‘It’s almost carbon-negative’: how hemp became a surprise building material

Two guesthouses on Wally Farms, in upstate New York, have been made using hempcrete bricks and timber to reduce their carbon footprint. Photograph: Laszlo Kovacs

Cannabis sativa, the plant of the thousand and one molecules, has a long and expansive reputation – as a folk medicine, a source of textile fibre for clothes, for making rope or plugging holes in ships.

But now cannabis – or specifically its non-psychoactive variant, hemp – is being touted for something greater still: building blocks for housing that may avoid some of the environmental, logistic and economic downsides of concrete.