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CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This is a Continuation of U.S. application Ser. No. 12/055,464, filed Mar. 26, 2008. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    It is known to use snow guards on roof structures, particularity in northern climates, where the weather conditions are such that snow and/or ice accumulates on roofs. Snow guards are used, most particularly when the roofs are steeply sloped, to provide protrusions or outwardly extending platforms that protrude outwardly and upwardly, generally perpendicular to the slope of the roof, to engage snow or ice that may accumulate on the roof, to keep sheets of snow or ice from sliding down the roof, off the roof, possibly causing damage to people, shrubs, etc. 
         [0003]    Typically, snow guards have, in addition to the protrusion or platform, a base that is disposed between underlying and overlying shingles on the roof. It is generally known that in colder climate conditions, snow guards are installed as the roof is built up, being placed over an underlying shingle or shingles in a course, prior to installing the next-overlying shingle in its overlying course. 
         [0004]    Most particularly, it is known that snow guards are desirable on steeply sloped roofs wherein the shingles on the roof are of natural slate or natural tile, being made of materials that are very rigid, often having outer weather-engaging surfaces that can be smooth, allowing snow or ice that accumulates on the outer surfaces of such shingles or tiles to slide downwardly along the highly sloped surface of the roof, most particularly as the snow or ice begins to thaw, with the protrusions or platforms of the snow guards engaging the snow or ice and breaking up large sheets of the same into smaller, generally harmless pieces of snow or ice not readily capable of causing damage to personnel, plants, bushes, etc. 
         [0005]    Where a roof is made up of naturally occurring materials, such as slate, shake or tile, it is known to install snow guards as the roof is being laid up, on top of courses of such roof materials that have already been applied, prior to applying an overlying course of such rigid slate, shake, or tile shingles thereover. However, in the case of an already-installed roof of rigid natural slate, shake, or tile shingles, if snow guards are later desired to be installed, it can become necessary to remove some shingles of slate, shake, or tile construction so that the same can be lifted upwardly an amount to install snow guards therebeneath, between shingles in two underlying-overlying courses. Where such slate, shake, or tile shingles of natural materials are rigid, they can break as they are being lifted upwardly. In the absence of breaking it becomes necessary to remove the nails or fasteners for such shingles an amount sufficient to raise such shingles upwardly to enable placement of a snow guard therebeneath, and then to re-fasten such rigid naturally occurring shingles back down to the roof. 
       The Present Invention 
       [0006]    The present invention is directed to providing snow guards for use with synthetic, generally thermoplastic materials that are either being installed on a roof, or when already-installed on a roof, such that the shingles are made so that they can be flexibly bent upwardly an amount within their elastic limit to permit insertion of snow guards under tab portions of shingles, wherein the snow guards have hooks thereon that engage behind shingles in a next-underlying course, and with the shingles that have been lifted upwardly, flexibly bent within their elastic limit, being then allowed to return to their original generally planar configuration, back down over the snow guard, leaving a protruding or platform portion of the snow guard disposed beneath the shingle, the tab portion of which had been flexibly bent upwardly. 
         [0007]    Accordingly, it is an object of this invention to provide a roof structure comprised of a roof base, synthetic shingles of thermoplastic material, and snow guards having hooks at their upper ends and protruding portions, such as platform portions protruding outwardly at their lower ends, beyond the shingled roof in the installed condition, wherein the shingles are sufficiently resiliently flexible to allow the snow guards to be inserted between overlying and underlying shingles after the shingles have been installed on a roof, without breakage of the shingles and without requiring partial or full removal of fasteners holding such shingles to the roof. 
         [0008]    It us a further object of this invention to provide a method of installing snow guards on a roof, consistent with the roof structure described above. 
         [0009]    It is yet another object of this invention to provide a roof structure and a method of installing snow guards on a roof structure, wherein the resilient flexibility of the synthetic shingle is sufficient to permit installing the snow guards with their protruding platforms temporarily beneath the uplifted roof shingles, so that downwardly and rearwardly facing hooks of the snow guards can engage over upper edges of next-underlying shingles in a course, and then to slide the roof guards downwardly, parallel to the slope of the roof out beyond the lower edge of an upwardly lifted synthetic shingle, allowing the shingle to return to its original position flat against the underlying shingle or shingles on a roof, and overlying a base portion of the snow guard that connects the hook and the outwardly protruding platform portion thereof, such that the platform portion of the snow guard engages at or below the lower edge of the temporarily upwardly bent shingle after that shingle is returned to its original position. 
