A clear polythene coated version of our standard BS 1521, class A1F building paper. This is our traditional reinforced kraft paper bitumen-bonded building paper laminate used within the construction industry, which meets the requirements of the highest grade of BS 1521 materials. Polybit is a clear polythene coated version our A1F Standard Building Paper, typically used where conditions require additional strength and durability. Unlike many other recent developments in building membranes (eg breathable roof underlays), BS 1521 does not give guidance on suitable use, and as such this product is a generic material, serving a wide range of end-user defined applications. However, typical usage for Polybit has naturally evolved over time including for example, vapour checks, underlay on uninsulated cladding, flat lead-sheet underlay, timber floor DPM and heavy-duty temporary protection. Applications Typically used where conditions require a material with additional strength and durability such as a moisture barrier, underlays on uninsulated cladding, Temporary Protection, Separation Layers, Bond Breaks, Draught and Damp exclusion barriers. Propertes Length: 25m. Width: 1m. Roll size: 25m2. Upper temperature stability: over 70C. Liquid water resistance minimum: over 24 hours. Chemical resistance: resistant to chemicals found in plaster & cement. Biological: does not attract insects or vermin. Grade: A1F Polybit. Certification: BS 1521.