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Your Home's Roofing system
EPDM is a long-lasting, highly pliable, elastomeric, and watertight synthetic rubber used as single-ply roof material for diverse purposes. EPDM is short for ethylene propylene diene monomer, which can also be regarded as the full chemical name of EPDM rubber.
EPDM roofing refers to low-slope single-ply roof systems where layers of EPDM rubber are added to make a watertight roof membrane. Rubber roofs are commonly talked about; whenever you pay attention to people talking about these roofs, you will realize they are referring to EPDM. EPDM is the only material of rubber nature that is used to build roof systems presently.
Although EPDM, which is not reinforced, tends to be easily broken through (e.g., by sharp tools), EPDM roofing is known to resist hail. Besides, rubber roof membranes are the easiest to fix in case of damage. Even people with little knowledge of roofing can find simple repairs on an EPDM roof effortless.
How EPDM Roofing Began
This type of roofing was created in the late 1940s and was used for the first time in the late 1950s. Additionally, it predominated the single-ply roofing sales world by the 1980s. It has also been established that it can last for more than 40 years when appropriately installed and carefully maintained.
It is used in nearly 20% of flat roof installations in America every year, plus new constructions and roof replacement. EPDM roofs are way more prevalent in the north when compared with the south in this era.
Due to LEED (Leadership in Energy and Environmental Design) requirements, reflective white membranes (e.g., TPO - Thermoplastic Polyolefin) have been used in place of EPDM in tropical climates.
Furthermore, semi-cured materials utilized for roof flashings tend to degenerate quicker under strict UV (Ultra Violet) radiation.
Types Of EPDM Roof Systems
The various kinds of EPDM roof systems include:
- Ballasted systems
- Mechanically-attached systems
- Fully-adhered systems
Ballasted EPDM systems
This roofing system uses concrete pavers stone such as river rock or blunt edges to hold the roof system in position. The roof membrane is laid loosely over the roof deck. Next, the ballast is mounted on top of the EPDM membrane.
This system does not use adhesives to join the roof system to the roof deck. It also does not involve the hard insulation cover board other systems utilize to produce complete resistance.
Due to this reason, ballasted EPDM roofing is way more vulnerable to punctures because of foot traffic compared with other systems. Additionally, the ballast stone degenerates over time which can eventually get pushed below the soft insulation by reckless footsteps.
Mechanically-attached EPDM systems
These roofing systems generally use batten metal strips to put the membrane in position. The battens are positioned across the roof, above the EPDM membrane, most often at the edges of the various sheets that make the membrane.
Battens are made with holes in them for easy drilling of fasteners; once they are positioned, they are drilled into them, passing through the roof system into the roof deck.
Few mechanically-fastened EPDM roofs don't utilize battens; they use fasteners installed with their plates in the style mentioned above. Of course, with the non-inclusion of battens.
Fully-adhered EPDM system
This kind of roofing system makes use of adhesives to join the whole roof membrane to the cover board of the insulation. The cover board and the insulation are attached to the metal roof deck using roofing screws. This is referred to as fully-adhered in place of just adhered because all EPDM roofing systems, at some point, use a certain amount of adhesive.
Size And Magnitude Of EPDM Membrane Sheets
The different sheets of EPDM rubber are in diverse lengths and widths. However, the standard size used for large roof installations is 10ft. x 100ft. Membrane thickness for the standards is 45 mils, around 1.14mm or 0.045 inches.
Some are 60-mil and 90-mil as far as unreinforced EPDM is concerned. Regarding EPDM strongly supported with polyester scrim, there are sizes ranging from 45-mil, 60-mil to even 75-mil.
Chemical Constituents Of EPDM Rubber
EPDM is an artificial rubber known as ethylene propylene diene terpolymer. It is known as ethylene propylene diene terpolymer because it is a polymer obtained from combining three monomers.
The main ingredient used in making the roof is the rubber which contains closely 40% exact EPDM. Other components include carbon black (25%) and oils (20%). The ingredients remaining are present in minute quantities; they are additives ranging from anti-oxidants, curing agents, fillers, fire retardants, and anti-ozonants.
The prevalent EPDM roofs these days utilize unreinforced sheets. However, the membranes are built with a polyester reinforcing scrim where required. This is mainly seen in mechanically-attached systems.
Components Of An EPDM Roof System
Many components are put together to make up the roof system. Some standard features are layers of insulation, an air barrier, the roof deck, the cover board, adhesives, ballast, and the membrane. A large percentage of the roof surface (the field membrane) is made from vast sheets of cured EPDM combined with adhesives when installing the roof.
Smaller pieces with full-curing or sometimes semi-curing materials are utilized to make the flashings of the roof's circumference. Occasionally, uncured materials are used in locations with sharp angles or above the curb's corners.
Properties Of EPDM Roofing
EPDM is a white or black, elastic, thermoset artificial rubber widely known for its durability. It can withstand moisture, heat, ozone, UV rays, and hail, including acids and alkalis. This roofing can resist tearing, has an elevated tensile strength, and is pliable in temperate conditions.
EPDM roofing colors
This is one of the significant colors of EPDM sheets since carbon black is used during the production process. Carbon black is almost pure carbon that is highly black. It is a powder that is obtained from coal which is purely refined. It comprises about ¼ of the ultimate product.
The tensile strength is increased, the molecular structure is reinforced, and the EPDM resin is toughened with the inclusion of carbon black. Another advantage that carbon black offers is the protection of the chemical bonds of the material; it does this by blocking detrimental UV rays.
This particular merit of carbon black is the actual reason behind the outstanding lifespan of rubber field membranes. Practically all EPDM roofs are black, which is why they are hardly referred to as cool roofing. However, they can qualify as cool roofs when coated with a reflective roof coating.
