I noticed a end to end crack in my ceiling in our converted graage. the home was build in the late 60's. We just bought it about 8 months ago and they were not there. Myself and a repairman was up in the attic about a month ago. Could that have caused it? What can I do to fix it. It look like it is on the line where the two parts join up. The drywall is what cracked. I have blown in insulation in the attic. I also notice the same type of cracking in our garge. Please help!!