Hempcrete is a bio-based building material made from hemp hurd (the woody inner core of the hemp stalk), a lime-based binder, and water. It's used as insulation, wall infill, and plaster in residential and commercial construction.
Unlike synthetic insulation like spray foam or fiberglass, hempcrete is carbon-negative — it absorbs more CO2 during its lifecycle than it produces. It's naturally fire-resistant, mold-proof, and improves indoor air quality by regulating humidity and absorbing pollutants.
How Hempcrete Is Made
Traditional hempcrete combines three ingredients:
- Hemp hurd — the chopped woody core of industrial hemp stalks, providing structure and insulating air pockets
- Lime binder — natural hydraulic lime (NHL) or hydrated lime that hardens through carbonation, creating a breathable mineral matrix
- Water — activates the lime and allows mixing
GaiaCrete® by Mr Hemp House™ enhances this formula with volcanic ash pozzolans, rice husk ash, and beneficial mycelium — creating a stronger, faster-curing material with superior antimicrobial properties (pH 12+, where mold cannot survive).
Hempcrete R-Value
Hempcrete provides R-2.0 to R-3.7 per inch depending on density and formulation:
- Light mix (wall infill): R-2.0 to R-2.5 per inch
- Standard mix: R-2.5 to R-3.0 per inch
- Dense mix (GaiaCrete®): R-3.0 to R-3.7 per inch
A standard 12-inch hempcrete wall achieves R-24 to R-44. But R-value alone doesn't tell the full story — hempcrete's thermal mass stores and releases heat slowly, reducing temperature swings and HVAC cycling. Many homeowners report needing 30-50% less heating and cooling.
How Much Does Hempcrete Cost?
Hempcrete pricing in 2026:
- Materials only: $4-8 per square foot
- Installed: $8-15 per square foot
- Full wall system (including framing): $15-25 per square foot
Compared to fiberglass at $0.30-$1.50/sq ft, hempcrete costs more upfront. But when you factor in:
- Zero mold remediation costs (hempcrete is permanently mold-proof)
- No replacement needed (100+ year lifespan vs 20-30 years for fiberglass)
- 30-50% lower HVAC costs from thermal mass performance
- No health-related costs from VOC exposure
Hempcrete's 30-year total cost is typically lower than fiberglass.