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.
| BASIC SITE REQUIREMENTS: | |
| Minimum Lot Size | 4000 sq.ft. |
| Minimum Lot Width | 25 feet |
| Minimum Lot Depth | 70 feet |
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.
| SETBACKS AND YARDS: | |
| Setback from lot lines | 5′ unless adjacent to an alley in which case the setback is 0 |
| Setback from other structures | 5′ |
| Maximum Lot Coverage | 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 | |
| Maximum Rear Yard Coverage | 40% of the area required for the rear yard. |
| Maximum Front Yard Coverage | Cottages not allowed in front yard. |
| Off Street Parking SMC 23.44.016 |
One space required – some exceptions apply. |
| Entry Location | 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. |
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.
| FLOOR AREA: | |
| Gross Floor Area SMC 23.86.007 |
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. |
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.
| HEIGHT LIMITS: | |||||
| Lot width | |||||
| < 30′ | 30′-35′ | 36′-40′ | 41′-50′ | 50′ < | |
| Max base height | 12′ | 14′ | 15′ | 16 | 16 |
| Max height with pitched roof | 15′ | 21′ | 22′ | 22′ | 23′ |
| Max height with shed or butterfly | 15′ | 18′ | 19′ | 20′ | 20′ |
| Max height above peak of existing home | 15′ | 15′ | 15′ | 15′ | 15′ |
| REFERENCES | |
| CAST Architecture | tim@CASTarchitecture.com
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 |
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| 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. |
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| 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. |
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*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. 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.
Download guide as a printable pdf