Avoidable costs – What is full fill cavity insulation?

13 March 2019 Kingspan Insulation UK
Elm Road 1 - K106

The cavity wall is the most popular wall construction here in Britain, seeing widespread use in property construction from the 1920’s onwards[i]. In this blog, we will explain full fill cavity wall insulation and the potential benefits of opting for a fully filled cavity.

The basic principle of the cavity wall is two leaves separated by, what used to be, a clear cavity. The cavity helped to resist any moisture penetration into the inner leaf, as well as reducing heat transfer through the wall, leading to a warmer property. Kingspan Kooltherm K106 Cavity Board fills the cavity space, leaving a small 10 mm residual cavity to reduce moisture penetration risk and to allow space for material and workmanship tolerances. This is deemed as a fully filled cavity.

Kingspan Kooltherm K106 Cavity Board utilises a polypropylene fleece facing, which helps against moisture ingress. This facing, combined with a self-adhesive breathable tape applied to all horizontal and vertical board joints, allows the required gap to be 10 mm, opposed to typical partial fill cavity wall insulation, which on average requires a minimum gap of 50 mm. 

Through continued research, innovation and development, cavity wall insulation has now evolved so cavity wall constructions can be made thinner, whilst maintaining a high level of thermal performance.

With new lower lambda phenolic insulation, such as Kingspan’s Kooltherm K100 range, cavity walls can be made even thinner, providing excellent thermal performance and moisture resistance. In this case, these benefits can then be fully realised by the homeowner.


[i] http://www.energysavingtrust.org.uk/home-insulation/cavity-wall