         [0010]    It is another object of this invention to provide snow guards with hooks that have beveled edges, either inwardly beveled, or outwardly beveled in the hook portion. 
         [0011]    It is yet a further object of this invention to provide snow guards for installation as described above, wherein the hooks are adapted to be resiliently or springingly engaged behind one or more shingles in a next-underlying course, when the snow guards are installed. 
         [0012]    It is a further object of this invention that the synthetic shingles have tracks or ribs on their rear surfaces for allowing sliding movement of snow guards that are being applied, upwardly along a said track, and that after the shingles are installed, the tracks can function to inhibit lateral movement of snow guards relative to overlying shingles. 
         [0013]    Other objects and advantages of the present invention will be readily apparent upon a reading of the following brief descriptions of the drawing figures, the detailed descriptions of the preferred embodiments, and the appended claims. 
     
    
     
       BRIEF DESCRIPTIONS OF THE DRAWING FIGURES 
         [0014]      FIG. 1  is a plan view of a sloped roof having a plurality of courses of synthetic shingles of thermoplastic materials applied thereto, with the roof being fragmentally illustrated, and wherein snow guards are shown with their platforms disposed below lower edges of applied shingles. 
           [0015]      FIG. 1A  is an illustration similar to that of  FIG. 1 , but wherein it is illustrated how snow or ice, when sliding downwardly along the highly sloped roof surface, can engage against outwardly protruding platforms of snow guards, and become broken-up into smaller, harmless pieces. 
           [0016]      FIG. 2  is an enlarged fragmentary side elevational view of a portion of the roof of  FIG. 1 , taken generally along the line III-III, showing an upwardly lifted synthetic thermoplastic shingle, that is flexibly bent upwardly an amount within its elastic limit, to permit insertion of a snow guard thereunder, with the snow guard to be slid upwardly beneath the shingle while overlying a shingle in a lower course. 
           [0017]      FIG. 3  is an illustration similar to that of  FIG. 2 , also taken generally along the line III-III of  FIG. 1 , but wherein the upwardly lifted, flexibly bent overlying shingle, shown in phantom, has been allowed to return to its original flattened position against the roof, sandwiching a base portion of the snow guard therebetween, and wherein the snow guard has had its hook at its upper end slid downwardly to engage behind the upper edge of an underlying shingle, and with the snow guard then being pulled downwardly to allow complete return of the overlying shingle against the base of the snow guard, and above the outwardly protruding platform thereof. 
           [0018]      FIG. 3A  is an enlarged detailed view of a portion of  FIG. 3 , showing more clearly the engagement of the hook of the snow guard beneath the upper end of a butt portion of a shingle in a next-underlying course. 
           [0019]      FIG. 4  illustrates a pair of synthetic shingles of thermoplastic material in accordance with this invention, arranged side-by-side in a given course, and with a snow guard installed therebetween, between opposing side edges of butt portions of the shingle, and with a next-overlying shingle being shown in phantom thereover, such that the snow guard itself may be seen in the installed condition, with greater clarity. 
           [0020]      FIG. 5  is an illustration of a prior art type of snow guard, having a straight upper end, to receive a fastener therein, and it is the type of a snow guard that can be used on a roof as a roof is being installed, to be fastened over a next-underlying shingle in a given course, prior to installation of a next-overlying course of shingles, wherein the shingles that are used with the type of snow guard of  FIG. 5 , are generally very rigid, being constructed of naturally occurring materials such as slate, shake, or tile, that are not flexibly bendable within their elastic limit either at all, or at least not an amount sufficient to install the snow guard of  FIG. 5  after the roof is installed. 
           [0021]      FIG. 5A  is a side elevational view of the shingle of  FIG. 5 . 
