The present invention relates to a roof system for installation on an existing roof. The existing roof has a plurality of open web steel joists with an existing metal deck thereon. The roof system includes a plurality of deck straps, a roof deck and roofing and insulation. The plurality of deck straps are attached to the open web steel joist through the existing metal deck. The deck straps have a plurality of alternating lower portions and upper portions. The lower portions are attached to the open web steel joist. The upper portions extend upwardly of the existing metal deck. The roof deck is attached to the upper portions of the continuous deck strap. The roofing and insulation is attached to the roof deck.