Selection of the right roofing system for new or existing construction

Selection of the right roofing system for new or existing construction is crucial to resisting the weather, like heat or cold and wind, fire performance, etc. The design of a roofing system varies depending on its functional requirements. Some materials used as roof coverings include tiles, asphalt shingles, slates, metal composite panels, and photovoltaic panels. In some systems, a deck, vapour barrier and insulation are incorporated. An insulated roofing system restricts undesirable heat loss and gain.


The CEN/TS 1187 is a test method in which a roofing system/assembly is exposed to an external fire source. With this test, the capacity of the system to restrict the spread of fire to its underside is evaluated. The test specimens are constructed as representative of the end-use application of the system. The tested sample includes the joints, type of materials, and material composition, including the thickness, density, and organic content similar to the product to be installed in the field.


Other than the designs and materials used, roofing systems also differ in terms of the pitch they are installed. Low-slope roofs, commonly called flat roofs, are installed on structures with a pitch less than or equal to ten degrees. This pitch is adequate to allow the flow of rainwater off the roof. Common types of flat roofing materials are polyvinyl chloride (PVC), ethylene propylene diene monomer (EPDM), modified bitumen and thermoplastic polyolefin (TPO).


Test method 4 of the CEN/TS 1187 standard allows for roofs to be tested horizontally (0°), at 45° and at specific angles other than 0° and 45°. A test conducted on a specimen mounted at 0° becomes applicable to roofs installed at a slope of 10° or lower. When tested at 45°, the test results apply to roofs installed at an incline between 10° and 70°. For a roof assembly tested at a specific angle, the results only apply to roofs installed at the tested angle.


The EN 13501-5 standard provides guidelines for the classification criteria for roofing systems tested according to the methods in CEN/TS 1187. For test 4, the class into which the tested specimen falls depends on its performance characteristics during the two stages of the test. A roof assembly that withstands radiant heat exposure for at least one hour with a flame spread less than 381 mm and a burning time of less than 5 min during stage 1 of the test is ranked highest as BROOF(t4).


The product parameters of a roofing system can influence the results derived from the roof tests. For instance, the thickness, density, type and position of joints, presence of air gaps and the mass per unit area are some factors that might affect the system’s fire performance. The CEN/TS 16459 guides the development of rules for the extended application of the test results.


An assumption shall not be made when addressing the influence of a given product parameter on the fire performance properties of the roofing system. Several tests can be conducted on variations of one product, with the rest of the components remaining the same. Out of this, a relationship between the two can be established.