Can I build a backyard home in Woodinville?
Since 2023, Washington law lets most city lots hold up to two more homes. Woodinville 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 Woodinville allows.
The headline standards. Open any card for the full wording and the code section.
ADUs per lotMaximum 2 ADUs per parent lotFull wording
Maximum 2 ADUs per parent lot
Max size300-1,500 sq ft habitableFull wording
300-1,500 sq ft habitable
Max height35 ftFull wording
35 ft — 'Maximum building and structure height' 35 ft in R-1, R-4, R-6 and R-8 (WMC 21.32.040 Table 21.32.040(2)); WMC 21.41.020 sets no ADU-specific height
Front setbackThe zone’s setbacksFull wording
Zone setbacks
Side setbackThe zone’s setbacksFull wording
Zone setbacks
Rear setbackThe zone’s setbacks; 0 ft at an alleyFull wording
Zone setbacks; a DADU may sit 0 ft from a lot line abutting a public alley
Lot coverageBuilding coverage steps down by lot size (R-4: 40% under 5,000 sq ft, 35% at 5,000–9,999)Full wording
Building coverage (roof area) steps down by lot size (WMC 21.32.050 Table 21.32.050(1), Ord. 792, 2025): R-4 40% under 5,000 sq ft, 35% at 5,000–9,999, 28% at one acre or more; R-6 50% under 5,000 sq ft to 40% at one acre; R-8 55% to 45%; R-1 40% down to 15% — the intermediate R-4/R-6/R-8 cells did not render in the fetch, confirm the exact cell for the lot. Minimum landscape coverage also applies (R-4 50%, R-6 25%, R-8 20%). No impervious cap in ch. 21.32
Parking1 stall per ADUFull wording
1 stall per ADU; detached one-unit dwelling 2 stalls (WMC 21.37.060 Table, Ord. 792, 2025). Chapter 21.37 has no one-half-mile major-transit-stop exemption — a potential conflict with RCW 36.70A.681 near major transit stops
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
Minimum lot size
Zone minimum applies
Do you have to live there?
Not addressed; prohibited as a requirement by state law inside the UGA
Can it be sold on its own?
Not addressed in WMC 21.41.020 or the definition at 21.11B.050; the RCW 36.70A.681 floor applies — confirm the process with the city
Pre-approved plans
None found
How long the city takes
City FAQ: single-family new construction about 4–7 weeks; single-family additions/alterations 2–5 weeks; site development 10–19 weeks; land-use permits generally 120 days from the completeness letter (https://www.woodinville.gov/FAQ.aspx?QID=80)
Impact fees
Park impact fee: ADUs 'shall pay only 50 percent of the park impact fee' calculated for the largest associated primary unit (WMC 3.36.080(2), Ord. 811, 2026; park fee by unit size $2,054 up to 1,500 sq ft). School impact fee: ADUs exempt (WMC 3.38.040(3), Ord. 800, 2025). Transportation impact fee ch. 3.39: no ADU provision found
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 Woodinville 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 Woodinville 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.
- www.codepublishing.com/WA/Woodinville/html/Woodinville21/Woodinville2141.html (WMC 21.41.020)
- .../Woodinville2121.html (use table 21.21.050)
- .../Woodinville2131.html (lot standards 21.31.030)
- .../Woodinville2132.html (21.32.030–.050)
- .../Woodinville2137.html (parking 21.37.060)
- www.codepublishing.com/WA/Woodinville/html/Woodinville03/Woodinville0336.html (park fees 3.36.080)
- .../Woodinville0338.html (school fees 3.38.040)
- www.woodinville.gov/347/Apply-for-a-Permit-Online
- www.woodinville.gov/413/Maps
- www.woodinville.gov/FAQ.aspx?QID=80
- RCW 36.70A.681 — the state floor for accessory dwelling units
Find out what your property could become.
Type your address. Within a few hours: what Woodinville allows, what could fit, and a planning cost range. Free, no obligation.