My mom has a metal roof about 8 years old and it started leaking this year she had some roofer come tell her that ever 5 years all the screws need replacing on the metal roofs so she told me that and I told her that I have never heard of such a thing so she found another roofer who come and looked and he replaced about 10 to 15 screws above where the leak was and it has not leaked since 1st roofer wanted 1500.00 plus the cost of all the screws 2nd roofer 150.00 total