Middle housing types are duplexes, triplexes, fourplexes etc, townhomes & row houses, cottage clusters and courtyard buildings.
The name ‘Middle Housing’ was coined in 2010 by architect Daniel Parolek who identified that the middle housing types were missing in modern design & permitting. American cities were only permitting single family homes & high-density apartment blocks. Parolek’s book The Missing Middle successfully advocated to reinstate the missing middle housing types. The goals are to increase affordability & increase density to make more vibrant & walkable neighborhoods.
The Washington State legislature passed HB1110 in 2023 and cities in Washington State are now required to permit middle housing in areas previously zoned ‘residential’. This means building in backyards.
It’s important to note that the new Middle Housing Bill only legislates that middle housing be built in cities, not beyond city-limits in the counties.
Large cities (75000 inhabitants or more) must permit more dwellings on a single lot, up to a 6-plex. The small cities (25000 inhabitants or less) are only required to permit duplexes.
Can I Build Middle Housing in Bellingham?
Middle housing can be permitted & built in Bellingham on lots zoned ‘residential’, effective Dec 8th, 2025. The key ordinance can be found here.
Bellingham is a city of 97000 people and this permits the development of 4 middle housing units per lot, plus it’s possible to permit an additional 2 units per lot if those units are affordable for 50 years, or the lot is located within 1/2 mile walking distance from a major transit stop.
Importantly the original house on a lot does not have to be demolished, and that house does not count towards the unit total.
Middle housing units can all be subdivided or condominiumized from each other & the original house (if it was kept), allowing middle housing units to be bought & sold.
The Middle Housing code contains some surprising details: the only parking requirement is one ADA-accessible parking spot per project, setbacks have been reduced, sub-standard streets may need to be improved, and middle housing is prohibited within the Lake Whatcom watershed to protect the reservoir.
NOTES: Middle Housing in Bellingham is called Infill Housing. Chapter 20.28 BMC explains the details, but be aware that the 20.28 code has not been updated to incorporate the 2025-12-35 ordinance and if there are contradictions, the 2025-12-35 ordinance has seniority. For clarity, this article will continue to use the phrase Middle Housing.
Also, it’s important to know that the Middle Housing code in Bellingham is a work-in progress and will be reviewed December 2026 for effectiveness.
Who Needs Middle Housing?
Housing shortages are nationwide but extreme in Bellingham. There is little unused land in Bellingham and the Middle Housing code creates many new opportunities to build new homes on existing lots.
Once enough new homes are built, we expect to see rents & house prices stabilize.
First time buyers will appreciate the wider diversity of choice created by middle housing development: With many units at or below 1000sf, the cost to buy a low-rise home in a walkable neighborhood will become more manageable.
Also, the creation of more small homes will help retirees to downsize but remain within the neighborhood in which they raised children, perhaps even living in the backyard of the lot within which they raised their flock!
The sidewalks of Washington State cities should begin to bustle as housing density increases. With walking and cycling becoming increasingly popular, there will be new customers for local retail, coffee shops and other neighborhood recreational & utilitarian destinations. Without the need for car parking, these new destinations will make attractive, human-scale places.
How Fast Can We Expect to See Neighborhoods Change?
The character of residential-zoned areas is protected by the 20.28 code. That code calls for “pedestrian-oriented design, street oriented front porches, entries, and windows, and architectural and landscape features that add human scale visual interest.” The scale of buildings in the residential neighborhoods will not change (the maximum permitted height is the same), frontages will bump-out by unit, and there will be plenty of tree & shrub planting. The city wants the new developments to fit.
The built environment changes slowly, and there is no reason to expect middle housing developments to happen remarkably fast.
The city of Bellingham supports the creation of middle housing and will watch through 2026 to monitor progress. A public review in Dec 2026 will evaluate the projects that happened throughout the year, and we can expect to see scrutiny of the entire middle housing code as it’s evaluated for effectiveness.
Here at Legend Homes we are excited to develop Net Zero middle housing, combining an appreciation of the earth’s resources with an appreciation of a Bellingham ready to maintain affordability. We see the evolution of more housing types as a celebration of pedestrian & bicycle cultures, realizing a vision of a vibrant city with a home for everyone.
Still have questions? Shoot us an email! We’d be more than happy to answer any questions you have!
Lynden Powerhouse Open House Tour with Sustainable Connections
Written by: Nicole Miller
Sustainable, innovative and efficient!
A couple weeks ago we were pleased to host a home tour of the Lynden Powerhouse project in conjunction with Sustainable Connections and with a presentation from Built Green! The clients were gracious enough to let us hijack their home for the evening for the event. The 3-hour event was a success, bringing in all different kinds of people with different backgrounds! We were all excited to share the success of the home.
Lynden Powerhouse is not only beautiful but highly advanced. Using its oversized solar array in combination with server battery backups, the house is able to run without contributions from the grid, and even spends the entire afternoon putting power back on to the grid, helping power the neighboring houses and reduce the need for a peaker plant!
Homeowner Bob presented to everyone the impressive data showing the solar production, battery charge, grid output and critical loads. He explained that their system runs entirely on their battery backup during the night (note the State of Charge (SOC) line from 0:00 to7:30am slowly reducing) but never getting below 30% charge, then as the sun rises, the PV system (note the green area) runs the home and charges the battery until it’s at peak charge around 1pm, then all the excess solar produced is exported back on the grid (note the yellow area). This is the cycle that repeats itself each day!
