room is tucked off to one side under the eaves.

The owner built a new patio with a gas fire place.  The stairs from the house were rebuilt align with the cottage.

Tuesday, March 6

backyard cottage workshop tomorrow - Wednesday, March 7th

Would you like to learn more about backyard cottages and meet others thinking about building a backyard cottage?  If so you might be wondering, can I build a backyard cottage on my lot and how much does it costs to build a backyard cottage?  To answer these questions we periodically assemble experts in the design, construction and of financing backyard cottages. Our workshops offer a unique opportunity to have your questions answered in an informal setting. 

backyard cottages for fun and profit   Wednesday March 7th,  from 7:00 to 9:00 pm, Blue Building Room 1. Phinney Neighborhood Center 6532 Phinney Avenue North

Backyard cottages can be used for many things including housing a family member or as a short term rental.  Join Microhouse and Ncompass Construction to learn more about backyard cottage design, construction, and use. Bring your ideas, after the presentation we will have plenty of time to answer questions about the specifics of your project. 

Microhouse and Ncompass Construction
$15 PNA member, $20 Public

Thursday, February 1

backyard cottage open house rescheduled for Saturday February 24th.

Cleanup and yard work continue for the Ballard backyard cottage scheduled for an open house on February 3rd.  The open house will take place on February 24th from 11:00 am to 1:00 pm instead.

Wednesday, January 17

backyard cottage open house scheduled

Come and see one or more new backyard cottages in Ballard on February 3rd between 11:00 am and 1:00 pm. For further information or sign up for our open house invitation list.