As the post title says, this may not be one of the most exciting looking materials but we think it’s pretty cool and can be used in a variety of different circumstances:

Essentially Calsitherm by Ecological Building Systems is a breathable insulation product used internally on buildings.

Calsitherm sample

We’ve used it in cottage restorations/refurbishments where external insulation wouldn’t be feasible; the link above gives more details but it’s key benefit is that the end product is breathable; this is particularly important on traditional stone cottages where dry lining internally with PIR (for example) would prohibit the breathability, leading to damp and mould buildup behind the insulation layer and wall disintegration during freeze/thaw cycles.

The conductivity of Calsitherm is not as good as more ‘modern’ materials such as EPS or PIR but it will improve the u-value of a stone wall by a factor of x3 (sample u-values of 400mm sandstone wall calculated by YT insulated with Calsitherm 0.79 W/m2K from 2.39 W/m2K. What you’re losing in Conductivity, you’re gaining in breathability.

We’ve also used it in a more modern scenario on a house that had retaining wall damp issues, once the water ingress was eliminated we dry-lined internally with Calsitherm (below) to

Plastered Calsitherm