Insulating secondary roof system

An insulative secondary roof system for installation over an existing metal roof having a plurality of structural roof panels, each panel having an elongate rectangular flat portion, the flat portion having an upturned edge along each longitudinal side thereof, the upturned edge being contiguous with an upturned edge of an adjacent panel and joined thereto, whereby each panel forms a rectangular channel, the secondary roof system comprising:

• a plurality of elongate, rectangular insulating panels, each of said insulating panels having a width approximately equal to the width of the existing roof channel and a thickness approximately equal to the depth of the channel, said insulating panels disposed in the existing roof panels in total contact with the flat portion of the roof panels;
• a plurality of elongate, rectangular secondary metal panels, one of said metal panels disposed over each of said insulation panels, each of said secondary metal panels having upturned edges, one of said edges having an inverted L-shaped portion and the other edge having an inverted U-shaped portion, said U-shaped portion of each of said secondary panels formed to fit over said L-shaped portion of its adjacent one of said secondary panels to thereby interlock with each other, said inverted U-shaped portion adapted to fit over and to contact the joints of said existing metal panels;
• and
• a plurality of screws driven through said inverted U-shaped portions, said inverted L-shaped portions, and said existing metal panel joints for securing said secondary panels to said existing roof structure.