           [0022]      FIG. 5B  is an illustration of a snow guard made in accordance with this invention, prior to bending the upper end of the snow guard into a hook formation prior to installing it with a hook behind a next-underlying shingle, in accordance with this invention. 
           [0023]      FIG. 5C  is a side elevational view of the snow guard of  FIG. 5B , after the upper end of the snow guard is bent into a hook configuration, and with the hook configuration shown in engagement behind a next-underlying shingle on a roof, and wherein the next-overlying flexibly bent tab portion of the shingle is shown in phantom and in full line positions, illustrating, respectively, the upward bend of the relatively flexible portion of a shingle in accordance with this invention, and its return to its permanent position overlying the base of the snow guard. 
           [0024]      FIGS. 5D ,  5 E,  5 F,  5 G,  5 H and  5 I are fragmentary portions of upper ends of snow guards for use in accordance with the present invention, whereby various bevels, bends and constructions for facilitating engagement of the upper ends of snow guards behind upper ends of butt portions of next-underlying shingles in a course are illustrated, as will be described in more detail hereinafter. 
           [0025]      FIG. 6  is a generally vertical section, taken through shingles and a snow guard in accordance with this invention, generally along the line VI-VI of  FIG. 1 , and wherein a fragmentary portion of a roof, with shingles thereon are shown fragmentally and with a snow guard installed in a track between ribs of a next-overlying shingle in accordance with this invention, are clearly illustrated. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0026]    Referring now to  FIG. 1  in detail, it will be see that a roof structure is illustrated, generally designated by the numeral  20 , with the structure comprising a fragmentary portion of a roof base  21 , steeply sloped as will be seen hereafter with reference to  FIGS. 2 and 3 , with a plurality of courses of synthetic shingles of thermoplastic materials applied thereto, with each course such as those  22 ,  23 ,  24 ,  25  and  26  being applied such that tab portions  27  of shingles, all generally identified by the numeral  28  in  FIG. 1 , are shown in overlying relation to butt portions  30  of underlying shingles. 
         [0027]    The thermoplastic shingles  28  are each preferably constructed of a thermoplastic resin material which may or may not have fillers therein, and which may or may not have reinforcement materials therein, such as lengths of fiber, for additional strength. The shingles  28  will also preferably be molded or shaped to simulate natural slate, tile or shake materials that are generally not flexible, although the shingles  28 , while simulating natural materials, will have sufficient flexibility that they can be upwardly, flexibly bent an amount within their elastic limit to permit insertion of snow guards therebeneath, and allow for retraction to their original, generally flattened or original configurations that existed prior to being flexibly bent upwardly, after the upward force that flexibly bends them is removed. 
         [0028]    The synthetic shingles may, if desired have separate materials for their core and capstock (outer, weather exposed portions, if desired). 
         [0029]    Each shingle  28  has an upper edge  31 , a lower edge  32 , a right edge  33 , and a left edge  34 . Right and left edges of adjacent shingles may be slightly spaced apart as shown at  35 , between their butt portions  30 . The shingles  28  may also have slots  36  between their right and left edges of their tab portions when the shingles  28  are disposed adjacent each other, as shown in  FIG. 1 . A plurality of snow guards  40  are shown between adjacent ones of the shingles. 
         [0030]    With reference now to  FIG. 1A , it will be seen that, as snow or ice  41  accumulated on the roof  20  begins to break apart, large pieces, clumps or sheets  42  thereof may break away, falling therefrom, as shown by the arrows  43  in  FIG. 1A , downwardly, to engage platform or protrusion portions  45  of the snow guards  40  as shown in  FIG. 1A , whereby the pieces, clumps or sheets  42  of snow or ice are broken up into smaller pieces or particles  46  as shown, which can then fall downwardly off the lower end of the roof, without damaging people, plants or shrubs. 
         [0031]    With respect to the enlarged fragmentary illustration of  FIG. 2 , it will be noted that the roof base  21  is illustrated, as having shingles  28  in an overlying course, with their tabs portions  27  overlying butt portions of shingles  28  in an underlying course. 
         [0032]    For ready reference, the illustrated shingle in  FIG. 2  that is in an overlying course is indicated as shingle  28 ′, and the shingle in the underlying course is denominated shingle  28 ″. 
