Question: I have a prefab fireplace and the back wall seems to be deteriorating. I can see the steel pieces in it. Do I or should i have it replaced. Can you suggest someone on Long Island? Answer: I assume that you are talking about the firebrick panel which protects the rear wall of the fireplace. These can crack over time from heat and the shock of being hit by pieces of wood. These pieces are usually held in place by s sheet metal clip and can be easily replaced. The trick is finding the exact replacement panel or cutting one to fit. Probably a job for your local chimney sweep who can either buy or make a replacement. If the cracks and missing areas are relatively small, perhaps 1" square or less, than you can simply patch them up using high temperature refractory cement which is available at building supply merchants.