Patent Publication Number: US-6698151-B2

Title: Shingle for optically simulating a tiled roof

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a division of application Ser. No. 09/429,940, filed Oct. 29, 1999, the contents of which are incorporated herein by reference now U.S. Pat. No. 6,421,976. 
    
    
     TECHNICAL FIELD AND INDUSTRIAL APPLICABILITY OF THE INVENTION 
     This invention relates in general to a shingle, and in particular, to a laminated roofing shingle including an overlay with various cutouts and an underlay with a shadow line such that the shingle operates to optically simulate the three dimensional ridges and valleys of a tiled roof when laid on a roof. 
     BACKGROUND OF THE INVENTION 
     In the past, roofing shingles have had to satisfy two main functions when applied to a roof deck. The first function is to provide a durable, weatherproof covering for the roof deck. Roof shingles, whatever their form, are intended to provide a means of sheltering the structure below the shingles from precipitation and the deleterious effects of sun and wind. Roof shingles installed on the roof deck must perform these protecting functions for a reasonable period of time. The second function is to present an aesthetically pleasing architectural feature which enhances the overall appeal of the structure to which the shingles have been applied. This aesthetic function has been satisfied by providing asphalt shingles with various butt edge contours and surface treatments which operate to simulate more traditional, and in most cases more expensive, forms of roof coverings, such as, thatch, wooden shakes, slates, and even tiles of various forms. 
     However, none of the prior art shingles have been able to combine the protective and aesthetic functions while providing a laminated, asphalt shingle that simulates a tile roof on a practical production scale. 
     SUMMARY OF THE INVENTION 
     This invention relates to a laminated shingle. The laminated shingle comprises an overlay member having a front surface, a rear surface, an upper portion and a lower portion. The upper portion includes a layer of granules on the front surface forming a first, darker shading area. The lower portion includes one or more tabs separated by cutouts. Each tab extends from a lower boundary of the upper portion to a lower edge. The lower edge has a generally curved contour. An upper edge of each cutout has a generally straight contour. The laminated shingle further comprises an underlay member having a front surface. The front surface is fixedly attached to the rear surface of the overlay member. The underlay member includes a layer of granules on the front surface forming a second, darker shading area. The underlay member further includes a lower edge. A portion of the lower edge has a generally curved contour. Each tab of the overlay member covers the second, darker shading area of the underlay member. 
     In another aspect of the invention, a laminated shingle comprises an overlay member having a front surface, a rear surface, an upper portion and a lower portion. The lower portion includes one or more tabs separated by cutouts. Each tab extends from a lower boundary of the upper portion to a lower edge. The lower edge has a generally curved contour. An upper edge of each cutout has a generally curved contour. The laminated shingle further comprises an underlay member having a front surface. The front surface is fixedly attached to the rear surface of the overlay member. The underlay member includes a layer of granules on the front surface forming a darker shading area. The underlay member further includes a lower edge having a generally straight contour. Each tab covers the darker shading area of the underlay member to optically simulate the three dimensional ridges and valleys of a tiled roof when the underlay member is fixedly attached to the overlay member. 
     In yet another aspect of the invention, a laminated shingle comprises an overlay member having a front surface, a rear surface, an upper portion and a lower portion. The lower portion includes one or more tabs separated by cutouts. Each tab extends from a lower boundary of the upper portion to a lower edge. The lower edge has a generally curved contour. An upper edge of each cutout has a generally straight contour. The laminated shingle further comprises an underlay member having a front surface. The front surface is fixedly attached to the rear surface of the overlay member. The underlay member includes a lower edge having a generally straight contour. 
     In another aspect of the invention, a composite laminated shingle comprises an overlay member having front and rear surfaces. The overlay member includes a headlap portion and a butt portion. The headlap portion includes a lower boundary portion of a generally straight contour. The butt portion includes a plurality of tabs separated by cutouts. Each tab extends in length from the lower boundary of the headlap portion to a lower edge to define a butt edge of the shingle. The lower edge of each tab has a generally curved contour. The shingle further comprises an underlay member having a front surface fixedly attached to the rear surface of the overlay member. The underlay member includes a lower edge, a portion of the lower edge having a generally curved contour corresponding to the lower edge of each tab and exposed portions extending between the tabs of the overlay member in the cutouts that separate the tabs. A lower edge of the exposed portions defines a portion of the butt edge of the shingle having a generally straight contour. The shingle operates to optically simulate the three dimensional ridges and valleys of a tiled roof when laid on a roof with other substantially identically shaped shingles in overlapping longitudinal courses in a predetermined assembly in which one of the tabs and cutouts of the identically shaped shingles in each course are vertically aligned with each other. 
