The present concept is a method of roofing a bare roof deck. Asphalt shingles and metal flashings are applied to a wood deck of a roof before flashings and asphalt capping are applied. Metal panels are applied overtop of existing asphalt roof, thereby creating a metal overlay configured such that substantially all of the asphalt shingles are covered with a metal panel for preventing further degradation of asphalt components by shielding from sunlight, UV rays, excessive moisture, snow, wind, ice and fire. No further flashings are installed thereby the metal panel overlay creates a semi-watertight seal wherein the metal panel overlay together with asphalt roof is adapted to create a watertight seal. The present concept is also a method for roofing an existing asphalt shingled roof where metal panels are applied overtop the existing asphalt shingled roof. This creates a metal overlay that covers substantially all of the asphalt shingles for preventing further degradation of asphalt components, and provides a method of preserving an asphalt shingled roof.