The bituminous membranes are undoubtedly one of the most widely used technology for the waterproofing in positive thrust of roofing and foundation structures. Although they are characterized by a low cost and wide versatility, the bituminous membranes have problems that, in the long term, may even compromise the correct waterproofing effect of the sealing layer made with them.
Those membranes indeed, have a low and limited resistance to foot traffic, a very low elasticity (regardless of ambient temperature), an early deterioration in case of direct exposure to UV rays, also in function of their inevitable black color, which often causes an overheating of the insulation layer, with its resulting crack or even separation from the substrate below.
Considering that they are prefabricated materials, generally supplied in rolls, it becomes also problematic the treatment of critical areas such as vertical / horizontal joints and angles, expansion joints, or any eventual passers-by corps such as chimneys or vents exhaust ventilation: in all these cases the bitumen sheaths must be modeled, with an high risk, caused by the limited elasticity of the material, and with a considerable increase in working time.
A further problem with bituminous membranes is the high probability of making mistakes by of the applicator: during the so-called "torch" of the material is sufficient just one point where the sheath is not fully stretched and well settled to create a discontinuity of the insulating layer. Discontinuities that inevitably represent a possible point of access to water.
The bituminous membranes are also a particularly critical type of support if you want to cover them with different types of materials: the presence of oils and greases that characterizes the polymer matrix of membranes makes particularly difficult to achieve the proper anchoring bridge (both chemical and mechanical), especially if using materials such as acrylic or polyurethane resins. As a result, mostly in the restructuring projects, they should be removed entirely, forcing people to sustain costs arising from their proper disposal as a special waste category.