A.The most effective approach is to seal all joints with butyl sealing tape, which should be available from the supplier of the metal roofing. The tape has a paper backing and is applied between the sheets as they are installed. It is more effective than caulk, and since the butyl does not cure, it tends to creep within joints to absorb the movement of the metal with changes in temperature. Where the problem is severe, two strips of tape may be necessary.
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