Hemp-Light clay LLS 300, sound insulation

Sound insulation in timber-framed houses

This variant of hemp light clay weighs 300 kg per m³ and, owing to its greater mass, is intended for floor build-ups with enhanced sound insulation. Under floorboards or screeds, the loose fill can be used as impact sound insulation and levelling fill. The light clay is installed in layers no more than 7 cm thick and lightly compacted with a tool. During compaction the hemp shives lie flat, so that no voids remain. The substructure for the floorboards can then be laid on top, with the fill used to level the second layer of battens. The floorboards can be screwed directly to the floating substructure; the load is transferred across the entire surface onto the slightly resilient light clay. The feel underfoot on this build-up is very soft and pleasant.

Impact sound and thermal mass

In a timber-framed house, LLS 300 from Hanffaser Uckermark is ideal for creating a shallow floor build-up with a high level of sound insulation. The light clay is spread over the clay-wrapped staves of the ceiling, and the battens for the floorboards are bedded in the light clay alongside the ceiling joists. The light clay is then filled up to the top edge of the battens. The load is distributed over the entire surface, and sound is no longer transmitted directly via a ceiling joist, as the floorboards and ceiling joists are not in direct contact. The key prerequisite here is the stability of the clay ceiling, which must always be checked. The reduction in impact sound is achieved not by the fill material but solely by the decoupling. Impact sound insulation systems must always be installed as floating systems, which means that the LLS 300 is compacted and the floor build-up is then constructed on the fill without any connection to the substructure.

With floor build-ups using LLS 300, please note that the insulation will settle slightly during the initial period. Skirting boards should therefore be fitted at a later stage, and the entire build-up should be constructed approximately 5 % higher than the intended final level. Once all voids have been compacted after the initial phase, the material does not settle any further, and no further abrasion of the material, with the associated settlement of the build-up, takes place.