Abstract:
An interlocking roofing panel is disclosed. The panel has longitudinal edges and large and small dikes extending along these edges. These dikes interlock to form a standing seam. Upon installation, the top wall of the small dike is sufficiently spaced below the top wall of the first dike of an overlapping longitudinally adjacent panel, defining an &#34;upper gap,&#34; to interrupt movement of water between the dikes. Also, the small dike features a concave portion which opens towards the primary panel portion and the first dike has a linking portion, so that the linking portion extends into the concave portion while being sufficiently spaced within the concave portion, defining a &#34;lower gap,&#34; that, during installation, upward movement of the first dike relative to the small dike is permitted.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to roofing panels. More particularly, this invention relates to interlocking side-by-side roofing panels. 
     2. Description of the Related Art 
     The roof of a structure can be protected by a wide variety of roofing materials such as asphalt, slate, or metal. It is also known that the roof of a structure may be protected by a series of side-by-side interlocking roofing panels. 
     However, problems arise in trying to secure such panels to a roof so that they survive substantial wind conditions and the capillary action of water (and the problems it causes to the underlying roof structure). Other problems in the art include economically increasing the strength of the interlock while decreasing the amount of time and difficulty associated with installing such panels. This list is by no means exhaustive. 
     Some of the solutions suggested for solving these problems include: the use of tightly engaging seams (see, e.g., U.S. Pat. No. 5,247,772); the use of slip plates (see, e.g., U.S. Pat. No. 4,878,331) and clip connectors or clips (see, e.g., U.S. Pat. No. 4,102,105 and U.S. Pat. No. 4,099,356); the use of sealants (see, e.g., U.S. Pat. No. 4,106,250); and the use of novel geometries for defining the seam or interlock between two panels (see, e.g., U.S. Pat. No. 4,759,166 (return bend recess) and U.S. Pat. No. 4,106,250 (double-wall skirt member)). 
     The present invention is effective in addressing the prior art problems disclosed above. In addition, it is effective in addressing a problem which has received little, if any, attention to date. Specifically, the panel disclosed herein is effective in providing a sound, integral, leak-resistant roofing structure over nonplanar roofs. 
     Thus, it is an object of the present invention to provide a roofing panel which is not only effective in covering well-constructed roofing structures but is effective in protecting non-planar surfaces. 
     SUMMARY OF THE INVENTION 
     The present invention is an interlockingly joinable panel with longitudinally-adjacent panels of the same type. Each roofing panel comprises a first and a second longitudinal edge, a large dike extending along the first longitudinal edge and a small dike extending along the second longitudinal edge, a primary panel portion between the dikes, and a secondary panel portion between the small dike and the second longitudinal edge. 
     The small dike is sized to be received within the downwardly opening channel defined by the large dike of a longitudinally overlapping panel. When the large dike is &#34;snapped&#34; into place over the small dike, a standing seam is formed. 
     Upon installation, the top wall of the small dike is spaced sufficiently below the top wall of the large dike of an overlapping longitudinally adjacent panel that an upper gap is defined. Among other things, this upper gap interrupts movement of water between the dikes. 
     The standing seam defines a lower gap as well. The descending wall of the small dike defines a horizontally opening channel which opens towards the primary panel portion. The large dike has a linking portion that extends into the channel and is sufficiently spaced within the channel that a lower gap is defined. During installation, this lower gap permits upward movement of the large dike relative to the small dike. This is particularly significant in the case of nonplanar roof surfaces. 
