Roof Leak In Knoxville TN Gets Repaired. This roof leak first look like it was coming from the metal exhaust pipe from the furnace. This is a common place for roofs to leak. An attic inspection was performed and it was evident that the area around the furnace exhaust have been leaking but it could possibly have been something else. Once it inspected occurred on the roof, It appears that that exhaust could possibly leak But there was a nail pop exactly in the area of this roof leak and that is the most likely cause of this issue.