Can I build a backyard home in Renton?
Since 2023, Washington law lets most city lots hold up to two more homes. Renton 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 Renton allows.
The headline standards. Open any card for the full wording and the code section.
ADUs per lot2 per legal lotFull wording
2 per legal lot (1 attached + 1 detached, 2 attached, or 2 detached)
Max size1,000 sq ftFull wording
1,000 sq ft; conversion of a full floor up to 1,250 sq ft
Max height24 ftFull wording
24 ft
Front setbackNo closer than the principal structureFull wording
No closer than the principal structure; per zone
Side setback5 ft in R-4, R-6 and R-8Full wording
5 ft in R-4, R-6 and R-8; 4 ft in R-10 and R-14; 25 ft in RC and R-1
Rear setback5 ft (may align with the rear line at an alley)Full wording
5 ft, with 25% of the rear yard to remain open when the unit is within 10 ft of the line; may align with the rear line at an alley
Lot coverageThe zone’s standardsFull wording
Zone standards
Parking1 space (waived within ½ mile of major transit)Full wording
1.0 space per unit; waived within 1/2 mile of a Major Transit Stop
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?
No — not required
Can it be sold on its own?
Permitted by state law
Pre-approved plans
Yes — Permit Ready ADU. 8 free designs from 415 to 1,000 sq ft, 32 plan sets with variations, pre-screening meeting required. PSRC reports 47 requests and 1 permit since 2021.
How long the city takes
not published yet — ask the city
Impact fees
Street improvements and sidewalks are not required. Fee waivers and reductions are cited by PSRC; the current schedule is 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 Renton 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 Renton municipal code and the city’s own pages on September 15, 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 Renton allows, what could fit, and a planning cost range. Free, no obligation.