Commercial and residential buildings can have two types of roofs: pitched or flat. These two different types of roofs use, for the most part, different roofing materials. Pitched roofs are more common in areas with harsher weather, such as heavy snow or rain, as they prevent water or snow building up on the roof, as would happen with a flat roof. Rubber and metal roofing materials are the main materials that can be sued on either flat or pitched roofs.
Types of Materials
Flat roofs can use many different types of roofing material, and are identifiable by the fact that they have a small rise of around 7 centimetres leading to a run of around 30 centimetres which allows water to flow to the edges of the roof and stops it pooling in the middle. The benefit of this design is that it can help prevent water damage and leaks. The small slope lets water run off the roof into the gutter. Tar and gravel are two of the materials which can be used on roofs such as this.
Tar and gravel roofs are built up with interspersed layers of saturated felt and tar or asphalt, and then topped off with a mixture of mineral and rock. This gives the rood a higher weather resistance and allows you to walk on it more easily. They are, however, quite messy to install because each layer of the roof is held together by the tar or bitumen. These can last for around fifteen years, and are very cheap, but are not recommended for high rain or heavy snow areas.
Modified bitumen is a similar material. Here the layers are made of polyester or fibreglass instead of felt, with bitumen rather than tar in between. Like tar and gravel, it is cheap to buy, but is not good for harsh weather climates. Roll roofing material is another common, economical material which can be used on flat roofs. Roll roofing has a short life span of only around ten years because it only has one layer. It is however, easier and neater to install because it is only made of an asphalt shingle mat.
EPDM (ethylene propylene diene monomer) is a rubber material which can also be used on flat roofs. It is simple to install because it is also laid in a single layer over a stiff insulation mat, and is more resistant to wind, rain, and snow than tar, gravel, or bitumen. Rubber will last much longer than tar, gravel, or bitumen, and can give a limited level of UV protection. In hotter climates, this can help in lowering energy costs for air conditioning.