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What is EPDM and what does it look like?

EPDM is an elastomeric compound that is manufactured from ethylene, propylene, and a small amount of diene monomer. The combination of these ingredients produces a product that is able to withstand ultraviolet light, weathering and abrasion, and extremely low temperatures. The ingredients used in EPDM are also resistant to acids, alkalis, and oxygenated solvents. In regards to appearance, black EPDM has a smooth surface similar to natural gray slate. It doesn’t contain the surface granules that can eventually be lost on other materials.

What is the difference between black EPDM and white EPDM?

The black EPDM contains carbon black, an ingredient that is added to enhance UV resistance. Titanium dioxide is used for the white membranes to achieve the same results.

What is the maximum size sheet for EPDM membrane?

Sheets as large as 50 feet in width are available but are mostly used in ballasted and mechanically fastened applications. The narrower widths are used for greater flexibility in membrane installation. Another benefit of narrower sheets is that they are produced without factory seams (seamless). This eliminates the T-joints that occur when seams intersect with field splices. The lack of T-joints obviously makes your roof significantly more water-tight and helps prevent leaks. Both narrow and wide sheets are manufactured in varying lengths from 50' to 200'.

How has EPDM performed since its introduction into roofing in the 1960’s and what is its expected longevity?

Over 1 billion square feet of membrane have been installed worldwide, and various laboratory studies and actual field installations have proven that EPDM is durable and effective in all climates. EPDM’s excellent performance is attributed to its structure and ingredients mentioned in question 1. As a result, EPDM …

    • has superior resistance to UV (ultraviolet) radiation
    • has unmatched resistance to thermal shock
    • exhibits superior resistance to cyclic fatigue
    • has superior resistance to hail damage
    • will not become brittle or shatter due to low temperatures

Many EPDM installations have already exceeded 40 years of exposure in various climates and have not shown alarming signs of degradation. Although its difficult to say for certain, studies have shown that EPDM could have a life expectancy of 50 years.

How long can an EPDM roofing system be warranted?

Generally speaking, system warranties that cover material and labor costs are available; and different manufacturers offer various assemblies with standard warranties that vary from 5 and 10 to 15 and 20 years. In addition, premium coverage up to 30 years is available and can include coverage for higher wind speeds, incidental puncture, and hail resistance.

Does EPDM require maintenance to extend its life expectancy?

No. No special coating or other surface treatment is required. General maintenance however, is recommended, and debris and leaves should be regularly removed.

Can EPDM be coated or painted?

Acrylic coatings are available that can be applied directly to a prepared EPDM surface. Preparation usually consists of cleaning the EPDM with a pressure washer and a detergent solution or wash. Latex-based paint products can also be used; however, the EPDM manufacturer should be contacted prior to application to ensure compatibility and continuation of warranty coverage.

Can EPDM membrane be used in roof top garden applications?

EPDM has a proven track record in various waterproofing and pond lining applications which somewhat resemble roof top applications. However, there are certain rules that should be followed when designing a roof top garden regardless of the type of membrane used:

    • Select a membrane with high puncture resistance
    • Establish redundancy in the waterproofing assembly by overlaying splices
    • Design the assembly to provide slope and proper drainage at the membrane level
    • Incorporate protection above the membrane to aid against root growth and possible puncture
    • Incorporate a drainage layer and a root barrier to influence root growth away from membrane
    • Select proper growth media for the type of roof garden intended

Is EPDM and its installation in any way limited by temperature?

In accordance with ASTM standard D 746, EPDM membrane has a brittleness temperature of -49ºF. While the membrane will remain flexible and pliable in extremely cold temperatures, adhesives, flashings and tapes should be kept at room temperature (hot boxes are usually used on the rooftop to rotate adhesive cans and rolls of flashing). Although roofing contractors may select not to work in sub-freezing temperatures due to safety concerns, many EPDM installations have taken place in temps below 20ºF.

How is EPDM affected by weather extremes?

In laboratory testing EPDM withstood some of the most extreme temperatures. In some cases, samples were subjected to 240ºF 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. In recent years, EPDM has been installed in some of the coldest regions of the United States (i.e., Alaska, Minnesota) as well as in the hot and humid climates of southern Florida and Texas. 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.

Is EPDM beneficial to the environment?

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.

Is EPDM cost effective?

Dollar-for-dollar, EPDM roofing systems are the greatest value in the low slope commercial roofing industry. While installation costs vary from system to system as well as from building to building, generally, ballasted roofing systems have the lowest installed cost per square foot followed by mechanically fastened and fully adhered systems.

How popular is EPDM?

Within the United States , EPDM accounts for over 1 billion square feet of new roofing annually and represents approximately 35% of the entire roofing market. In Europe the market share is around 12% and growing. While it is difficult to predict percentages in other markets, accelerated growth is reported in the Middle East and China as well.

Can EPDM be easily repaired?

Yes. One of the most unique attributes of EPDM is its ability to be easily repaired as well as its potential for restoration unparalleled in the roofing industry. The characteristics of the membrane are such that, even after years of field service and exposure to the elements, repairs and/or modifications, such as the installation of a new rooftop unit, repair can be accomplished with ease and with the expectation of long-term performance.

What are some other uses of EPDM besides roofing?

EPDM has been used in various installations such as pond liners, tunnels, foundations, thru-wall flashings, terraces, garden roofs, and RV roofs.

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