Kirkland is one of the easier places in Washington to build an ADU, and unlike many cities its code has actually caught up with state law. Two ADUs are permitted per single-family house — one attached and one detached, two attached, or two detached — at up to 1,200 sq ft each, with no owner-occupancy requirement, no parking within half a mile of a major transit stop, a detached unit allowed within five feet of a rear property line (or right on it if the lot backs an alley), free rein to convert an existing garage even if it breaks current setbacks, and a library of pre-approved detached ADU plans that can cut permitting to a few weeks. Washington's HB 1337 (2023), codified at RCW 36.70A.681, is what forced most of that, and Kirkland adopted it in Ordinance O-4905 (June 17, 2025) and Ordinance 4913 (September 16, 2025). Two gaps are worth knowing: shoreline properties are held to one ADU by the city, and the statute's own carve-out at RCW 36.70A.681(4) means none of these protections apply to a lot designated with critical areas or their buffers — which in Kirkland means steep slopes, streams and wetlands.
Zoning & Size Requirements [1][2][3][4]
Yes — Kirkland allows ADUs. A detached ADU can typically be up to 1,200 sq ft under current Washington and Kirkland zoning rules.
See what this means for your lot — get 5 free quotes from Kirkland ADU builders →
| Allowed Zones | Permitted as an accessory use anywhere a Detached Dwelling Unit is allowed in the low density residential zones — RS 35, RS 12.5, RS 8.5, RS 7.2, RS 6.3, RS 5.0; RSX 35, RSX 12.5, RSX 8.5, RSX 7.2, RSX 5.0; RSA 1, 4, 6 and 8; and PLA 3C, PLA 6E and PLA 16 (Kirkland Zoning Code 15.20.060, Special Regulation PU-23 → KZC 115.07). Two exceptions in the local table run narrower than state law: the WD II waterfront zone's Detached Dwelling Unit row does not carry PU-23, and PU-21 limits RSA 4 lots in the Goat Hill Overlay Zone to one attached ADU. RCW 36.70A.681(1)(c) requires two ADUs in all zoning districts inside an urban growth area that allow single-family homes, so state law would override — except that RCW 36.70A.681(4) exempts lots designated with critical areas or their buffers. Confirm your own parcel with Kirkland Planning and Building at 425-587-3600 |
| Max Size (Detached) | 1,200 sq ft of gross floor area (Kirkland Zoning Code 115.07(4)) — 200 sq ft above the 1,000 sq ft floor state law guarantees (RCW 36.70A.681(1)(f)). Area with less than five feet of ceiling height, uncovered rooftop decks and at-grade patios, and up to 200 sq ft of other covered and uncovered exterior elements do not count. The practical catch is floor area ratio: only the first 500 sq ft of a detached ADU on a lot under 8,500 sq ft, or the first 800 sq ft on a lot of 8,500 sq ft or more, is exempt from F.A.R., and then only when the structure sits behind the main house (KZC 115.42). If F.A.R. would push your ADU below 1,000 sq ft, raise RCW 36.70A.681(1)(f) with the planner |
| Max Size (Attached) | Same 1,200 sq ft cap. Where an attached ADU sits entirely within existing gross floor area on a single floor, the Planning and Building Director may allow more square footage in order to use the floor area efficiently (Kirkland Zoning Code 115.07(4)) |
| Max Size (JADU) | Not a category in Washington — Kirkland's code has no junior ADU designation. The nearest equivalent is an attached ADU carved out of the existing house |
| Max Height | The height limit that applies to a single-family dwelling in your zone (Kirkland Zoning Code 115.07(5)) — 25 feet above average building elevation in the RS, PLA 3C and PLA 6E zones, and 30 feet above ABE in RSX, RSA and PLA 16 (KZC 15.30.060). State law bars any city from setting an ADU roof height limit below 24 feet unless the principal unit's own limit is lower (RCW 36.70A.681(1)(g)). Separately, if you use the five-foot rear setback allowance, the part of the structure inside the required rear yard may be no taller than 15 feet above ABE (KZC 115.115(3)(o)(3)) |
| Max Units | 2 ADUs per single-family dwelling — one attached and one detached, two attached, or two detached (Kirkland Zoning Code 115.07). The code closes the obvious loophole itself: an ADU "shall not be considered a 'dwelling unit' in the context of special regulations in Chapters 15 through 56 KZC which limit the number of Detached Dwelling Units on each lot to one." This matches RCW 36.70A.681(1)(c). The city's ADU Regulations page limits property in the Residential-L Shoreline Environment to one ADU |
Setback Requirements [1][2][3][4]
Kirkland requires a rear setback of about 10 ft for a detached ADU, and one off-street parking space is required. Owner-occupancy is not required — you can rent it out without living on the property.
