An EPDM roofing assembly can be designed to meet Underwriters Laboratories (UL) and Factory Mutual (FM) fire classifications. Like in many other roofing assemblies, the fire retardancy level will depend on roof slope and the various components utilized. Current UL and FM publications contain numerous listings of various approved assemblies.
EPDM membrane is manufactured in various thicknesses (.045″ to .090″ thick) and is available as a non-reinforced or reinforced sheet (depending upon application). Other thicknesses are also available for use in non-roofing applications as a special order.
Reinforced membranes contain an internal fabric that is completely encapsulated within the EPDM membrane sheet and is available in various thicknesses (.045″ to .075″). Occasionally, a fleece layer can be added to the underside of the sheet that serves as a built-in underlayment for direct re-roof applications over certain types of existing roofing material.
EPDM is also manufactured as vulcanized (cured) or non-vulcanized (uncured) membrane. Vulcanized membranes have set physical properties due to the vulcanization process and exhibit consistent behavior throughout the sheet that allow the membrane to have memory – this means when the membrane is stretched, it will return to its original state. On the other hand, non-vulcanized EPDM does not have set physical properties because it is not cured when manufactured. This makes the uncured material ideal for use as flashing where the material can be stretched, formed, and shaped.
Structural deflection, improper drain placement, or an insufficient number of drains can result in low areas on the roof that allow moisture to collect and pond over a period of time. Therefore, one of the most important characteristics of a roofing membrane is its moisture resistance. EPDM has excellent moisture absorption resistance that makes the material more tolerable to entrapped moisture than most roofing membranes. Since the early 60s, the material has been successfully used in canals, pond lining and other irrigation systems before its debut as a roofing membrane.
With many EPDM installations exceeding 40 years of exposure in the field under various climatic conditions, none of the material tested has shown alarming signs of degradation. Even though it would be difficult to predict, studies have shown aged EPDM membrane as having a potential life expectancy of 50 years.
EPDM is one of the most sustainable and environmental materials used today in the construction industry. Its excellent performance transfers to low life cycle costs and less impact on the environment.
The initial production of the membrane has a low embodied energy number (the amount of energy required to produce and implement a product from material extraction, manufacture, and installation). In addition several other components (such as cleaners, primers and adhesives) were developed for use with the EPDM membrane to reduce VOC (Volatile Organic Compounds) emissions during installation.
Post-industrial products can be reincorporated (recycled) into the manufacturing of other roofing products and accessories (i. e. , walkways and roofing tiles), thus minimizing the impact on landfills.
In laboratory testing EPDM is subject to the most severe heat aging where samples are subjected to temperatures of 240 F for 4 weeks. Also, in several studies field samples were collected from various geographic locations after years of exposure and in both cases (laboratory and field), the physical properties of the samples exceeded the original ASTM specification. Presently, there are numerous EPDM installations throughout colder regions in the U. S. (i. e. , Alaska, Minnesota) as well as in the hot and humid climates of southern Florida and Texas. For the past 25 years, EPDM has been the roofing membrane of choice for many commercial and manufacturing facilities internationally. The material will not shatter in extreme, cold temperatures and remains flexible under severe thermal shock such as in dessert areas where evenings are extremely cold and days extremely hot.
No. No special coating or other surface treatment is required. General maintenance in the form of good housekeeping should periodically be performed to remove debris and leaves, and to investigate the performance of other components.
In addition to the oils and the polymers used to make an EPDM membrane, another ingredient is added to the mix to enhance UV resistance. In the case of a black membrane, carbon black is added, which converts UV rays into heat. With white membrane, in lieu of carbon black, titanium dioxide is typically used to reflect UV rays and prevent it from attacking the polymer.
Sheets as large as 50 feet in width are produced mostly for use in ballasted and mechanically fastened applications. Narrower widths are also produced to offer applicators greater flexibility in positioning membrane.
Narrower sheets are also produced without factory seams (seamless) for use primarily in adhered and mechanically fastened applications. The major advantage of seamless material is the elimination of factory splice T-joints that occur when factory seams intersect with field splices. This reduction in T-joints significantly increases the potential for watertight performance by eliminating potential “water channels” into field splices.
Both narrow and wide sheets are manufactured in varying lengths from 50′ to 200′.
With over 1 billion square feet of membrane installed worldwide, EPDM has established itself as the membrane for all climatic conditions. This is supported by various laboratory studies and actual field installations. This excellent track record is the result of unique and unmatched physical characteristics: