Hempcrete is a bio-composite building material made from hemp hurd (the woody core of the hemp stalk) mixed with a lime-based binder and water. It's used as a cast or sprayed wall infill around a structural frame — not as a standalone structural material.
How it's made
- Hemp stalks are processed to separate the woody hurd from the outer fiber.
- The hurd is mixed with a lime-based binder and water to form a thick paste.
- The mix is placed into formwork around a frame, or sprayed directly onto it.
- It cures over several weeks, hardening while remaining breathable.
How it's used
Hempcrete is most commonly used as wall infill in timber-framed buildings, providing insulation and thermal mass while letting walls breathe and manage moisture.
Hempcrete vs. traditional insulation
Unlike many synthetic insulation materials, hempcrete is vapor-permeable, meaning walls can release moisture rather than trap it.
Is hempcrete right for your build?
Hempcrete works best with a timber or other structural frame, in builds where breathability and thermal mass matter.
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FAQ
Is hempcrete the same as hemp insulation?
Related but not identical: hempcrete is a cast or sprayed wall material, while hemp insulation is typically a batt or loose-fill product. Both use hemp hurd and fiber.
Is hempcrete fireproof?
We won't call it fireproof without a source to back that up. What we can say is that lime-based materials are not combustible in the way wood framing is.
Is hempcrete legal to build with in the US?
Yes. Industrial hemp materials are federally legal, though local building codes vary, so check with your local building department.
Does hempcrete contain THC?
No. Hempcrete is made from the woody hurd (core) of the hemp stalk, not the flower, and contains no meaningful THC.