Q: When I bought my 1983 house recently, the men who came in to do some work said: "Look at all that exposed fiberglass in the basement ceiling. Uncovered, it can be a hazard to your health and ...

If the underlayment is skip sheathing, a layer of 1/2-inch plywood or oriented strand board (OSB) is nailed down to stiffen the roof rafters and accept the fasteners for the new roof singles.