| 1.
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What
is EPDM?
EPDM is an elastomeric compound that is manufactured
from ethylene, propylene, and a small amount of diene
monomer. These ingredients are synthesized to produce
a product that exhibits a high degree of ozone, ultraviolet,
weathering and abrasion resistance, and outstanding
low temperature flexibility. These ingredients also
contribute to resistance to acids, alkalis, and oxygenated
solvents (i.e., ketones, esters, and alcohols).
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| 2.
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What
does EPDM look like?
Black EPDM has a smooth surface similar to natural gray
slate and does not contain surface granules that can
eventually be lost on other materials. |
| 3.
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As
a vulcanized (thermoset) elastomer, how does EPDM differ
from other types of single-plies (i.e., PVC, TPO, Single-ply
or non-vulcanized elastomer)?
EPDM membrane is a vulcanized/thermoset membrane that has been fully cured in the manufacturing process prior to shipment and delivery to the job site. With aging, EPDM membrane will not leech or emit hazardous chemicals. Unlike non-vulcanized elastomers that may begin curing in the field once exposed to moisture and heat, EPDM membrane has no shelf life. Its physical properties remain stable, which makes repairs much easier in the unlikely event of cuts or tears.
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| 4.
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How
can the performance of EPDM be gauged over the last
40 years?
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:
- EPDM has superior resistance to UV (ultraviolet) radiation
- EPDM has unmatched resistance to thermal shock
- EPDM exhibits superior resistance to cyclic fatigue
- EPDM has superior resistance to hail damage
- EPDM will not become brittle and will not shatter due to low temperature flexibility
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| 5.
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What
makes EPDM membrane suitable for non-exposed assemblies
(i.e, protected membrane applications and double slab
installations)?
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.
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| 6.
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What
is the maximum size sheet for EPDM membrane?
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'.
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| 7.
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What
are the available thicknesses and types of EPDM single-ply
membrane?
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.
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| 8.
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What
is the difference between black EPDM and white EPDM
membrane?
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.
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| 9.
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Are
EPDM membrane roofing assemblies fire retardant?
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 retardency level will depend on
roof slope and the various components utilized. Current
UL and FM publications contain numerous listings of
various approved assemblies.
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| 10.
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Does
EPDM require systematic maintenance or additional coatings
or treatment to achieve its life expectancy?
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.
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| 11.
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Is
the performance of the EPDM membrane adversely affected
geographically due to temperature extremes?
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.
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| 12.
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Is
EPDM environmentally beneficial?
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.
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| 13.
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Is
EPDM UV resistant?
After more than two decades of field exposure
in different climatic conditions, samples collected
of EPDM membrane show no evidence of crazing or cracking.
As a result of the excellent UV resistance, EPDM membrane
can be warranted up to 30 years.
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| 14.
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Is
EPDM UV resistant?
After more than two decades of field exposure in different
climatic conditions, samples collected of EPDM membrane
show no evidence of crazing or cracking. As a result
of the excellent UV resistance, EPDM membrane can be
warranted up to 30 years. Does ponded water have any
affects on the performance of EPDM membrane? Since its
infancy, when EPDM was used primarily for pond lining
and canals, it has demonstrated excellent resistance
to moisture absorption. This characteristic made the
membrane a candidate for many underground waterproofing
applications where the material was buried in saturated
soil. (EPDM meets ASTM D 3083 "Resistance to Soil Burial
for Underground Application.")
Moisture found in ponding areas has caused decay of
organic felts (built-up roofs), algae growth (light
colored roofs), granule loss (modified bitumen roofs),
and premature curing and surface cracking (non-vulcanized
thermoplastic membranes). This moisture has absolutely
no affect on EPDM membrane.
While it is always good roofing practice to provide
positive drainage for any roofing assembly, EPDM membrane
offers greater safety margins in the event of deflection
and subsequent ponding.
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| 15.
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What is the expected longevity of EPDM 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.
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| 16.
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Does
hail affect the physical characteristics of EPDM?
EPDM passes the Factory Mutual (FM) 4470 testing procedure
that includes hail resistance, and does not show fatigue
from the impact the membrane must endure during a hailstorm.
Hail warranties are available and offer protection against
1 inch and 2 inch diameter hail.
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| 17.
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How
does EPDM perform in expansion and contraction situations?
Should relief or control joints be utilized the same
as on a built-up roof?
Relief or control joints are commonly used with built-up roofs to subdivide a larger roof area and segregate possible damage into one small area. EPDM, due to its flexibility (-49 F) and elongation, will accommodate stresses caused by temperature extremes, structural movement, and deflection. In cases where the building is designed with expansion joints, the design should be carried all the way through to the roof and an expansion joint should be incorporated into the roof design.
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| 18.
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What
is the cause of bridging that has been seen in the past
at angle changes in some EPDM loose-laid applications?
Some membrane bridging has been observed in the past in some loose-laid ballasted membrane assemblies. The bridging was not seen in adhered or mechanically-fastened applications where the membrane is adhered or secured in place. The cause of this bridging relates to membrane movement experienced in ballasted roofing systems and insufficient securement in the angle change at the base of parapets. This phenomenon was not seen in every ballasted loose-laid assembly but only some (mostly in colder regions) where improper securement is present. Examples include:
-
Roofing nails used to anchor the roofing membrane to a horizontal wood nailer
- Improperly anchored beveled wood nailers fastened to the vertical wall (warping and buckling of the wood occurred)
- Rubber nailing strips fastened horizontally or vertically
In 1987, the method of securement was changed to incorporate 2" diameter plates and threaded fasteners spaced at 12" on center or a reinforced strip (glued to the underside of the roofing membrane at the angle change) to anchor the roofing membrane. This change in securement method eliminated the bridging. Both NRCA and SPRI have endorsed this securement.
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| 19.
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Have
the ASTM standards for linear dimensional stability
(for EPDM) been modified?
The ASTM standard for linear dimensional stability (ASTM
D 1204) was originally 2% maximum. In the mid-90s the
standard was changed to 1% maximum. The change in the
ASTM standard was influenced by the belief that membrane
shrinkage may be a contributor to the bridging seen
on some old ballasted applications. In reality, EPDM
has always exhibited a dimensional stability value of
much less than 1%, even when the ASTM Standard was 2%.
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| 20.
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Is
there an ASTM Standard for EPDM membrane?
Yes, ASTM D 4637.
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| 21.
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Are
there standard details for use with EPDM systems?
Yes. The National Roofing Contractors Association (NRCA)
and the Single-Ply Roofing Association (SPRI) publish
standard details. However, manufacturers may have modified
versions of these details which may not exactly match.
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| 22. |
What can I put on snow and ice to facilitate melting and one effect the EPDM or my warranty?
Calcium Chloride will work in most conditions. It can either be spread over the area of concern or placed in a nylon stocking and placed along/around the areas in need of melting. While the Calcium Chloride will not harm the EPDM caution should be taken in regards to where the melt water run will drain, and verification that it will not affect the materials and or vegetation it comes in contact should be obtained prior to placing the Calcium Chloride on the roof.
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| 23. |
Do I have to worry about stain hardening and potential deterioration in the future when a hail storm comes in contact with my EPDM Roof?
Neither manufacture of EPDM has seen evidence of strain hardening in EPDM membrane at anytime in there life.
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