UPDATED AUG. 8th 2019

Now that the new legislation is in place we’ve updated Quickstart Guide for 2019. Please keep in mind that this information is intended as a high level primer for the code that governs backyard cottages in Seattle… 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.

Download guide as a printable pdf

We've seen an unexpected level of interest in backyard cottages in the 2 months since the new ordinance has been in effect. Perhaps the most interesting thing about the projects is the diversity of needs for each one... We have a young couple with a small house on a large lot that would like an outbuilding with a workshop and guestroom. We have a couple planning to build and occupy a cottage in their backyard in order to open up their home for their children and grandchildren to live in. We have a third couple who have separated but are committed to raising their children together. They currently live in the same house and believe that adding a backyard cottage to the property will maintain the proximity they need to raise their children together while providing them the space they need as individuals.

In a bit of a surprise, we have yet to see anyone looking to build a cottage for the sole purpose of rental income. Although one of the guys here at the office has been running the numbers and is strongly considering building a cottage for rent in his backyard.

We've completed the first round of design on our CAST architecture case study backyard cottage.

Kate and Ric's cottage is intended to serve as an art studio, workshop and guest house. It is also designed so that it may function as a rental home if needed. Our initial round of planning looked at how the spaces might work as a rental thinking that those functional requirements would be more restrictive than the requirements for an art studio and workshop.

Elements common to all three schematic design options:

All three options place the cottage at the SW corner of the site, chosen for it's relationship to the more public areas of the existing home and for an opportunity to create a shared outdoor room for both the cottage and the home. They all have a gable roof which was chosen for the height bonus allowed in the ordnance and to help marry the form of the cottage to the form of the existing home. All three options have the kitchen, living and bath rooms on the first floor and a bedroom loft on the second floor. Another feature common to all the options is the use of salvaged galvanized steel scaffolding components (see image below) which we plan to use as treads for ladder to the loft spaces.

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SCHEMATIC DESIGN OPTION 1

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This design incorporates an existing garage which more or less sits on the South and West property lines. The city land use desk (walk in) indicated that it was probable that we would be able to grandfather the building envelope of the existing garage into a new backyard cottage but they were unwilling to guarantee it. They recommended that we go through formal land use approval early in the process. Regardless of their final call we did know that we would have to stick within the building envelope of the garage for all portions of the backyard cottage that did not conform to the new ordinance. The potential advantage of using the existing garage is that it would allow us to use up less of the yard space for our new structure.

This drawing illustrates the site plan and floor plans. The existing garage is the portion of the structure that bumps out to the south and the west.

This is a view of the cottage from the SE. You can see the envelope of the existing garage on the south side of the structure.

A view from the NE looking through the shared outdoor room.

A view looking from the dining room, past the scaffolding ladder and into the living area.

A view from the living room into a private shade garden inspired by small Japanese courtyard gardens and created in the 5' setback from the lot line. a four foot concrete wall and cedar fence above create a very private and intimate indoor/outdoor space.

A view from the street.

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SCHEMATIC DESIGN OPTION 2

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The major element in this design is the creation of a covered outdoor workspace to the south of the cottage.

The covered patio to the south provides a sheltered outdoor workspace. The loft space is pulled back from the east wall allowing two stories of light to fill the first floor studio.

View from the SE

View from the NE

Loft space

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SCHEMATIC DESIGN OPTION 3

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This scheme ended up being the winner with Kate and Ric. They felt it was the best fit for their needs in terms of layout and size. It features a simple open plan on the first floor and a second floor that is more private than the lofts in the first two options.

Pass through doors and a simple plan define this scheme.

View from the SE.

View from the NE.

Entry from shared outdoor room

Looking toward the kitchen and dining room.

Bath with a private shade garden.

Loft.

The Department of Planning and Development (DPD) has posted a new client assistance memo (CAM) to outline the citywide backyard cottage ordinance. CAMs are guides intended to help people navigate the building permit processes in the city of Seattle.

CAM 116B, Establishing a Backyard Cottage (Detached Accessory Dwelling Unit) "This Client Assistance Memo (CAM) explains the requirements and process for establishing a detached accessory dwelling unit (also called a DADU or mother-in-law unit) on an owner-occupied Single Family zoned lot in southeast Seattle."

If you are considering building a cottage in your backyard it is still worth reviewing the DPD's older, more comprehensive (but now somewhat inaccurate) publication: "A Guide to Building a Backyard Cottage in Southeast Seattle."

Greenwood resident Kate Lichtenstein contacted us last spring to help her design a backyard studio / guest house for her modest 650 square foot 1920's one bedroom home (shown above). While the home's scale fits nicely with Kate's desire to have a simple and ecologically responsible lifestyle it falls a little short when it comes to a rough and ready workshop space for art, bicycle repair, ski tuning and building projects. Kate's home also lacks the space for a home office / guest room - something that she would like to integrate into the new structure.

