Zoning determines what you can build on your lot, and in Seattle, the rules are more complex than most homeowners realize. Seattle’s land use code was significantly revised in recent years to add density, allow more ADUs, and create new residential zone categories. This guide explains the key zoning concepts Seattle homeowners need to understand before starting any construction project.
Seattle’s Residential Zone Types
Neighborhood Residential (NR) Zones
Seattle renamed its single-family zones Neighborhood Residential in 2022, and a 2025 ordinance replaced them with a single NR zone. NR zones allow single-family homes, ADUs (up to two per lot, attached, detached or stacked), and attached, detached and stacked units on every NR lot, with up to four units allowed on lots under 5,000 sq ft when the code’s conditions are met.
Residential Small Lot (RSL)
RSL zones allow townhomes, rowhouses, and cottage clusters in addition to single-family homes. RSL is common in areas near frequent transit service. Projects on RSL lots have more flexibility but also more design review scrutiny.
Lowrise Multifamily (LR1, LR2, LR3)
Lowrise height limits are 32 feet in LR1, 40 feet in LR2 and 40 or 50 feet in LR3, depending on the zone designation. Many Seattle homeowners are surprised to find their property is in an LR zone, which opens up development options beyond a single-family zone.
Key Zoning Concepts
Setbacks
In Neighborhood Residential zones, required setbacks are: front 15 feet (10 feet with three or more units), rear 15 feet (10 feet with three or more units, and none where the rear abuts an alley), and sides 5 feet on average with a 3 foot minimum. Setback exceptions apply for small structures, ADUs in certain configurations, and covered porches.
Height Limits
In Neighborhood Residential zones the base height limit is 32 feet, and the ridge of a pitched roof may extend up to 5 feet above it. Certain listed types, such as three or more units with a 20 foot front setback, or lots that keep a Tier 1 or Tier 2 tree, get 42 feet. ADUs follow the same standards as the house unless the zone says otherwise; an accessory structure located in a required setback is limited to 12 feet, with a pitched ridge up to 3 feet above that. Projects in Design Review have more scrutiny on height relative to neighboring properties.
Floor Area Ratio (FAR)
FAR limits the total gross floor area as a multiple of the lot area. One house on a 5,000 sq ft Neighborhood Residential lot gets an FAR of 0.6, or 3,000 sq ft of chargeable floor area. Underground floor area, and parts of a story no more than 4 feet above grade, do not count, and lots under 5,000 sq ft may have up to 2,500 sq ft. Understanding FAR is critical for custom home sizing.
Planning a project?
Working out what your lot will allow, and what it will cost?
Send David the address and a few lines about what you want. The first feasibility check is free and usually takes about a day: what the site and the code are likely to allow, and what to check first.
Architect since 1996, member of the AIA and NCARB. Three Masonry Excellence Awards; the Carr residence was featured in Above The Lake and Lux magazines.
ADU Rules in Seattle (2026)
- Up to two ADUs on a lot, attached, detached or stacked in any combination
- No owner-occupancy requirement (eliminated 2019)
- ADU size limit: 1,000 sq ft with up to two bedrooms, or 1,200 sq ft with three or more; underground stories, up to 250 sq ft of attached garage and up to 35 sq ft of bike parking are not counted
- Both ADUs can be rented simultaneously
- Parking replacement not required when removing a garage for ADU conversion
Eastside Zoning: Kirkland, Bellevue, Redmond
If your property is in Kirkland, Bellevue, or Redmond, you are subject to that city’s land use code, each with its own zone designations and specific requirements. The rules are set out zone by zone in the Kirkland zoning guide and the Bellevue zoning guide, and in separate guides for Mercer Island, Medina, Clyde Hill, Redmond, Sammamish and Issaquah. Piper Cole Architects is experienced in the land use codes of all Eastside cities. Our residential architecture service includes a complete zoning and feasibility analysis before design begins. See our design process to learn how we assess and navigate local regulations on every project.
Related guide: Lot Coverage, Setbacks & FAR Explained.
Critical Areas and Environmental Overlays
Seattle’s Critical Areas Ordinance protects environmentally sensitive land and limits what can be built on it or next to it. Seattle’s critical areas code designates six types, including geologic hazard areas and abandoned landfills, and shorelines are regulated separately under the Shoreline Master Program. The ones homeowners meet most often:
- Wetlands, including seasonally wet areas, with buffers typically 25 to 300 feet depending on the wetland category
- Steep slopes, areas of 40% or greater grade, or with known landslide hazards
- Wildlife habitat, designated urban wildlife habitat corridors
- Flood-prone areas, within the 100-year flood plain
- Shoreline jurisdiction, within 200 feet of Puget Sound, Lake Washington, Lake Union or a major waterway
Building within or next to a critical area requires additional study and review: a geotechnical report, a wetland delineation, a biological assessment, or a shoreline substantial development permit. Each one adds time and cost.
