Hempcrete
Hemp hurd + lime binder — vapor-open, fire-resistant, and carbon-storing across the entire wall assembly.
Toxicity Screening — All Clear
This material screens clear across all seven independent toxicology authorities we use on every project.
Material Type
Plant-Based Composite Wall Fill
Material Description
Hempcrete is a bio-composite of hemp hurd (the woody inner core of the hemp stalk) and a lime-based binder, cast wet into formwork between framing members. The result is a structural-infill wall material that's vapor-open, fire-resistant, insulating, and a net carbon sink across its life cycle — hemp grows fast, sequesters CO₂, and the lime binder absorbs atmospheric CO₂ during cure. R-value is moderate (~R-2 per inch) but the assembly's thermal mass and humidity-buffering give it real-world comfort advantages that exceed what its raw R-value suggests. Hempcrete is non-load-bearing — it fills around timber framing or a separate structural system.
Composition & Origin
Health Profile — All Endpoints Clear
Severity scored 0–10 against the same 10 hazard endpoints we use for the chemical families on the avoid list. Every score is 1–2 — essentially no signal across every endpoint.
Common Forms & Brands
- Tradical / Lhoist hempcrete binder systems
- Just BioFiber pre-cast hempcrete blocks
- Hempitecture HempWool (related but distinct insulation product)
- Common framing: cast-in-place wall fill, pre-cast block, sprayed application
Why We Use It
- Net carbon sink across full life cycle
- Vapor-open assembly — exceptional moisture handling
- Fire-resistant — lime binder is non-combustible
- Termite, rodent, and mold resistant
- Repairable and recyclable end-of-life
Where It Performs Best
- Wall infill between timber framing members
- Pre-cast block exterior wall construction
- Roof and floor cavity fill applications
- Insulating retrofits of solid masonry walls
Building Applications for Hempcrete
Listed alphabetically. Where in a home this material earns its keep.
Cast-in-Place Wall Infill
Floor Slab Insulating Layer
Pre-Cast Hempcrete Block Walls
Retrofit Insulation of Stone Walls
Roof Cavity Fill
Sub-Slab Vertical Edge Insulation
Hempcrete on a Bay Area Home
Hempcrete earns its place in our assemblies. We design mold free homes by keeping water out and letting walls dry in both directions, and the materials have to cooperate with that — which is why this one is on the approved list and most of its competitors are not.
If you are planning a new house or a deep remodel and you want this level of material control, that is the whole job we do. Earth Bound Homes builds in Atherton, Palo Alto, Redwood City and across the San Francisco Bay Area.
Related materials we specify
- 70% Replacement Concrete
- Hexavalent Chromium-Free Metals
- Recycled Structural Steel
- Rice & Wheat Straw Panels