I have two chimneys with crumbling brick, one needs to be rebuilt from the roof up and the other to be repaired. The guy who came to give a quote said that the chimney which needs to be rebuilt can be rebuilt to 18 inches above the roof which would make it shorter than it is now, it is used by the hot water tank. For the other chimney the guy said he would bring it down to the solid brick and just concrete and cap it, this chimney is a fireplace chimney that we don't use. Is it okay to do what the guy suggested? Would it be within regulations? I'm in Ontario, Canada. The house is a backsplit, the chimney used by the hot water tank is located near the middle of the lower roof, the fireplace chimney is located on the upper roof at the back of the house.