Modified bitumen is commonly referred to as "torch-on" roofing. This is usually a 2-ply system incorporating a smooth surface base sheet and a torched-on or self-adhered, granulated cap sheet. Modified bitumen is a premium membrane designed to last 30+ years.
Single-Ply Elastomeric Systems
EPDM is typically a slate grey colour. Details and joints are sealed with contact-type adhesives and tapes. These are very economical systems and can be used effectively in a wide range of situations. EPDM membranes last in the range of 20+ years, but you can upgrade your system by using a thicker gauge or using a mesh reinforced option.
(PVC and TPO)
These systems come in a multitude of attractive colours and can be specified when esthetics of the membrane is a factor. You can have an energy-saving "green roof" when using a lighter colour of membrane because its reflective value increases during sunny summer days to reduce your cooling costs. Custom Roofing Inc. uses a heat welding process to seal joints and details. As with EPDM these membranes are effective approximately 20+ years.
Four-Ply Built-Up Roofing of Tar and Gravel
These membranes consist of several layers of felt and tar - asphalt - and usually are covered with an embedment of gravel. Built-up roofing has been used for centuries and still has a place in today's marketplace, but its cost and relatively low life expectancy - 15+ years - makes it less attractive to most building owners.