Hybrid Oversill & Window Sills

Our Hybrid oversill and window sill products are designed to work with any construction type, and are installed in the same way as a traditional concrete sill.

Originally designed with large-scale developments in mind, our Hybrid products have become increasingly popular across our customer base, from large developers to self-builders. 

We believe the Passive Sills Hybrid oversill and window sill products signals the future of lightweight, thermally efficient sills, offering increased durability thanks to our acrylic resin render, which is finished with a spray coating of our Passive Sills custom flexi coat. The hybrid sill does not require any sealant and can be painted. Our hybrid sills and oversills are available in a primed, white paint finish.

As an extra water ingress prevention measure we advise applying extended upstands to our hybrid sills, especially when being used for ICF builds. Extended upstands prevent driving rain penetrating behind the sill.

The Hybrid sill’s excellent insulation value improves the overall performance of your windows by reducing the cold bridging at this point. 

Passive Sills windowsills are approximately 10% of the weight of a traditional concrete or stone sill and reduce the risk of manual handling injuries on site.

Why choose a Hybrid Sill?

More Durable


Quick & Easy Installation

64% more thermally efficient than concrete

Lower carbon footprint

No telescopic loader required

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