Sometimes the solution is plain to see: a roof hole, missing shingles, leaks, or animals living in your attic. Sometimes the indications that your roof needs replacing are a little more subtle. In order to prevent problems brought on by a damaged roof, it may be time to replace your roof if it is older than 12 to 15 years. Ice dams, missing or broken flashing, curled or curling shingles, and discolored walls and ceilings are other telltale signs that it's time to replace your roof.