Below is a listing and brief description of the most common roof categories.
BUR (Built Up Roof)
Built-up roof membranes are composed of asphalt, glass fiber and polyester or organic reinforcing felts. The membrane is typically surfaced with aggregate, mineral granules or fluid-applied coatings. These roofs require routine maintenance and typically last 8-20 years.
Modified
Modified membranes are asphalt-based and are typically found installed with one or more base or underlying interplies. This is the most common system for residential roofs. Modified products are typically either smooth surfaced, granule surfaced or foil-faced. Additionally, they may be field surfaced with a coating or a flood coat of asphalt and aggregate. The typical lifespan for modified roofs are relatively low at 8-15 years.
Metal Roof
Metal roofs provide long-lasting protection and can endure severe weather conditions. They come in a variety of finished coatings, colors and styles. The metal itself can last up to 50 years but penetrations and fasteners should be re-sealed and maintained every 2-3 years.
Thermoplastic Membranes
These single-ply membranes are composed of polymers, which soften when heated and harden when cooled. This process is repetitive provided the material is not heated above the point at which decomposition occurs. These membranes can usually be hot air welded throughout their service life. There are many different types of Thermoplastic Membranes including the following:
TPO (Thermoplastic Olefin)
- lifespan = 15-25 years when maintained
PVC (Polyvinyl Chloride)
- lifespan = 15-20 years when maintained
thermoset Membrane
Thermoset Membranes
These roofs are “rubberlike” and are actually made of large pieces of synthetic rubber. When welded together, the rubber pieces are chemically bonded, forming a single-layer membrane. When stretched, they will elongate, but will return to their original shape when released. Included in this category are the following types of membranes:
EPDM (Ethylene Propylene Diene Monomer)
- lifespan = 12-15 years
Hypalon (CSPE)
- lifespan = 15-20 years
SPF (Spray Polyurethane Foam)
These roofs are usually composed of a polyurethane foam, sprayed from a pressurized gun, and an elastomeric acrylic coating. Once sprayed, the foam forms a solid, seamless membrane that waterproofs and insulates. These roofs need to be maintained on a regular basis and are not as common in hot areas, such as the southwest, because UV rays from sunlight cause the foam to crack and become brittle. SPF roofs are also highly susceptible to hail, bird, and insect damage. Every 10-15 years, these roofs should be cleaned and re-coated. If installed and maintained properly, an SPF roof can last as long as 50 years.
Tile Roof
Tiles can be concrete, clay and slate. The tiles themselves can last 40-75 years but the membranes beneath the tiles will not last this long. When good materials are used and proper installation is carried out, the underlayment system can last 30 years. If the quality of the underlayment is not up to par or improperly installed, it may need to be replaced within the first 5-10 years.
