Patent Publication Number: US-2023132860-A1

Title: Roofing panels with water shedding features

Description:
REFERENCE TO RELATED APPLICATIONS 
     The present Patent Application is a continuation of co-pending U.S. Pat. Application No. 17/103,998, filed Nov. 25, 2020, which claims the benefit of U.S. Provisional Pat. Application No. 62/940,448, filed on Nov. 26, 2019; and U.S. Provisional Pat. Application No. 62/951,252, filed on Dec. 20, 2019; and U.S. Provisional Pat. Application No. 62/962,298, filed Jan. 17, 2020. 
    
    
     INCORPORATION BY REFERENCE 
     The disclosures made in U.S. Pat. Application No. 17/103,998, filed Nov. 25, 2020, U.S. Provisional Pat. Application No. 62/940,448, filed on Nov. 26, 2019, U.S. Provisional Pat. Application No. 62/951,252, filed on Dec. 20, 2019, and U.S. Provisional Pat. Application No. 62/962,298, filed Jan. 17, 2020, are specifically incorporated by reference herein as if set for in their entireties. 
     TECHNICAL FIELD 
     This disclosure relates generally to roofing systems or structures and roofing panels for buildings and more specifically to roofing systems or structures and roofing panels with integrated water shedding features. 
     BACKGROUND 
     The application of structural roofing panels to the roof of a building has long been a construction practice, particularly in commercial roofing. More recently, interest in applying this construction practice to sloped residential roofs has grown. Issues with traditional roofing panels include the fact that they must be sealed along the junctions of individual panels after application. This can be done in a variety of ways including, for example, applying a roofing membrane over the panels, taping the junctions of the panels, applying a traditional shingled roof over the panels, and combinations thereof. All of these sealing options are labor intensive and subject to human error and deterioration over time. 
     A need exists for roofing panels for sloped roofs that, upon installation, collect and/or shed water without the need for ancillary sealing or roofing strategies, and/or which can incorporate design features that inherently provide effective water shedding at critical panel junctions while being easily installable on a roof deck. It is to the provision of such roofing panels that the present disclosure is primarily directed. 
     SUMMARY 
     Briefly described, roofing panels are constructed with integral water collection and shedding features. The roofing panels are installed as part of a roof structure, such as for a sloped roof, and the water collection and shedding features of the panels can be configured to align automatically and cooperate to collect rainwater and shed the rainwater down the slope of and off the roof. No ancillary sealing strategies need be employed, but shingles or other aesthetic roofing features can be installed atop the panels if desired. 
     In one example embodiment, the roofing panels can each include a base, and at least one water shedding feature extending along at least one of an upper surface, a lower surface, and/or a peripheral edge portion of the base. The at least one water shedding feature is configured to receive and direct water along a drainage path away from the base. In some embodiments, a waterproof layer is applied to the base, being applied to at least one of the upper surface and lower surface of the base. The waterproof layer further can include a portion that overlaps an adjacent roofing panel. A drip edge further can be applied along at least one peripheral edge portion of the base. In embodiments, the water shedding feature generally is integrally formed with the base, while in other embodiments, the water shedding feature can be connected or secured to the base so as to be substantially integrated therewith. The water shedding feature further will comprise at least one of a flexible strip, a trough, or a cover strip located along adjacent peripheral edge portions of the bases of adjacent roofing panels. 
     In another embodiment, the roofing panels can each include a base having a series of side edges; and a water shedding feature extending along at least one side edge of the base. The water shedding feature can comprise a drip edge or lip seal extending along the at least one side edge of the base, and a water trough configured to receive and direct water flows along a drainage path and away from the base. The drip edges or lip seals of adjacent roofing panels further can be engaged in an overlapping arrangement. In addition, a cover strip can be mounted along a seam defined between adjacent roofing panels. 
     In a further embodiment, each of the roofing panels can include a base having upper and lower surfaces; and a waterproof layer applied to at least one of the upper and lower surfaces of the base, the waterproof layer having a water shedding feature along a peripheral portion thereof that overlaps with a peripheral portion of a waterproof layer of an adjacent roofing panel to define a headlap or sidelap seam between adjacent roofing panels. For example, the waterproof layer can comprise a drip edge. 
