Q: Our home is 23 years old and has a pitched roof with common shingles. The roof does not leak, but the shingles are starting to curl and are just plain ugly. We have received different opinions on what to do, and the cost difference makes me want an unbiased opinion. The roof has just one layer of shingles. One contractor wants to remove the old shingles and replace with new ones, and another company said they could cover the existing shingles, saving me several hundred dollars. I want to save as much as I can, but don't know whom to trust.
A: A lot depends on the slope of the roof, or how steep it is. A low-sloped roof allows water to pool during heavy rains, whereas a steeply pitched roof sheds water rapidly and doesn't retain heavy snow piles. In areas with minimal snowfall, it may be possible to add a second layer of shingles. But that's never the best choice. When a home has a low-pitched roof, it is always necessary to remove the existing shingles before adding a new roof covering. The weight of the shingles, anywhere from 220 pounds per 100 square feet to 340 pounds per 100 square feet, is also a factor in determining what the roof's structure can support.
In some cases, it may be necessary to add bracing to the roof rafters before installing a heavier-grade shingle. There will also be some existing damage to the roof's decking when the older shingles are removed. The damaged areas will have to be repaired. All of this adds to the cost of replacing the shingles, as opposed to simply covering the existing shingles.
You also need to consider that having more than one layer of shingles reduces the life expectancy of the new layer. Reduced cooling and drying of the second layer will cause the shingle to lose anywhere from three to five years of useful life expectancy. By adding a second layer of shingles, you are just putting off the inevitable in order to save a few dollars. Sooner rather than later, the shingles will have to be removed.
Despite the higher cost, I would trust the contractor who is being honest about having to strip the shingles rather than the contractor who is willing to cut corners to save you a few dollars today. Where will that contractor be when the second layer of shingles starts to fail?
(Dwight Barnett is a certified master inspector with the American Society of Home Inspectors. Write to him with home improvement questions at C. Dwight Barnett, Evansville Courier & Press, P.O. Box 286, Evansville, Ind. 47702 or e-mail him at d.Barnett(at)insightbb.com.)
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