There are over a hundred manufacturers of single-ply roofing materials. These materials fall into one of three general categories; namely, uncured elastomer’s, cured elastomer’s and thermoplastics. The one property they all have in common is that waterproofing the roof is achieved by the application of one layer (or ply) of membrane material. This can be contrasted to traditional built-up roofing (BUR) that requires multiple overlapped layers of roofing felt and asphalt to achieve a waterproof membrane.
Single-ply systems are generally more elastic and flexible than other materials and are therefore more forgiving of roof and building movement – a frequent cause of splitting in other roofing systems.