         [0033]    As shown in  FIG. 2 , the shingle  28 ′ has its tab portion lifted arcuately upwardly, being flexibly bent, as shown, in the direction of the arrow  50 , such that the tabs portion of the shingle  28 ′ is moved from the phantom line position  28 ″′ therefor, to the full line position, therefor, as shown in  FIG. 2 . 
         [0034]    With the shingle  28 ′ flexibly bent upwardly as shown in  FIG. 2 , the snow guard  40  can be moved from its full line position therefor shown in  FIG. 2 , to be slid upwardly beneath the flexibly upwardly bent tab portion  27  for the shingle  28 ′ such that the downwardly bent hook  51  of the upper end  52  of the snow guard  40  can be moved upwardly in the direction of the arrow  53 , overlying the butt portion of the shingle  28 ″′, to engage behind the upper edges  31  of two adjacent shingles  28 ″ (as shown in  FIG. 3 ). It will be noted that, in some embodiments, the amount “D” of upward bend for the shingle  28 ′ as shown in  FIG. 2  in the direction of the arrow  50  is greater than the dimension D′ shown in  FIG. 2 , for the outward protrusion of the platform portion  54  of the snow guard  40 , to allow for movement of the snow guard  40  upwardly in the direction of the arrow  53  an amount that the platform portion  54  of the snow guard  40  can be beneath the upwardly bent portion of the shingle  28 . The snow guard  40  has an optional protuberance  29  extending between spaced apart opposing edges of tab portions of underlying shingles, as shown, which can effectively inhibit lateral movement leftward and rightward of installed snow guards. 
         [0035]    With reference now to  FIG. 3 , it will be seen that the hook  51  of the snow guard  40  is in place, beyond and around the upper edges  31  of the butt portions of the underlying shingles  28 ″, and that the snow guard  40 , with its base  55  that connects the hook portion  51  and platform portion  54  has now been slid vertically downwardly in the direction of the arrow  56 , such that the outwardly protruding platform portion  54  is now at a sufficiently low level with the hook  51  engaged over the upper edges  31  of the shingles  28 ″, such that the upwardly flexibly bent tab portion of the overlying shingle  28 ′ that is shown in phantom in  FIG. 3  can now be allowed to return downwardly into an overlying full line position therefor, shown at  57 , overlying the snow guard base  55  and overlying the butt portions of shingles  28 ″, such that, due to its inherent memory, the upwardly flexibly bent tab portion of the shingle  28 ′ also overlies the butt portions of the underlying shingles  28 ″, with the lower edge  32  of the shingle  28 ′ disposed just above the platform  54  of the snow guard  40  as shown. 
         [0036]    In cold weather conditions, or whenever shingles  28  become somewhat brittle, an application of heat via a blow dryer or some other heating device may be helpful to make the resilient shingle more flexible, so that cracking of the shingle is avoided when the shingles are upwardly bent for installation of snow guards. 
         [0037]    With respect to  FIG. 3A , the detail enlargement shows more clearly that the hook  51  is disposed behind the upper edges  31  of the butt portions of the shingles  28 , as is the return to flattened position of tab portion  57  of the overlying shingle via inherent memory of the tab portion  57  of the overlying shingle  28 ′. 
         [0038]    Referring to  FIG. 4  in detail, it will be seen that a pair of side-by-side adjacent shingles  28  are illustrated in the same course, with the base  55  of a snow guard disposed between opposed side edges  33 ,  34  of the shingles  28 , in the space  35  between those shingles, and with the snow-engaging platform portion  54  of the snow guard  40  being disposed immediately beneath and substantially adjacent to a lower edge  32  of a next-overlying shingle  28 , shown in phantom, so that it can be seen how the base  55  of the snow guard  40  extends between right and left edges of butt portions of adjacent shingles, so that the adjacent shingles  28  can inhibit lateral movement leftward and rightward, of installed snow guards, when the installed snow guards are in their installed position as shown in  FIG. 4 . Alternatively, the base  55  of a snow guard can overly the butt portions of the shingles  28 , overlying the side edges  33 ,  34  thereof. 
