For example, flexible tiles or ondulin are suitable for the winter roof only in theory. Since laying ondulin in conditions of minus temperature and it is simply impossible not to damage it because the installation of polymer-bitumen and bitumen materials is carried out with an unit of the lower layer, which allows you to glue it to the crate, and at minus temperature it will be very difficult. So there is a large risk of overheating, which provoke damage to the material, which will ultimately bring it into complete unsuitability.