     A number of fastening arrangements are also disclosed which are effective for securing the panels to the roof. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A better understanding of the present invention can be obtained when the following detailed description of the preferred embodiment is considered in conjunction with the following drawings, in which: 
     FIG. 1 is a perspective view of a building illustrating a plurality of the standing seam roofing panels of the present invention; 
     FIG. 2 is a perspective view of a roofing panel in accordance with the present invention; 
     FIG. 3 is a cross-sectional view of a roofing panel of the present invention; 
     FIG. 4 is a detail cross-sectional view of the standing seam of the present invention; 
     FIG. 5 is a detail top cut away view of the present invention; 
     FIG. 6 is a detail cross-sectional view of as taken along line 6--6 of FIG. 5; 
     FIG. 7 is a cross-sectional view of an alternate embodiment of the present invention; and 
     FIG. 8 is a detail view of the smaller dike of the present invention taken along line 8--8 of FIG. 7. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIGS. 1-2, FIG. 1 shows a building 9 having a roof 11 made up of standing seam roofing panels 10. Although FIG. 1 depicts a single panel spanning the length from the ridgeline to the eve of the roof, in many cases it is likely that several horizontal rows of similarly aligned panels would be used to completely span the slope of the roof. Referring to FIG. 2, each panel 10 is generally rectangular in shape and made of a rigid sheet of metal 12, preferably steel of 28 to 20 gauge metal, still more preferably steel of 26 to 24 gauge metal. Although steel of the stated gauge is preferred, it will be understood by those skilled in the art that other metals (e.g., aluminum, copper) and gauges may be employed. Each panel 10 has an upper surface 14 and a lower surface 16. A large (or upper) dike 24 projects upwardly from upper surface 14 along one longitudinal edge 20, and a small (or lower) dike 26 projects upwardly from the upper surface 14 along an opposing longitudinal edge 22. The portion of the panel between dikes 24 and 26 is termed the primary panel portion 10a; the remaining portion of the panel between the small dike and its longitudinal edge is called the secondary panel portion 10b. 
     Referring now to FIG. 3, portions of three panels (10&#39;, 10, 10&#34;) are shown. In FIG. 3, each of the panels is secured to a roof from left to right (although the panels may be installed in mirror-image fashion just as well from right to left if the orientation of each panel is reversed). As shown, the left-hand panel includes primed reference numerals (e.g., 10&#39;); the middle panel includes non-primed reference numerals (e.g., 10); and the right-hand panel includes double-primed reference numerals (e.g., 10&#34;). 
     Referring still to FIG. 3, small dike 26&#39; of left-hand panel 10&#39; is visible; this portion of the left-hand panel has been secured to a roof board 28 by means of fasteners 18&#39;. The next panel (middle panel 10) is secured in place in two ways. First, the large dike 24 is snapped into an interlocking relationship with small dike 26&#39; of left-hand panel 10&#39;, forming a standing seam (shown in detail in FIG. 4). Second, as in the case of the left-hand panel, the secondary panel portion 10b is secured to the roof board 28 by means of nails 18. Finally, note in FIG. 3 the large dike 24&#34; of the right-hand panel 10&#34; which is about to be snapped into position; like middle panel 10, panel 10 will be fully secured when fasteners 18&#34; are applied to its secondary panel portion 10b&#34; (not shown). 
     Referring now to FIG. 4, the standing seam of the present invention is shown. Large dike 24 projects upwardly along the length of first longitudinal edge 20, and a small dike 26&#39; projects upwardly along the length of an opposing second longitudinal edge 22&#39;. Large dike 24 includes an ascending wall 40, a top wall 42, and a descending wall 44; similarly small dike 26&#39; includes an ascending wall 46&#39;, a top wall 48&#39;, and a descending wall 50&#39;. 
     The interior of large dike 24 defines a downwardly opening channel 30; likewise, the interior of small dike 26&#39; forms a downwardly opening channel 32&#39;. Small dike 26&#39; has been sized so as to be received within channel 30. Furthermore, small dike 26&#39; and the large dike 24 have been sized in such a way (note the relative lengths of their ascending walls) that, upon installation, the top wall 48&#39; of small dike 26&#39; is sufficiently spaced below the top wall 42 of large dike 24 that an upper gap 34 is formed. Among other things, upper gap 34 serves to interrupt potential capillary movement of water between the dikes. 
     The engagement of small dike 26&#39; with large dike 24 also serves to define a lower gap 36. The descending wall 50&#39; of the small dike defines a horizontally opening channel (also termed a concave portion or linking channel) described by its upper wall 52, its middle wall 54, and its lower wall 56. This horizontally opening channel of the small dike opens towards the primary panel portion 10a. The large dike has a linking portion 58 extending from the bottom of the descending wall 44 of the large dike. In FIG. 4, linking portion 58 is a hook which extends into the horizontally opening channel defined by the small dike and is sufficiently spaced below the upper wall 52 of the horizontally opening channel to define lower gap 36. Lower gap 36 ensures that upward movement of large dike 24 relative to the small dike 26&#39; is permitted during installation. 