         [0039]    With reference now with  FIG. 5  and  FIG. 5A , a prior art type of snow guard  63  is illustrated, with a projecting platform portion  61 , connected to an upper end  62  thereof, by a base  60 . The base  60  also carries an angular support  64 , for supporting the platform portion, as shown, as does the snow guard of the present invention. 
         [0040]    However, at the upper end  62  of the snow guard  63 , there is shown a nail or other fastener hole  65  for fastening the snow guard  63  over an underlying course of shingles, when shingles of a very rigid type, such as natural slate, shake or tile that are being applied to a roof (not shown). In such types of installations, the base  60  overlies a shingle lying therebeneath or extends between adjacent shingles in a course, and the upper end is secured to the base roof surface by means of nails or other fasteners applied through holes  65  in the snow guard base  60 , such that the snow guard  63 , as a practical matter, can only be installed during the original installation of rigid, non-flexible shingles of such natural materials or rigid synthetic materials resembling natural materials. 
         [0041]    With reference now to  FIG. 5B , a snow guard  70  is illustrated, having a base  71  connecting the platform portion  72  thereof to the upper end  73  of the snow guard  70 , with an angular support  74  also provided. However, with the snow guard of  FIG. 5  B, the upper end is sufficiently long that it can be reversely bent back on itself, as shown in  FIG. 5C  to provide a hook  75  to be disposed over the upper end of a shingle  28 , as shown, when a tab portion  76  of a next-overlying shingle that has been resiliently upwardly bent within its elastic limit as shown in phantom in  FIG. 5C , to allow the insertion of the snow guard  70  therebeneath, as is discussed above with reference to  FIGS. 2 ,  3  and  3 A, after which the upwardly bent portion  76 , shown in phantom, is allowed to relax into a position overlying the snow guard, as shown by the full line illustration  77  of the tab portion of the overlying shingle. 
         [0042]    With reference now to  FIGS. 5D ,  5 E,  5 F,  5 G,  5 H and  5 I, a plurality of alternative embodiments for the hook portion of each of the snow guards of the present invention will now be illustrated. 
         [0043]    In  FIG. 5D , the snow guard  80  has a hook  81  that has a bevel  82  on the right end of the hook  71  of the snow guard, for facilitating and sliding of the same behind a next-underlying shingle, or plurality of shingles, in a course. 
         [0044]    In  FIG. 5E , a snow guard  84  is shown with its hook  85  also having a bevel  86  on its outer end, cut more pointedly than that shown in  FIG. 5D , but otherwise functioning similarly thereto, when installed behind the upper edge of a next-underlying shingle. 
         [0045]    In  FIG. 5F , a snow guard  88  has a bevel  90  on the inside of the hook  91 , also to facilitate its disposition behind the upper end of a next-underlying shingle to facilitate sliding of the same behind a perhaps somewhat thicker shingle. 
         [0046]    With respect to  FIG. 50 , the upper end of a snow guard  93  is shown, with its hook  94  being arcuately bent, and having a lower portion  95  thereof that is at an angle “a”, as shown, to the upstanding surface  96  of the rear of the base portion of the snow guard  93 , such that the edge  97  of the hook  94  may frictionally engage behind the next-underlying shingle, over which the hook of the snow guard  93  is installed, for secure, frictionally-engaged fastening of the hook behind that shingle. 
         [0047]    In  FIG. 5H , an alternative upper end of the snow guard  100  is shown, in which the hook portion  101  thereof is arcuately bent as shown at  102 , to facilitate greater flexibility in bending a snow guard as shown in  FIG. 5B , to have a hook portion thereof formed in the field from an otherwise straight base snow guard as shown in  FIG. 5B , rather than having the hook formed at a site of snow guard manufacture. 
         [0048]    In  FIG. 5I , yet another alternative upper end  110  of a snow guard  111  is shown, whereby its hook  112  is formed by first bending a portion  113  of the upper end at an angle to the left surface  114  of the snow guard of  FIG. 5I , whereby the angled portion  113  can more readily enable retrofitting an installation of previously applied synthetic slates or tiles on a roof, whereby the angled portion  113  can more readily slide under the next-overlying tab of a shingle. Preferably, the embodiment of  FIG. 5I  would be used with a shingle having a hollowed or ribbed undersurface, to be readily slid beneath the same, preferably within a track thereof, for example, between ribs of a hollowed-out structure, as will be addressed hereinafter with respect to  FIG. 6 . The sloped portion  113 , with the downwardly bent hook  112  encourages a spring-loaded lock during installation and reduces or eliminates the marring of surfaces of the shingle over or under which the snow guard is applied, minimizing the likelihood of damage due to scraping of a portion of the snow guard thereagainst. 