| Rear Setback | 10 feet is the zone standard for a house (Kirkland Zoning Code 15.30.060), and an ADU takes the same. But KZC 115.115(3)(o) then relaxes it: a detached ADU without alley access may sit as close as five feet to the rear property line provided the portion inside the required rear yard is no taller than 15 feet above average building elevation and the rear yard does not abut an access easement regulated as a rear property line; and a detached ADU may extend all the way to a rear property line abutting an alley, so long as its eaves do not cross the line and it meets the sight-distance rule in KZC 115.135. State law separately requires alley-abutting lot line siting (RCW 36.70A.681(1)(i)) |
| Side Setback | The same side yard as the house — five feet in the RS zones, but the two side yards together must total at least 15 feet (Kirkland Zoning Code 15.30.060 and Special Regulation DD-9); a flat five feet in the RSX and RSA zones. State law bars setbacks for ADUs more restrictive than those for principal units (RCW 36.70A.681(1)(h)) |
| Front Setback | 20 feet, the same front yard as the house, in the RS, RSX, RSA, PLA 3C, PLA 6E and PLA 16 zones (Kirkland Zoning Code 15.30.060). On a corner lot with two required front yards, only one must be 20 feet — the other is regulated as a side yard in RSX and RSA (DD-15) or as a rear yard where the two fronts are essentially parallel (DD-16) |
| Parking Required | None within one-half mile of a major transit stop (Kirkland Zoning Code 115.07(7); RCW 36.70A.681(2)(a)(i)). Read that carefully: the city's own ADU Regulations page states Kirkland's only current major transit stop is the STRIDE (I-405) bus rapid transit station, with future stops along King County Metro's RapidRide K Line once construction is under way. Beyond the half mile, KZC 115.07(7) requires one off-street space only where there is more than one ADU on the lot, and waives even that if on-street parking is available within 600 feet or the property is within half a mile of transit with 15-minute commute-hour headways. The city's ADU Regulations page describes the same rule as one space for the first ADU — the two readings differ, so confirm with Planning and Building at 425-587-3600. Either way state law caps what Kirkland may demand at one space per unit on lots under 6,000 sq ft and two per unit on larger lots (RCW 36.70A.681(2)(a)(ii)-(iii)) |
| Owner Occupancy | Not required, and Kirkland could not require it if it wanted to — "the city or county may not require the owner of a lot on which there is an accessory dwelling unit to reside in or occupy the accessory dwelling unit or another housing unit on the same lot" (RCW 36.70A.681(1)(b)). Kirkland goes further: an ADU may be segregated in ownership from the single-family dwelling unit, and one or more ADUs other than stacked units may be subdivided within a unit lot subdivision (Kirkland Zoning Code 115.07(2)-(3)). The city's ADU Regulations page notes an exception for properties in the Residential-L Shoreline Environment |
| Min Lot Size | No ADU-specific minimum. State law requires a city to allow an ADU on any lot that meets the minimum lot size for the principal unit (RCW 36.70A.681(1)(e)), and Kirkland's KZC 115.07 imposes none. The district minimum for the lot itself runs from 3,800 sq ft in RSA 8 and 5,000 sq ft in RS 5.0 and RSX 5.0 up to 35,000 sq ft in RS 35 and RSX 35 (Kirkland Zoning Code 15.30.060, Special Regulations DD-7 and DD-11) |
Permit Process & Fees [5][6][7][8]
An ADU permit in Kirkland goes through a standard permit review. Typical timeline: Roughly 3 months for a standard ADU permit, with additional time for design and construction; a pre-approved DADU application takes less — the city says as little as a few weeks (City of Kirkland, Planning Your ADU and Explore Kirkland's Pre-Approved Plans). Permit fees: Confirm current permit and plan review amounts with Kirkland Planning and Building at 425-587-3600 — no ADU fee schedule is published on the city's ADU Toolkit pages. If you use a pre-approved plan, budget separately for licensing it from the designer, which the city puts at up to $1,000.
