Hemp Fiber Insulation

Hemp-fiber insulation is a building insulation material made from the long [[hemp-bast-fiber|bast fibers]] of the hemp plant, processed into batts (pre-cut to fit standard stud cavities), rolls (continuous lengths), or loose-fill (blown-in). The hemp fibers may be processed alone or blended with small amounts (typically 10–20%) of recycled cotton, low-melt polyester, or other binding fibers that hold the batt together during installation.

Material properties

A non-exhaustive map:

• Thermal performance. R-value approximately R-3.5 to R-3.7 per inch — roughly comparable to fiberglass batt insulation and slightly better than cellulose. Performance is consistent across temperature and humidity ranges (unlike fiberglass, which loses R-value when wet).
• Moisture management. The principal performance advantage. [[hemp-bast-fiber|Hemp fiber]] is hygroscopic — it absorbs moisture into the fiber structure and releases it later without losing insulation value. In a wall assembly, this allows the wall to manage condensation events without producing the mold and rot that destroys fiberglass-insulated assemblies after sustained wetting.
• No off-gassing. Conventional fiberglass batts are bound with formaldehyde-based resins; spray foam off-gasses isocyanates and other VOCs; polystyrene off-gasses styrene. Hemp insulation has no such emissions.
• No skin/lung irritation. [[hemp-bast-fiber|Hemp fiber]] is large enough that it does not produce the airborne particulates that make fiberglass installation a respiratory hazard. Installers can handle it without respirators or protective clothing.
• Pest resistance. [[hemp-bast-fiber|Hemp fiber]] resists insects and rodents better than most natural insulations, attributed to lignin content and (in some manufacturers) borate treatment.
• Fire resistance. Hemp insulation chars rather than melts; properly tested products meet residential building-code fire-resistance requirements.
• Acoustic performance. The dense, fibrous structure provides substantially better sound attenuation than fiberglass; hemp insulation is preferred in interior walls where acoustic privacy matters.

Embodied carbon

The principal environmental advantage. The accounting:

• [[carbon-sequestration|Carbon sequestration]] during growth. A hectare of hemp absorbs approximately 8–15 tons of CO₂ during its 90–120 day growing season. Some fraction (typically 60–70%) of that carbon is locked into the bast fiber.
• Processing energy. Decortication, [[hemp-decortication|fiber separation]], and batt manufacturing require energy, but substantially less than fiberglass production (which requires melting silica at ~1,500°C).
• Transport. Domestic hemp insulation has substantially lower transport-carbon than imported fiberglass; this is one of the principal arguments for U.S. domestic production.
• End of life. Hemp insulation is biodegradable; can be composted or incinerated cleanly at end of life. Fiberglass, by contrast, is functionally permanent.

The net result: hemp insulation is typically carbon-negative across its life cycle (sequesters more carbon than its production releases), while fiberglass is substantially carbon-positive.

Installation

A few practical notes:

• Standard tools. Hemp batts cut with utility knives, install in standard stud cavities, fit standard 16” and 24” framing.
• Fit. Hemp batts are slightly stiffer than fiberglass; they hold their shape in cavities without sagging.
• No protective gear required. Installers can handle without gloves, respirators, or coveralls (though gloves are still recommended for general hand protection).
• Cost. Currently substantially more expensive than fiberglass — typically 2–4× per square foot of installed insulation. Cost is a function of supply-chain immaturity rather than fundamental material economics; volume scaling is expected to substantially close the gap.

Manufacturers

A non-exhaustive list:

• HempWool by [[hempitecture|Hempitecture]] (Idaho, USA) — the principal U.S. domestic producer.
• Thermo-Hanf by Hock GmbH (Germany) — long-running European producer.
• IsoHemp — Belgium-based; principally a hempcrete-block producer but also makes insulation.
• NatureFibre — various European brands.
• Several other European producers; the U.S. market remains thin.

What this gives the platform

Hemp-fiber insulation is the lowest-friction entry point for hemp building materials in conventional construction. A homeowner or builder considering hemp homes can install hemp insulation as part of a standard wood-frame project without changing the rest of the assembly. [[0mn1one|The platform]]‘s hemp-homes-101 product addresses this entry point; future product work will extend deeper into the hempcrete-and-beyond territory.

See also

Auto-generated from this entry’s typed relations: frontmatter, grouped by relation type so the editorial signal isn’t flattened.

• Subset of: [[hemp-bast-fiber]]
• Parallels: [[hempcrete]]
• Member of: [[ingredient]]

Sources

1. [[hempcrete|Hemp Lime]] Construction. Rachel Bevan & Tom Woolley. IHS BRE Press, 2008 (rev. 2017). Source class: book / definitive technical reference (covers insulation alongside hempcrete).
2. Hempitecture HempWool technical documentation. https://www.hempitecture.com. Source class: manufacturer / technical specifications.
3. [[us-hemp-building-association|U.S. Hemp Building Association]] — technical bulletins. Source class: institutional / continuing trade body.
4. Various life-cycle-analysis studies of hemp insulation vs. conventional alternatives. Source class: scholarly literature.

Lenses still to grow

• HempWool in detail as the principal U.S. product.
• Comparative LCA vs. fiberglass, mineral wool, cellulose, spray foam.
• Fire-resistance testing in detail.
• Building-code recognition — current status across jurisdictions.