What Is a Single Ply Roof?

Definition

• A single ply roof is covered in a single layer of a flexible membrane, typically thermoset or thermoplastic, according to A to Z Roofing. Thermoset membranes are created from rubber polymers and require an adhesive, such as tape or contact cement. Single ply roofs with thermoplastic membranes are hot-air welded, so they require no adhesive, and most are manufactured to include a reinforcement layer of polyester or fiberglass.

Types

• Single ply roofing systems made of thermoset are available with either unreinforced or reinforced membranes, with reinforced membranes offering less resistance to tearing. The most common type of thermoset membrane is EPDM (ethylene propylene diene monomer). This membrane is generally between 30 and 90 millimeters in thickness and is available in wide sheets for large roof areas. The two most common types of thermoplastic membranes are PVC, made from a combination of resin, stabilizers, pigments, fillers, plasticizers and biocides, and TPO, which is a blend of polypropylene plastic, ethylene propylene rubber, and/or ethylene propylene diene terpolymer rubber.

Installation

• There are two different methods for installing single ply roofing systems. One is to use fasteners, which will work on most types of roofs, including wood, metal and cement. According to Buildings.com, the manufacturers of single ply roofing systems will often recommend driving the fasteners through the insulating concrete and into the structural deck, particularly when lightweight insulating concrete, such as cementitious wood fiber or gypsum, is used. Another installation method is to use adhesives to glue the roof into place then use mechanical fasteners at the perimeters. This option is recommended for buildings in areas prone to high winds.

Advantages

• Single ply roofs have a reputation for being more environmentally-friendly than traditional roofs, and those with a thermoplastic membrane are particularly ideal for energy conservation. Single ply roofs may last up to 40 years and can be installed relatively quickly and at low cost. For construction companies, single ply roofs are an excellent choice as they require no heavy equipment and can be installed in any type of weather. Depending on the type of membrane and the manufacturer, single ply roofs may reduce the danger of fire and smoke pollution.