When you think of having a green roof, you may envision roofing materials that are ecologically friendly or sustainable, like shingles made from recycled waste materials. They may be made of wood fiber, rubber, or plastic. However, there might be another way to look at having a green roof.
A true eco-friendly, green roof is a "cool" roof—one designed to maintain a lower surface temperature in bright sunshine than traditional roofs. The truth is your roof is a great producer of the greenhouse effect. As the sun shines on your roof, the light is reflected back into the atmosphere. The angle and intensity of reflected light generate a heat island in cities, which erodes the atmosphere. Even worse, if the roof lacks insulating properties, a secondary environmental issue spawns as you turn up the air conditioner inside your home.
So, having a green roof means having a cool roof, and it's more than just what material is used. Sometimes it's how that material is used. Here are a few kinds of cool roofs.
This is not the tar sitting in your high school's parking lot. The importance lies in its modification. In this case, it is modified with a plastic and layered with a reinforcing material. Modified bitumen can be used alone or to top off an insulated roof. In some cases heat is used in order for the sheet to adhere to the roof, but other methods are just as effective without creating fumes. This roof type can be made resistant to fire and wind as well.
Look no further than tile for a roof that lasts a hundred years or more. Furthermore, tile creates a cool roof simply due to its composition and shape. The unique curve helps with ventilation, and tile is heavy; that superior thermal mass keeps cool air inside during extreme heat. Of course, choosing a lighter color tile reflects less heat into the atmosphere.
Simply a roof membrane made from natural gas and oil, this type or roof cures and bonds to roofing materials, making the roof well-sealed and insulating the building. Even better, thermoset membranes withstand the damaging effects of the sun. In addition to black, manufacturers are creating these membranes in white, which is the best color for a cool roof.
Thermoplastic differs from thermoset in that is does not have to be bound to the same kind of material. Instead, they are welded shut and can be installed over older types of roof when it is not practical to tear it down. Additional fire retardants and materials absorb ultraviolet light, making them a great cool roof. Even better, the surface is slick and comes in gray and white, which helps reflect sunlight.
Shakes and Shingles
Among the most popular roofing materials, shakes and shingles are the least cool of cool roofing options. That is, they are the least reflective and you want your roof to reflect, not collect heat. However, you can improve their green qualities by treating them with reflective pigments or painting them a bright white.
A roof composed entirely of pavers is quite heavy—more than 24 pounds per square foot. In a home designed to carry the load, the roof has enormous insulating benefits. Roof pavers, simply paving tiles designed for a roof, are more than 2 inches thick and reflect back large amounts of ultraviolet light.
Your cat won't be hot on this tin roof because this is not regular metal. Metal for this type of roof is coated, not bare. Once painted a light color, or with light-reflecting pigment, it is now a cool roof. Metal roofs can even be installed over an existing roof.
Consider making your roof a green roof by actually making it a cool roof instead. To learn more, contact local roofing contractors.