EPDM - EPDM is a synthetic rubber most commonly used in single-ply roofing because it is readily available and simple to apply. Seaming and detailing has evolved over the years and is fast, simple and reliable. Often membranes include factory applied tape, resulting in a faster installation. It is a low-cost option and when properly applied in appropriate places, its warranted life-span has reached 30 years and its expected lifespan has reached 50 years.
An advanced EPDM has been combined with a polyester fleece backing and a patented hot-melt adhesive that provides a strong bond between the fleece backing and the membrane. This nearly eliminates shrinkage of the product. It can stretch up to 300% and will move with the building through the seasons. The polymer fleece backing improves puncture and tear resistance.
EPDM roofs are known for their resistance to weathering and can withstand extreme temperatures and uv rays. They are also great energy savers.
PVC - PVC roofing is also known as vinyl roofing. Vinyl resin may be blended with pigments for color, additives for durability and plastics for flexibility. Its seams form a permanent, watertight bond that are stronger than the membrane itself.
A PVC vinyl roof provides an energy-efficient roofing option due to its light coloring. While the surface temperature of a black roof can increase by nearly 90 degrees in the full sun, a white, reflective roof increases no more than 10–25 degrees Fahrenheit.
Vinyl can also be used to waterproof a roof. This is often used in association with planted roofs.
TPO - TPO is similar to rubber but has better seam, puncture, and tear strength. It can be fully adhered, mechanically fastened, or ballasted. Its seams are three to four times stronger than comparable EPDM roofing systems.
TPO is a popular choice for "Green" building since there are no plastics added and it doesn't degrade under UV radiation. It is available in white, grey, and black. White PTO roofs lessen the "heat island effect" and the solar heat gain in buildings. It is also safer for installers and recycles without any chemical byproducts.
In recent years TPO roofing products have far exceeded the sales of all other flat roofing materials combined. TPO's increased acceptance over the last twenty years by contractors, shows it meets the needs of consumers and is here to stay for some time.
Built Up - Built UP Roofs generally fall into two categories, Asphalt and Coal Tar Pitch.
There are four types of Built Up asphalt roof types, Type I, Type II, Type III and Type IV. Each type is created by heating and then blowing with oxygen. The longer the process the higher the melt-point of the asphalt. As a result, Type I asphalt has characteristics closest to coal tar and should only be used on flat surfaces. Type II, is considered flat and can be applied to surfaces up to 1/4" in 12" slopes. Type III, is considered to be "steep" asphalt but is limited to slopes up to 2" in 12", and Type IV is "special steep". The drawback is, the longer it is processed, the shorter the life. Dead level roofs where Type I asphalt was used as the flood and gravel adhesive has performed nearly as well as coal tar.
Asphalt roofs are also sustainable by restoring the life cycle by making repairs and recoating with compatible products. The process can be repeated as necessary at a significant cost savings with very little impact on the environment. An asphalt Built Up Roof is made up of multiple layers of reinforcing plies and asphalt forming a redundancy of waterproofing layers. The reflectivity of built up roofs depends on the surfacing material used. Gravel is the most common and they are referred to as asphalt and gravel roofs.
A coal tar pitch Built Up Roof is covered by heating the coal tar and applying it between layers of tar paper. These roofs age very slowly and are waterproof and oil resistant. They have limitations in regards to their use on dead level or flat roofs with slopes less than 1/4 in 12. They have a tendency to soften in warm temperatures and "heal" by themselves. They are typically ballasted with gravel to provide a walking surface, however a mineral surface membrane is available. Coal tar provides an extremely long life cycle that is sustainable and renewable. Coal tar pitched roofs that get regular maintenance commonly last 50 to 70 years, with some roofs performing for over a century.
In recent years, a number of cold process coal tar pitch products have been introduced that almost eliminate the fumes associated with its typical hot process version.
Metal Flat Roofing - While metal can be an expensive option in the short term, the superior durability and easy maintenance of metal roofs saves money in the long term. Metal is one of the few roofing options that can be used for both pitched roofs and flat roofs. Flat or low-slope roofs can be covered with steel, aluminum, zinc, or copper just like pitched roofs. However, metal shingles are not practical for flat roofing and so roofers recommend standing-seam and screw-down metal panels.
Metal roofs are also one of the most environmentally friendly roofing options, with most metal roofing material already containing 30-60% recycled content. Metal roofs are 100% recyclable. The value of recyclable scrap metal can also provide a benefit to the homeowner; upon roof replacement, scrap metal from the old roof can be sold to recoup a potentially large share of original material costs.