Can I build a backyard home in Snohomish?
Since 2023, Washington law lets most city lots hold up to two more homes. Snohomish 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.
What Snohomish allows.
The headline standards. Open any card for the full wording and the code section.
ADUs per lot2Full wording
2 — 'Up to two ADUs may be permitted on any lot containing a principal dwelling unit' (SMC 14.170.030.B); ADUs do not count toward density (14.170.030.A). A principal unit must exist on the lot (14.170.020)
Max sizeNo maximumFull wording
No maximum — 'ADU size: No maximum size; subject to setback requirements' (SMC 14.170.040 table)
Max height30 ftFull wording
30 ft; 24 ft if located less than 4 ft from an alley (SMC 14.170.040; measured per 14.210.030.E)
Front setbackDetached: not in the front setback; attached: the zone’s front setback (20 ft)Full wording
No detached ADU in the front setback; attached ADUs in front of the house follow the zone front setback — 20 ft from a street in SFR/LDR/MDR/HDR, 10 ft from a lot line with no street in LDR/MDR/HDR (SMC 14.170.040; 14.210.240 Table 2)
Side setback5 ft interiorFull wording
5 ft interior; street side = half the front setback (SMC 14.170.040), unless the zone allows less
Rear setback5 ft detached (0 ft at an alley)Full wording
5 ft for a detached ADU with no alley; 0 ft on an alley; attached ADUs same as the principal structure (SMC 14.170.040)
Lot coverage80% in LDR / MDR / HDR / C; SFR keeps 20% open space insteadFull wording
80 % in LDR, MDR, HDR and C; SFR has no coverage figure but requires 20 % open space (SMC 14.210.240). ADUs may not be built in critical areas or their buffers (14.170.030.C)
Parking1 off-street stall per ADUFull wording
1 off-street stall per ADU (SMC 14.170.050)
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.
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 — accessory dwelling units are a permitted use (P, note 2) in SFR, LDR, MDR, HDR, C, HBD, BP and MID; attached or detached, subject to Chapter 14.170 SMC (SMC 14.207.070; 14.170.020). Not allowed in PIL, I, AI, POP
Minimum lot size
None for an ADU. Zone minimums for new lots: SFR 7,200 / LDR 7,200 / MDR 6,000 / HDR 5,000 / C 5,000 sq ft (SMC 14.210.240)
Do you have to live there?
No — only if an ADU is used as a short-term rental (SMC 14.170.030.D)
Can it be sold on its own?
Yes — condominium under Chapter 64.90 RCW or unit lot subdivision under SMC 14.215.125, as an administrative decision (SMC 14.170.060)
Pre-approved plans
None found in the SMC as of 2026-10-02; confirm with Planning
How long the city takes
Not published — city FAQ: 'The time required to obtain other permits will vary with the plan reviewer's workload'; ask the Permitting Center for the current estimate (Katie Hoole, Permit Coordinator, 360-282-3156). Permits are valid for two years from issuance
Impact fees
ADUs pay impact fees at 50 % of the principal-unit rate in effect at permit issuance (SMC 14.170.030.F, Ord. 2536, 2026). Current fee schedule not read not published yet — ask the city
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.
What Snohomish 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.
Where this page comes from.
Read from the Snohomish municipal code and the city’s own pages on October 8, 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.
Find out what your property could become.
Type your address. Within a few hours: what Snohomish allows, what could fit, and a planning cost range. Free, no obligation.