| Approval Process | Apply for an Accessory Dwelling Unit permit with the Kirkland Planning and Building Department, including an affidavit signed by the property owner agreeing to the requirements of KZC 115.07. Where the improvements do not require a building permit, a registration form is filed instead. Either way the owner files a property covenant with the City for recording with the King County Recorder's Office, noting the presence of the ADU; the covenant runs with the land as long as the ADU is maintained (Kirkland Zoning Code 115.07(9)(a)). A decision of the Planning Official is appealable under Chapter 145 KZC. State law bars the city from requiring public street improvements as a condition of permitting an ADU (RCW 36.70A.681(1)(l)) |
| Review Timeline | Roughly 3 months for a standard ADU permit, with additional time for design and construction; a pre-approved DADU application takes less — the city says as little as a few weeks (City of Kirkland, Planning Your ADU and Explore Kirkland's Pre-Approved Plans) |
| Permit Fees | Confirm current permit and plan review amounts with Kirkland Planning and Building at 425-587-3600 — no ADU fee schedule is published on the city's ADU Toolkit pages. If you use a pre-approved plan, budget separately for licensing it from the designer, which the city puts at up to $1,000 |
| Impact Fees | Capped by state law at 50 percent of the impact fees that would be imposed on the principal unit (RCW 36.70A.681(1)(a)). Kirkland does not publish an ADU-specific figure on its ADU pages — confirm the current park and school impact fee amounts with Kirkland Planning and Building at 425-587-3600, and cite the 50 percent cap if the quote looks high |
| Plan Check | Standard building plan review. The portion of a single-family dwelling in which an attached ADU is proposed must meet all applicable health and safety codes, except that space legally constructed as habitable space need not meet current International Building Code ceiling height requirements (Kirkland Zoning Code 115.07(8)). If an ADU was created without a finaled building permit, an ADU inspection is required before an ADU permit will issue (KZC 115.07(9)(a)(3)). Applicants planning two attached ADUs are told to call Planning and Building at 425-587-3600 for extra Building Code help |
| Pre-Approved Plans | Yes — Kirkland runs a Pre-Approved Detached ADU Plans program. The plans are drawn by architects and designers, pre-reviewed by the City for code compliance, and cover units under 600 sq ft, two-bedroom family layouts, single-level accessible plans and modern or eco-focused designs. You pick one from the city gallery, license it from the designer (up to $1,000), and have the designer adapt it to your site. Custom plans remain an option |
Get Free ADU Quotes in Kirkland
Tell us about your project and we'll connect you with ADU builders serving Kirkland. Free, no obligation — you choose who to work with.
1. Tell us your project
Takes about a minute.
Takes about a minute.
2. We match local pros
Up to 5 independent local ADU builders — never more, and we tell them nothing you don't submit here.
Up to 5 independent local ADU builders — never more, and we tell them nothing you don't submit here.
3. You choose
Compare quotes, verify license & insurance, hire (or don't). No spam either way.
Compare quotes, verify license & insurance, hire (or don't). No spam either way.
🔒 Your info is secure. We share it only with contractors quoting your project. No spam, no obligation.
Just browsing? Search ADU builders near you by ZIP code.
Construction Costs [9]
Building an ADU in Kirkland typically costs $250,000-$450,000 ($300-$500 per sq ft); a garage conversion runs $120,000-$250,000.
