"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
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Redmond ADU & DADU rules, in plain English
What Redmond's code allows for attached and detached ADUs since the Redmond 2050 code update of June 2025, rule by rule. Written by MNBE founder Aharon Ben Elisha. Checked October 28, 2026.
RZC 21.04.1110 In force since Jun 28, 2025 2 ADUs per lot, any mix
Redmond 2050
What changed in Redmond.
Redmond rewrote its zoning code as part of Redmond 2050. Ordinance 3220 took effect on June 28, 2025 and moved the ADU rules from the old RZC 21.08.220 to RZC 21.04.1110. The update raised the limit from one ADU to two, removed the parking requirement and the recorded covenant, and dropped the rule that an ADU must match the house.
Redmond's older ADU handout from 2023 is still online and shows the old height and setbacks, so we work from the code itself. The rules on your lot also depend on its zone, critical areas and trees, so treat this guide as the starting point. We confirm the current code for your address before design begins.
What we saw on our Redmond DADU
Our Redmond DADU started as a century-old structure. We took it down to the studs, built a new floor system, and carried it through City of Redmond permits and inspections to the certificate of occupancy. Watch it in the Redmond DADU film, or see every stage on the project page.
Redmond · RZC 21.04.1110
Redmond'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, including two detached ADUs.
1,000sq ft
Size cap
Per ADU, attached or detached.
0
Parking spaces
No parking is required for an ADU anywhere in Redmond.
5feet
Rear setback
3 feet on interior sides, and on the lot line at a public alley.
The Code
Redmond ADU rules, line by line.
Values for the Neighborhood Residential (NR) zone, which covers most single-family lots in Redmond.
| Rule | What Redmond allows | Source |
|---|---|---|
| ADUs per lot | Two ADUs or tiny homes on each residential lot, in any combination, including two detached. They count toward the zone's limit on units per lot. | RZC 21.04.1110 |
| Size | 1,000 sq ft per ADU; tiny homes, 400 sq ft. The city may allow a larger ADU when it fills a whole floor of the house, or on lots over 10,000 sq ft when it is an affordable unit or provides another public benefit the city accepts. | RZC 21.04.1110 |
| Total floor area | The NR zone also caps total floor area on the lot by the number of units, and garages and basements count toward it. | RZC 21.08.200 |
| Height | An accessory building with an ADU may reach the zone's height limit, 38 feet in NR. Other accessory buildings are limited to 22 feet. | RZC 21.04.1120 |
| Backyard footprint | The combined footprint of accessory buildings, a DADU included, may not exceed 60% of the house's ground-floor living area, not counting the garage. On many lots this sets the DADU's footprint. | RZC 21.04.1120 |
| Setbacks | Front 10 feet, street side 10 feet, interior side 3 feet, rear 5 feet. A detached ADU may sit on a lot line that meets a public alley or right-of-way, but not in the front setback. | RZC 21.08.300 |
| Lot coverage | Generally 50% in NR, or 60% on lots of 18,000 sq ft or less with three or more units. Impervious surface is generally limited to 70%, and 20% open space is required. | RZC 21.08.200 |
| Minimum lot size | No separate ADU minimum lot size. The lot still has to meet zoning, critical area, utility and building code requirements. | RCW 36.70A.681 |
| Parking | None required for ADUs or tiny homes. | RZC 21.40.010 |
| Owner occupancy | Not required. State law prohibits it. | RCW 36.70A.681 |
| Selling separately | The old ban on separate ownership was removed, and state law allows selling an ADU as a condominium unit. | RCW 36.70A.681 |
| Address | Under Redmond's fire department addressing standard, an ADU uses the house address with a unit number added. | Redmond addressing standard |
| Existing structures | State law requires allowing the conversion of an existing structure even where it breaks today's setbacks or lot coverage. The building official may waive ceiling height for older buildings. | RCW 36.70A.681 |
| Fire sprinklers | Redmond requires fire sprinklers in new homes and detached ADUs. | Residential permits |
| Trees | Significant trees are 6 inches in diameter and up; landmark trees, over 30 inches. At least 35% of significant trees must be kept. Redmond is rewriting its tree code. | RZC 21.72 |
Checked October 28, 2026 against RZC 21.04.1110, RZC 21.04.1120, RZC 21.08.200, RZC 21.08.300, RZC 21.40.010 and RCW 36.70A.681. Critical areas and shoreline rules add their own limits. A plain-English summary, not legal advice. The code governs, and we confirm it for your lot.
Your Lot
How we check a Redmond 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 for critical areas, streams and wetlands, which can move or shrink the buildable area.
Zoning
02
Trees
We locate significant and landmark trees and check the 35% retention rule before we place the ADU.
Tree code
03
Fit the footprint
We test size, setbacks, lot coverage, the 60% backyard footprint cap and the lot's total floor area against your house, and whether an existing building can be converted.
Footprint
04
Utilities and fire
We check water, sewer and power connections, and plan the fire sprinkler system a detached ADU needs.
Utilities
05
Design and permit
We draw the plans in house, submit to Redmond, 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 · Redmond ADU rules
Redmond 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 residential lot, in any combination, including two detached ADUs or tiny homes. They count toward the zone's limit on units per lot.
Up to 1,000 square feet per ADU. The city can allow more when the ADU fills a whole floor of the house, or on lots over 10,000 square feet when the ADU is an affordable unit or provides another public benefit. Backyard buildings, a DADU included, are also capped at 60% of the house's ground-floor living area.
An accessory building with an ADU may reach the zone's height limit, 38 feet in the Neighborhood Residential zone, so two-story DADUs are allowed.
No. Since the Redmond 2050 update in June 2025, no parking is required for ADUs or tiny homes.
Redmond's residential permit page lists fire sprinklers as required for detached ADUs. We plan the system into the design and the water service from the start.
No. Redmond has no owner-occupancy rule, and state law (RCW 36.70A.681) prohibits one.
Contact Us · Free Estimate
Tell us about your project.
We'll check your address against Redmond'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 Redmond'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