     In yet another aspect of the invention, a roof covering includes a plurality of successive generally horizontal courses of laminated shingles. The shingles in each course are laid in a side-by-side relationship and horizontally offset from the shingles in adjacent courses. Each laminated shingle comprises an overlay member having front and rear surfaces. The overlay member includes a headlap portion and a butt portion. The headlap portion includes a lower boundary portion of a generally straight contour. The butt portion includes a plurality of tabs separated by cutouts. Each tab extends in length from the lower boundary of the headlap portion to a lower edge to define a butt edge of the shingle. The lower edge of each tab has a generally curved contour. The shingle further comprises an underlay member having a front surface fixedly attached to the rear surface of the overlay member. The underlay includes a lower edge. A portion of the lower edge has a generally curved contour corresponding to the lower edge of each tab, and exposed portions extending between the tabs of the overlay member in the cutouts that separate the tabs. A lower edge of the exposed portions defining a portion of the butt edge of the shingle having a generally straight contour. The shingle operates to optically simulate the three dimensional ridges and valleys of a tiled roof when laid on a roof with other substantially identically shaped shingles in overlapping longitudinal courses in a predetermined assembly in which one of the tabs and cutouts of the identically shaped shingles in each course are vertically aligned with each other. 
     Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded view of a shingle for optically simulating a tiled roof according to a first preferred embodiment of the invention; 
     FIG. 2 is a top planar view of the completed shingle of FIG. 1; 
     FIG. 3 is a top planar view of a portion of a roof deck covered with the shingles of FIG. 1; 
     FIG. 4 is a perspective view of a portion of a roof deck covered with the shingles of FIG. 1; 
     FIG. 5 is an exploded view of a shingle for optically simulating a tiled roof according to a second preferred embodiment of the invention; 
     FIG. 6 is a top planar view of the completed shingle of FIG. 5; 
     FIG. 7 is a top planar view of a portion of a roof deck covered with the shingles of FIG. 5; 
     FIG. 8 is a perspective view of a portion of a roof deck covered with the shingles of FIG. 5; 
     FIG. 9 is an exploded view of a shingle for optically simulating a tiled roof according to a third preferred embodiment of the invention; 
     FIG. 10 is a top planar view of the completed shingle of FIG. 9; 
     FIG. 11 is a top planar view of a portion of a roof deck covered with the shingles of FIG. 9; 
     FIG. 12 is a perspective view of a portion of a roof deck covered with the shingles of FIG. 9; 
     FIG. 13 is an exploded view of a shingle for optically simulating a tiled roof according to a fourth preferred embodiment of the invention; 
     FIG. 14 is a top planar view of the completed shingle of FIG. 13; 
     FIG. 15 is a top planar view of a portion of a roof deck covered with the shingles of FIG. 13; and 
     FIG. 16 is a perspective view of a portion of a roof deck covered with the shingles of FIG.  13 . 
    
    
     DETAILED DESCRIPTION AND PREFERRED EMBODIMENTS OF THE INVENTION 
     Referring now to the drawings, there is illustrated in FIGS. 1-4 a shingle, shown generally at  10 , according to a first preferred embodiment of the invention. Referring now to FIGS. 1 and 2, the shingle  10  is of a type of roofing shingle generally known as a laminated type shingle consisting of an overlay member  12  and an underlay member  14 . The overlay and underlay members  12 ,  14  are preferably constructed of a suitable mat of fiberglass or other construction that is permeated with a preferably asphaltic substance of a type well-known in the art. Typically, a plurality of granules are dispersed over the front surface and are held by the adhesive characteristics of the asphaltic substance permeating the front surface. It should be appreciated that the invention is not limited by the material composition of the overlay and underlay members  12 ,  14 . For example, the overlay and underlay members  12 ,  14  may comprise a laminar felted material comprising organic or inorganic fibers, or a mixture of both, that are held together with a binding agent. The fibers may be subsequently coated, saturated, or otherwise impregnated with an asphaltic bituminous material according to processes well known in the roofing industry. 
