"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
4.8 STAR RATED40+ CUSTOMER REVIEWS
LICENSED · BONDED& FULLY INSURED
Seattle HB 1110 Middle Housing Builder
HB 1110, the 2023 Washington middle housing law, requires cities to allow two to four units per residential lot. MNBE designs, permits, and builds duplexes, triplexes, fourplexes, courtyard apartments, and townhomes across Seattle and the Eastside. King, Snohomish & Pierce County.
Duplex to fourplex
Permits handled in house
Founder supervised
What HB 1110 Does
Two to four homes where Washington once allowed one.
HB 1110 is Washington's 2023 middle housing law. It preempts city zoning to require that residential lots inside cities of 25,000 or more allow at least two housing units, and lots within a quarter mile of major transit allow at least four. Codified in RCW 36.70A.635, it opens a path for the homes that used to be banned on single family lots. We design, permit, and build that middle housing across Seattle and the Eastside, from Bellevue and Kirkland to Redmond, Sammamish, and Mercer Island.
In practice HB 1110 unlocks the duplex, triplex, and fourplex, plus townhomes, courtyard apartments, stacked flats, and cottage housing, on lots that previously allowed only a single family home. It is the primary residence companion to HB 1337, which expanded ADU rights. As a single design build team we carry your project from drawings through final inspection, and most Seattle and Eastside cities have already updated their codes, so we build to the new rules, not the old ones. Start with a site feasibility study to confirm exactly what your lot supports, then explore the rest of our new construction work, including infill new construction and lot-owner custom home builds.
Schedule Free Estimate
4.8 STAR RATED40+ CUSTOMER REVIEWS
LICENSED · BONDED& FULLY INSURED
HB 1110 Rules · 2026
The rules now work in your favor.
Washington's HB 1110 reshaped what you can build on a residential lot.
2
Units per lot, minimum
Cities of 25,000 or more must allow at least two homes on every residential lot.
4
Units near transit
Lots within a quarter mile of major transit must allow at least four units.
6+
Building types
Duplex, triplex, fourplex, townhomes, courtyard apartments, and cottage housing.
2023
Signed into law
Codified in RCW 36.70A.635, with city compliance staggered through 2025.
What does HB 1110 middle housing cost?
Priced to your project.
Every duplex, triplex, or fourplex is priced to your specific lot and unit count, never a generic per square foot number. The drivers that move a multi unit build are separate dwelling unit egress, shared wall fire ratings, separate utilities per unit, off street parking analysis, and the utility capacity charges and stormwater requirements that come with adding homes. We walk your property and run the engineering first, then give you a written fixed price that covers design, permits, and construction, and the number we sign is the number we build to.
Every MNBE middle housing build includes
- Architectural drawings and multi unit design
- Structural, fire separation, and utility engineering
- Permits, plan check corrections, and inspections
- Full construction by our own licensed crew
- One fixed price contract, founder supervised
How It Works
From feasibility to keys, one team.
No handoffs and no surprises. Here is exactly how your duplex, triplex, or fourplex goes from idea to a finished, rentable building.
01
Site feasibility
We confirm what HB 1110 allows on your lot, including unit count, transit proximity, and critical area triggers.
No cost
02
Design & engineering
Multi unit drawings with egress, shared wall fire ratings, and separate utilities, plus a written fixed price bid.
4 to 6 months
03
Permits
We submit to your city, answer every plan check correction ourselves, and manage approval at the DCI.
4 to 8 months
04
Build
One licensed crew, founder supervised, from foundation to finishes, on the fixed price we signed.
12 to 18 months
05
Keys
Final inspection, unit by unit address assignment, and a finished building ready to live in, rent, or sell.
Move in ready
Reviews
What Seattle homeowners say about building with MNBE.
Verified five star reviews from owners who built their home, ADU, or renovation with us.
"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
Sammamish, WA · Whole home renovation
"We hired MNBE for a major exterior renovation: a 900 sq ft custom deck with metal railings, full exterior painting and new siding. From start to finish the experience was exceptional, responsive, meticulous and patient."
Santosh S.
Redmond, WA · Deck & exterior
Schedule Free Estimate
4.8 STAR RATED40+ CUSTOMER REVIEWS
LICENSED · BONDED& FULLY INSURED
FAQs · What Clients Ask Us
HB 1110 questions Seattle homeowners ask before they sign.
Six practical answers from a builder who runs middle housing projects under the new law. If yours is not here, call us. We answer the phone Monday through Saturday.
HB 1110 is the Washington state middle housing law passed in 2023. It requires cities of 25,000 or more to allow at least two units per residential lot statewide, and four units within a quarter mile of major transit. Some cities allow more. The law preempts local zoning where local code conflicts. Codified in RCW 36.70A.635. It is distinct from HB 1337, which expanded ADU rights, but complementary.
HB 1337 covers accessory dwellings: two ADUs per lot, owner occupancy bans made illegal, and parking minimums eliminated near transit. HB 1110 covers primary residences in middle housing forms: duplex, triplex, fourplex, townhomes, and courtyard apartments on lots that previously allowed only single family homes. Both took effect in 2023, with city compliance deadlines staggered through 2025 across Seattle and the Eastside.
Almost certainly yes if you're in a city of 25,000 or more. HB 1110 mandates that cities allow at least two units per residential lot, and Seattle, Bellevue, and Kirkland allow up to four units within a quarter mile of major transit. Your lot must meet the minimum size for the unit count, but HB 1110 capped those minimums too.
Design typically runs four to six months, permits four to eight months at Seattle DCI, and construction twelve to eighteen months. The process resembles a custom home with multi unit additions: separate dwelling unit egress, shared wall fire ratings, separate utilities, parking analysis that's often zero required near transit, and unit by unit addresses. The longest pole is design and engineering coordination.
Sometimes. HB 1110 does not directly enable separate sale, but related Washington condominium law allows multi unit buildings to be platted as condos and sold individually under specific conditions. The structuring decision happens during design with appropriate legal coordination. We have built fourplexes intended for single owner rental and fourplexes intended for individual condo sale. The construction is similar; the legal structure is different.
We publish every question Seattle homeowners ask us about HB 1110, permitting, and construction. Browse the full FAQ library for expert guidance.
View all FAQs
Contact Us · Free Estimate
Tell us about your project.
We'll get back to you within one business day with a clear next step.
Contact information
Thank you for considering MNBE for your middle housing project. We respond within one business day, Monday through Saturday.
(206) 637 0044
info@mnbe-wa.com
2014 Fairview Ave Unit 2308, Seattle, WA 98121