Q–I need to have a new roof placed on my house. I haven’t hired a roofing contractor yet, but I’ve looked at roofing tile, mostly asphalt selections.
What I’m wondering is if it would make sense to choose a lighter-colored tile. Would that make a difference on hot summer days in terms of my attic really heating up? And would it help me with the cost of my air conditioning?
A–While it’s well known that lighter-colored materials deflect the warming rays of the sun and darker colors absorb that heat (ask anyone who has worn a black T-shirt versus a white T-shirt on a hot, sunny day), that rule does not apply to roof tile, say roofing experts.
Instead, what really matters is if the attic is properly ventilated, which will allow that warm air to escape on hot sunny days.
In fact, if you have a properly vented attic, a lighter-colored roof tile will only reduce the temperature in the attic by a few degrees, says Drew Hupp, chairman of the steep roofing committee for the Chicago Roofers Contractors Association and general manager of Mader Roofing in Oak Park.
“You’re talking a slight difference–maybe between 120 and 123 degrees,” he says.
A soffit to ridge ventilation system that runs continuously along the length of the house is a good way to ventilate the attic.
That will allow warmed air to constantly run along the underside of the roof, preventing that warm air from building up in the attic to peak temperatures of 140 degrees-plus.
The general industry rule of thumb is that there should be 1 square foot of free ventilation for every 150 square feet of attic space.
Another plus of proper attic ventilation, says Hupp, is it will help minimize ice damming problems in the winter. Heated air that escapes from the living space below can warm the underside of the plywood on the roof. That in turn melts the snow on the higher parts of a home’s roof.
The melted snow runs down the pitched roof and into a cold gutter, where it freezes into an ice dam. That ice dam can then back out of the gutter and push up roof shingles.
Ventilation alleviates that warm air build up.
Having insulation on the attic floor will also help that warm air from reaching down to the cool confines of your living space, says Tom Bollnow, the director of technical services for the National Roofing Contractors Association. “Insulation helps keep the downstairs cooler in the summer and warmer in the winter,” he says.
The recommendation for attic insulation in the Chicago area is about 12 inches of blanket insulation for an R value of 38.
So choose the color of roof tile that best suits the color and style of the rest of the your home, say the experts.
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Got a question about home energy or home environmental issues? Write to Energy Q&A, Chicago Tribune, Your Place section, 435 N. Michigan Ave., 4th Floor, Chicago, IL 60611. Or you can e-mail energyqa@aol.com.
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