See what this means for your lot — get 5 free quotes from Kirkland ADU builders →
| Average Build Cost | $250,000-$450,000 |
| Cost per Sq Ft | $300-$500 |
| Garage Conversion | $120,000-$250,000 |
| Prefab ADU (Installed) | $180,000-$350,000 |
Finance Your ADU Project
Most ADU projects are funded through HELOCs, construction loans, or cash-out refinancing. Compare rates from top lenders.
Some links on this page are affiliate links. We may earn a commission at no extra cost to you. Learn more
Rental Income Potential [10][11][12]
A 2-bedroom ADU in Kirkland rents for around $2,500-$3,300/mo, an estimated 5-7% annual return.
| Avg Rent (1 Bedroom) | $1,950-$2,600/mo |
| Avg Rent (2 Bedroom) | $2,500-$3,300/mo |
| Short-Term Rental | Yes, with a city business license — and with real limits. Kirkland's business licence chapter defines "single-family residence" to include accessory dwelling units, both attached and detached (Kirkland Municipal Code 7.02.030(s)), so renting an ADU short-term or long-term requires a licence, and short-term rentals owe lodging excise tax (KMC 7.02.310). KMC 7.02.300 then adds special provisions for short-term rentals of detached dwelling units: unlimited when the owner or authorised agent continuously occupies part of the unit as a primary residence; capped at 120 days a year where the owner occupies it at least 245 days a year and a property manager is available within 15 miles; and never more than two short-term rental agreements in effect at a single detached dwelling unit at one time. Whether those day caps reach a detached ADU as opposed to the house itself is not settled on the face of the code — confirm with the City at 425-587-3600 before you list |
| Est. Annual ROI | 5-7% annual return |
Explore Prefab ADU Options
Prefab ADUs can save 20-40% vs. traditional construction and cut build time in half.
Some links on this page are affiliate links. We may earn a commission at no extra cost to you. Learn more
Recent Law Changes
What's Changed Recently
- Washington HB 1337 (2023 c 334), codified at RCW 36.70A.681, preempts local ADU regulation in cities planning under the Growth Management Act: two ADUs on every lot in a zoning district inside an urban growth area that allows single-family homes, no owner-occupancy requirement, no maximum floor area under 1,000 sq ft, no roof height limit under 24 feet, no setbacks or yard coverage limits more restrictive than for the principal house, mandatory conversion of existing structures including detached garages, ADUs at the lot line where it abuts a public alley, impact fees capped at half the principal unit's, no public street improvements as a condition, and no parking within half a mile of a major transit stop
- Kirkland Ordinance O-4905, adopted June 17, 2025 and effective July 2, 2025, rewrote the Zoning Code for Washington's middle housing and ADU laws — amending KZC 115.07, 115.08, 115.42 and 115.115 and adding a Major Transit Stop definition at KZC 5.10.497
- Kirkland Ordinance 4913, adopted September 16, 2025 and effective September 27, 2025 (codified in the October 6, 2025 version of the Zoning Code), further amended KZC 115.07 and 115.115 and the Chapter 15 use and dimension tables
- KZC 115.08 was amended to state expressly that the accessory structure size limit — 1,200 sq ft plus 10 percent of lot area over 7,200 sq ft — "does not apply to Accessory Dwelling Units," so a tool shed or detached garage no longer eats into your ADU allowance
- RCW 36.70A.681(4) exempts lots designated with critical areas or their buffers under RCW 36.70A.060 from every one of the state's ADU protections — in Kirkland that means steep slopes, streams, wetlands and their buffers, and it is the single most common reason a Kirkland lot will not deliver what the statute promises
Tips for Building an ADU in Kirkland
