It is possible, but not something a reliable roofing contractor would recommend. You’ll want your metal roof to have a solid structure, correct insulation, and sufficient ventilation–but it may not have these essentials when there’s a moldering roof still installed beneath it. Having the old system torn off completely before installing your new metal roof remains the best option.
ARE YOU A LICENSED ROOFING CONTRACTOR?
Most states require roofing contractors to be licensed in that state to work; but codes and requirements will differ between states, which