Cities · Snohomish County

Can I build a backyard home in Lynnwood?

Since 2023, Washington law lets most city lots hold up to two more homes. Lynnwood writes its own rules on top. Here’s what the code says, in plain English — and a free report on what may fit on your lot.

Read from the Lynnwood code on October 9, 2026 · confidence medium-high · a summary, not legal advice. Rules change; the report re-reads them for your parcel.

The short version

What Lynnwood allows.

The headline standards. Open any card for the full wording and the code section.

ADUs per lot2 (the state floor; the code sets no number)Full wording

2 by the state floor — the UDC sets no number; the city's Director's determination (July 11, 2025) states LMC 8.35.0310 'does not modify the minimum requirements established by HB1337' and that the city must 'Allow two ADUs per residential lot, which may be attached, detached, or a combination of both.' RN base density 3 units per lot, up to 4 (LMC 8.30.0320)

Max size1,000 sq ft (by definition)Full wording

1,000 sq ft by definition — 'A dwelling unit of 1,000 square feet or less located on the same lot as a single-family housing unit, duplex, triplex, townhome, or other housing unit.' (LMC 8.99.0250); the determination notes the UDC 'omits a specific maximum size' beyond that definition

Max height35 ft (the RN zone height)Full wording

No ADU-specific height; RN 'Maximum Building Height | 35 ft' for detached, attached and stacked configurations (LMC 8.30.0320 Tables 8.30.07/.11/.15). The 15-ft accessory-building cap does not apply because 'Accessory buildings do not include habitable dwelling units.' (LMC 8.30.0810)

Front setback10 ft from the street (RN)Full wording

'Minimum Street Setback | 10 ft' in RN; minimum driveway length 20 ft (LMC 8.30.0320 Tables 8.30.04/.08/.12)

Side setback5 ft (RN)Full wording

'Minimum Interior Setback | 5 ft' in RN (LMC 8.30.0320 Table 8.30.04)

Rear setback5 ft (RN)Full wording

5 ft — RN has one interior setback for side and rear: 'Interior setbacks are measured from the side and rear interior lot line.' (LMC 8.30.0940(C)(4); 8.30.0320)

Lot coverageNo percentage — size is set by floor-area ratio: 0.6 with one unit, 0.8 with twoFull wording

No lot-coverage percentage in RN — the city regulates building size by floor area ratio (FAR), set by the number of units on the lot: FAR 0.6 with one unit, FAR 0.8 with two (Table 8.30.07, LMC 8.30.0320(D)(2)). FAR = total gross floor area of all buildings ÷ buildable land area. City example: a 10,000 sq ft lot allows 6,000 sq ft of GFA with one unit and 8,000 sq ft with two. An ADU must be 1,000 sq ft or less. (City of Lynnwood Planning, email 2026-10-09)

ParkingNone under 1,200 sq ftFull wording

Effectively none for an ADU of 1,000 sq ft or less — exemption for 'Dwelling units under 1,200 square feet in gross floor area' and for middle housing within one-half mile of a major transit stop; otherwise 1.0 stall per unit of 1,200 sq ft or more (LMC 8.40.0720(A)(1), (A)(7), Table 8.40.70, Ord. 3492, 2025)

Where a city figure reads stricter than the state floor (RCW 36.70A.681), the floor may control — the report flags it for your parcel.

The rest

Living there, selling it, plans, time and fees.

Each answer is the code’s own wording, with the section it comes from. “Not published yet” means the city hasn’t posted a figure — the report asks the city, not the internet.

Are backyard homes allowed?

Yes — Title 21 (incl. the old 21.42.110) expired June 30, 2025; the Unified Development Code lists 'ADUs' as permitted (P) in RN, RM-45, NC and CDM (LMC Table 8.35.0210, Ord. 3481, 2025); 'Detached Accessory Dwelling Unit (DADU)' defined at LMC 8.99.0250; the RN district supports 'single-family, accessory dwelling units, duplex, triplex, fourplex' (LMC 8.30.0320(A)(1)(a))

Minimum lot size

RN 'Minimum Lot Size | 6,000 sq ft'; minimum lot area per unit 2,000 sq ft (LMC 8.30.0320 Table 8.30.03); no ADU-specific minimum

Do you have to live there?

No — Title 8 has no owner-occupancy rule for ADUs; the Director's determination (July 11, 2025) quotes HB 1337: the city 'May not require the owner to occupy the property, except if the ADU property is a short-term rental.' The old ADU checklist still online cites expired LMC 21.42.110 and an owner-occupancy affidavit — outdated

Can it be sold on its own?

Yes by the state floor — the UDC is silent; the Director's determination: the city must 'Allow the sale of ADUs as independent units.' The expired 21.42.110(G) condominium prohibition is no longer in force — confirm the process with the city

Pre-approved plans

In development — the city 'is developing a pre-approved DADU construction plan program'; designer submission window closed July 2, 2026; no plans published yet (https://www.lynnwoodwa.gov/Services/Apply-for-a-Permit/Pre-Approved-DADUs)

How long the city takes

Planning (2026-10-09): first-round review currently 1–2 weeks intake plus 4–8 weeks for New Residential permits — DBS 'Estimated Review Times' (July 22, 2025): https://www.lynnwoodwa.gov/files/sharedassets/public/v/2/dbs/permit-applications-amp-forms/permit-center-review-times-2025.07.22.pdf; later building reviews 2–4 weeks. 2024 actuals: new residential 70 days mean to issue

Impact fees

Transportation impact fee: ADUs exempt — 'Any legal accessory dwelling unit ... is considered part of the single-family use' (LMC 3.105.080(A)(3), still citing the expired Title 21). Park impact fees under LMC 3.107, current rates from Jan. 1, 2026 (rate PDF not read). No 50% ADU cap found in the LMC — the RCW 36.70A.681 cap applies

Your lot

The code is half the answer. Your parcel is the other half.

Lines and easements

Where the lot lines really are, which setbacks apply on each side, and whether a utility or access easement takes the corner you had in mind.

Critical areas and slope

Steep slopes, wetlands and streams come with buffers that no citywide number shows. The report reads the county’s maps for your parcel.

Sewer, septic, water, trees

Whether sewer reaches the lot or it’s on septic, where the water service is, and which trees a city protects — the things that decide where a unit can actually go.

Free, within a few hours, no obligation.
What Lynnwood allows, what could fit on your lot, and a planning cost range. If something won’t fit, the report says so — and shows what might.

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Sources

Where this page comes from.

Read from the Lynnwood municipal code and the city’s own pages on October 9, 2026. The same table feeds the HousUp report, so the report and this page never disagree. Cities amend their codes; before you design anything, confirm the current wording with the city.

Nearby

Other places in Snohomish County.

Edmonds 1,200 sq ft Everett Under 1,000 sq ft by definition Lake Stevens 1,000 sq ft gross floor area Marysville 1,000 sq ft or 50% of the residence, whichever is greater, capped at 1,400 sq ft Mill Creek 1,000 sq ft Mountlake Terrace 200-1,000 sq ft excluding garage All cities →

Find out what your property could become.

Type your address. Within a few hours: what Lynnwood allows, what could fit, and a planning cost range. Free, no obligation.

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