         [0049]    Any of the snow guards of  FIGS. 5D ,  5 E,  5 F,  5 G and  5 I can have their upper ends arcuately bent like the bend  102  shown in  FIG. 5H . Also, the hook portion  101  of the snow guard of  FIG. 5H  could be tapered or configured like any of the hook portions of any of the snow guards of  FIGS. 5D ,  5 E,  5 F, 5 G, and  5 I. The bending of any of the snow guards to form hooks can occur at any time, including during manufacture of the snow guard in a manufacturing installation or on site of installation of the snow guards on a roof. Also, the bending can, on some occasions, occur on site to reflect a bend that is dependent upon the height of the shingle between its upper and lower edges, especially in the situation of previously-installed shingles, where the bending would normally occur in the field, or at the site of application of the snow guards on a roof. 
         [0050]    With reference now to  FIG. 6 , it will be seen that a shingle  28  is applied to a roof base  21 , as described above, but wherein the shingle  28  has a plurality of tracks  115  in its lower surface, which tracks are formed by generally vertically disposed ribs  116  that form stand-offs between one or more underlying surfaces  120 ,  121  (such as the underlying shingles  122 ,  123 ) and the undersurface of the shingle  28 . By inserting the bases of the snow guards  40  in this manner, in tracks  115  after the shingles have been installed on a roof, and beneath the tab portions of shingles  28  that are flexibly bent outwardly within their elastic limits, the tracks  115  with their ribs  116 , form a guiding medium for sliding the bases  55  of snow guards upwardly from a lower edge of an overlying shingle, up over the upper edge of a next-underlying shingle, for facilitating engagement of the hook (not shown) of the snow guard  40  shown in  FIG. 6  behind the rear surface of the butt portion of a next-underlying shingle. 
         [0051]    In a case where all shingles  28  are of the same dimension, snow guards may be centered under the overlying course or over or within the gap between adjacent shingles of the underlying course. If the width of shingles varies then the “tracks” could help in placement of the snow guards. In a case where all shingles are the same size, tracks guide the snow guards between adjacent shingles of an underlying course, as does the gap between the shingles of the underlying course. When varying widths of shingles are employed, tracks formed from ribs of a hollowed-out structure act as guides or installation tracks to assist in placement of the snow guards. The tracks can also assist in redusing lateral movement of installed snow guards. 
         [0052]    It will be apparent for the foregoing that various modifications may be made in the details of construction as well as in the use and operation of the components of this invention, all within the spirit and scope of the invention as defined in the appended claims.

Summary:
A roof structure and a method of installing a snow guard on the base of a roof is provided, wherein the roof structure includes a plurality of synthetic shingles of thermoplastic materials, and where a snow guard is provided having an outwardly projecting snow-engaging platform and an oppositely provided hook at an upper end, wherein the hook is adapted to engage over and upper edge of a butt portion of one or more shingles in an underlying course of shingles, and wherein a tab portion of a shingle in a next-overlying course of shingles is disposed over the upper end of the snow guard, substantially covering its base, and wherein the snow-engaging platform is adapted to receive snow and ice that may slide down the roof, to intercept the same or break the snow or ice up into small harmless particles. The synthetic shingles of thermoplastic materials allow for the upward bending of the overlying tab portions of shingles a substantial amount within their elastic limit, to permit insertion of snow guards under tab portions of overlying shingles, where such tab portions of overlying shingles are already-installed on a roof, followed by a relaxation of the upwardly bent tab portions of shingles back to a flattened condition overlying the butt portions of shingles in an underlying course of shingles, and overlying the base of the snow guard between the platform and hook, due to the inherent memory of the original flattened shape of the shingles that have their tab portions flexibly upwardly bent.