Insulation for under window & door sills


Doors and windows form part of a building’s thermal envelope. Positioning them within their openings to achieve continuity of insulation can be a detailing challenge, making it more likely that the edges of the opening act as a thermal bridge - particularly at ground level below a door or full-height window.


Where doors and windows do not line up with surrounding wall insulation, masonry can allow heat energy to bypass the thermal envelope. Providing sufficient insulation where a floor screed or slab meets a door or window cill is difficult - especially where level access requirements through a doorway mean there is no step into the building. As a load-bearing insulation element, PERINSUL HL is the perfect solution to the thermal bridge.

Downloadable documents

      system characteristics

      • Proven concept: ‘time-tested’ thermal performance, so declared thermal conductivity remains the same for the life of the building.
      • Energy efficiency: provides a thermal break between the wall and foundation, maintaining continuity of the ground floor insulation.
      • Load-bearing: “insulation that thinks it’s a brick” can be coursed in with existing masonry at the right level to suit the floor insulation.
      • Healthy living: consistent, comfortable surface temperature across the whole wall surface, removing cold spots and reducing risk of surface condensation and mould growth.


      how to install perinsul hl

      under window and door sills

      legal notice

      about PERINSUL products

      The information relating to the products and systems contained on this website is provided in good faith and for general information purpose only. Such information is in any event subject to our product’s legal notice, the content of which users are invited to acknowledge under the following link: Legal Notice