     The overlay member  12  includes a headlap or upper portion  16  and an exposed butt or lower portion  18 . The lower portion  18  includes one or more tabs  20  which are separated by one another by one or more cutouts  22 . An upper edge  24  of each tab  20  is substantially defined by and corresponds to a lower boundary  26  of the upper portion  16  of the overlay member  12 . An upper edge  28  of each cutout  22  also defines a portion of the lower boundary  26  of the upper portion  16 . In the first preferred embodiment, a lower edge  30  of the tab  20  has a generally concave or negatively curving contour, and the upper edge  28  of each cutout  22  has a generally straight contour. 
     In the first preferred embodiment, the width  32  of the lower edge  30  of each tab  20  is approximately equal to the width  34  of the upper edge of each tab  20 . Thus, each tab  20  has generally straight, parallel sides extending from the lower edge  30  to the lower boundary  26  of the upper portion  16 . Similarly, each cutout  22  has generally straight, parallel side extending from the lower edge to the lower boundary  26  of the upper portion  16 . Preferably, the width  32  of each tab  20  and the width  34  of each cutout  22  are substantially the same magnitude. 
     In the first preferred embodiment, the upper portion  16  of the overlay member  12  includes a layer of granules on the front surface  35  forming a darker shading area  36  adjacent the lower boundary  26  of the overlay member  12 . The darker shading area  36  preferably extends along the lower boundary  26  in a generally straight line to provide the roofer a guide in applying the shingles in a straight line, one next to the other, and in applying successive courses, one over the other. The height  38  of the darker shading area  36  is preferably in the range between about 0.5 inches to 2.0 inches, and more preferably about 1.0 inches. However, it should be appreciated that the height  38  of the darker shading area  36  can be varied depending on the dimensions of the shingle  10  and the desired optical effect when similar shingles are laid on the roof deck. Preferably, the width of the darker shading area  36  generally corresponds to the width, W, of the overlay member  12 . Alternatively, the width of the darker shading area  36  may be interrupted intermittently along the width, W, of the overlay member  12 . 
     In the first preferred embodiment, the underlay member  14  has a height  42  of approximately one-half of the height, H, of the overlay member  12 . The width of the underlay member  14  is approximately equal to the width, W, of the overlay member  16 . The underlay member  14  includes one or more lower edges  44  having a generally concave or negative curving contour separated by a lower edge  46  having a generally straight contour. Preferably, the widths of the lower edges  44 ,  46  of the underlay portion  14  are substantially equal to the widths of the tabs  20  and cutouts  22  of the overlay member  12 , respectively. 
     In a manner similar to the darker shaded area  36  provided on the overlay member  12 , the underlay member  14  includes a layer of granules on the front surface  37  forming a darker shading area  48 . The darker shading area  48  preferably extends the entire width, W, of the underlay member  14  in a generally straight line to provide a guide when fixedly attaching the overlay and underlay members  12 ,  14  to each other. Alternatively, the width of the darker shading area  48  may be interrupted intermittently along the width, W, of the underlay member  14 . The height  49  of the darker shading area  48  is preferably in the range between about 0.5 inches to 2.0 inches, and more preferably about 1.0 inches. However, it should be appreciated that the height  49  of the darker shading area  48  can be varied depending on the dimensions of the shingle  10  and the desired optical effect when similar shingles are laid on the roof deck. 
     Referring now to FIG. 2, the rear surface  41  (FIG. 4) of the overlay member  12  and the front surface  37  of the underlay member  14  are fixedly attached to each other to form the laminated shingle  10 . This can be accomplished by using adhesive materials applied to the surfaces  37 ,  41  between each tab  20  and the corresponding underlying portion of the underlay member  14 . Additionally, it may be desirable to provide a common bonding area  43  which is the area of overlap between the upper edge  45  of the underlay member  14  and the lower boundary area  26  of the overlay member  16 . Preferably, the common bonding area  43  extends substantially the entire width, W, of the shingle  10  above the upper edge of each of the cutouts  22  and approximate to the lower boundary  26  of the overlay member  16 . The width of the common bonding area  43  depends on the height of the tabs  20  and cutouts  22  with respect to the height  42  of the underlay member  14 . In addition, the width of the common bonding area  43  depends on the height, H, of the completed shingle  10 . Preferably, the common bonding area  43  has a width in the range of about 1 to 2 inches, and more preferably about 1.5 inches (3.8 cm). 
