Proponents of the material tout its non-toxic and mould, fire and infestation-resistant properties

by Edward Helmore

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.

The cement industry is responsible for about 8% of planet-warming carbon dioxide emissions, alongside problems created by unyielding surfaces and low insulation, or R-value, properties. The search for large-scale alternatives has so far yielded few results, but on a small scale there are intriguing possibilities, including the use of hemp mixed with lime to create low-carbon, more climate healthy building materials.