Metal roof construction

DETAILED DESCRIPTION According to the invention, an improved, strengthened metal roof construction has been provided wherein the panels of the roof have a relatively flat central portion and have substantially vertically upstanding side walls.
The roof construction is secured to a plurality of roof support means, such as conventional purlins, and comprises a plurality of elongated panels joined together at the edges thereof, each panel having a relatively flat central portion flanked by a pair of upstanding substantially vertical side walls with inwardly directed flanges at the top portions thereof.
Means extend between adjacent panels and over the top of the inwardly directed flanges of the panel side walls for securing the panels to the roof support means.
An elongated batten strip is crimped around the joint between adjacent panels at the side wall flanges so that the side walls of the panels are in abutting relationship substantially along the entire height thereof.
According to the invention, an elongated, shallow step strengthening rib is formed in the panel central portion and extends the length of each panel in closely adjacent relationship to each side wall thereof.
The step rib is shallow enough so as to maintain the relatively flat nature of the panel central area and is positioned with respect to the side walls so that flexure of the panel central portion under high upward stress takes place at the strengthening rib.
Further, the step rib is so shaped and positioned that it strengthens the base of the side wall against buckling, thereby significantly decreasing the buckling of the panels at the bottom portion of the side walls under high upward stresses.
The size, shape and position of the step strengthening ribs are quite important in providing the needed strength to achieve high wind ratings.
The perameters will vary depending on the relative sizes of the central and side wall portions of the panels.
Each of the ribs is in the nature of a small step which can extend above or below the plane of the panels at the edges of the side walls