Single-Ply Membrane: Thermoplastic Olefin (TPO)
Single-ply sheet membranes are produced using one of three manufacturing processes: calendering, extruding or spread coating. The membranes may contain reinforcement layers. Common reinforcements for single ply membranes include polyester fabrics or scrims, glass fibre, or a felt or fleece backing.
A finished sheet’s thickness typically is referred to as mil thickness. Common mil thickness for these sheet membranes ranges from 30 mils to 60 mils. Single-ply membranes can be installed fully adhered, mechanically attached or held down with ballast. Most single-ply roof systems do not receive surfacing. In many instances, a combination of attachment methods is used to secure a roof system.
For instance, an insulation may be mechanically attached to the substrate with the roof membrane fully adhered to the insulation.
What is Thermoplastic Olefin (TPO)?
Another example of a Single-Ply Membrane is the thermoplastic TPO or PVC roofing system. These membranes can be repeatedly softened by heating or hardened when cooled. Because of the materials’ chemical nature, thermoplastic membranes typically are seamed by heat welding with hot air or solvent welding. The most common thermoplastic roof membranes are PVC and TPO.
TPO membranes are produced by calendering with lamination, extrusion with lamination, or extrusion-coating techniques. TPO sheets are a blend of polypropylene and ethylene propylene polymers and usually are reinforced with polyester. TPO sheets contain colourant, flame retardants, UV absorbers and other proprietary substances to achieve desired physical properties.
- Sheet widths range from 6 feet to 12 feet wide
- Sheets are typically 40 mils to 100 mils thick
- Seams are sealed by heat welded with hot air
- TPO membranes Commonly are white or black