Materials commonly used in flat roof installation and repair:
Otherwise referred to as tar or tar and gravel roof, this roof comprises of 3-5 layers of asphalt laminated with coal hot tar, hot asphalt or pitch. Gravel is finally added for protection from UV rays. This is now becoming less popular owing to its short life, abundant heat gain, non-energy efficient, requirement of continuous maintenance and aesthetically unpleasant nature.
This is just modified asphalt to enhance the plastic and rubber-like properties. The commonly employed modifiers include Atactic Polypropylene and Styrene Butadiene Styrene. When this roof is properly installed, this can last up to around 15 years.
Metal Roof Installation
Metal roofs are installed normally with underlying asphalt saturated as well as coated roof. Underlayment is inadequate mostly in low slope roofs. It is better to apply an underlayment of asphalt, then modified bitumen product and finally a metal product. This roof is also less commonly installed owing to its expensive nature, limited material warranty, etc.
Single Ply Membrane
It is a myth that all single ply membranes are similar. The single ply membranes include different membranes and their performance varies. The main requirements of the single ply membrane nature that must be satisfied are being waterproof, non-flammable, compliant with building codes, easy to work with as well as repair, pliable at different temperatures and weldable. Most widely employed membranes are CPE, EPDM, Hypalon, TPO, PVC, CPA, etc.
TPO has been used only for the past ten years and hence its performance cannot be determined yet. EPDM, otherwise called rubber, is a black single ply. Many EPDM installations have failed owing to improper installation, material failure and harsh climates. CPA and PVC are similar in properties and performance, the only difference existing in the chemical composition and viability of material.