     The completed shingle  10  is of a generally rectangular shape having a width, W, of approximately 40 inches (101.6 cm) and an overall height, H, of approximately 17.0 inches (43.2 cm). The overall height, H, is divided between the upper or headlap portion  16  having a dimension of approximately 9.5 inches (24.1 cm) and the lower or exposed butt portion  18  having a dimension of approximately 7.5 inches (19.1 cm) when arranged with other similar shingles on a roof deck as described below. It should be appreciated that the invention is not limited by the dimensions of the shingle  10 , and that the invention can be practiced with any dimensions. For example, the width, W, may be approximately 36 inches (91.4 cm) and the height, H, may be approximately 24.0 inches (61.0 cm). 
     One feature of the first preferred embodiment of the invention is the overlapping cooperation of the curved contour of the lower edge  30  of each tab  20  with the straight contour of the upper edge of each cutout  22 , in combination with the darker shading areas  36 ,  48 , to optically simulate the three dimensional ridges and valleys of a tiled roof when laid on a roof with other shingles of similar shape. As seen in FIG. 2, the darker shading area  48  of the underlay member  14  is covered by each tab  20  of the overlay member  12 . In other words, only each cutout  22  of the overlay member  14  exposes the darker shading area  48  of the underlay member  14 . 
     Referring now to FIGS. 3 and 4, there is illustrated a fragmentary roof deck, D, with a roof covering made with a plurality of roofing shingles  10  according to the first preferred embodiment of the invention. In general, the roofing shingles  10  are arranged in a series of horizontal courses of which a portion of three such courses C 1 , C 2  and C 3  are shown. Shingle  10 A in course C 1  is shown being overlapped by shingle  10 B in course C 2 . Likewise, shingle  10 B in course C 2  is shown being overlapped by shingle  10 C in course C 3 . The extreme left-most and right-most edges of shingles  10 A,  10 B,  10 C are shown without the shingles which would normally precede and succeed these shingles in each of the courses, C 1 , C 2 , C 3 . This is done in order to more fully illustrate the desired placement of each shingle in each overlapping course. Thus, it is understood that the roof deck, D, in the finished tile simulating roof covering would be substantially completely covered by a plurality of substantially identically shaped shingles  10 A,  10 B, and  10 C. 
     One feature of the invention is the desirable sequence in which the shingles making up each overlapping course are laid. Preferably, the shingles  10 A making up course C 1  would be laid for a substantial horizontal distance along deck, D. Then, shingles  10 B making up course C 2  are laid in an overlapping fashion such that the headlap portion  16  of the shingles  10 A making up course C 1  are covered by shingles  10 B in course C 2 . Also, it should be noted that the identically shaped shingles in overlapping longitudinal courses (for example, C 2  and C 3 ) are longitudinally offset by a predetermined distance, X. This longitudinal offset serves to prevent the joint which is formed between each adjacent shingle in each course from corresponding to the joint between the shingles in the subsequent overlapping course. If this were not done, water from precipitation may inevitably penetrate these joints and find its way to a potentially damaging location in contact with the underlying roof deck, D. In offsetting these joints, there is no direct path for such water between each shingle. 
     In addition to preventing the penetration of water from precipitation, offsetting shingles in subsequent overlapping courses provides an overall aesthetic effect. In the first preferred embodiment, the distance, X, is equal to approximately one fourth of the overall width, W, of each shingle  10 A,  10 B, and  10 C. The choice of this distance, X, vertically aligns each tab  20  of the shingles  10 A,  10 B, and  10 C in each longitudinal course, C 1 , C 2  and C 3  up the roof deck, D. Because each tab  20  and each cutout  22  are substantially identical in shape and dimension, the choice of the distance, X, also vertically aligns each cutout  22  of the shingle in each longitudinal course, C 1 , C 2  and C 3  up the roof deck, D. 
