Dallas Roofing: Article About TPO and PVC Roofs
Business owners and companies have several roofing options to consider when they construct new buildings or replace existing coverings. Since a majority of these buildings have roofs with little to no slopes, a roof membrane is the most logical choice. One option that they have in the single ply classification of roof membranes is a thermoplastic membrane, the most common types of which are TPO and PVC. Before a business hires a Dallas roofing company for its TPO or PVC roof installation, it should know what these types of membranes are and how they are different.
Thermoplastic membranes are roofing materials that can soften and harden repeatedly when they are heated and cooled. Due to their chemical nature, the seams of the materials are usually welded together with a solvent or via the application of hot air. There are several categories of thermoplastic membranes, but TPO and PVC are the most commonly used for commercial roofing.
TPO stands for thermoplastic olefin, and PVC stands for polyvinyl chloride. There are several similarities between these two materials, including that they both are highly fire resistant and typically white or light gray. TPO and PVC roof membranes are also Energy Star rated as "cool" because of their reflective and energy saving properties. Additionally, both types can be installed ballasted, fully adhered or mechanically attached.
Although there are a few differences between TPO and PVC membranes, the biggest difference is their compositions.
The expert roofers at Total Roofing of Dallas can assist you with any questions regarding roof maintenance or residential roofing.
TPO membranes are a blend of ethylene propylene and polypropylene polymers, and these chemicals are often reinforced with polyester. They are generally manufactured in sheets through extrusion coating, extrusion with lamination or calendering with lamination. The sheets also contain colorants, flame retardants, UV inhibitors and other materials to make them flexible and resistant to the elements. Other additives may be introduced to obtain certain physical properties.
PVC membranes are a blend of chlorine, which is derived from salt, and ethylene, which is processed from natural gas or petroleum. They, too, are manufactured into sheets, but the process may involve calendering, extrusion or spread coating. The composition is usually reinforced with glass fiber mats or polyester. To impart flexibility, durability and other physical properties, manufacturers add biocides, plasticizers, stabilizers and UV inhibitors. Some PVC sheets have a nonwoven fleece backing on the underside as well.
The different compositions also make the sizes of TPO and PVC membranes different. While both range in width from six to twelve feet, TPO sheets are usually 40 to 100 thousandths of an inch thick, but PVC sheets are usually 45 to 90 thousandths of an inch thick. Unlike TPO, PVC is available in a range of colors, and it's the more expensive of the two.