Find yourself a good roofer and get his/her advice. Unfortunately, competent roofers are truly rare commodity. I've had four roofers work on my house. The original roofer did a lousy job and used the wrong materials. The second roofer was even worse. The third roofer was great, but got himself killed in a drug deal gone bad. The fourth one is golden, and knows more about standing seam metal roofing (which is what I have) than anyone I have ever met.

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1984 300TD