"We hired MNBE to build our ADU in Bellevue, and the entire experience was amazing. They handled everything from foundations and framing to kitchen, siding, windows and HVAC."
Zena Heywood
Bellevue, WA · Attached ADU
FIVE-STAR RATEDRATED ON GOOGLE
LICENSED · BONDED& FULLY INSURED
Renton ADU & DADU rules, in plain English
What Renton's code allows for attached and detached ADUs today, rule by rule, with the code section behind each one. Written by MNBE founder Aharon Ben Elisha. Checked October 28, 2026.
RMC 4-2-110C In force since Jun 30, 2025 Permit-ready ADU plans
The Update
What changed in Renton.
Renton brought its ADU rules in line with HB 1337 in Ordinance 6160, effective June 30, 2025 (city HB 1337 page). The rules sit in RMC 4-2-110C. Renton also offers a Permit Ready ADU program with free base plans.
Our Renton plan
We designed a 640 sq ft one-bedroom DADU with a covered deck for a Renton lot. See the plan on the Renton DADU page.
Rules for other cities are in our ADU rules by city guide.
Renton · RMC 4-2-110C
Renton's ADU rules, by the numbers.
The four numbers homeowners ask about first. Check them against your lot with a feasibility study →
2
ADUs per lot
Attached, detached or one of each.
1,000sq ft
Size cap
Floor area, and building area including an attached garage.
24feet
DADU height
To the highest ridge. Permit-ready plans are exempt.
5feet
Rear setback
0 feet at an alley.
The Code
Renton ADU rules, line by line.
The main single-family zones. Zone-specific numbers vary, so we confirm them for each lot.
| Rule | What Renton allows | Source |
|---|---|---|
| ADUs per lot | Two per legal lot: one attached and one detached, two attached, or two detached. In the RC, R-1, R-4, R-6 and R-8 zones the second ADU meets the house's location and setback standards. | RMC 4-2-110C |
| Size | 1,000 sq ft of gross floor area, not counting an attached garage, porches or exterior stairs, and no more than 1,000 sq ft of building area, which does include an attached garage. Permit-ready plans are exempt from the building-area limit. | RMC 4-2-110C |
| Height | 24 feet to the highest ridge, measured to the average on a shed roof. Permit-ready plans, including two-story models, are exempt. | RMC 4-2-110C |
| Setbacks | Side: 5 feet in R-4, R-6 and R-8. Rear: 5 feet, keeping part of the rear yard open, and 0 feet at an alley. At least 4 feet from the house, or the ADU counts as attached. | RMC 4-2-110C |
| Coverage | Building coverage and impervious surface: 35% and 50% in R-4, 40% and 55% in R-6, 50% and 65% in R-8. | RMC 4-2-110A |
| Minimum lot size | None. ADUs are allowed on any legal lot. | RMC 4-2-110C |
| Parking | One space per unit, none within half a mile walking distance of a major transit stop. | RMC 4-4-080 |
| Owner occupancy | Not required. | RCW 36.70A.681 |
| Existing structures | Buildings built before June 30, 2025 are exempt from the ADU coverage, setback and size limits when converted. | RMC 4-2-110C |
| Design | Renton's residential design standards apply: colors, siding materials, windows and modulation. A DADU of 800 sq ft or less can use a covered porch instead of modulation. | RMC 4-2-115 |
| Permit-ready plans | Free base plans from 418 to 1,000 sq ft, one and two stories, after a pre-screening meeting with the city. | Permit Ready ADU program |
| Trees | Significant trees are 6 inches and up; landmark trees, 24 inches and up. Retention rules apply to development permits. | RMC 4-4-130 |
| Street improvements | Not required for ADUs. | City HB 1337 page |
Checked October 28, 2026. Sources: RMC 4-2-110C, RMC 4-2-110A, RMC 4-2-115, RMC 4-4-080, RMC 4-4-130, the Permit Ready ADU program and RCW 36.70A.681. A plain-English summary, not legal advice. The code governs, and we confirm it for your lot.
Your Lot
How we check a Renton lot for an ADU.
The code sets the outer limits. Your lot sets the real ones. This is the order we work in during the free site visit and feasibility.
01
Zone and overlays
We confirm your zone and check Renton's maps for critical areas, shoreline and slopes, which can move or shrink the buildable area.
Zoning
02
Trees
We locate the trees the code protects and their root zones before we place the ADU.
Tree code
03
Fit the footprint
We test size, height, setbacks, coverage and floor area against your house, and whether an existing building can be converted.
Footprint
04
Utilities
We check whether water, sewer and power can come from the house or need their own connections.
Utilities
05
Design and permit
We draw the plans in house, submit to Renton, answer corrections and carry the project through inspections.
City review
Reviews
What Seattle homeowners say about building with MNBE.
Verified five star reviews from owners we guided through ADU feasibility, permitting, and construction.
"We hired MNBE for a full renovation of our 100 year old home and the results exceeded expectations, structural upgrades, new insulation, a luxury bathroom, a high end kitchen, a new roof and mini split AC."
Dave Gierok
Redmond, WA · DADU
"My mom hired MNBE Construction for her two-bedroom DADU in Seattle, and watching the process up close was impressive. They did it all: design, architectural plans, the building permit, and the full construction. … The communication was excellent and there were never any surprises."
Maryam Z.
White Center, WA · ADU
Schedule Free Estimate
FIVE-STAR RATEDRATED ON GOOGLE
LICENSED · BONDED& FULLY INSURED
FAQs · Renton ADU rules
Renton ADU questions we hear on site visits.
Short answers from the code. For your exact lot, call us or book the free site visit.
Two per legal lot: one attached and one detached, two attached, or two detached.
1,000 square feet of floor area, and no more than 1,000 square feet of building area, which counts an attached garage. Permit-ready plans are exempt from the building-area limit.
24 feet to the highest ridge. The city's permit-ready plans, including two-story models, are exempt from that limit.
Yes. The Permit Ready ADU program offers free base plans from 418 to 1,000 square feet, after a pre-screening meeting with the city.
One space per unit, unless the lot is within half a mile walking distance of a major transit stop.
Contact Us · Free Estimate
Tell us about your project.
We'll check your address against Renton's ADU code and get back to you within one business day with a clear next step.
Contact information
Thank you for considering MNBE. Thank you for considering MNBE. Tell us your address and we will tell you, in writing, what Renton's code allows on your lot. We respond within one business day, Monday through Saturday.
(206) 637 0044
info@mnbe-wa.com
2014 Fairview Ave Unit 2308, Seattle, WA 98121