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§6.4).[2]