     In a still further embodiment, a plurality of roofing panels can be provided. Each roofing panel can include a body having water shedding features formed adjacent peripheral portions of the body. The water shedding features can be configured to overlap with corresponding water shedding features of adjacent roofing panels to deter migration of water through joints between the adjacent roofing panels. A frame also can be provided. The frame can be configured to extend about the body. A series of water shedding features can be arranged along the frame that are configured to collect and direct water along drainage paths. The water shedding features can comprise troughs and/or drip edges along sides of the frame. A cover can be applied over and can cover the drip edges of adjacent roofing panels. 
     A method of installing roofing panels with water shedding features also is disclosed. In some aspects, the method can include arranging a plurality of roofing panels in spaced series, and coupling adjacent ones of the roofing panels along sidelap or headlap seams with the water shedding features of the roofing panels in an overlapping or engaging arrangement to collect and direct water flows along a drainage path and away from the roofing panels. In addition, portions of waterproof layers applied to the adjacent ones of roofing panels can be overlapped. 
     In some aspects, a roof structure comprises a plurality of roofing panels each configured to extend across a section of the roof structure, each of the roofing panels comprising a base having an upper surface, lower surface, and peripheral edge portions; and at least one water shedding feature extending along at least one of the peripheral edge portions of the base and configured to convey water along at least one drainage path away from the base; wherein the at least one water shedding feature of each roofing panel is configured to cooperate with a corresponding water shedding feature of an adjacent roofing panel to reduce migration of water between the roofing panel and the adjacent roofing panel. 
     In additional embodiments, the roof structure comprises a waterproof layer positioned along at least one of the upper and lower surfaces of the base. The waterproof layer can comprise a polymer membrane, and include at least one projection that overlaps the adjacent roofing panel to define a headlap or sidelap seam between the roofing panel and the adjacent roofing panel. 
     In some embodiments, the waterproofing layer is positioned along the lower surface of the base, and further comprising a roof deck on which the roofing panels are received, and vapor barrier layer positioned along the roof deck and configured to enable passage of moisture therethrough. 
     In other embodiments, the roof structure comprises an edge frame positioned about the peripheral edge portions of the base of the panels; and wherein the at least one water shedding feature is at least partially formed by edge frames of the adjacent ones of the roofing panels; wherein each edge frame includes an extension portion defining a water shedding feature configured as a water stop or drip edge. 
     In some embodiments, the extension portions of the edge frames of the adjacent ones of the roofing panels are configured to overlap along a seam between the adjacent ones of the roofing panels and form the at least one water shedding feature therebetween. 
     In further embodiments, the base of the roof structure comprises an oriented strand board (OSB), polyisocyanurate (ISD) plywood, foam board, structural foam, polystyrene, polyvinyl chloride (PVC) plastic, concrete, a solar panel, a solar tile, pressed recycled materials, structural insulated panel materials, or combinations thereof. 
     In other embodiments, the base comprises a waterproof material. 
     In still other embodiments, the at least one water shedding feature of the roofing panels comprises at least one of a flexible strip, a trough, a ramp, or a cover located along a seam between the adjacent ones of the roofing panels. 
     In some embodiments, the roofing panels are configured to extend between a ridge of the roof structure and an eave of the roof structure. In addition, the roofing panels further can comprise substantially self-supporting panels each having an upper end mounted to the peak of the roof structure, and a lower end mounted to the eave of the roof structure, and wherein the at least one water shedding feature of each of the adjacent roofing panel extends between the ridge and eave of the roof structure. 
     In another aspect, a roofing system, comprises a plurality of roofing panels, each roofing panel comprising a base having upper and lower surfaces; and a waterproof layer applied to at least one of the upper and lower surfaces of the base and having at least one projection that overlaps with a portion of a waterproof layer of an adjacent roofing panel to define a sidelap or headlap seam between the roofing panel and the adjacent roofing panel, wherein the waterproof layer includes at least one water shedding feature extending along the sidelap or headlap seam for reducing migration of water through the sidelap or headlap seam. 
     The at least one water shedding feature further comprises a drip edge or water trough positioned along at least one peripheral edge of the base, and a cover configured to be applied over and cover the drip edge and/or water trough of adjacent roofing panels. 
     In some embodiments, the roofing panels comprise structural panels configured to be substantially self-supporting panels having a length sufficient to extend between a ridge of the roof structure and an eave of a roof structure, and wherein the at least one water shedding feature extends between the ridge and the eave of the roof structure. 
