SEATTLE BACKYARD COTTAGE QUICK START GUIDE

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.

lot_dimensions

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:

4000 sq.ft.

Minimum Lot Size

25 feet

Minimum Lot Width

70 feet

Minimum Lot Depth

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BUILDABLE-AREA

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:

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

Setback from lot lines

5'

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

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GROSS-FLOOR-AREA-3

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:

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)

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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'

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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

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.