What is EPDM?
EPDM is derived from its inclusion of Ethylene, Propylene, Diene Monomer. EPDM is an elastomeric compound, which consists of oil-based by-products and other inclusions of modifiers and stabilizers. It was during the late 1960s that EPDM rubber roofing was first introduced as a roofing material. This formulation replaced the more labor intensive, Built-Up-Roofing (BUR) also known as Hot-Tar-and-Gravel Roofing.
The video below shows EPDM leaks due to adhesives failing to maintain bonding properties. Notice the ease with which the rubber cover tape is removed.
Thin EPDM Membranes on Commercial Flat Roofs
EPDM membranes are available in three thicknesses: 45 mil., 60 mil., and 90 mil. (the mil. refers to .001 or a thousandth of an inch). A membrane that’s 60 mil., would be 1/16th of an inch thick, and about equal to the thickness of a quarter. Most roofing contractors will install the 45 mil. membrane unbeknownst to their clients, however, a 45 mil. membrane is too thin and susceptible to tears and punctures.
Ultraviolet/Climate Degradation of EPDM
Regardless of its popularity, EPDM has a set of drawbacks as a roofing system. Field tests over 4 generations, have shown that no matter the thickness installed, the black color of the EPDM absorbs harmful UV rays. This causes adhesives to fail and the rubber to become brittle over time, providing only a 15 year time frame of protection.
EPDM Adhesives Fail
When any EPDM rubber membrane is fastened to a substrate, like plywood or insulation board, adhesives are applied with a roller. EPDM adhesives are also used for flashing rooftop units, such as, skylights, vents, drains, a/c units, extractor fans, stove pipes, and chimneys. These adhesives fail to maintain their bonding properties due to harmful UV rays. Adhesives are such an integral component of the entire roof system, yet, have failed time and again, even though new formulations have been introduced 5 times since the early 1970s. To date, there are no proven remedies.
Traffic on EPDM Flat Roofs
It is inevitable that flat roofs will have foot traffic for snow removal and from maintenance workers servicing air conditioners, vents, skylights and the like. Snow shovels can pierce the EPDM rubber and create gouges and gashes which may become leaks. Also, service workers drop and unintentionally leave behind screws, nails, and other sharp objects. When these sharp objects are stepped on, they will pierce the membrane and eventually cause leaks.
EPDM is not a Viable Commercial Roofing System
Many roofers believe in the overall practicality of an EPDM single-ply roof, but faulty installations and materials’ failures have resulted in damage causing the need for long-term, intermittent repairs. Installing a 2 Ply Modified Bitumen Torch Down Rubber Membrane on a commercial roof will offer a more durable, low maintenance, long-lasting solution.