Many new solutions for flat roofs use polymer-asphalt self-adhesive roofing felt, put on hard, non-absorbent thermal insulation boards. The main advantage of these roofing papers is the vapor permeability that diffuses from the inside of the flat roof to the outside. Another advantage is the possibility of using a single-layer roof covering, a protective layer is applied under the sealed rubber membrane, if required by the substrate, and the felt paper is not covered with a non-woven plastic fabric on the underside. In practice, two types of heat-sealing membranes made of modified asphalt are used, the so-called. APP-atactic polypropylene modified with plastomers and SBS-styrene-butadiene-styrene modified with elastomers. Polyester fibers and polyvinyl fibers are also worthy of attention as reinforcement inserts for heat-sealable roofing paper., guaranteeing their high puncture and tear resistance.

Parameters that characterize a given type of heat-sealable roofing paper are: type of modifier, type of warp (non-woven mesh, plastic fabric), thickness (3-5,5 mm), breaking force, elongation at break in [N] and the scope of flexibility in [%]. Among the covering materials made of plastics, EPDM elastomer membranes are increasingly used, i.e. ethylene-propylene-diene terpolymer and plasticized PVC films reinforced with polyester or glass fiber.

Separating and protective materials
Separating and leveling layers should transfer the stresses from elongation and contraction of the base materials or the load-bearing structure caused by the influence of temperatures and the external climate. The separating materials also perform the function of leveling the roughness of the substrate and protect the surface layers against the chemical effects of the lower layers of the flat roof..
The arrangement of the release layer can be performed as follows: loose arrangement without gluing, strip gluing, point or all-over. The following materials are used to make the separating and protective layer: perforated bitumen sheets, non-woven fabrics of plastics, foam mats, polyethylene films. Separating layer, between the supporting structure of the flat roof and thermal insulation, it is also a vapor barrier.