Our initial goal was to have her project under construction by late summer 2009 but we were unable to get the project off the ground by that time. In hindsight, the stalling of the project turned out to be a stroke of luck...

In March of 2009 Seattle Mayor Greg Nickels proposed legislation that would allow Seattle homeowners to construct backyard cottages on their property. The legislation was reviewed and ultimately passed by the Seattle city council on November 2nd 2009 (with a 9 to 0 vote too! Kudos to Seattle voters for electing progressive urbanists for city council members!).

For Kate the ordinance has opened up new possibilities for a structure that can both accommodate her current needs and provide a potential source of income as a rental unit if her finances ever fall on hard times. Besides allowing for a legal detached rental unit the ordinance also allows for the construction of a two story structure – an arrangement that will work well for Kate’s needs and will help to preserve the spaciousness of her backyard.

Kate is planning to build with a mind toward sustainability and has a special interest in using recycled building materials whenever possible (she is, at this time, planning to write a parallel blog on the topic of recycled building materials). For us at CAST architecture Kate's project is an exciting chance to test out the new backyard cottage ordinance and work with a client who is committed to building green. We see her project as an excellent opportunity to provide the general public with information about the process of designing and building a backyard cottage in Seattle. Kate and her partner Ric Cochrane are always game for an adventure and have graciously agreed to allow us to share their experience with you. To that end, we are planning to blog about Kate's project as we travel through the design and construction process. Please subscribe to our feed if you would like to follow along in future posts…

The ordinance  to allow backyard cottages in the other three quarters of Seattle just passed 9-0!  The council's comments focused on the exhaustive community outreach, successful pilot program and benefit of having this housing choice for Seattle. Excellent work by the planning commission, DPD and council.

Usually, the city's process oriented decision making can be cumbersome, and having spent hours in meetings, testifying, and communicating with council, I feel vindicated that our involvement has helped in some small way to bring some innovation to the Single Family zoning.

We're excited to design some of these--in part because of the opportunity to foster multi-generational housing, and the option of building a smaller free standing structure rather than building an addition.  Plus, it is a really fun scale--I think more people will be thinking about bonus studios rather than housing units.

With the impending vote on the backyard cottage ordinance, everyone in the office has been doing a little daydreaming about the DADUs and what they would build.  I have been working on a idea that started with a little ink drawing. It's now developed into a preliminary model/floor plans.  I've flipped the shed roof to have more volume in the shop/studio and worked out the bathroom so that my shop could easily be converted into an open kitchen/living space.

I have also been working out a simple steel structure, clad with structural insulated panels for easy construction and minimization of waste.  The goal is prefabrication of the components offsite, then assemble.

I'd love to try out using a geothermal pre-heating loop, with a hydronic radiant system run of a domestic hot water heater and test the new PV shingles, but that might get a bit expensive.

We're almost there--the committee passed the measure to allow backyard cottages in Seattle.  Next stop will be City Council. There are some notable amendments to the ordinance--the 50 per year allowed cap has been eliminated.  The heights have changed somewhat.  A discussion to limit the cottage height to no more than 15' above the primary residence's roof (which would affect sloped lots primarily) was tabled without conclusion.

The discussion is a little strange, in that some of the requirements being tossed around are more stringent than for building a single family house.  Case in point--if this relative height limit section passes, you will need a topographic survey to prove that the cottage conforms (not required on a new house if well within setbacks and under height), thus added about $2000 to the pricetag for the drawings.  This doesn't make any sense if the city is serious about this as being an affortable option.

Another case in point--Councilmember Rasmussen was leaning toward a neighborhood notice, similar to a MUP, but the neighbor's recourse, provided the cottage design fits the requirements, is nil.  The cottage is a Level 1 decision (no notice necessary, just like a new single family house), but creating such a provision would form a special class of notice ("Here is what is happening next door, but there is nothing you can do about it.  Thanks for coming down.").

Unfortunately, I had to run out before the discussion on the privacy issue, another NIMBY favorite, but in the end the ordinance is one step closer to fruition.

You can see the entire meeting online at the Seattle Channel here.  Backyard Cottage discussion starts at 107.30.

Seattle's DPD just announced a program to accelerate permitting for sustainable projects, called Green Q, as in 'queue.' Applicants need to commit to construction waste recycling, dwelling units under 2400 sf, and meet LEED silver or better, or BuiltGreen 4 star or better.

The Planning, Land-Use and Neighborhood Committee is planning on voting on the Backyard Cottages on October 8th.  Last chance to make yourself heard on this issue! It will be a packed agenda, with discussions of the Multi-family code revision as well as the design review process (which will be mandatory in Multi-family).