The slate in bitumen hydro insulation has a purpose to reinforce them. It has an impact on membrane`s mechanical performance as well as their behavior during the installation depending on the application technique, base and temperature. It also has an impact on various physical-construction values such as SD-value and performance of the roof structure during fire from outside. The most common are reinforcement from fiberglass, fiberglass fabric and polyester wool.

Fiberglass reinforcement provides shape and dimensional stability of the membrane and has impact on performance during fire. The fiberglass fabric reinforcement not only stabilizes the shape and dimensions of the membrane but also increases its strength, resistance to tearing and puncture. It prevents further tear of hydro insulation membrane even when the membrane already has cuts, holes. It also increases the fireproofing properties of the membrane. Reinforcement with polyester increases strength and expansibility of the bitumen hydro insulation. It increases the resistance to tear puncture.