Q. My 1950’s home has recently developed ceiling cracks running lengthwise through all of the rooms. Recently, I had a new shingle roof put on, and the roofing contractor told me that I could save a little money by putting the new shingles on top of the old ones. I wonder if this could be contributing to the cracking of my plaster ceilings.

A. The new roof over the old is most likely the reason for the ceiling cracks. Some roofing contractors will put new shingles over old ones because it saves them time and money, but this is no benefit to the home owner. Your house was framed to handle the weight of one shingle roof, but not the weight of two. The extra load on the structure is placing stress on the rafters, braces and ceiling joists, and causing stress cracks in your plaster ceilings. At this point, your best option is to just live with the cracks, because if you patch them without relieving the extra load on the roof, the cracks will just come right back. Next time you are ready for a new roof, insist that the roofer remove all of the old shingles, felt, tar paper and any other materials right down to the plywood or boards and start from scratch. This will not only eliminate the extra weight problem, it will give you a better looking, tighter and longer lasting roof.