Something about bitumen membranes
Bitumen membranes have been available in Europe for over 100 years and are manufactured by responsible companies, using high-tech methods, who are dedicated to providing environmentally safe and economically competitive products.
The idea of using a bitumen-like binder to coat roofing felts was first published in a paper of the Royal Swedish Academy of Sciences in 1784. By 1870, several types of machines existed to manufacture rolls of roofing felts around Europe.
This was the starting point for an enormous development of the roofing material based on bitumen binders. Today the use of polymer modified bitumen membranes for flat roofing is still the most common method for creating watertight flat roofs. All over Europe more than 60 % of all new flat roofs are covered with bituminous membranes.
A bituminous membrane is build out of a reinforcement (e.g. polyester nonwoven, glass grid or fleece, combination reinforcements (glass and polyester), metal foils (e.g. copper, aluminum)) coated on both sides by bitumen and surfaced with e.g. mineral granules, flakes of slate, sand or thin foils.
The bituminous membranes usually are soft applied to the roof by torching or hot air welding. Increasingly you can find also the cold application of the material by peel and stick. In former times the pour and roll technique was used, where liquid bitumen was poured on the roof substrate and the membrane was rolled into this bitumen. Nowadays this technique is becoming uncommon.
Bitumen membranes are products under the Construction Product Regulation (CPR) in Europe. Harmonized CEN Standards (hEN) exists for the characterization of the products, they are labeled with a CE-mark. Some special applications (e.g. mechanically fasted system) are covered by European Technical Assessments (ETA). Bitumen membranes are high quality products, they are produced under permanent factory production control, which has to be certified by an independent notified body.
The bitumen membranes could be installed as a single layer waterproofing and as well as a double layer system. Due to the chemical nature of bitumen, the maintenance of a bituminous roof could be carried out easily, since the new material will always be compatible with the installed membrane.