One of the topics at the heart of the struggle to create more affordable housing in Seattle is the backyard cottage. Seattle City Councilmember Mike O’Brien released a proposal earlier this year to make it easier for Seattle homeowners to build mother-in-law units and backyard cottages but it’s been met with opposition in some areas of the city (Queen Anne, mostly).
But let’s say that you’re interested in building a cottage in your backyard, either for personal or rental use. While we wait to find out if some restrictions will be lifted, make sure you know the rules before you build.
So what, exactly, defines a backyard cottage?
The city defines it as "a backyard cottage is a room or set of rooms designed and established by permit to be a separate dwelling unit." A backyard cottages shares a lot with a single-family home in a single-family zone. Oh and that lot must be at least 4,000 square feet.
Inside, a backyard cottage generally has everything a small apartment would have. A living area, sleeping area, kitchen, and bathroom. It also must have a lockable door.
Does the property owner have to live in the main house?
Yes. You can’t have a backyard cottage on the same lot of a house you also rent out. You have to live on the property, either in the main home or in the cottage for at least six months out of the year. You also must have at least a 50 percent ownership stake in the property.
Where does the backyard cottage resident park?
The owner of the single-family home property is required to provide one off-street parking space or garage.
How many people can live in the cottage?
Well, the rule is that eight people can live amongst both the main house and backyard cottage. So, use your discretion but don’t try to pack nine people on your property.
So can I build seven backyard cottages?
Sorry, no. Each lot is only allowed one ADU or backyard cottage.
How big can my backyard cottage be?
The total gross floor area can’t be any bigger than 800 square feet, and that includes any garage or storage. We’re trying to keep things cozy, not build five-story monstrosities on top of single-family homes (unless you’re a developer...ZING).
What if I want to convert my detached garage into a backyard cottage?
That’s cool but that doesn’t change any of the aforementioned rules. You still have to meet all the preexisting codes and limits.
What if I live in a townhouse or rowhouse? Can I build a backyard cottage?
Totally! But the rules are a little different because you’re in a lowrise zone. The backyard cottage itself can’t be bigger than 650 square feet and the floor area of the cottage can’t be more than 40 percent of the total floor area on the lot used for residential purposes (excluding garages, storage sheds, and other non-habitable spaces). Parking isn’t required for a backyard cottage in a lowrise zone, so there’s that.
What if I buy a property with an ADU/backyard cottage but don’t want to rent it out?
That’s okay but you will have to remove the features that make it a separate unit. So if it’s connected to your house, you have to make it into a connected room instead of a place with a separate entrance.
So what are these changes Mike O’Brien wants to make?
O’Brien proposed nine changes to the code in order to make it easier for people to build backyard cottages. They include...
- Allowing for a backyard cottage AND accessory dwelling unit to exist on the same property with a single-family home.
- Increasing backyard cottage height limits, depending on widths, that would make it easier to build two-bedroom cottages.
- Removing the requirement that owners must provide an off-street parking space in many areas.
- One-story cottages can cover up to 60 percent of the rear yard, up from 40 percent.
- Requiring owners to live on the property for at least one year after the cottage or ADU is created. This one is meant to prevent developers from just swooping in and building backyard cottages on all their developments.
- Lowering the lot-size requirement to be able to build a cottage from 4,000 square feet to 3,200 square feet.
- Increase the max size of a backyard cottage from 800 square feet to 1,000 square feet, which makes it easier to create two-bedroom cottages and provide enough space for families.
- If a backyard cottage is built above a garage, the garage is no longer included in the maximum floor area equation, allowing for bigger units.
Now you know the rules (and potential new rules). You gonna build that backyard cottage or what?