     In yet another aspect, a method of forming a roof, comprises arranging a plurality of roofing panels in spaced series across the roof, each of the roofing panels comprising at least one water shedding feature; coupling adjacent ones of the roofing panels along sidelap or headlap seams with the at least one water shedding feature of the adjacent ones of the roofing panels in an overlapping or cooperative arrangement configured to reduce migration of water between the sidelap or headlap seams between the adjacent ones of the roofing panels. 
     In another embodiment, the roofing panels each include a waterproofing layer, and further comprising overlapping portions of the waterproof layers of the roofing panels with the adjacent ones of the roofing panels. 
     In other embodiments, the roofing panels comprise substantially self-supporting panels configured to extend across a span of the roof; and wherein arranging the plurality of roofing panels across the roof comprises mounting the substantially self-supporting panels in positions extending between an eave and a ridge of the roof, and attaching end portions of each of the roofing panels to the eave and ridge of the roof. 
     In additional embodiments, the method further comprises positioning at least a portion of the substantially self-supporting panels along one or more spaced rafters. 
     In still another aspect, a roof system, comprises a plurality of panels configured to extend across sections of a roof; wherein each of the panels comprises a base having upper and lower surfaces and a plurality of peripheral edges; and at least one water shedding feature positioned adjacent at least one of the plurality of peripheral edges of the base; wherein the at least one water shedding feature of each panel is configured cooperate with a corresponding water shedding feature of an adjacent panel to reduce migration of water between the sidelap or headlap seams between the adjacent ones of the roofing panels; and a cover or trough extending along the sidelap or headlap seams between adjacent panels and configured to overlap the water shedding features of adjacent panels. 
     In embodiments, the roof system further comprises an edge frame positioned along the peripheral edges of the base, and wherein the at least one water shedding feature comprises at least one upturned or downturned edge portion of the edge frame projecting away from at least one of the peripheral edges of the base; and wherein the cover or trough comprises a channel or strip extending over each of the upturned edge portions of edge frames of the adjacent panels. 
     In embodiments of the roof system, the at least one water shedding feature of each panel comprises a compressible seal member received in a channel defined along the lower surface of each panel adjacent the peripheral edges of the base, and wherein the cover or trough comprises a water channel strip positioned along the sidelap or headlap seams between the adjacent panels and projecting across the lower surface of adjacent panels sufficient to cover the compressible seal member. 
     In embodiments of the roof system, each panel further comprises an edge frame, and wherein the at least one water shedding feature and the cover are integrated with the edge frame of each panel. 
     In embodiments, the roof system further comprises an edge frame positioned along the peripheral edges of the base, and wherein the edge frame of each panel comprises connectors for releasibly coupling the panel to the roof and/or to the adjacent panels such that each panel is removable. 
     In embodiments of the roof system, the panels comprise interchangeable panels, including solar panels, biologic and vegetative panels, lighting panels, roof access panels, patterned or decorative panels, panels having roofing shingles, or combinations thereof. 
     In embodiments of the roof system, the connectors comprise hooks, clips, magnets, snap connectors, locking brackets or battens, or combinations thereof. 
     In other aspects of the present disclosure, a roofing system can be constructed with a plurality of individual roofing panels installable on a roof deck in overlapping courses. Each roofing panel may be molded from a thermo-formable or compression moldable polymer material and can have V-shaped ridges along its side edges, with an upstanding rib extending transversely between the V-shaped ridges near the upper edge of each panel and a nailing flange with a nail zone disposed above the rib. The lower edge of each panel can be downturned to form a drip edge. In use, multiple panels can be installed in courses on a roof with fasteners driven through the nailing flanges of the panels, with the lower edge portion of each roofing panel of an upper course of roofing panels overlapping the nailing flange and the upstanding rib of a roofing panel of a lower course of roofing panels, and with the downturned drip edges of the upper course of roofing panels disposed just forward of the upstanding ribs the roofing panels of the lower course of roofing panels. A lower edge portion of each roofing panel of each upper course also may be secured to a roofing panel in a next lower course, such as with a bead of adhesive or sealant that can be applied behind the downturned drip edge. The arrangement of the roofing panels can thus help define or provide water shedding features or pathways. 