- Find out whether you are inside half a mile of the STRIDE (I-405) bus rapid transit station before you design parking — that is the city's only current major transit stop, and inside that radius no off-street parking may be required at all
- Convert before you build where you can: KZC 115.07(6) exempts a permitted conversion of an existing structure, detached garages included, from current setback and lot coverage requirements, provided you do not make an existing nonconformity worse
- If your lot backs an alley, a detached ADU may go right to the rear property line — a genuinely large gain in usable yard, and it is guaranteed by RCW 36.70A.681(1)(i), not just by local grace
- Start with the pre-approved DADU gallery. The plans are already reviewed for code compliance, permitting can drop to a few weeks, and licensing one from the designer runs up to $1,000 — far less than a custom set
- Do the floor area ratio maths early. Only the first 500 sq ft (lots under 8,500 sq ft) or 800 sq ft (8,500 sq ft and up) of a detached ADU behind the house is exempt from F.A.R., and in RS 35 the F.A.R. is just 20 percent of lot size
- You can sell it. Kirkland allows an ADU to be segregated in ownership and, outside stacked units, to be placed on its own lot through a unit lot subdivision — a resale option most cities do not offer
- Check for critical areas first, not last. RCW 36.70A.681(4) switches off every state protection on a lot designated with critical areas or their buffers, and Kirkland has plenty of steep slopes and stream buffers
- Shoreline lots are different: the city's ADU Regulations page limits property in the Residential-L Shoreline Environment to one ADU, requires detached units to sit landward of the principal residence in the Residential-L and M/H shoreline environments, and conditions separate ownership in the M/H environment on a Substantial Development Permit
ADU Builders in Kirkland
Looking for an ADU builder in Kirkland? ADU projects need a contractor experienced with local zoning, the permit process, and utility connections — not every general contractor has built one. We match Kirkland homeowners with experienced local ADU contractors who provide free, no-obligation quotes. Getting at least three bids typically saves 20-40% on the same scope.
Sources & References
All data on this page is sourced from official government records and verified market data. View our full methodology.
- Kirkland Zoning Code 115.07 — Accessory Dwelling Units (Ord. 4913 § 17, 2025; Ord. 4905 § 10 (Exh. J), 2025) Municipal Code — Accessed 2026-09-01
- Kirkland Zoning Code Chapter 15 — Low Density Residential Zones (permitted uses, density/dimensions tables) Municipal Code — Accessed 2026-09-01
- RCW 36.70A.681 — Accessory dwelling units, limitations on local regulation (2023 c 334 s 4, HB 1337) state_statute — Accessed 2026-09-01
- ADU Regulations — City of Kirkland Planning and Building Department Planning Department — Accessed 2026-09-01
- Planning Your ADU — City of Kirkland ADU Toolkit (permitting timeline; 425-587-3600) Planning Department — Accessed 2026-09-01
- Explore Kirkland's Pre-Approved Plans — City of Kirkland ADU Toolkit Planning Department — Accessed 2026-09-01
- Kirkland Ordinance No. 4905 (adopted 6/17/2025, effective 7/2/2025) — enactment record Municipal Code — Accessed 2026-09-01
- Kirkland Ordinance No. 4913 (adopted 9/16/2025, effective 9/27/2025) — enactment record Municipal Code — Accessed 2026-09-01
- Angi — ADU Construction Cost Data Market Data — Accessed 2026-09-01
- Kirkland Municipal Code 7.02.030 and 7.02.300 — Business licences; short-term rentals, special provisions Municipal Code — Accessed 2026-09-01
- Zillow Rental Manager — Market Rent Data Market Data — Accessed 2026-09-01
- HUD Fair Market Rents Government Data — Accessed 2026-09-01
- The Kirkland ADU Toolkit — City of Kirkland Planning Department — Accessed 2026-09-01
- U.S. Census Bureau QuickFacts — Kirkland city, Washington Government Data — Accessed 2026-09-01
Frequently Asked Questions
Can I build an ADU in Kirkland?
