In the UK most of our roofs are covered in multi layered mineral felts or asphalt.
The main reason for this is that although they are still very efficient they are cheaper and easier to instal rather than the single ply membranes.
Single ply membrane is normally made from various combinations of man made synthetic materials. They were first created in Germany but are now used worldwide.
These products have to be installed by only fully trained tradesmen, we only use people who have been trained with the individual products which are requested.
We can explain more about these various products on request.