USB Windtop UV is a dual layer heat sealed breathable membrane for walls. The polyester fabric backing has a special UV resistant polyurethane coating. This particular composition makes USB Windtop the ideal membrane for waterproofing and windproofing thermal cladding in ventilated walls in which the top covering has a discontinuous surface (slats, panels, planks, etc.) which allows the passage of light and UV rays through gaps. In order to guarantee a correct seal, the gaps in the discontinuous external coating should not be larger than 20 mm.