Kirkland zoning explained: what the code lets you build on your lot

Short answer: on a typical Kirkland single-family lot you can build one house, plus up to two accessory dwelling units, as long as it fits inside your zone’s yards, a floor area cap written as a percentage of the lot, lot coverage that counts paving as well as roof, and a height limit measured from the average grade around the house.

For how I work here, see my Kirkland architect page. Every code figure below comes from the Kirkland Zoning Code (KZC), current through Ordinance 4947 of September 1, 2026, or the city’s own zoning pages. Figures are as of September 2026, so confirm with the city before you rely on any number.

Kirkland’s single-family zones: RS, RSX and RSA

Chapter 15 of the zoning code, Low Density Residential Zones, covers the city’s low density residential zones: RS 35, 12.5, 8.5, 7.2, 6.3 and 5.0; RSX 35, 12.5, 8.5, 7.2 and 5.0; RSA 1, 4, 6 and 8; and a few special zones (WD II, PLA 3C, PLA 6E, PLA 16). There is no separate RSX or RSA chapter in the current code: Ordinance 4476 (2015) repealed the old Chapters 17 and 18 and replaced Chapter 15. They all share the density and dimensions table in KZC 15.30.

In RS and RSX zones the number is the minimum lot size in thousands of square feet, so RS 8.5 means 8,500 square feet. RSA works differently. The number is the maximum homes per acre, and RSA 4, 6 and 8 each have their own minimum lot (7,600 square feet in RSA 4, for example). Only one house is allowed per lot, whatever its size, unless the project uses the middle housing rules. KZC 115.07 also allows two accessory dwelling units, attached or detached; see my Kirkland ADU guide.

In the permitted uses table (KZC 15.20), the review process for a detached house reads “None.” There is no land use hearing; zoning is checked inside the building permit review.

How to find your zone

The city’s Zoning Code FAQ gives the quickest route. Open Kirkland Maps, click the Task tab, then the Address button, and enter your address. Clicking the Parcel and Permit History link shows the zoning, and the Parcel Zoning link takes you to the matching part of the online code. The city also posts a citywide zoning map as a PDF.

Look for overlays too. The Holmes Point (Chapter 70) and Goat Hill (Chapter 71) overlays add rules, and a lot within 200 feet of Lake Washington also falls under the shoreline chapter (Chapter 83). Read every numbered special regulation, and the general regulations too.

The core numbers, zone by zone

These are the standards for a detached house in the three zone families.

Source: KZC 15.30.060 with special regulations DD-6 and DD-9. ABE is average building elevation. RSA lots in the Juanita Beach Camps and Carr’s Park plats get 35 feet (DD-21).

The floor area cap, called F.A.R. (floor area ratio), is set zone by zone:

Source: KZC 15.30 special regulations DD-7, DD-11, DD-12, DD-17 and DD-19. In RSA zones, F.A.R. does not apply to property inside the shoreline jurisdiction.

Two examples. A 10,000 square foot RS 8.5 lot can carry 5,000 square feet of floor area (10,000 x 0.50), and 5,000 square feet of footprint, driveway and patio combined. A 40,000 square foot RSX 35 lot is held to 8,000 square feet of floor area (40,000 x 0.20) while coverage would allow 20,000.

Setbacks, and the 15 foot rule in RS zones

• Front yard. 20 feet in RS, RSX and RSA. On a corner lot in RSX or RSA, only one front yard has to be 20 feet and the others are treated as 5 foot side yards.
• Side yards. In RS, each side is at least 5 feet and the two must add up to at least 15 feet. RSX and RSA need 5 feet on each side, with no combined total. On a 60 foot wide lot that is the difference between a 45 foot wide house (60 minus 15) and a 50 foot wide one (60 minus 10).
• Rear yard. 10 feet.

What can sit in the yards (KZC 115.115): eaves, chimneys and bay windows may project 18 inches into a yard, but chimneys and bay windows may come no closer than 4 feet to a property line, and a one-story covered entry porch open on three sides can come to 13 feet from the front line. A front yard driveway is generally limited to 20 feet wide and must stay 5 feet off the side lot lines.

Floor area, lot coverage and height

What counts as floor area. Under KZC 115.42, F.A.R. counts the entire area inside the exterior walls on every level, including an attached garage, plus the roof area of any carport. It leaves out attic space under 5 feet of headroom, floor area whose ceiling is less than 6 feet above finished grade, uncovered decks, and porches open on at least three sides. Rooms with ceilings over 16 feet count twice, so a 400 square foot living room with an 18 foot ceiling uses 800 square feet of your allowance.

There is a design bonus: an additional 5 percent F.A.R. above the zone maximum if the house uses at least two of these: center-peaked roofs of at least 4 in 12, side setbacks of 7.5 feet, or upper floors at least 15 percent smaller than the ground floor.

Lot coverage is more than the roof. KZC 115.90 counts all structures and all other hardscape, so the driveway, patio, walks and sport court all come out of the 50 percent. Small pavers (10 by 10 inches or less) and grass grid paving count at half, but that discount cannot exceed 10 percent of the lot.

Height. Kirkland measures height above average building elevation, a weighted average of existing grade at the midpoint of each wall segment (KZC 115.59). It uses pre-development grade, and if fill was placed in the prior ten years, the grade from before the fill. Chimneys and vents may exceed the limit, skylights by 6 inches (KZC 115.60).

