The roofers moved and broke the brick mortar joints below the roof line at least a couple feet. From the roof top the chimney is about 4 foot tall and the roofers probably did not realize the severity of the damage to the mortar joints. Can the chimney be disassembled below the roof line until solid mortar joints occur and then replace the chimney with metal piping? What kind of adaptation is needed if the only thing connected to the chimney is a water heater two stories below?