Single Ply Roofing

EPDM, TPO and PVC

Single-ply membranes are flexible sheets of compounded synthetic materials that are manufactured in a factory. There are three types of membranes: thermosets, thermoplastics, and modified bitumens. These materials provide strength, flexibility, and long-lasting durability. The advantages of pre-fabricated sheets are the consistency of the product quality, the versatility in their attachment methods, and therefore, their broader applicability. They are inherently flexible, used in a variety of attachment systems, and compounded for long lasting durability and watertight integrity for years of roof life.

PVC (CPA)

  • PVC – Polyvinyl Chloride – a thermoplastic membrane utilizing a reinforcement scrim between the two plies of equal thickness. Top ply contains Cool Roof pigments, UV stabilizers, and other components to extend the life of the membrane. Bottom ply contains PVC ingredients to provide consistent weld of top and bottom plies and fillers. Material Warranty Period: Up to 25 years Commercial / Lifetime Residential. PVC roof system life expectancy: 30+ years.

TPO

  • TPO – Thermo Plastic Olefin – a thermoplastic membrane utilizing a reinforcement scrim between the two plies. 35/65 % thickness for top & bottom ply respectively. Top ply contains Cool Roof pigments, UV stabilizers, and other components to extend the life of the membrane. Bottom ply contains TPO ingredients to provide consistent weld of top and bottom plies and fillers. Material Warranty Period: Up to 25 years. TPO roof system life expectancy – 22-30 years.

EPDM Rubber

  • EPDM Rubber – Ethylene Propylene Diene Monomer – a rubber-like black membrane, usually non-reinforced. Most common application method is a fully adhered (glued down) membrane with glued seams / flashings.
  • Material Warranty Period: Up to 40 years. EPDM roof system life expectancy 22-35 years. Although the material warranty goes up to 40 years for a 90-mil EPDM from some manufacturers, it does not cover the seams. Failing seams are the main cause of EPDM roof leaks followed by ponding water, for which EPDM has no warranty either.

Special Notes: EPDM is the least expensive single ply roofing type and requires no special equipment to install it (unlike PVC and TPO which require hot-air welding equipment) and thus is the first choice for roofing contractors entering the flat roofing market and asphalt shingle roofers who 'install rubber here and there'.

Thermoset Membranes

Thermoset membranes are compounded from rubber polymers. The most commonly used polymer is EPDM (often referred to as "rubber roofing"). Thermoset membranes make successful roofing materials because they can withstand the potentially damaging effects of sunlight and most common chemicals generally found on roofs. The easiest way to identify a thermoset membrane is by its seams – it requires the use of adhesive, either liquid or tape, to form a watertight seal at the overlaps.

Thermoplastic Membranes

Thermoplastic membranes are based on plastic polymers. The most common thermoplastic is PVC (polyvinyl chloride) which has been made flexible through the inclusion of certain ingredients called plasticizers. Thermoplastic membranes are identified by seams that are formed using either heat or chemical welding. These seams are as strong or stronger than the membrane itself. Most thermoplastic membranes are manufactured to include a reinforcement layer, usually polyester or fiberglass, which provides increased strength and dimensional stability.

There is a lot of confusion about single ply membrane roofing. Many Americans think any single ply membrane is the answer to their flat roofing problems. This however is far from being the truth. In reality, single-ply roofing membranes have only one thing in common – they are single ply or just one layer of membrane that is a water proofing barrier. The similarity stops there.

Single ply membrane formulation, or the components a membrane is made of, is what makes the difference between different types of single-ply flat roofing membranes. Single ply roofing membranes come in various widths, ranging from 6 to over 100 feet. In theory, the wider the membrane is, the less overlapping seam you have, thus reducing the possibility of leaks. The reality is different however, and most commonly used membranes do not exceed 10 feet in width for Thermoplastic membranes and 25'x50' for EPDM membranes.

The most crucial aspect to the reliability and longevity of single ply roofs is the method of attaching overlapping seams together. That is where 99% of flat roof leaks occur. Therefore having permanently attached seams, is the most important factor in the longevity of a flat roof installation. We will discuss it in more details as we review different single ply roofing technologies.

Single-ply membrane installation methods:

Single ply membranes are installed either as a fully adhered, mechanically attached or ballasted system depending on each roof's condition on other factors, as well as installer's preferences in some cases. Underneath the membrane there s usually a separation barrier and/or some sort of insulation board. Most common insulation is ISO or EPS foam board. Both types have an R-value ranging from 4-R to 6-R per 1 inch of insulation thickness.

Mechanically attached installation uses heavy duty screws and barbed plates to hold membrane down tightly, and is not affected by possible ISO de-lamination. Membrane is attached using 12" O.C. pattern with perimeter sheets attached 6" O.C. This ensures even the hurricane-type wind will not tear off your roof. Mechanically attached installation method does not require use of heavy and expensive ballast, and is a preferred choice if your building is located in the high-wind area such as along the coast line or on a high hill. This type of installation is very typical in the American roofing market.

Fully adhered single ply membranes are glued to the fiberglass sheet laminated to both sides of ISO insulation that in turn is attached to the roof deck. While quick and simple, fully adhered method has one serious disadvantage. If condensation forms underneath a roofing membrane, which often happens and may be cause by improper ventilation of the roof deck, it will 'de-laminate' ISO board and/or adhesive that is holding membrane in place. If membrane becomes loose, it is prone to a wind blow-off, which will leave your roof unprotected. Results of such blow-off will be catastrophic not only to your roof, but to the entire building. Many installations in American roofing applications are fully adhered EPDM and while there are many reputable contractors installing them, Roofed Right America is among the very best.

Three most common single-ply roofing types:

Today, single ply roofing became the prime choice when it comes to flat roof replacement. More and more roofing contractors are switching from old roofing types like BUR, Asphalt, and Tar & Gravel roofs to single-ply membrane installation, which is easier, safer and faster. Single ply roofing installation does not use the torching used in Modified Bitumen roofs installation, and therefore there is no fire hazard/possibility to burn down your home / business.

There are 3 most-used single ply membrane types present in the American market today: PVC/CPA, EPDM rubber and TPO. While these abbreviations probably won't tell you much, about these roof types, bellow we provide a brief summary of each of these technologies.

Contact American flat roof specialists for more information.

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