Energy efficient roofing is available in a material that will fit any home. As with traditional roofing materials, your final choice of the right new roof for your home will depend, to a large extent, on where you live, the architectural style of your home, and local preferences. Most discussions of residential roofing options, however, tend to focus on the materials most commonly used on pitched roof styles. If you have a flat roof, your needs are somewhat different. There are highly energy efficient options for a flat roof for you to consider.
Flat roofs are very popular in the San Francisco Bay Area and in the desert Southwest. Certain architectural styles used in the Deep South also incorporate flat roofs or parts of roofs. Low-pitched roofs can often use the same energy efficient materials very effectively.
Flat roofs present several challenges:
  • Much more difficult to install
  • Very difficult to maintain
  • Few long-lasting solutions available
  • Persistent drainage problems
  • Inadequate insulation
There are energy efficient roofing materials for flat and low-pitched roofs that offer most of the same benefits as other materials for steeply pitched roofs. Some of these materials are commonly used on commercial buildings very effectively.
New energy-efficient roofing systems promise reduced cooling costs, longer roof life with less maintenance, better wind resistance (up to 110 mph), better seals and less likelihood of leaks and penetration by wind-driven water, and better insulation to prevent heat exchange.
The energy efficient roofing systems recommended for flat and low-pitched roofs are foam sprays and membranes. There are three main types of materials options for the flat roof.
Spray Roofing – Seamless Spray Roofing Membrane or Sprayed Polyurethane Foam (SPF). Two liquids are mixed at the spray nozzle and release a chemical reaction that causes the foam to expand twenty or thirty times, forming a solid, unbroken roof system that adheres across the entire roof. These spray roofing materials provide outstanding water resistance and thermal insulating properties. They can be as much as 500 times more energy-efficient than the traditional tar and gravel. Because the sprays will adhere to almost anything, it is not necessary to remove the old roofing materials. The foam is then treated with a protective “elastomeric” coating. In other words, the coating protects the foam and stretches with it in heat or cold. It has been shown to reduce energy costs by as much as 58% and in some places can pay for itself in as little as four and a half years. If cleaned, primed and recoated properly every ten to fifteen years, the spray roofing can last 50 years or move.
Thermoplastic Olefin or Polyolefin (TPO). This material creates a single-ply roof membrane. It is made of ethylene propylene rubber, providing great durability with good flexibility to respond to building movement. It is ozone and algae resistant and resistant to punctures and tears from impacts. Seams are welded in a way that allows manufacturers to claim that they are almost a single piece. The membrane is attached around the perimeter and at all penetrations and then held in place with ballast.
Ethylene Propylene Diene Monomer (EPDM). This single-ply membrane has been used in the U.S. since the 1960s. It is a very common roofing material for flat roofs because it is less expensive than some of the other options and relatively easy to install. EPDM is a rubber material, which makes it flexible enough to handle building movement. It can be installed in three ways, depending upon the local weather (particularly wind). It can be fully adhered across the entire roof, mechanically fastened to the substrate, or loose-laid and covered with a ballast (often river rock) to hold it in place. The seams are sealed using special splicing tapes.
Three primary material options are available to homeowners with flat or low-pitched roofs. All of these systems offer energy efficient options for homes with a flat roof. Several companies make the materials and the sealants that must be applied regularly. Talk with your roofing contractor about the best option for a flat roof in your region.