In Belfast, aging in place with a super-insulated ADU

Conny Hatch, 73, of Belfast, said moving from her two-story, 2,200-square-foot home to a one-story, 1,300-square-foot Croft home has given her peace of mind that she can age in place in a home that has a minimal environmental footprint. The super-insulated building is heated and cooled by a single heat pump.

“For me, moving to a smaller, efficient house and not using fossil fuels is definitely a positive experience,” she said.

The house’s 16-inch-thick walls block nearly all sound from the street. Those walls are packed with straw.

When most people hear the word straw in the context of housing, their minds jump straight to fairy tales—you know the one. But Croft, a Maine-based design and building company, is making a strong case that straw may actually be one of the most practical building materials available, especially for smaller homes, like accessory dwelling units (ADUs).

Based in Rockland, Croft designs and manufactures climate-friendly, prefabricated buildings using innovative offsite construction techniques. Croft blends healthy, locally sourced materials, high-performance construction, and thoughtful design to create buildings that last longer, cost less to operate, and feel better to live in. And yes—sometimes that means insulating walls with straw.

Why Straw? Because Maine.

Let’s get this out of the way: straw insulation is not new, experimental, or fragile. Straw bale construction has been used for more than a century, and modern versions are tightly engineered, code-compliant, and remarkably tough. For a cold, damp, and increasingly unpredictable climate like Maine’s, straw turns out to be an excellent match.

Straw is a natural insulator with impressive thermal performance. Thick, straw-insulated walls keep heat in during the winter and help homes stay cool in the summer. That means lower energy bills, fewer drafts, and more consistent indoor temperatures—something anyone who has lived through a Maine winter can appreciate.

Straw also manages moisture well when detailed correctly, helping reduce mold and mildew—two persistent problems in older housing stock across the state. For Croft, that’s not a side benefit; it’s a core reason to build differently.

Then there’s the carbon story. Straw is an agricultural byproduct, and using it locks carbon into the walls of a building rather than releasing it into the atmosphere. In other words, Croft’s buildings don’t just use less energy—they actively help reduce climate impacts from the moment they’re built.

Croft’s compressed-straw wall panels are much thicker than a typical stick-built wall, and that thickness is a key reason they perform so well and deliver high insulation values. Standard wall panels come in 12-inch and 16-inch thicknesses, not including finishes.

Not Your DIY Straw Shack

The offsite approach used by Croft and other ADU builders — such as Backyard ADUs, Canbury Homes, The Knickerbocker Group and Tiny Homes of Maine —  offers clear advantages for ADUs. Backyard construction projects are disruptive, slow, and unpredictable. Prefabrication shortens construction timelines, reduces surprises, and makes the entire process less stressful for homeowners and neighbors alike.

Labor costs for construction in Maine are high, so assembly-line construction can lower the costs of new housing. And despite what the word prefab might suggest, these buildings don’t feel generic.

Croft’s high-end designs are clean, warm, and thoughtfully scaled. Natural materials, abundant daylight, and efficient layouts make small spaces feel comfortable rather than cramped.

Costs for Croft’s weathertight building shells range from $58,000 to $105,000 for ADU-sized units. These prices do not include foundations, windows and doors, utilities, or interior finishes.

Hatch said her home arrived 10 months after she placed her order. The prefabricated panels were delivered on a flatbed truck and hoisted onto the foundation by a large crane. Workers completed the installation in three days.

Her home has two bedrooms and two bathrooms. The total cost, she said, including the foundation, steel roof, utilities, and interior finishes, was $650,000.

Building for the Long Haul

At the heart of Croft’s mission is the idea that Maine needs a shift in how housing is built, said Evan Ryan, the company’s co-founder. Too much of the state’s existing housing stock comes with hidden costs: constant maintenance, high energy use, and unhealthy living conditions. Croft’s response is to build fewer compromises into the structure from day one.

“Our mission is not only to add more housing in the state of Maine, but to deliver structures that are higher quality, less expensive to operate, healthier to live in, and more durable,” Ryan said.

Using straw insulation, high-performance assemblies, and durable materials isn’t about novelty. It’s about creating homes that are more comfortable, more affordable to operate, and better suited to Maine’s climate and values.

So yes—straw is doing some heavy lifting here. For Croft, it’s part of a very real, very practical approach to building smarter ADUs.