02 Apr Cool Roofs Versus Green Roofs
More recently, we’ve entered an era where new alternatives are available. Of these, “cool roofs” and “green roofs” may be particularly appealing to Florida homeowners. According to Roofing Contractor, both reduce the heat that enters the home on a daily basis. Both also offer environmental benefits and help reduce energy consumption, but in most other ways they are very different.
A “cool roof” limits the amount of heat that enters the house via the roof, and enhances the home’s ability to radiate heat out from the interior. The primary feature of a cool roof is a light-colored roofing shingle or other covering. Light colors reflect light, while dark colors absorb it and convert it to heat, so all by themselves, light-colored shingles will keep a home cooler. But shingles that are designed specifically for energy savings have special materials in the mineral granules that enhance reflectivity further.
Beneath the shingles is a sheet material called underlayment. Conventional underlayments tend to trap heat inside the house, but cool-roof underlayments are specially engineered to allow heat to penetrate them and escape to the outside.
A “green roof” is one that is covered, in whole or in part, with living plants. It is both literally and figuratively green. The plants on a green roof use sunlight for photosynthesis instead of reflecting or absorbing, which keeps the roof cooler. They also remove toxins from the air, according to the U.S. Department of Energy.
Of course, you can’t grow a garden on a high-pitched roof. Green roofs have to be flat. Because soil must be kept moist to keep plants healthy, a special waterproof membrane is required to prevent leakage. Other features, including a root barrier, drainage, and irrigation systems may also be part of the installation.
A Glaring Problem
One problem associated with cool roofs is glare. The light they reflect has to go somewhere, and that could be into a neighbor’s window. So while it’s keeping your home cool, it might be warming up the rest of the neighborhood.Green roofs don’t have that problem, because grass, flowers, and foliage aren’t highly reflective.
Carry That Weight
A cool roof weighs the same as any conventional roof. If you’re replacing a conventional asphalt shingle roof with a cool roof, there will be no problems with structural strength.
On the other hand, with several inches of moist topsoil spread across a flat surface, plus irrigation systems and the weight of the plants themselves, green roofs weigh a lot. Many existing roofs will not be able to support them without structural enhancements. For new construction, however, the roof can be engineered from the start to support the additional weight.
Sunlight eventually breaks down most materials. Because cool roofs reflect more light than dark roofs, they last longer. They’re not immune to this breakdown, however, and like other roofing shingle systems, eventually, they need to be replaced. But between replacement – a matter of decades – they’re virtually maintenance-free.
The soil and plants on a green roof protect the surface of the roof itself from sunlight, so that sunlight damage isn’t a factor. On the other hand, green roofs have constant ongoing maintenance costs. Taking care of the plants requires irrigation, fertilizer and other resources – especially manpower.
When you’re ready for a cool roof on your Jacksonville-area home, call the experts at Quality Discount Roofing: 904-396-5000. Our team can survey your home, formulate a plan and complete the project quickly. In just a few months, you’ll see a difference in energy usage and comfort around the home.