The largest hemp project in the United States consisting of 12 duplex units in Newburyport, MA will open to residents this month. Builder David Hall and architect Keith Moskow of Hall and Moskow Corporation have been working since 2023 on the Hillside Center for Sustainable Living, an attainably-priced multi-family housing development, from their own design of hempcrete over steel frame panels. The new hempcrete development moved in its first residents on February 15.
“I think it’s fascinating that Newburyport was a major hemp hub in the 1700’s where they made all the sails and rope for the ship building that was here,” said Hall, who was inspired by this when he and Moskow were looking for sustainable materials to use in their project.
Moving away from concrete and toxic foam
In 2018, the partners formed Hillside Living LLC to embark on the sustainable housing project which will eventually have 48 one-to-three bedroom units. They got to work figuring out what to build it from to make it sustainable and passive. The development is built on the remediated site of a coal ash dump from which 3,000 tons of toxic ash were removed.
The first two sets of multi-unit buildings are made from concrete and expanded polystyrene foam.
But Hall was focused on carbon sequestration, and he wanted a material that would be lighter and still serve that purpose. His research led him to Cameron McIntosh, of Americhanvre, who uses a French hempcrete spray system called Ereasy.
McIntosh, an industry pioneer who was the first to import a hempcrete spray installation system, was a key member of the group who got hempcrete ASTM-certified and is an innovative and enthusiastic builder. When Hall found him through his research, he thought “This guy knows what he’s doing!”
Hall noted that permitting is not easy and that they are lucky to have a building inspector with a very open mind with whom they have worked for years. “The fact that Cam and others had helped develop hemp-lime residential housing codes (2024 IRC Appendix BL) that has been adopted is huge.”
Company started in 1985
The company has been around since 1985, when the friends took over from their fathers, who had been developing in the area for decades prior.
Their fathers, he said, had always set an example of stewardship and conservation, so it was a natural direction for them to take Hall and Moskow. In 2004 they added a 60-kilowatt array on the roof to one of their first projects that had been built decades earlier, a redevelopment of a toxic former tannery into a shopping center. The solar power was, at that time, the largest privately owned solar array in the region, Hall notes with pride.
Panels weigh less than concrete
To make the hempcrete panels for the new 12 units, they replaced a lot of the structural concrete elements from their previous panel design with wood and tubular steel, and adapted the process for hempcrete. Hall realized that in order to make hempcrete a viable commercial material that would scale, he’d have to panelize the walls and then do tilt-up, which he says is a fairly common method in the US. “The bigger your panels and the fewer your seams,” he says, “the better off you are.”
Hillside’s hempcrete panels weigh 13,000 pounds (compared to concrete’s 25,000) and are 14 inches solid of hemplime fiber mix.
The building process proved a challenge with the new material.
“I would say the process demands respect,” Hall says of the Ereasy hempcrete system, noting that it is “moderately difficult” to perfect the application.