     Lower gap 36 also serves a number of other purposes. For example, it permits the installation of a panel 10 over nonplanar surfaces. Lower gap 36 also permits the removal of panels 10 following installation without significant damage. Finally, lower gap 36 relieves the effects of thermal expansion and contraction which have been problematic for roofing structures featuring tightly fitting panels. 
     Referring back to FIG. 3, large dike 24&#34; and small dike 26 are arranged so that the maximum width of downwardly opening channel 32 of small dike 26 (sometimes termed the &#34;bridge of the nose&#34;) is slightly greater than the maximum width W of the downwardly opening channel 30&#34; of large dike 24&#34;. This maximizes the stress between the large and small dikes which acts in a direction generally normal to the areas of contact between the dikes (the ascending and descending walls of the dikes). This provides frictional force which secures the panel in place once installed. 
     Referring now to FIGS. 5 and 6, an alternative fastening arrangement is shown. Fasteners 18 secure panel portion 10b to the roof board 28. Panel portion 10b in FIG. 6 includes a recessed section 60. This recessed section is adapted to receive fasteners 18 for securing the panel to the roof board and serves to prevent the head of the fasteners from indenting the top portion 10a of the adjacent panel, a problem commonly referred to as &#34;read through.&#34; 
     Recessed section 60 could take any number of shapes. Generally, local recessed section 60 includes a descending wall 70 and a bottom wall 72. The recessed section 60 includes a slot 62 for receipt of fastener 18. Slots 62 serve to accommodate and relieve thermal expansion and contraction of adjacent panels which occurs due to changes in temperature. 
     Referring now to FIGS. 7 and 8, an alternate embodiment of the panel and fastening arrangement is shown. Rather than employing a plurality of local recessed sections 60 as shown in FIG. 5, FIGS. 7 and 8 show a single recessed section, or longitudinal channel 64, to receive the fasteners. The channel 64 comprises a descending wall 74, a bottom wall 76, and an ascending wall 78 which generally describe a &#34;U&#34; shape. As shown in FIG. 8, an effective design includes a plurality of slots 62 which guide placement of the fasteners 18. 
     Whether or not the alternative fastening arrangement discussed above is used, some part of secondary panel portion 10b is likely to project somewhat above the plane of the upper surface of the roof board 28. If the panel is comprised of a particularly thin sheet of metal, or the metal is particularly malleable, the problem of &#34;read through&#34; of the fasteners will arise. That is, the head of the fastener will indent the top surface 14 of the primary portion 10a of the adjacent panel. If read through isn&#39;t expected, then the primary panel portion 10a may comprise a completely flat (i.e., planar) portion of the panel spanning from dike to dike. 
     If read through is expected, then a fastener dike may be employed. Referring back to FIG. 3, large dike 24 further includes a fastener dike 86 positioned over the secondary panel portion 10b of an underlapping adjacent panel. Fastener dike 86 comprises an ascending portion 88 and a top portion 90 which covers the fasteners below. Many users would consider a visually perceptible line generated by the ascending portion 88 to be a pleasant alternative to intermittent read through of the fasteners in the absence of the fastener dike. 
     Returning to FIG. 7, this panel 10a includes one or more structural indentations or ribs, here termed structural dikes 66, to provide additional strength to the panel. Dikes 66 comprise an ascending wall 80, a top wall 82, and a descending wall 84 which generally describe an inverted &#34;U&#34;. These dikes serve to significantly increase the panel&#39;s ability to carry a load. This capability may be important, for example, whenever the roofing panels are installed directly upon a plurality of roofing boards, rather than a continuous roofing surface or deck. 
     The foregoing disclosure and description of the invention are illustrative and explanatory only, and various changes in the size, shape, materials, and components, as well as in the details of the illustrated construction and method of operation, may be made without departing from the spirit of the invention.