Until recently rolled roofing materials were the most popular. They attracted customers by their relatively low cost. Besides, this roofing material did not have many alternatives. The situation has changed with the appearance of heat hot roofing materials, liquid rubber and roofing bitumen.
Modern roofing materials have a more complicated structure, new types of base and are more elastic and cold-proof. Experts note that the so called “patch repair” of existing roofing can extend roof service life only for so long. Production of bitumen mix used as a base for roofing materials:
- is based on air blown bitumen;
- involves application of polymer additives.
The first case is characterized by instability to ultraviolet exposure and fast aging. In particular, we can note the reduced plasticity, excessive stiffness and brittleness. For the above reasons, materials based on air blown bitumen are predominantly used as the lower layer of roof coating. In other cases, protection from solar radiation is required. This can be achieved by application of special roofing sand. Application of air blown bitumen is feasible in places without large temperature variations. In this case it can serve up to 15 years.
Polymerized bitumens are classified according to the kind of polymer used. For roofing purposes the following polymers can be applied:
- isotactic polypropylene;
- atactic polypropylene;
- styrene butadiene styrene.
Isotactic polypropylene (IPP) is a plastomer of high density, high tear strength, cold resistance and good resistance to static loads. The main limitation to mass application of materials based on isotactic polypropylene in the roofing industry is their high cost.
Atactic polypropylene (APP) is also a plastomer produced from IPP. It inherits some properties of its predecessor: extended aging period, cold resistance, reliable adhesion to various surfaces.
Styrol butadiene styrol (SBS) is an elastomer adding increased elasticity and high cold resistance to roofing mixes. Beside these advantages, SBS can replicate the surface texture precisely. A mix produced on the basis of SBS is also known as artificial rubber or bituminous-rubber.
Beside impregnating, hot fusing material consist of a base, which is an equally important component. Most often this function is performed by fiberglass cloth, polyester fiber and fiberglass mats. Hybrid bases from polyester and fiberglass cloth are known to have been used also.
All polymer fibers have an important advantage over cardboard: they do not decay.
Fiberglass mats are made by chaotic placement of glass fibers fixed together by glue or by any other method. It has the lowest cost compared to other bases, due to the use of various byproducts in production. However, with the low cost fiberglass mats have a short lifespan. Compared with fibreglass mats, fiber glass cloth is 3-5 times more durable, although the durability comes at a cost.
Polyester – is the most expensive and convenient base, with increased durability and plasticity. It adsorbs grout compounds and ensures good adherence perfectly.