Hemp fibre insulation is a growing category in green building. It offers thermal performance comparable to mineral wool or fibreglass while providing natural moisture management, sound absorption, and carbon storage benefits. The material is increasingly available in batt, panel, and loose-fill formats for building applications.
Types of hemp insulation
Hemp batt insulation
The most common format. Hemp fibres are bonded with non-petroleum binders (often other natural fibres, low-VOC adhesives, or bio-based resins) into rolls or pre-cut batts that install between wall studs, ceiling joists, and floor framing.
Hemp loose-fill insulation
Loose hemp fibres blown into wall cavities or attic spaces. Suits retrofits and non-uniform spaces. Lower density than batt insulation.
Hempcrete (technically not pure insulation)
A mixture of hemp hurd, lime binder, and water. Used as wall infill that provides both insulation and structural support. Covered in detail in the dedicated hempcrete article.
Hemp panels and boards
Rigid or semi-rigid panels of compressed hemp fibre. Used for ceiling tiles, wall panels, and other surface applications. Combines thermal insulation with acoustic absorption.
Thermal performance
| Insulation type | R-value per inch | Common installation depth |
|---|---|---|
| Hemp batt | R-3.5 to R-4.0 | 3.5" or 5.5" (2x4 or 2x6 walls) |
| Hemp loose-fill | R-3.0 to R-3.5 | 8-12" for attic |
| Hemp panels | R-3.5 to R-4.5 | 0.5-2" depending on application |
| Hempcrete (wall infill) | R-2.0 to R-2.5 | 10-12" typical wall thickness |
For comparison:
- Fibreglass batt: R-3.0 to R-4.0 per inch
- Mineral wool batt: R-3.7 to R-4.2 per inch
- Closed-cell spray foam: R-6.5 per inch
- Open-cell spray foam: R-3.5 per inch
- Cellulose: R-3.5 to R-3.7 per inch
Beyond R-value: what makes hemp insulation different
Moisture management
Hemp fibre is hygroscopic, it can absorb and release moisture without losing thermal performance. This helps regulate indoor humidity and prevents moisture problems in walls. Fibreglass and mineral wool can lose R-value when wet; hemp generally does not.
Indoor air quality
Hemp insulation is a natural material with no off-gassing concerns. Unlike formaldehyde-bonded fibreglass or polyurethane-based spray foams, hemp insulation does not emit volatile organic compounds (VOCs) into building air.
Sound absorption
Hemp's fibrous structure absorbs sound effectively. Sound transmission class (STC) ratings for hemp batt walls are comparable to mineral wool, typically STC 50-55 for a standard wall assembly with hemp batt.
Fire performance
Hemp insulation typically receives Class A or Class B fire ratings depending on the binder system used. Some products are treated with fire-retardant additives (borate-based) for enhanced fire resistance.
Pest resistance
Hemp insulation is naturally resistant to many common building pests. The fibres do not attract rodents or insects in the way cellulose or wood-based materials can.
End-of-life considerations
Hemp insulation is biodegradable and can be composted at the end of a building's life. This contrasts with fibreglass (landfill) or spray foam (difficult to remove and recycle).
Cost considerations
Hemp insulation costs more than conventional alternatives:
- Fibreglass batt: $0.50-$1.50 per sq ft installed
- Cellulose loose-fill: $1.00-$2.00 per sq ft installed
- Hemp batt: $3.00-$6.00 per sq ft installed
- Mineral wool: $1.50-$3.00 per sq ft installed
- Spray foam (closed-cell): $2.00-$4.00 per sq ft installed
The price premium reflects manufacturing scale (hemp insulation is a niche product) and importing costs (most hemp insulation in North America is imported from Europe). Domestic production capacity in Canada is growing but limited.
Applications for hemp insulation
- New residential construction targeting premium green building certifications
- Renovation of historic buildings (compatible with traditional wall assemblies)
- Health-sensitive environments (homes for chemically-sensitive individuals)
- Buildings prioritizing indoor air quality
- Net-zero and Passive House construction
- Areas with high humidity or moisture concerns
- Commercial buildings seeking carbon-storage credits
Building code considerations
Hemp insulation is not a standard listed material in most Canadian building codes. Projects using hemp insulation typically require:
- Engineered specifications
- Manufacturer fire and thermal performance data
- Sometimes alternative solutions documentation
- Inspector education about the material
Building permits with hemp insulation often take longer to approve than conventional construction, though this is improving as familiarity grows.
Canadian availability
Hemp insulation is sold in Canada by specialty green building suppliers. Most product is imported from European manufacturers (notably Nature Plus in Germany and Isohemp in Belgium). Domestic Canadian manufacturing of hemp insulation is small but emerging, primarily focused on Prairie facilities serving the western Canadian construction market.