Hempcrete & construction
How does hempcrete compare to concrete?
Direct answer
Concrete is a high-strength structural material (often 20–40 MPa); hempcrete is a low-density insulation/enclosure material (~0.5–1 MPa). They solve different problems and are often used together — frame + hempcrete infill vs. load-bearing concrete walls.
Key numbers at a glance
Hempcrete strength
~0.5–1 MPa
Enclosure
Concrete strength
~20–40 MPa
Structural
Hempcrete density
~300–500 kg/m³
Insulating
Concrete density
~2,300 kg/m³
Mass structure
Roles in a building
Reinforced concrete carries compressive and tensile loads in foundations, columns, and slabs. Hempcrete fills wall panels between studs or around a timber post-and-beam frame, providing thermal resistance and hygrothermal buffering.
Performance contrast
- Structure: Concrete yes; hempcrete no (standard mixes).
- Insulation: Concrete poor; hempcrete good (~2.5–3.5 R/inch typical).
- Vapor: Concrete relatively closed; hempcrete vapor-open when finished correctly.
- Carbon: Concrete cement is CO₂-intensive; hempcrete stores biogenic carbon in hurd and recarbonates lime — but LCAs must include binders and transport.
- Fire: Both behave differently — hempcrete chars; concrete spalls under extreme heat but is non-combustible.
Marketing that pits hempcrete “against” concrete as a universal replacement mis-specifies the product. Compare it to insulated wall assemblies, not to footings.