"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
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Bothell ADU & DADU rules, in plain English
What Bothell'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.
BMC 12.14.135 No parking minimums citywide 2 ADUs per lot, any mix
The Update
What changed in Bothell.
Bothell, which spans King and Snohomish counties under one code, updated its ADU rules through its middle housing and zoning ordinances of 2024 and 2025, and in July 2025 dropped minimum parking citywide. The rules sit in BMC 12.14.135.
Bothell renamed its residential zones (R-C, R-L1, R-L2, R-M), so older handouts using names like R 9,600 or R 7,200 are out of date.
Rules for other cities are in our ADU rules by city guide.
Bothell · BMC 12.14.135
Bothell'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
Any combination. One on lots with critical areas.
1,200sq ft
Size cap
Conversions can go larger with city approval.
30feet
DADU height
33 feet over an existing accessory building.
0
Parking spaces
No minimum off-street parking in Bothell.
The Code
Bothell ADU rules, line by line.
The main single-family zones. Zone-specific numbers vary, so we confirm them for each lot.
| Rule | What Bothell allows | Source |
|---|---|---|
| ADUs per lot | Two in any combination. Only one on a lot with middle housing, or with critical areas or their buffers. | BMC 12.14.135 |
| Size | 1,200 sq ft. Converting existing space can go larger with the director's approval, up to 40% of the house's floor area. DADUs are exempt from the general cap on accessory buildings. | BMC 12.14.135 |
| Height | 30 feet, or 33 feet when built over an existing accessory structure. | BMC 12.14.135 |
| Setbacks | The rear setback is the house's: 35 feet in R-C, 15 feet in R-L1 and R-L2, 10 feet in R-M. The zoning table allows 0 feet at an alley in the R-L and R-M zones, not in R-C. Sides: generally 5 feet. | BMC 12.14.030 |
| Hard surface | Maximum hard-surface coverage: 35% in R-C, 55% in R-L1, 60% in R-L2, 70% in R-M1. | BMC 12.14 |
| Minimum lot size | No ADU-specific minimum. | BMC 12.14.135 |
| Parking | No minimum off-street parking anywhere in the city since July 2025. | BMC 12.16 |
| Owner occupancy | Not required. | BMC 12.14.135 |
| Address | An ADU permit application needs a city-assigned address letter before submittal. | City ADU checklist |
| Existing structures | Garage and accessory-building conversions are allowed, with the size and height allowances above. | BMC 12.14.135 |
| Design and covenant | No ADU design standards, covenant or registration. | BMC 12.14.135 |
| Trees | Significant trees are over 8 inches in diameter, not counting alder and cottonwood. Retention applies by zone, with an exemption for existing homes on lots of 20,000 sq ft or less. | BMC 12.18.030 |
| Fire and utilities | A water and sewer certificate and a fire flow letter come with the application. Sprinklers or alarms can be required where fire access, hydrant distance or fire flow fall short. | City ADU checklist |
Checked October 28, 2026. Sources: BMC 12.14.135, BMC Chapter 12.14, BMC 12.16, BMC 12.18.030, the city ADU checklist 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 Bothell 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 Bothell'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 Bothell, 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
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FAQs · Bothell ADU rules
Bothell 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 in any combination. Lots with middle housing, or with critical areas or their buffers, get one.
1,200 square feet. Converting existing space can go larger with the director's approval, up to 40% of the house's floor area.
30 feet, or 33 feet when built over an existing accessory structure.
No. Since July 2025 Bothell has no minimum off-street parking anywhere in the city.
Yes. Bothell's ADU checklist asks for a city-assigned address letter before the permit is submitted.
Contact Us · Free Estimate
Tell us about your project.
We'll check your address against Bothell'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 Bothell'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