Two Roofs are Not Better Than One
Q: I have an old tract house with composition roof shingles. I need to re-roof but the roof has two layers of shingles on it already. Do I have to have them taken off? Also, which rate or weight of composition shingles is best to use?
—Irene, Riverside, Calif.
A: Tom Silva replies: Yes, you need to strip the shingles. I don't like to shingle over any old shingles, but one layer is acceptable. Two is not. A single layer looks better, lasts longer, and won't put any unnecessary extra weight on the roof.
As to which shingles to use, the longer the warranty, the heavier the shingle and the greater the cost. You want to look for the best warranty you can afford.