Garages, ADUs and accessory structures

• Attached garage. It counts toward F.A.R. like any other room. If its doors face the street, it cannot sit forward of the rest of the ground floor facade, and the doors cannot take up more than 50 percent of the facade width (waived on lots under 55 feet wide). If an alley serves the lot, garages must enter from the alley (KZC 115.43).
• Detached garage or ADU behind the house. The first 500 square feet (lots under 8,500 square feet) or 800 square feet (larger lots) is left out of F.A.R. when the structure sits behind the house. Without an alley, a garage or detached ADU may come within 5 feet of the rear line if the part inside the rear yard is no taller than 15 feet above ABE (KZC 115.42 and 115.115).
• Sheds, detached garages, greenhouses and similar accessory structures. Together they are capped at 1,200 square feet plus 10 percent of the lot area above 7,200 square feet. On a 10,000 square foot lot that is 1,480 square feet (1,200 + 0.10 x 2,800). Their height is the lower of the zone limit or 15 feet above the roof peak of the house. ADUs are not part of this cap (KZC 115.08).

Waterfront lots on Lake Washington

I often work on waterfront lots, and on these lots the shoreline chapter often decides more than the zone table. The code defines shorelands as the land within 200 feet of the ordinary high water mark (OHWM), and for Lake Washington it sets the OHWM at a lake elevation of 18.5 feet (NAVD 88). You establish it by survey (KZC 83.80, 83.90).

• Shoreline setback. Measured from the OHWM, and it depends on your shoreline environment designation. In the Residential-L environment it runs from the average setback of the neighboring houses, never less than 15 feet, in R-L (A), to percentages of the average parcel depth elsewhere: for example 30 percent, at least 30 feet and never required to exceed 60 feet, in R-L (B).
• The submerged part of the lot does not count. Land waterward of the OHWM cannot be used to determine lot size (KZC 15.10.020 and 83.190).
• Its own chart. For shoreline uses, the dimensional standards come from the chart in Chapter 83 (KZC 15.05.020), so check height and coverage there as well as in the zone table. That chart sets 50 percent lot coverage for a detached house in the Residential-L environment, and where its height limit differs from the zone table, the lower of the two applies (KZC 83.190).
• No middle housing. Chapter 113 does not apply inside shoreline jurisdiction.

How I approach design on these lots is on the Kirkland waterfront architect page.

The tree code (KZC 95)

A new house or a demolition needs a tree retention plan from a qualified arborist. A regulated tree is 6 inches in diameter or more, and a landmark tree is 26 inches or more. Landmark trees, groves and any viable tree with its trunk in a required yard rank as high retention value. Additions and remodels below 50 percent of the existing footprint, with no work in a regulated tree’s critical root zone (a radius of 1 foot per inch of trunk diameter), do not need the plan.

No tree may come down until the plan is approved and permits are issued, and not during demolition unless the city approves it in writing. On the other side, the code says the city will not require retention that would reduce the maximum F.A.R. or lot coverage, or prevent ADUs allowed under KZC 115.07. New planting must reach at least 50 tree credits per acre. For how tree rules shape design in general, see my guide to building around trees.

Recent changes: middle housing and ADUs

On June 17, 2025 the City Council adopted Ordinance O-4905, which brought the code in line with state law on middle housing (HB 1110), ADUs (HB 1337), parking and design review. The city states that property owners are not required to add middle housing and can still build a single house.

What the middle housing chapter (KZC 113) now allows in these zones, as an alternative to one house: cottages, multiplexes of up to four units, townhouses and stacked flats. A lot may have the greater of four units, or twice the number of houses the zone allows, and six units within a quarter-mile walk of a major transit stop. F.A.R., lot coverage and height follow the base zone, and the yards are 20 feet front, 5 feet side and 10 feet rear from the project’s outer lines. The chapter does not apply in RSA 1, the Goat Hill overlay or shoreline jurisdiction. More on the state law is in my HB 1110 guide.

Remodeling a house that breaks today’s rules

Plenty of older houses sit inside today’s yards or above today’s height limit. KZC 162.35(7) is the rule to know: any structural alteration of a roof or exterior wall that does not comply with the height or required yard standards means the nonconforming height or setback must be brought into conformance. Repair and maintenance of structural members is excepted. So if a wall already sits 3 feet from a side line, rebuilding that wall or the roof above it can mean pulling it back to the setback. Other nonconformances must be corrected when the work in any 12 month period costs more than 50 percent of the improvement’s replacement cost.

When the plan you want triggers these rules, compare it honestly with a rebuild. As planning ranges, a whole house renovation runs $300 to $550 per square foot, new custom construction $400 to $900 per square foot, and demolition typically $20,000 to $50,000. The wider decision is in remodel or tear down.

How zoning fits into the permit

Zoning is reviewed inside the building permit, alongside the tree plan and, on the water, shoreline review. The steps are in my Kirkland building permit guide. For planning I use Seattle's permit times as a benchmark, 6 to 10 months for a new house and about 2 to 3 months for a remodel, and 18 to 30 months from design start to occupancy; big trees and waterfront push toward the long end. The full sequence is in the custom home timeline.

I put the survey, the arborist’s tree plan and the F.A.R., coverage and ABE numbers on one site plan first, so the house is drawn inside the real envelope. Piper Cole designs houses and administers construction on your behalf; the firm does not build.

Questions