The home has also proved its efficiency during family gatherings – in peak summer heat with children running in and out of the doors and with 20 folks inside, the home still never got above 75° inside and still exported 75% of the PV electricity generated.
I don’t know about you, but we’d call that an epic success!
A huge thank you to our adored clients, the homeowners of Lynden Powerhouse, and to Sustainable Connections!
Case Study & 2024 HIA Winner: The Lynden Powerhouse
Written by: Talia Dreicer, Nicole Miller & Senna Scott
The Lynden Powerhouse Case Study, written by Talia Dreicer, was featured in this season’s Master Builders Association Publication!
“The Lynden Powerhouse is a highly efficient, net-positive energy home that cultivates meaningful aging-in-place living and community connections in Lynden, Washington. Designed by Powerhouse Designs and built by TC Legend Homes, this 5-bedroom, 4.5-bath home features three distinct living areas and seamlessly merges innovative design techniques, a high-efficiency HVAC system, and automation technology to create a beautiful and comfortable home. Receiving DOE Zero Energy Ready Home, ENERGY STAR, and EPA Indoor airPLUS certifications, along with a Built Green 5-star certification, this home is a shining example of high-performance housing.
In the years leading up to their retirement, Baby Boomer couple Lee Anne Caylor and Bob Edmiston saw two potential paths. According to the couple, the choice was “a decision between lives of generativity or stagnation.” Caylor and Edmiston chose the path of generativity, focusing on creating a future where they could share time and knowledge with family, friends, and community. They started envisioning their future home, the Lynden Powerhouse, as an accessible, comfortable, and healthy living environment that would enable meaningful intergenerational living and support human connection. The COVID-19 pandemic only furthered their interest in positively impacting the lives of their family, community, and the planet, helping them refocus from their professional goals towards providing solicitude for both younger and older family members alike. The couple also saw the Lynden Powerhouse as a chance to push the high-performance housing envelope. Edmiston, a self-described “mad scientist” with a technical background and keen mind for understanding how things work, wanted to incorporate automation technology and add resiliency measures to optimize resources and reduce future financial burdens. Seeking a team that could deliver on their project goals, Caylor and Edmiston approached Powerhouse Designs and TC Legend Homes to design and build the Lynden Powerhouse.”
Additionally, we were excited to hear this week that Lynden Powerhouse is one of the 2024 DOE Housing Innovation Award winners! We don’t know what category the home has won yet, but we are beyond ecstatic and grateful to be receiving yet another win.
This was truly possible because of the collaboration with our incredible clients who were willing to push the envelope with us. We have the deepest appreciation for them and the innovative smart home features they created!
We are excited to announce our Net Zero Energy Co-Housing spec project that’s currently under construction!
Titled “Woburn House” on our social media, this 5-bedroom home is intended to house multiple family units and has an accessible first-floor bedroom and bathroom. Our hope is for this to be a multigeneration home creating a small, tight-knit community.
As always, this home will create its own power, leaving the residents with zero electric bills. We also anticipate it will receive Built Green 5-Star, Indoor AirPlus, EnergyStar, and Zero Energy Ready Home certifications.
Once completed, this home will be open for lease or purchase!
There seems to be a lot of confusion around Structural Insulated Panels (SIPs) in home building. In this article, we will run through the most common questions we’ve seen!
Are SIPs panels non-combustible? / Are SIPs panels fire resistant?
While SIPs can still catch fire, they are less combustible than traditional stick-framed homes. That’s, in part, due to less wood being used and because of the flame retardants used on the foam. In combination with the gypsum drywall, the whole assembly has a 1-hour fire rating. SIPs construction also does not require an attic space, which can be a fire hazard, thereby eliminating a major threat.
How are SIPs panels made?
SIPs are manufactured off-site to the exact specs of the house. Each panel is made up of two OSB panels sandwiching an EPS or GPS foam core. During the manufacturing process, workers cut out each window and door opening and cut all of the pieces perfectly to size, so that when they are installed on site, they will fit together perfectly like Legos. This also means that the panel off-cuts can be recycled and reused at the manufacturing plant, reducing the overall waste!
Are SIPs panels load bearing? / Are SIPs panels structural?
Yes! SIPs can be used for the entire exterior shell of a house. According to Insulspan, “SIPs have structural properties similar to that of a steel I-beam.” In fact, SIPs are actually considered more structurally sound than traditional stick-framed homes.
Are SIPs panels environmentally friendly?
Yes! SIPs are generally considered to be more environmentally friendly than traditional stick-framed homes. That being said, SIPs can use either EPS or GPS foam cores and EPS is not a very eco-friendly option. So, it’s best to use GPS SIPs in order to lessen the home’s overall carbon footprint. Also, since SIPs are manufactured off-site, they are made to the specific dimensions of a home which reduces the waste. Any scraps produced during manufacturing are also reused. Furthermore, when shipped, the panels are tightly flat-packed together reducing fuel needed for transportation.
Can SIPs panels get wet?
Yes! SIPs are built to dry out and can withstand exposure to the elements for many months. The foam core doesn’t absorb water unless it’s physically submerged or constantly wet for a long time. In all the years we’ve built using SIPs in the rainy Pacific Northwest, we have never had an issue with the SIPs compromising due to moisture.
How long will a SIPs house last?
SIPs are a super sturdy and hardy building material. Assuming you are properly maintaining your house (i.e. replacing your roof every 30-50 years, fixing any broken siding or trim, fixing leaks as soon as they happen, etc.), then a SIPs house will last 100+ years.
Still have questions? Shoot us an email! We’d be more than happy to answer any questions you have!
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