Insulating plaster – expanded glass and lime
Lime insulation is usually implemented in the form of a lime insulating plaster. Unfortunately, there are very few lime insulating plasters that can do without the addition of cement. The declaration of the ingredients is also often inadequate or misleading.
There is a lime insulating plaster without any cement for interiors: Hessler HP 9 SL (SL stands for super light). For exterior use, a lime insulating plaster needs added cement, as this is the only way to reach the strength required for an external plaster. For this reason, the Hessler insulating plaster for exteriors also contains a small proportion of white cement.
Layer by layer
With HP 9 SL the insulation thickness can be varied: any number of layers can be applied on top of each other. The thicker the layers, the longer final drying and hardening take. It is not advisable to apply more than 6 cm in one layer. The next layers should only be applied after drying.
Lightweight aggregate: HP 9 SL contains expanded glass as its lightweight aggregate.
Machine application: the expanded glass is pressure-resistant and stays intact when applied with a plastering machine, so the insulation value actually achieved matches the manufacturer’s data.
Further processing: HP 9 SL works as a single-coat plaster and can be floated the next day and then painted.
Hemp-lime
In addition to these insulating materials, there exists also the hemp-lime, which can be used as a prefabricated building elements (masonry blocks) for a timber frame or as loose fill between ceiling joists or behind formwork.
Kanop: insulating the top floor ceiling
For the top floor ceiling under an unconverted loft, hemp-lime is also available ready to pour: Kanop by IsoHemp, made of hemp shiv and a lime-based mineral binder (λD 0,054 W/(m·K)). It is poured between the joists by hand, without mixing and without a machine.
- at a fill height of 225 mm: R = 4 m²K/W, phase shift 14 h, weight 36 kg/m²
- fill heights 140–240 mm: R = 2,6–4,3 m²K/W (incl. Rsi and Rse)
- in lofts that are not walked on, Kanop can remain exposed; otherwise close with OSB boards
- before installation, have the permissible load of the ceiling checked by a qualified professional
