“Did I smoke grass when I was young?” he said, standing beside a poster for the original Woodstock concert. “Sure, I did, but it wasn’t like I was looking for a way to make money off hemp. It just happened to be the thing with all the attributes we were looking for in a building material.”

He came upon hempcrete through a simple Internet search.

The material was developed in the 1980s in France, though it has roots going back centuries not only to homes as far away as Japan but also to Merovingian bridges in ancient Gaul.

Hempcrete has since caught on across Europe, where hemp cultivation was never criminalized. Hundreds of buildings now use hempcrete, including a seven-story office tower in France, a Marks and Spencer department store in the United Kingdom, and even a home built by Prince Charles.

Though the illicit aspects of hemp may have held it back in this country, marijuana’s growing popularity could finally be helping hemp’s spread. “Some people thought hemp might help get marijuana accepted, but it’s going the other way around,” said Eric Steenstra, executive director of the Hemp Industries Association. “I don’t think you’d see quite the same excitement if we were building with flax or jute.”

Image The chips are mixed with lime and turned into a paste that is dried to make hempcrete insulation. Credit... Preston Schlebusch for The New York Times

Yet federal regulators remain dubious, with virtually no domestic hemp production. It is legal to use it, but generally not to grow it. The farm bill passed last year began to allow for hemp-farming pilot projects, and while New York and Connecticut have both begun programs, no crops have been planted. At the moment, all raw material must be imported, and last year Canada alone shipped $600 million of hemp to American businesses.

A bigger hurdle may be getting hemp-lined homes past building inspectors.

“If you show them two-by-fours filled with fiberglass, they know what they’re dealing with,” said Tim Callahan, an architect in Asheville, N.C., “but you mention hemp, and they scratch their heads.” He has worked on about a dozen hempcrete structures, including what is thought to be the first home in this country to use hempcrete, built in 2010.