Single Ply roof systems are generally those that are factory fabricated and installed in the field as a single layer. Single ply roofing systems come on a roll and can be loose-laid, adhered, or mechanically attached to the substrate. The laps of these systems are heat or chemically welded or glued together with an adhesive. Single ply roofing systems offer ease of installation, lighter weight, and usually a lower cost because of labor installation savings. Some of the concerns are puncture resistance, ponding water, delamination, and chemical resistance. The following are the major categories of single ply systems available today.
Types of single ply
- TPO – (Thermoplastic Polyolefin) Advantages include bitumen and polystyrene compatibility, very good low temperature flexibility, excellent puncture resistance, and increased welding rates. TPO is the fastest growing product type in the roofing industry.
- EPDM – (Ethylene Propylene Diene Monomer) is a membrane that is essentially rubber with an additive to provide tensile strength. In the case of black EPDM the major additive is carbon black. Black EPDM is one of the least expensive roofing systems to manufacture and install, and thus accounts for one half of the single ply industry. The EPDM membrane is available in very large sheets; therefore the quick covering of large roof areas is possible. EPDM membrane is available in several thicknesses and optionally reinforced with a polyester scrim. EPDM cures after weathering and requires cleaning and priming before repairs are possible.
- PVC – (Polyvinyl Chloride) is a membrane that is thermoplastic material that is available in a variety of thicknesses and optional reinforcements. Like most single ply systems, the material can be formed into many shapes and conditions using heat and adhesives. PVC membranes are prone to plasticizer migration and should be monitored.
Advantages of single ply roof systems
- Offering cool roof savings
- No fumes or odors from asphalt
- Find a variety of colors (limited to material)
- Easy to cut pre-fit areas to patch and repair
- Less expensive than most other roof systems
Disadvantages of single ply roof systems
- Can be punctured with heavy traffic
- Installation of flashing detail is very important
- May shrink if not properly installed
- Weight (ballast system)
- Seams and laps can separate if not cleaned properly