Flat roofs aren’t as flat as they are thought to be. The have really low roof slopes. They are used especially on tall buildings because of the high speed winds.
The material is usually organic or fiberglass felt that is saturated in asphalt. The problem with this type of coating is that it’s very vulnerable to wind, even low speed ones. That is why the coating needs to be applied perfectly. It can be glued with cold asphalt cement or nailed it the roof’s substrate is made of wood. It can also be covered by gravel.
This coating is made from plastics like thermoplastic polyolifin or polyvinyl chloride. They have great reflective properties and that is why they are usually used in warmed climates. Another reflective material is the ethylene propylene dience monomer. Also rubberizes asphalt is a single-ply system. These coatings can be glued to the roofs by adhesive such as hot asphalt, or self-adhering sheets.
Built up roofs
This is one of the most common flat-roof systems. They are very durable and cheap, that’s why they are so very used. They consists of multiple layers of felt and asphalt. They can also be covered with gravel.
These are actually bituminous membranes, only that they are slightly modified. They are a blend or asphalt and polymers, appearing to be single-ply systems.
These systems can be used for flat roofs and for pitched roofs as well. They are made from thin sheets of metal, like copper, stainless steel, lead-coated copper. The sheets are soldered at the edges to prevent moisture penetration. They are highly used because of their aesthetic qualities.