Flat Membrane Roof with Several Leaks in Knoxville, TN. Repair or Replacement? Older flat membrane ballasted roof with leaks and some ongoing issues. The membrane is aged, probably 25 years or more. The rubber is beginning to fail at the seams, and the rubber is becoming brittle and will tear more quickly with age. This roof is still repairable. However, complete replacement is recommended. Repairs would not be under warranty.