     The use of the darker shading areas  36 ,  48  becomes apparent with reference to FIGS. 3 and 4. As can be readily seen, each shingle in each subsequent overlapping course is positioned so that not only are each tab  20  and each cutout  22  vertically aligned with a tab and cutout, respectively of a shingle in the next lower or previously laid course of shingles, but also the lower edge  30  of each tab  20  in subsequent overlapping courses is positioned to substantially correspond to the upper edge  28  of each cutout  22  (and the lower boundary  26  of each shingle). Positioning each shingle in each subsequent overlapping course in this manner exposes a portion of the darker shading area  36  of the underlying shingle. More specifically, the portion of the darker shading area  36  of shingle  10 A in course C 1  is exposed by the lower edge  30  of the shingle  10 B in course C 2 . Because the lower edge  30  has a curved or negatively curving contour, the portion of the darker shading area  36  that is exposed by the shingle  10 B will also have a curved or negatively curving contour, enhancing the tile simulating aspect of the invention. This feature, in combination with each cutout  22  exposing the darker shading areas  48  as described above, produces an alternating pattern of generally rectangular shaped darker shading areas  48  and curved shaped darker shading areas  36  along each longitudinal course C 1 , C 2  and C 2 , further enhancing the tile simulating aspect of the invention. 
     In addition to the dark shadow areas  36 ,  48  enhancing the tile simulating aspect of the invention, the positioning of the lower edge  30  of each tab  20  to subsequently correspond to the upper edge  28  of each cutout  22  results in an apparent edge thickness at the lower edge  30  of each tab  20  to have a thickness of twice the tab  20  of the underlying shingle. More specifically, the lower edge  30  of each tab  20  in the shingle  10 B of the course C 2  has an apparent edge thickness of twice each tab  20  in the shingle  10 A of the course C 1 . Further, each tab  20  in the shingles  10 A,  10 B, and  10 C are twice as thick as the underlay member  14  exposed by each cutout  22 . This feature, combined with the double thick portion of the lower edge  30  of each tab  20 , provides a heightened shadow effect, further enhancing the tile simulating aspect of the invention. 
     As described above, the vertical alignment of each tab  20  and each cutout  20  in the shingles  10 A,  10 B, and  10 C emphasizes the vertical components of the pattern which simulate the ridges and valleys (also known as caps and water courses) of a tiled roof. As each shingle is made up of four sets of one tab  20  and one cutout  22 , the offset distance, X, of one fourth the overall width, W, (or the distance equal to one tab and one cutout) of each shingle not only results in maintaining the vertical alignment of tabs and cutouts, but also prevents water leakage through a roof deck covered with such shingles. However, it should be understood that the invention is not limited by the number of tabs and cutouts, and that the invention can be practiced with any number of tabs and cutouts forming the shingle. For example, the shingle could have as few as two tabs and two cutouts, or as many as six tabs and six cutouts, or more, without departing from the invention. 
     FIGS. 5 through 8 illustrate a shingle  50  according to a second preferred embodiment of the invention. The shingle  50  is in many aspects substantially identical to the shingle  10 . More specifically, the shingle  50  is made up of an overlay member  52  and an underlay member  14  that is identical to the underlay  14  shown in FIG.  1 . The overlay member  52  is also substantially identical to the previously described overlay member  12  and includes a headlap or upper portion  56  and an exposed butt or lower portion  58 . The lower portion  58  includes one or more tabs  60  which are separated from one another by one or more cutouts  62 . An upper edge  64  of each tab  60  is substantially defined by and corresponds to a lower boundary of the upper portion  56  of the overlay member  52 . An upper edge  66  of each cutout  62  also defines a portion of the lower boundary of the upper portion  56  of the overlay member  52 . A lower edge  70  of the tab  60  has a generally concave or negatively curving contour, and the upper edge  66  of each cutout  62  has a generally straight contour. 
