There are two types of roofs that commercial and residential buildings use: pitched roofs and flat roofs. Each of these types of roofs needs specific types of roofing material with very few overlaps. Pitched roofs are normally used on residential housing and on commercial buildings when built in a very rainy or snowy climate so that the precipitation flows off of the roof rather than sitting and forming puddles that can cause damage like on flat roofs. The main overlaps in roofing material for these two styles of roofs are metal and rubber roofing material.
Types of Materials
There are several different types of flat roofing materials available on the market today. The first type is tar and gravel styles of roofs. These can be used on roofs that are considered flat, which means there is less than three inches rise to twelve inches of run. This slight amount of rise allows water to run to the sides of the roofs where there is a drainage system to remove it rather than forming puddles, as would happen if the roof was completely flat.
Tar and gravel flat roofing material is a built-up roof, where the roofing contractor lays down three to five layers of saturated felt material, slathering it with tar and asphalt in between each layer. When the top layer is reached, it is topped with a mineral and rock mixture to allow for walking across the roof and also more protection from the elements. This type of roof is very inexpensive, but it is also very messy, does not last more than fifteen years on average, and is not for high rain or snow types of climates.
Modified bitumen is a similar flat roofing material, which layers polyester or fiberglass rather than saturated felt, and also uses bitumen rather than tar and asphalt. This also is a low cost flat roofing material, but it does not last long either and is not for high raid or snow climates. Roll roofing material is the cheapest and is applied in a single layer, so that it is not messy like the other two, but since it is only a single layer, it only lasts about ten years.
More lasting flat roofing material is ethylene propylene diene monomer or EPDM which is a rubber roofing material. This type of material is also applied in a single layer, but it is much better in high winds or hail than the tar and gravel or modified bitumen roofs. It also has a longer life, usually lasting at least twenty years and is UV resistant, which helps with the air conditioning bill in the summer.