A retrofit involves working within the existing frame and replacing only the sash and the glazed unit of a skylight or patio door or replacing the actual exterior door and/or sidelites of an exterior door system.
A Complete Tear Out
Thisis where the entire assembly is removed right back to the rough opening and replaced with a completely new exterior door, patio door or skylight, including the frame.
Which Is Better?
Generally, a complete tear out will result in a more energy efficient installation as insulation, air barrier and weather seal will all be redone. This will ensure minimal heat loss and air leakage around the perimeter between the opening and the frame.