     However, the overlay member  52  of the shingle  50  includes some distinctions when compared to the overlay member  12  of the shingle  10  of the first preferred embodiment of the invention. One distinction is that the width  72  of the lower edge  70  of each tab  60  is larger than the width  74  of the upper edge  64  of each tab  60 , unlike the first preferred embodiment of the invention. As a result, each tab  60  tapers from the lower edge  70  along generally straight sides to its narrowest dimension at the upper edge  64  adjacent the lower boundary of the upper portion  56  of the overlay member  52 . Oppositely, the width  76  of the upper edge  66  of each cutout  62  is larger than the width  78  of the lower edge of each cutout  62 . Preferably, the narrowest dimension of each tab  60  and each cutout  62  (dimensions  74  and  78 , respectively) are substantially the same magnitude. Similarly, the widest dimension of each tab  60  and each cutout  62  (dimensions  72  and  76 , respectively) are substantially the same magnitude. The tapered tabs and cutouts can be made by modifying the cutout cylinders that cut the shingles into the overlay members. The cutting arrangement could provide that the cutouts and tabs of one shingle would be complementary to the cutouts and tabs of another shingle. 
     As best seen in FIG. 6, the right-most cutout  62  differs along its right-most edge  80  from being exactly identical to the shape and symmetry of the other cutouts  62  in the shingle  50 . The reason for this can be seen when the right-most edge is positioned adjacent to the left-most edge of the just subsequent shingle  50  in each course of a covered roof deck, and in particular to an overlap portion  82  of the left-most tab  60 . When positioned adjacent to the just previous shingle, the overlap portion  82  of the subsequent shingle overlaps the right-most edge  80  of the just previous shingle. Such overlapping cooperation not only results in the right-most cutouts  62  of each shingle having identical shape (i.e., tapered) and symmetry with other cutouts  62 , but also provides a more waterproof roof deck covering. 
     Referring now to FIGS. 7 and 8, the distinctions in the overlay member  52  provide for a different optical simulating effect when compared to the first preferred embodiment of the invention. In particular, the tapering of each tab  60  and each cutout  62  provides an increased three-dimensional optical effect, further enhancing the tile simulating aspect of the invention when compared to the earlier preferred embodiments of the invention. 
     FIGS. 9 through 12 illustrate a shingle  90  according to a third preferred embodiment of the invention. The shingle  90  is in many aspects substantially identical to the shingles  10  and  50 . For example, the shingle  90  is made up of an overlay member  92  and an underlay member  94  substantially identical to the previously described overlay members  12 ,  52  and underlay members  14 . 
     The overlay member  92  includes a headlap or upper portion  96  and an exposed butt or lower portion  98 . The lower portion  98  includes one or more tabs  100  which are separated from one another by one or more cutouts  102 . An upper edge  104  of each tab  100  is substantially defined by and corresponds to a lower boundary of the upper portion  96  of the overlay member  92 . An upper edge  106  of each cutout  102  also defines a portion of the lower boundary of the upper portion  96  of the overlay member  92 . A lower edge  108  of the tab  100  has a generally concave or negatively curving contour. 
     However, the overlay member  92  includes some distinctions when compared to the overlay members  12 ,  52  of the first and second preferred embodiments of the invention. One distinction is that the upper edge  106  of each cutout  102  of the overlay member  92  has a generally convex or positively curving contour, rather than a generally straight contour as in the first and second preferred embodiments. Another distinction is that the overlay member  92  does not include the dark shadow area  36  as in the first and second preferred embodiments. Those skilled in the art will appreciate that a further embodiment includes a similar shading effect to that shown in the embodiment illustrated in FIGS. 1-4, by providing a dark shadow on the underlay  94  in the area corresponding to the lower edge  108  of the tab  100 . 
     The underlay member  94  also includes some distinctions when compared to the underlay members  14  of the first and second preferred embodiments of the invention. One distinction is that the underlay member  94  has a generally rectangular shape in which the lower edge  95  has a generally straight contour, rather than including one or more lower edges  44  having a generally concave or negative curving contour, as in the first and second preferred embodiments. 
     Referring now to FIGS. 11 and 12, these distinctions in the overlay member  92  and the underlay member  94  of the shingle  90  provide for a different simulating tile effect when compared to the earlier preferred embodiments of the invention. In particular, the upper edge  106  of each cutout  102  and the lower edge  108  of each tab  100  provide for a serpentine shaped continuous contour. The upper edge  106  having a contour which is inverted from the contour of the lower edge  108 . Further, the dark shadow area  48  of the underlay member  94 , in combination with the convex or positively curving contour of the upper edge  106  of each cutout  102 , enhances the shadowing effect of the shingle  90 . In addition, each tab  100  is twice as thick as each cutout  102 , further enhancing the shadowing effect of the shingle  90 . 
