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.

A roof panel includes a planar body having top and bottom edges, with a downturn edge extending therebetween, and an opposing channel edge. The downturn edge overlays a channel edge of an adjacent panel. The bottom edge overlays a top edge of another adjacent panel. A plurality of courses extends between the channel and downturn edges. Each course includes a nesting ridge to receive the downturn edge of an adjacent panel and to position a top surface of the panel flush with adjacent panels. Surface channels and contoured ridges are defined within each course. A drain aperture of the drip edge aligns with an adjacent channel edge to direct material through the drain aperture and onto adjacent panels. A gable member engages an edge when the panel has one or fewer laterally adjacent panels, wherein the gable member is flush with the adjacent planar body.

A roof ridge shingle unit including: a substantially elongated cover element shaped like a plurality of shingles longitudinally overlapping partially each other and having a substantially inverted V-shaped transversal cross-sectional configuration defining a pair of opposed side edges and a zenith ridge extending longitudinally therealong between the side edges, the cover element defining a top surface and an opposed bottom surface, the cover element defining longitudinally opposed first and second ends; and a first end attachment provided substantially adjacent the first end and a second end attachment provided substantially adjacent the second end. The first and second end attachments are configured and sized so that the first end attachment of the roof shingle unit is attachable to the second end attachment of a similar roof shingle units so that the roof ridge shingle units are secured to each other in a predetermined positional relationship relative to each other.