Built-up Roof Systems
This roofing system, which has been used for almost 150 years, makes use of multiple plies of reinforcing felts laid shingle fashion into continuous moppings of hot asphalt . The system is then covered with aggregate set in an asphalt flood coat or surface coatings . The plies can consist of organic membranes or glass fiber membranes .

EPDM Roof Systems
This roofing system is also known as single ply. This is primarily synthetic single-layer sheets of ethylene propylene diene monomer . EPDM systems can be installed using a variety of means, including - loose laid and ballasted, fully adhered, or mechanically attached .

PVC Roof Systems
This roofing system is basically the same as the EPDM system except the synthetic single ply sheets are made of polyvinyl chloride . As with the EPDM membrane, the PVC membrane can be installed using a variety of means including loose laid and ballasted, fully adhered, or mechanically attached .

Modified Roof Systems
This roofing system uses modified bitumen membranes which are factory rolled products with rubberized or polymeric asphalt applied to one side at the factory. It can be installed by mopping on hot asphalt to adhere the membrane to the roof, or more commonly by using a propane torch to heat the underside of the coating. This turns it into a near - liquid and the membrane is then rolled onto the roof in a continuous operation.

Each of the above flat roof systems is normally applied in conjunction with a variety of insulations and vapour retarders, the insulation type dependent on the R-value desired, the type of roof deck, the type of roof system used, the amount of traffic on the roof and cost considerations. Insulations are installed loose laid, with adhesives or mechanically fastened.