Buffers are measured from the critical area itself, not from your property line. A 100-foot wetland buffer means nothing can be constructed within 100 feet of the wetland boundary, an ADU included. This is the single most common surprise on a sensitive lot.
Property inside Seattle’s shoreline jurisdiction carries further overlay requirements under the city’s Shoreline Master Program. Substantial development, currently work valued at $8,504 or more, requires a Shoreline Substantial Development Permit unless another exemption applies.
Entitlements and the Washington Development Review Process
Entitlements are the approvals that establish what you can legally build on a site: the permitted use, how much of it (density and floor area ratio), and its form (height, setbacks, lot coverage). They are not the same thing as building permits. Entitlements answer “is this project allowed here?” Permits answer “are these construction documents code-compliant?”
In Washington the process usually runs in this order:
- Zoning and feasibility confirmation. Verify the zone and what it allows: use, density, height, setbacks, lot coverage and FAR.
- Pre-application meeting. Many Washington jurisdictions offer or require a pre-application conference, where staff flag problems early. It is a low-cost step that routinely saves months.
- Environmental review (SEPA). The State Environmental Policy Act requires review of environmental impact for many projects, and can attach conditions or require studies.
- Land use and design review. Larger or corridor projects often go through design review and public comment, particularly in Seattle and the Eastside urban villages.
- Permitting. Once entitled, construction documents go in for building permits and correction cycles.
What complicates entitlements: critical areas such as wetlands, steep slopes and shorelines, which trigger extra review; rezones or variances, where the project does not fit the base zoning; public comment and appeals on discretionary approvals; and SEPA conditions requiring traffic, drainage or environmental mitigation. Each adds time and uncertainty.
HOA and Neighborhood Design Review
Plenty of Seattle-area homeowners find out only after hiring an architect that their project also needs review by a homeowners association architectural committee, on top of city permitting.
HOA architectural review is common in Issaquah Highlands, Snoqualmie Ridge, Sammamish and Newcastle communities, many planned neighborhoods in Redmond, Bothell and Woodinville, and some Bellevue neighborhoods. Seattle Landmarks and historic districts also carry design review, but that one is city-administered rather than an HOA.
HOA guidelines typically govern exterior materials and colors, roof form, window and door types, garage door style, fence heights and materials, landscape screening, and the overall massing of an addition. Some require an addition to match the original house exactly; others ask only for compatibility and allow variation.
HOA review is separate from city permitting and has to be finished before or alongside permit submittal. Committees that meet monthly can take 4 to 8 weeks. HOA approval does not substitute for a city permit, and a city permit does not override an HOA restriction.
A denial can force design changes that hit both schedule and budget. An architect who already knows a given HOA’s guidelines can design to them from the start, which is the cheapest way to avoid a revision round.
Next, from David
Frequently Asked Questions
How do I find the zoning for my Seattle property?
Look up your address using the Seattle Department of Construction and Inspections GIS map or the city parcel viewer. Your zone designation determines what you can build, how large, and how tall. An architect can pull and interpret the zoning for your specific lot.
What is FAR and how does it limit what I can build?
FAR, or floor area ratio, is the ratio of total building floor area to lot size. If your lot is 5,000 square feet and holds one house, the Neighborhood Residential FAR limit is 0.6, so you can build 3,000 square feet of chargeable floor area (5,000 x 0.6), not counting underground floor area. Adding units raises the FAR the lot is allowed. FAR is one of the main constraints on how much house you can add.
What are setbacks in Seattle?
Setbacks are the minimum distances a structure must sit from the front, side, and rear property lines. They vary by zone and by structure type, and they often determine where an addition or ADU can physically go on your lot.
How tall can I build on a Seattle residential lot?
Height limits depend on your zone. Neighborhood Residential zones allow 32 feet for a house, plus up to 5 feet for the ridge of a pitched roof, and 42 feet for certain listed development types. Accessory structures in required setbacks are limited to 12 feet, plus 3 feet for a pitched ridge; a detached ADU otherwise follows the same height standard as the house.
What is lot coverage and why does it matter?
Lot coverage is the percentage of your lot that structures are allowed to cover. Exceeding it is one of the most common reasons a design has to be revised, so it is checked early in the design process.
Can I build an ADU on my Seattle lot?
Every lot in a zone that allows housing may have up to two ADUs, attached, detached or stacked, subject to size and zone standards. A feasibility review confirms what your specific lot allows.
Authoritative sources
Regulatory requirements referenced in this guide are set by the official agencies below. Rules change, always confirm current requirements with the source:
