Types Of Roofs And How They Can Be Made Cool:
There are many types of roof systems available, but the surface exposed to the sun is the one that determines if a roof is cool or not.
Cool roof coatings are white or special reflective pigments that reflect sunlight. Coatings are like very thick paints that can protect the roof surface from ultra-violet (UV) light and chemical damage, and some offer water protection and restorative features. Products are available for most roof types.
FLAT OR LOW SLOPED ROOFS:
Single-ply membranes are pre-fabricated sheets rolled onto the roof and attached with mechanical fasteners, adhered with chemical adhesives and are usually white. Some older single ply roofs installed were be black and can be coated white.
Built-up roofs consist of a base sheet, fabric reinforcement layers, and (usually) a gray granular protective surface layer. The top layer is available with a factory applied white coating, like the GAF Energy Cap, or these roofs may be able to be coated to make them energy efficient.
Modified bitumen membranes have one or more layers of rubber material with reinforcing fabrics, and are surfaced with mineral granules. The top layer is available with a factory applied white coating, like the GAF Ruberoid Energy Cap, or these roofs may be able to be coated to make them energy efficient.
Spray polyurethane foam roofs are constructed by mixing two liquid chemicals together that react and expand to form one solid piece that adheres to the roof. Foams are highly susceptible to mechanical, moisture, and UV damage, and rely on a protective white coatings to make them cool.
Structural Metal Panel Roofs can be coated with a white energy efficient finish.
Gravel topped built-up, modified and coal tar roofs were very popular before newer systems became main stream and are actually very energy efficient and cool. Some municipalities do not allow gravel as it could become projectiles in a high wind condition.
Garden Roofs are as green as it gets. By installing a special waterproofing system, root protection and drainage system, a roof top can be landscaped and be transformed into a beautiful garden. The views on some roof tops are incredible!
STEEP SLOPED ROOFS:
Asphalt shingle roofs consist of overlapping panels made from fiberglass asphalt. Cool asphalt shingles come with specially coated granules that provide better solar reflectance. (Coating existing asphalt shingles to make them cool, however, is not recommended or approved by shingle manufacturers or Miami-Dade as the shingles and nails will rot from trapped moisture and will need to be replaced in about a year!.)
Tile roofs can be made of clay, slate, or concrete. Tiles can be glazed to provide waterproofing or coated to provide customized colors and surface properties. Some are naturally reflective enough to achieve cool roof standards, and surface treatments can transform tiles with low solar reflectance into cool roof tiles. Simply selecting a white tile or coating it white will make it energy efficient.
Metal roofs are available with natural metallic finishes, oven-baked paint finishes, or granular coated surfaces. Unpainted or mill finish metals are typically good solar reflectors but poor thermal emitters, so they rarely satisfy low slope cool roof requirements. Metal roofs come with factory applied finishes that increase its solar reflectance and thermal emittance, allowing it to achieve cool roof status. Alternatively, you can apply cool reflective coatings to existing metal roofs.