Change Summary
What are the changes in the Interim Legislation 120969 for neighborhood residential zones (formerly known as Single Family zones)?
We know folks are probably not tracking Seattle’s current land-use code changes as much as we are, so we wanted to help you understand what’s happening.
First, we want to mention that the interim legislation, Council Bill 120969, is not technically the Comprehensive Plan that is being discussed currently. This interim legislation had to pass to meet compliance with State Bill 1110, which requires jurisdictions to increase densities on residential lots. This interim legislation is largely due to our City Council and Mayor’s office failing to meet the original timelines to pass the Comprehensive Plan in time for House Bill 1110 to take effect (June 30th, 2025).
While the interim legislation is a different piece of legislation, it’s very likely the same rules will remain in the Comprehensive Plan once the full legislation passes (which may have happened by the time you read this).
Below is a quick summary of the differences between the old land-use code and the new. This should only be treated as a guide because we are leaving some of the technicalities out. We must also acknowledge the fast-paced process of these changes, and our initial interpretations could vary. It’s always smart to engage with an architect who can help you navigate the nuances for your particular site.
Before we get started, you will see the term "lot area" used, which is simply the square footage of land of the lot. You will also see us use the term "dwelling unit," which is simply a unit that a person or family would inhabit. This could be a house, accessory dwelling unit, apartment, etcetera. We chose to omit Residential Small Lot (RSL) zones in the table for simplicity, so please know the rules are different for RSL zones. Our understanding is RSL will be phased out after the comprehensive plan is passed. There is also nuance with smaller lots (less than 5000 sf) that isn’t fully presented.
Lot Coverage (SMC 23.44.010)
Lot coverage is anything that covers the grade of your lot. We like to tell clients anything that covers the ground at 36 inches or higher counts towards lot coverage. There are a few exceptions like fences and the first 36 inches of eaves, but overall, the 36-inch rule above grade plane is a great way to think of it. There is also a bonus provided for lots that are adjacent to alleys, which allows one to increase the lot area for this calculation by half the width of the alley adjacent to the property. Say you have a 16’ wide alley and your rear property line is 50’ wide; one can add 400 sf (8’ half the alley width x 50’) to this calculation.
Old Lot Coverage:
• Lots that are equal or greater than 5000 square feet: 35% of the lot area
• Lots that are less than 5000 square feet: 15% of lot area + 1000 square feet
New Lot Coverage:
• 35% of the lot area or 15% of lot area + 1000 square feet for lots less than 5000 square feet for the Primary Dwelling unit and any attached accessory dwelling unit. (no change)
• 50% of the lot area for any lot that has two or more detached dwelling units (primary dwelling unit, house, and detached accessory dwelling unit).
The code reduced the barriers to put additional detached dwelling units on a lot by increasing the lot coverage allowed and prevents property owners with one dwelling unit from getting the same benefit, leaving the lot coverage what it was prior to the bill passing.
It should also be noted that no change to the alley lot bonus, continuing to support additional area where alleys are present.
Image showing lot coverage in red
Floor Area (SMC 23.44.011)
Floor area is the area measured from the interior face of the exterior walls. We tell our clients the interior walls and stairs count, but the exterior walls do not. The maximum floor area is expressed as a ratio, which is why many people refer to this as FAR, standing for Floor Area Ratio. Like lot coverage, this ratio is applied to the lot area to provide the maximum floor area permitted on a site.
Old Floor Area: 0.5 of the lot area
Exemptions:
• Areas below grade (less than 4’ between grade and ceiling)
• Accessory Dwelling Units
• 500 square feet of detached accessory structure (think shed or garage) or 250 square feet for an attached garage
New Floor Area:
• 1 dwelling unit per 4000 square feet or greater: 0.6 of lot area
• 1 dwelling unit per 2,201-4000 square feet: 0.8 of lot area
• 1 dwelling unit per 2,200-1,601 square feet: 1.0 of lot area
• 1 dwelling unit per 1,600 or less: 1.2 of lot area
Exemptions:
• Areas below grade (less than 4 feet between grade and ceiling)
• Common walls separating individual attached dwelling units
The code increases floor area maximums based on how many units are provided on a lot. It should be noted that the exemptions for accessory dwelling units, accessory structures, and garages have been removed, but we have found the increase in max floor area makes up for that. You will see, much like lot coverage, a property owner with only one dwelling unit does not get any additional allowable floor area from current code.
Floor plans showing floor areas
Maximum Height (SMC 23.44.012)
This is simply the highest a structure can be on a lot.
Old Maximum Height: 30 feet with a 5 foot bonus given to gable roofs with a pitch of 4:12 or greater
New Maximum Height: 32 feet with a 5 foot bonus given to gable roofs with a pitch of 4:12 or greater
This increases the maximum height by 2’.
Image showing maximum building height for this home
Yards (SMC 23.44.014)
Yards are the terminology that Seattle uses for residential lots, and most people understand them better as setbacks. A yard is a restriction of placing a structure within a certain distance from the property line. Seattle has front, side, and rear yards.
Old Yards:
Front: 20 feet or the average of neighbors (which can’t be less than 15 feet)
Side: 5 feet
Rear: 25 feet or 20% of the lot depth
There are a lot of exceptions we’re excluding from this summary.
New Yards:
Front:
• Lots with one or two dwelling units: 15 feet
• Lots with three or more dwelling units: 10 feet
Rear:
• Lots not abutting an alley with one or two dwelling units: 15 feet
• Lots not abutting an alley with three or more dwelling units: 10 feet
• Lots abutting an alley: no rear yard
Side: 5 feet (no change)
Similar exceptions, with an additional exception for Queen Anne Boulevard as submitted by Rob Kettle to exclude that right of way from these requirements.
This reduces setbacks overall in the front and rear depending on the situation you find on a particular lot.
Site plan showing yards
Overall we are excited to start seeing the impacts these changes will have on our city and hope the outcome is more affordable housing to meet our needs. If you have any questions about these changes, please feel free to contact us.