Seattle Land Use Code

Stong support for more Backyard Cottages

Wow, strong support for all of the changes to the DADU / backyard cottage code!

Last night, CM Mike O'Brien and Nick Walsh from the city planning office had an open house to take the temperature of the community with regards to a series of incremental revisions to the DADU code.  Some of the proposed changes on the table, plus results from the straw poll as of the beginning of the meeting: 

25 for/ 9 against eliminating the owner occupancy requirement

23 for /6 against allowing a DADU and an ADU on the same lot (and possibly change the number of unrelated persons allowed to live on an Single Family lot.  

14 for / 5 against /13 maybes for Increasing the Rear Yard Coverage allowed

28 for/4 against eliminating the parking requirement

I didn't get the tallies for the height limit increase and other development standard improvments but they were also supported by a plurality.  

The reception was generally positive and civil, and more importantly according to the straw vote for the various measured, there was overwhelming support for all of the provisions.  

Next open house is 6 pm, February 3rd at the Wallingford Community Center. 

Multi-family code passes 9-0

A triumph for the 'Seattle Way'--years of contentious hearings, studies, tweaks resolve into ultimately a unanimous decision.  There is a certain super-tanker inertia about the city process that eventually prevails but it does it take a quite a while to steer the ship of state toward higher goals. Big thanks to Councilmember Sally Clark, the DPD staff, and CORA supermen:  Brandon Nicholson, Bradley Khouri, and David Neiman.

New Multi-family code: vote on Monday?

L3-max-front-NE-2The new Multifamily Code is scheduled to come up for a vote before Council on Monday.  After years of process, hearings, and work shaping the outcomes, the new code will have some new attributes geared toward more flexibility in heights, parking, setbacks, and density.  It disincentivizes the '6 pack' townhomes everyone dislikes and gives out bonuses for green building, designs that hid parking and give a better streetscape.

For those of us who participated in the sausage-making legislative process over the years, it is great to see that it will finally come up for a vote.  If you want to see the vote, and who wouldn't, it will be at City Hall at 2pm Monday.


The Seattle channel recently interviewed myself and CAST clients Kate Lichtanstein and Ric Cochrane regarding the backyard cottage we are currently working on together. They included our project in a broader story that profiles an owner of a recently completed backyard cottage and gives a basic outline of the new Seattle backyard cottage ordinance.

Seattle Channel Video can be played in Flash Player 9 and up


Are you considering building a backyard cottage? We've put together a Seattle Backyard Cottage Quick Start Guide* to help homeowners better understand Seattle's citywide backyard cottage ordinance and the opportunities available to them.


The first step is to figure out whether or not your lot is large enough to qualify for a backyard cottage. The chart below outlines the minimum requirements for lot area and dimensions.


4000 sq.ft.

Minimum Lot Size

25 feet

Minimum Lot Width

70 feet

Minimum Lot Depth


The next step is to figure out what portion of your lot is buildable under the backyard cottage ordinance. Setbacks, yard requirements and maximum lot coverage all factor into whether or not a cottage is feasible.


5' unless adjacent to an alley in which case the setback is 0

Setback from lot lines


Setback from other structures

Maximum Lot Coverage (SMC 23.44.010)

Lots less than 5,000 sq. ft. - 1,000 sq. ft. + 15% of lot area

Lots 5,000 sq. ft. or more - 35% of lot area

40% of the area required for the rear yard.

Maximum Rear Yard Coverage

Cottages not allowed in front yard.

Maximum Front Yard Coverage

One space per dwelling unit required - some exceptions apply.

Off Street Parking (SMC 23.44.016)

May not be located on the side facing the nearest lot line unless that lot line abuts an alley or other public right of way.

Entry Location


Once you've verified that your lot can accommodate a backyard cottage the next step is to take a look at the the floor area and height restrictions in order to determine if you can meet your objectives within those boundaries.


800' square feet max.Gross Sq. Ft. is measured from interior finished surface to interior finished surface. If you are planning a two story structure the floor area of each story counts toward the total.

Gross Floor Area (SMC 23.86.007)


There are three factors that set the height limit for your cottage, the width of your lot, the type of roof you choose and the height of your home.


Lot width

< 30'




50' <

Max base height






Max height with pitched roof






Max height with shed or butterfly








CAST Architecture

Feel free to email me with any questions you may have regarding Seattle's Citywide backyard cottage ordinance

Seattle Department of Planning and Development (DPD)

Seattle Backyard Cottage Ordinance

This is the definitive legal document covering Seattle Backyard Cottages.

DPD's Land Use Q&A Service

Any ambiguities or clarifications unanswered by the ordinance document (above) can be addressed through the DPD's Land Use Q&A Service

DPD CAM 116B - Establishing a Backyard Cottage

The DPD's client assistance memo (CAM) outlining the citywide backyard cottage ordinance. CAMs are guides intended to help people navigate the building permit processes in the city of Seattle.

A Guide to Building a Backyard Cottage in Southeast Seattle

This is an out of date but very useful guide put together by the DPD for Backyard Cottages in Southeast Seattle. The ordinance the guide was written for has changed (proceed with caution) but the value of the guide is still intact. It covers many of the issues you are likely to encounter and does a good job of mapping out design considerations you should be aware of.


*This guide is intended as an overview of the backyard cottage ordinance and does not include detailed conditions and restrictions that may affect individual properties. Please note that the guide was last updated in May 2017 and that zoning codes may have changed since then. As such, it should only be used as a basic starting point for planning. If you would like to move forward with the design and permitting of a backyard cottage for your home we recommend careful scrutiny of the entire ordinance and the assistance of an architect or design professional.