TPO Membrane Roof Systems
EPDM Membrane Roof Systems
Built-up Roof Systems
Modified Bitumen Roof Systems
Structural Metal Roof Systems
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GHC Professional Roofing has a specialized team of professional roofing technicians equipped to handle any of your commercial/low-slope application requirements. We specialize in PVC, TPO, EPDM, and Metal (both structural and non-structural) roof systems. Whether you need repair, or complete tear-off and reinstallation, we know and can explain the best roof commercial system for your situation.
There are about 7 main groups of low-slope/commercial roofing application families: Modified Bitumen (both ballasted and non-ballasted), Built-Up Roofing (30# asphalt saturated felt with hot mopped asphalt applied as the felt is interwoven across the surface field), Thermoplastic Single-Ply Roofs (PVC and TPO – TPO being one of the most common applications in this region), Thermoset Plastic Single-Ply Roofs (EPDM, or rubber membrane roofing – another very common application in this region), SPF (or Spray Polyurethane Foam), Metal (both structural & non-structural panels – the other most common application in this region), and finally, Vegetated Roofs (also known as Green Roofs, these are on the rise in larger cities). There are also a variety of coatings that may be applied as part of maintenance of low-slope commercial applications.
Thermoplastic Olefin (TPO) Brief History:
TPO roofs were introduced in Europe during the mid 1980’s. The first non-reinforced TPO roof was installed in the United States in 1987. TPO gained popularity in the US in the mid-1990’s. In 2008, 16.4% of low-slope commercial application, both new and re-roofing, was captured by TPO roofing.
TPO is usually white or gray in color and is a blend of polypropylene and ethylene propylene polymers. Other additives include: flame retardants, pigments, and UV absorbers. There is normally a polyester reinforcement component added to this “fabric” roof covering. TPO is available in a variety of thicknesses: .045 mils, .060 mils, and .080 mils (to .10 mils) thick and is 6’ to 10’ wide rolls. The most common application in this region is .045 mils.
Some TPO characteristics: Inherently flexible, does not contain chlorine, it is tough; resists tears & punctures, it is flexible at cold temperatures, does not support microbial growth, and great for restaurant application as it is resistant to animal fats & vegetable oils. TPO is also puncture resistant; another great reason to choose it for your low slope/commercial application.
Thermoset [EPDM – Ethylene propylene diene monomer (or terpolymer)] often called “rubber” roofing:
Thermoset plastic single-ply membranes are often utilized when: Weight is a consideration, when some movement can be expected in the building structure, when roofing over an existing membrane, or when roofing over a metal roof.
Characteristics: By definition, thermoset plastics (EPDM “rubber roofing”) keep their shape until charred or burnt. EPDM is flexible with a minimum elongation of 200%. It is also lightweight at 0.29 to 0.45 lbs per square foot. One interesting difference between thermoset plastics (e.g. EPDM “rubber” among several various types and proprietary systems) and thermoplastics (e.g. TPO roofing among others) is that thermoset plastics have cross-links between long-chain molecules whereas thermoplastics do not.
The chemical process of installing cross-links is known as “curing” or “vulcanization” and can take place either during manufacture or over time on the roof. Curing on the roof requires heat and moisture which is why brand new EPDM roofing often appears grayer in color than black, as black is the notable color of most EPDM “rubber” roof systems, and may have a few wrinkles or air pockets. Over just a few days with some direct sunlight and morning dew, the EPDM membrane roofing cures, expands, and starts take on its notable characteristics.
There are a variety of different metals that have been chosen throughout the centuries (reference in the book of Chronicles from The Holy Bible - circa +/- 600 BC). There are naturally weathering materials such as: Copper, Lead, Zinc, and Lead-coated copper, Terne metal, and so on which are designated as Non-structural metal applications. Structural metal roof coverings include: Aluminum, Stainless steel, and Terne-coated stainless steel. There are a variety of metallic-coated steels such as: Aluminized steel, Galvanized steel, Galvalume, & Terne metal.
The most common metal roofing that we at GHC Professional Roofing offer is non-structural Terne-metal roofing which is enamel coated with either Kynar 500, or Hylar 5000; both contain 70% resin, are about 1 mil thick, are high quality and have 20-year expectations for their lifespan.
There are at least 9 different and/or proprietary methods to locking panels together in a Standing Seam fashion. Standing Seam roofing is by far a much better fastening system than the screw-down variety of metal roofing. Screwing down the panels leaves all fasteners exposed, which the fasteners do have EPDM washers at their base to create a firm seal and to protect against water leaking into the interior structure; although this does render the roof system quite vulnerable after about 10-15 years when the EPDM traditionally begins to show signs of wear and dry-rot. The advantage of screw-down metal roofing panels lies solely in its inexpensive cost (about as much as Architectural, asphalt composition, fiberglass-mat shingles) and is primarily marketed as a viable residential roof system solution applied quite commonly in this region. It is characterized by its contiguous ribbed panel look (AG panel) and by its many obvious exposed screws (fasteners) which are often visible to the naked eye from the ground level. When you see such a roof, just know that in a few years someone will be chasing down several leaks and/or re-screwing the entire surface of the roof system.
Whether performing residential roofing or commercial roofing, if metal panel roofing is specified as the preferred roof system choice, it is our recommendation to carefully consider choosing Standing Seam style application. The only problems one may expect to face will be the maintenance of re-coating the surface after about 20-25 years of leak free service. As long as such maintenance is performed, the Standing Seam metal roof will last and last.