Since black is an excellent absorbent, the membrane absorbs the heat when the sun rises and can reach high temperatures of greater than 170 degrees on a sweltering day. White roofing membranes or black EPDM can be used depending on how hot or cold the region is.
White EPDM is the membrane to be used whenever a cool roof is warranted. It is obtained from a white colorant, titanium dioxide. Majorly because of its lower resistance to UV compared to black carbon, it seems to have less durability when compared to the latter.
White rubber roofs are less common than black roofs because they are more costly. The presence of PVC and TPO has also contributed to the uncommonness of white rubber roofing.
Elastic nature of EPDM
Elasticity can simply be referred to as a substance or material's ability to return to its original position when distorted without experiencing damage. When the material is new (unreinforced), particularly the ones used in fully-adhered systems, it can lengthen when pulled more than three times its original size.
However, this ability reduces with the aging of the membrane. Meanwhile, reinforced EPDM is typically used in mechanically-attached systems and is held within close bounds by the reinforcement (polyester scrim).
This can only be lengthened when pulled to about close to 40% before damaging. This particular characteristic is what makes EPDM more superior to PVC (can stretch to about 15%) and TPO (25%) before breaking.
Thermoset nature EPDM
During the manufacturing process, the polymer chains' cross-linking using chemical agents and heat is called thermosetting. This process makes the material stable to heat, and it can only get denatured when temperatures are heightened.
This simply implies that you must not use a hot welder on it after it has been manufactured. This is why thermoplastic roof membranes such as TPO are welded using scorching air, and EPDM requires adhesives to join the pieces together.
Material nature (Uncured and Cured)
Complete chemical cross-linkage of materials used as a field membrane is what is known as fully-cured EPDM. The incomplete chemically cross-linked materials are called uncured or semi-cured EPDM and are utilized as flashing materials. Since the EPDM polymer chains are not fully cross-linked, the materials can comfortably conform to angles following installation.
This does not happen in fully cured EPDM because of the complete chemical cross-linkage, which causes it to return to a flat shape. Additionally, these materials are more susceptible to heat and UV radiation, and because of this, they will degenerate faster.
EPDM of the fully-cured nature is one of, if not the most, long-lasting roofing materials that are readily attainable. It is molecularly stable, has outstanding UV resistance, and does not react with corrosive environmental substances like ozone, alkali, water, and even acids.
Due to these reasons, the field membrane of the roof can last for more than 50 years. More often than not, when the rubber has reached its termination point, it's primarily because of the inability of the adhesive to keep functioning. The field membrane is usually the last thing to not function properly.
Lasting Nature Of EPDM Rubber Roof Systems
The critical determinant factor when considering the lifespan of EPDM rubber roof systems is how thick the membrane material is. This is besides correct installation, high-quality materials, and impeccable workmanship. An extra thing to look out for is the mode of attachment.
If you want the system to last long, use very thick membranes. The fully-adhered membranes are more durable than mechanically-attached membranes, which are longer lasting than ballasted membranes.
How long the type of EPDM lasts also depends on the size. The longest-lasting are usually fully-adhered roofs of around 90 mils (35 years), while the ones with a shorter lifespan are ballasted roofs of about 45 mils (15 years).
However, if poorly maintained, any type of roofing can stop functioning faster than its stipulated lifespan. This can also be the case when it is subjected to harsh weather conditions for long, damaging chemicals and foot traffic.
What Damages EPDM Rubber Roof Membranes
Various materials or items can cause damage to rubber roof membranes. Some of them include:
- Sharp objects
- Compatibility with asphalt
Some rubber roof membranes, particularly those that are not reinforced, experience punctures more easily. Objects featuring sharp points and edges, such as knives and nails, often spread on roofs during installation or repairs, can make holes in this membrane when stepped upon. This leads to roof leaks.
Care should be taken when walking on old ballasted systems because there is usually a large amount of unevenly cut stones all over those kinds of roofs.
Compatibility with asphalt
EPDM roofing is incompatible with roofing cement and roofing mastics, referred to as solvent-based roofing materials that are asphaltic. This is because these materials mix petroleum-derived solvents with asphalt to produce solvents that will spoil the EPDM roofing membranes in no time.
However, there isn't much to worry about when there's temporary contact with pure asphalt. Despite this, play safe by avoiding the usage of an asphalt-based product on an EPDM roof.
When petroleum-based products (liquid or gas) are spilled on a roof and poorly cleaned or not even cleaned, the membrane will break down within weeks. Hence, whenever work is done on your roof, one should always check the area where the work was carried out and clean it up properly.
Grease emanating from kitchen restaurants is mainly a significant concern with EPDM roofing. It's not a rare occurrence that kitchen grease affects EPDM roofing the same way petroleum products do. Roof damages are always noticed close to kitchen exhaust fans because kitchen grease pile up on the surface of the roof.
You can avoid this damage by using a protective layer with a material resistant to grease and placed close to the exhaust location. If your EPDM roof has already been harmed by grease, it should be replaced.
Property supervisors should always be on the lookout and ensure that tenants who own restaurants make more authorized roof penetrations. Whenever a new tenant is launching a restaurant, they should check to ensure that they have installed enough protection for the roof.
EPDM Roofing By Professional Roofers
Now that you have a good idea of what EPDM rubber roofing is, you can better take care of an EPDM roof and ensure it is protected from anything damaging it, as discussed in this article. Suppose you're planning on getting an EPDM roof or repairing your current one. In that case, working with professional roofers is essential as you can easily damage this type of roofing material if not handled properly.