Regulators finally approve hempcrete for US homes

That’s why this environmentally friendly building material rocks.

Last month, the International Code Council (ICC) approved hempcrete — a mixture of the woody innards of hemp stalks and lime — as an acceptable material for paving in US homes.

Credit for the change comes from the US Hemp Building Association (USHBA), which submitted a proposal for and championed the policy in January.

While hempcrete has already found a large audience in Europe, it can finally help Americans find a pragmatic and eco-friendly solution for insulating their homes. The new directive applies to single-family houses, two-family houses and terraced houses.

“As an architect, it is paramount to include hemplime in the building code,” Pennsylvania-based architect Ana Konopitskaya, who helped write the USHBA application, told HempBuild Magazine, which broke the news. “It will allow architects like me who are focused on sustainability to specify this product in every community in the US,” she added.

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What is hempcrete?

Before we get too far ahead of ourselves, let’s take a minute to talk about the material itself.

Hempcrete – also known as hemplime – contains a mixture of lime and hemp stalk shives. Also known as “shiv,” Hurd refers to the woody innards of the hemp stalk. Wood chips have a consistency similar to wood chips.

The recipe for making hempcrete is very simple: mix four parts hemp stalk shards with one part lime binder. Then add part of water. From there, the hempcrete is typically formed into bricks.

Why do many people consider it environmentally friendly?

Hempcrete has quickly gained a reputation for being much more environmentally friendly than traditional concrete structures. Here’s why:

• Hempcrete is considered carbon negative because the hemp plant absorbs more carbon during its growth than hempcrete processing emits.

Hempcrete offers a sunny spot in the larger conversation about cannabis’ carbon footprint: Indoor growing operations require massive amounts of energy, particularly to power sodium lamps and HVAC needs.

What other advantages does hempcrete offer?

The benefits of hempcrete go beyond its environmental appeal.

As Leafly pointed out back in 2015, it’s “non-toxic, airtight yet breathable, unaffected by mold and pests, and virtually fireproof.”

Finally, hempcrete facilitates moisture control: it absorbs and releases moisture in the air.

What’s next for hempcrete?

The new hempcrete directive for private households will come into force from 2023.

Proponents may next consider allowing hempcrete for larger residential and commercial buildings. This decision would be governed by the separate International Building Code (IBC). Proposals to amend the IBC can be made every three years and the hempcrete industry will next have the opportunity to propose an amendment to this code in 2025.