6.2 Insulating mats for the construction industry (fibres)

The hemp bast fibre can be processed into a mat, eventually bound with a small amount of plastic fibre. For fire retardancy, some soda (an additive also permitted in food) is added.^[1] Hemp fibre is mixed with finer jute fibres to improve the insulation value.

The density of such mats is approx. 35 – 40 kg/m³. The insulation value lambda is approx. 0.04 W/m.K, comparable to insulation materials made of flax, cotton, wood fibre, or cellulose pulp.

A fibre mat can also be 'bonded' by so-called needling of the fibre mat. The density of such mats is higher, approx. 130 - 175 kg/m³. These mats are suitable for sound insulation under floating floors and as a growth substrate for horticulture (§6.4).^[2]

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Hemp-based fibre mat for thermal insulation of buildings.

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Hemp-based fibre mat for sound insulation, e.g. under floating floors. Photos Thermo-Hanf.

[1] https://www.thermo-hanf.de/en/products/thermo-hemp-combi-jute-insulation-mat/

[2] https://www.thermo-hanf.de/en/products/building-materials/thermo-hemp-footfall-sound-insulation/