Roof-Over Shortens Shingle Life To the Editor: "Reroofing Over Asphalt Shingles" (5/99) was a great article. The pride of workmanship in John Curran's jobs shows through. However, in South Dakota we have such temperature swings that reroofing over asphalt shingles can shorten the life expectancy of the new roof by 30% or more. Like John, I have worked in my hometown for 25 years and have reshingled some homes more than four times due to hail and high wind damage. A couple of years ago we had a severe hail storm and most local homes needed roof repair. I had the opportunity to reshingle houses that I had added on to in the past ten years. I was amazed