     FIGS. 13 through 16 illustrate a shingle  130  according to a fourth preferred embodiment of the invention. The shingle  130  is in many aspects substantially identical to the shingles  10 ,  50  and  90 . In particular, the shingle  130  is made up of an overlay member  132  and an underlay member  134  substantially identical to the previously described overlay members  12 ,  52 ,  92  and underlay members  14  and  94 . The overlay member  132  includes a headlap or upper portion  136  and an exposed butt or lower portion  138 . The lower portion  138  includes one or more tabs  140  which are separated by one another by one or more cutouts  142 . An upper edge  144  of each tab  140  is substantially defined by and corresponds to a lower boundary of the upper portion  136  of the overlay member  132 . An upper edge  146  of each cutout  142  also defines a portion of the lower boundary of the upper portion  136  of the overlay member  132 . A lower edge  148  of each tab  140  has a generally concave or negatively curving contour. The upper edge  146  of each cutout  142  has a generally straight contour. Thus, the overlay member  132  is substantially identical to the overlay member  12 , except that the overlay member  152  does not include a darker shading area  36 . 
     The underlay member  134  is generally rectangular in shape and is substantially identical to the underlay member  94 , except that the overlay member  134  does not include a darker shading area  48  as in the earlier preferred embodiments. Those skilled in the art will appreciate that a further embodiment includes a similar shading effect to that shown in the embodiment illustrated in FIGS. 1-4, by providing a dark shadow on the underlay  134  in the area corresponding to the lower edge  148  of the tab  140 . 
     Referring now to FIGS. 15 and 16, the identically shaped shingles in overlapping longitudinal courses (for example, C 2  and C 3 ) are longitudinally offset by a predetermined distance, ½ X, rather than the distance, X, as in the earlier preferred embodiments. This longitudinal offset serves to prevent the joint which is formed between each adjacent shingle in each course from corresponding to the joint between the shingles in the subsequent overlapping course, similar to the earlier preferred embodiments of the invention. 
     However, in this preferred embodiment, the distance, ½ X, is equal to exactly one eighth of the overall width, W, of each shingle  130 A,  130 B, and  130 C, rather than one-fourth of the overall width, W, in the earlier preferred embodiments. The choice of this distance, ½ X, vertically offsets each tab  20  of the shingles  130 A,  103 B, and  103 C with each tab  140  in shingle in the immediately previous adjacent course. Because each tab  140  and each cutout  22  are substantially identical in shape and dimension, the choice of the distance, ½ X, also vertically aligns each tab  140  of the shingles  130 A,  103 B, and  103 C with each cutout  142  of the shingle in the immediately previous adjacent course. As a result, each tab  140  of the shingle  130 B in the course C 2  is vertically offset from each tab  140  in the shingle  130 A in the course C 1 , and each tab  140  of the shingle  130 B is vertically aligned with each cutout  142  in the shingle  140 A. 
     This longitudinal offsetting of the shingles  130 A,  130 B,  130 C a predetermined distance of ½ X provides for a different tile simulating aspect of the invention than the previous preferred embodiment of the invention. In particular, each tab  140  is vertically aligned with each cutout  142  in the immediately previous adjacent course, providing for an alternating pattern optical effect. This effect, in combination with each tab  140  in the immediately subsequent adjacent course being three times as thick as the vertically aligned cutout  142  in the immediately previous adjacent course, provides for a heightened shadowing effect, further enhancing the tile simulating aspect of the invention. Although this embodiment does not include darker shading areas, it should be realized that this preferred embodiment of the invention can also be practiced by providing dark shadow areas on the underlay and/or overlay members  132 ,  134  to provide a different tile simulating aspect of the invention. It will be apparent to those skilled in the art that the embodiments shown in FIGS. 9-16 may be modified to provide tapered tabs and cutouts in these embodiments in a manner similar to that provided in FIGS. 5-8, to provide the 3-dimensional effect described herein with respect to FIGS. 9-16. 
     In accordance with the provisions of the patent statutes, the principle and mode of operation of this invention have been explained and illustrated in its preferred embodiments. However, it must be understood that this invention may be practiced otherwise than as specifically explained and illustrated without departing from its spirit or scope.