Yes. ADUs are allowed in Permitted as an accessory use anywhere a Detached Dwelling Unit is allowed in the low density residential zones — RS 35, RS 12.5, RS 8.5, RS 7.2, RS 6.3, RS 5.0; RSX 35, RSX 12.5, RSX 8.5, RSX 7.2, RSX 5.0; RSA 1, 4, 6 and 8; and PLA 3C, PLA 6E and PLA 16 (Kirkland Zoning Code 15.20.060, Special Regulation PU-23 → KZC 115.07). Two exceptions in the local table run narrower than state law: the WD II waterfront zone's Detached Dwelling Unit row does not carry PU-23, and PU-21 limits RSA 4 lots in the Goat Hill Overlay Zone to one attached ADU. RCW 36.70A.681(1)(c) requires two ADUs in all zoning districts inside an urban growth area that allow single-family homes, so state law would override — except that RCW 36.70A.681(4) exempts lots designated with critical areas or their buffers. Confirm your own parcel with Kirkland Planning and Building at 425-587-3600 in Kirkland. The maximum size for a detached ADU is 1,200 sq ft of gross floor area (Kirkland Zoning Code 115.07(4)) — 200 sq ft above the 1,000 sq ft floor state law guarantees (RCW 36.70A.681(1)(f)). Area with less than five feet of ceiling height, uncovered rooftop decks and at-grade patios, and up to 200 sq ft of other covered and uncovered exterior elements do not count. The practical catch is floor area ratio: only the first 500 sq ft of a detached ADU on a lot under 8,500 sq ft, or the first 800 sq ft on a lot of 8,500 sq ft or more, is exempt from F.A.R., and then only when the structure sits behind the main house (KZC 115.42). If F.A.R. would push your ADU below 1,000 sq ft, raise RCW 36.70A.681(1)(f) with the planner. Owner-occupancy is not required, so you can rent out the ADU.
How much does an ADU cost in Kirkland?
ADU construction in Kirkland typically costs $250,000-$450,000. Garage conversions run $120,000-$250,000, and prefab ADUs cost $180,000-$350,000.
How much can I rent an ADU for in Kirkland?
Average ADU rents in Kirkland are $1,950-$2,600/mo for a 1-bedroom and $2,500-$3,300/mo for a 2-bedroom unit.
Do I need parking for an ADU in Kirkland?
None within one-half mile of a major transit stop (Kirkland Zoning Code 115.07(7); RCW 36.70A.681(2)(a)(i)). Read that carefully: the city's own ADU Regulations page states Kirkland's only current major transit stop is the STRIDE (I-405) bus rapid transit station, with future stops along King County Metro's RapidRide K Line once construction is under way. Beyond the half mile, KZC 115.07(7) requires one off-street space only where there is more than one ADU on the lot, and waives even that if on-street parking is available within 600 feet or the property is within half a mile of transit with 15-minute commute-hour headways. The city's ADU Regulations page describes the same rule as one space for the first ADU — the two readings differ, so confirm with Planning and Building at 425-587-3600. Either way state law caps what Kirkland may demand at one space per unit on lots under 6,000 sq ft and two per unit on larger lots (RCW 36.70A.681(2)(a)(ii)-(iii)). Check with Kirkland planning department for the latest Washington ADU parking rules, as many states have relaxed requirements in recent years.
How long does it take to get an ADU permit in Kirkland?
The permit review timeline in Kirkland is Roughly 3 months for a standard ADU permit, with additional time for design and construction; a pre-approved DADU application takes less — the city says as little as a few weeks (City of Kirkland, Planning Your ADU and Explore Kirkland's Pre-Approved Plans). Permit fees: Confirm current permit and plan review amounts with Kirkland Planning and Building at 425-587-3600 — no ADU fee schedule is published on the city's ADU Toolkit pages. If you use a pre-approved plan, budget separately for licensing it from the designer, which the city puts at up to $1,000.
Ready to Build in Kirkland?
Get free, no-obligation quotes from top-rated ADU contractors in Kirkland.
Get Free Quotes →Build ADUs in Kirkland?
Homeowners read this page while planning, then ask us to connect them with a local builder. We pass those requests to builders who cover Kirkland — a flat fee only on the leads you accept, no subscription, and you contract directly with the homeowner.
See who's waiting in Washington →