Every time we publish an article about Hempcrete, we get a lot of comments on social media - with a certain level of irony - about what would happen if the material caught fire. This is actually a legitimate question, as there is still a lot of confusion about the differences between marijuana and hemp, both of which come from the same plant species (Cannabis Sativa). But while marijuana has psychoactive effects due to tetrahydrocannabinol (THC), mainly present in the flowers of the plant, hemp-based building materials are produced from its stem, which contains small amounts of THC. To quickly answer the title question: no, the building won't be destroyed in the event of a fire. In fact, some tests have shown that these materials have excellent behavior against fire, dissipate flames, maintain structural integrity, and don't emit toxic smoke.
The use of hemp in civil construction is a fairly old practice and several studies have shown how beneficial this plant can be for the future of the industry. It is a material with a negative carbon footprint, meaning that it absorbs more carbon than it emits in its production and, at the end of its useful life, it can be returned to the environment, degrading naturally. In concrete mixers, hemp, powdered limestone and water are mixed to obtain a thick paste, which through chemical reactions petrifies and becomes a light but very resistant block. For wall construction, the mix can be laid out as non-structural blocks, sprayed, or poured into linear shapes, in the same way as mud walls. Hempcrete has excellent thermoacoustic properties, helps regulate indoor temperature and humidity, and is resistant to mold.
