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.
METAL ROOF HANDLE WIND, RAIN, FIRE, LIGHTNING, AND HAIL?
If you’re concerned that your metal roof won’t stand against the weather and elements, you can relax. Metal roofing can handle winds