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: PERINSUL HL performs for the life of the building. Excellent dimensional stability means it does not degrade or shrink in situ.
    • Energy efficiency: significantly reduces heat loss through a hard-to-insulate thermal bridge.
    • Watertight: closed cell properties of cellular glass can be particularly beneficial when planning and detailing retrofit solutions.
    • Load-bearing: higher compressive strength than all other common insulation materials.
    • Healthy living: improves occupant comfort and removes the 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