     In addition, in some embodiments, the roofing panels, or portions or components thereof, can be further configured or provided with water shedding features. For example, an accessory in the form of a drain trough can be attached to the roof deck and extend beneath abutting side edges of horizontally adjacent panels. In another embodiment, a cap can extend along the tops of horizontally adjacent V-shaped ridges and can be secured or fastened in position along a seam or joint (i.e. along a headlap or sidelap seam) between the adjacent panels with a spline. As a result, water is reduced or substantially restricted from seeping between panels and can be effectively shed from the roof structure. 
     In still a further aspect, a roof system comprises a plurality of panels, each formed from a waterproof material comprising at least one of a thermo-formable polymer, metal, foam, structural insulated panel materials, or combinations thereof; wherein each of the panels comprises an exposure region, a nailing flange extending along a portion of the exposure region, and at least one water shedding feature along at least one peripheral side edge of each panel; and wherein the panels are configured to be installed in overlapping courses of panels along a sloped roof, and wherein the at least one water shedding feature of each of the panels in a higher course of panels is configured to cooperate with corresponding water shedding features of the panels of a lower course of panels to define pathways for directing and reducing migration of water through seams between adjacent panels of the overlapping courses of panels. 
     In an embodiment of the roof system, the water shedding features comprise V-shaped ridges along the peripheral side edges of the panels flanking the exposure region. 
     In another embodiment of the roof system, the water shedding features comprise at least one of ridges, drip edges, drain troughs, caps or combinations thereof. 
     A kit for constructing a roof structure, incorporating any of the foregoing types and/or constructions of roofing panels also can be provided. 
     The foregoing other aspects and advantages of the roofing panels and roofing systems of the present disclosure will become more apparent upon review of the detailed description set forth below taken in conjunction with the accompanying drawing figures, which are briefly described as follows. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS.  1   a  -  1   g    show various examples of how a roofing panel may be installed on a roof according to aspects of the present disclosure. 
         FIGS.  2   a  -  2   c    show three general examples of for roofing panels that embody principles of the present disclosure. 
         FIG.  3    shows two side-by-side roofing panels with water shedding features incorporated in a top layer of each roofing panel. 
         FIG.  4    illustrates two side-by-side roofing panels with water shedding features incorporated in a bottom layer of each roofing panel. 
         FIGS.  5   a  -  5   g    illustrate alternate embodiments of sidelap water shedding features for a roofing panel as shown in  FIG.  3   . 
         FIGS.  6   a  -  6   f    illustrate alternate embodiments of sidelap water shedding features for a roofing panel as shown in  FIG.  4   . 
         FIGS.  7   a  -  7   g    illustrate alternate embodiments of roofing panels as shown in  FIG.  2   a   . 
         FIGS.  8   a  -  8   g    illustrate alternate embodiments of sidelap water shedding features for a roofing panel as shown in  FIG.  2   c   . 
         FIGS.  9   a  -  9   e    illustrate alternate embodiments of sidelap water shedding features for a roofing panel as shown in  FIG.  2   c    using ancillary seals. 
         FIGS.  10   a  -  10   f    illustrate alternate embodiments of headlap water shedding features for a roofing panel as shown in  FIG.  2   b   . 
         FIGS.  11   a  -  11   e    illustrate alternate embodiments of headlap water shedding features for a roofing panel as shown in  FIG.  4   . 
         FIGS.  12   a  -  12   e    illustrate alternate embodiments of headlap water shedding features for a roofing panel as shown in  FIG.  2   c   . 
         FIGS.  13   a  -  13   d    illustrate alternate embodiments of headlap water shedding features that utilize ancillary seals to prevent water penetration. 
         FIGS.  14   a  -  14   g    illustrate alternate embodiments of headlap water shedding features for a roofing panel as shown in  FIG.  2   a   . 
         FIG.  15    illustrates the installation of roofing panels of the present disclosure in an offset relationship or in an aligned relationship. 
         FIGS.  16  and  17    illustrate roofing panels installed in offset relationships. 
         FIG.  18    illustrates an embodiment of roofing panels according to the present disclosures may be installed on the roof of a house in offset relationships. 
         FIG.  19    illustrates how roofing panels according to the present disclosures may be installed on the roof of a house in aligned relationships. 
         FIG.  20    illustrates the basic concept of using large roofing panels according to the present disclosures on the roof of a home with the roofing panels extending across a roof section or span between the peak or ridge of the roof and an eave of the roof, without requiring a roof deck or supporting rafters or beams. 
         FIG.  21    illustrates the use of roofing panels according to the present disclosure having the size of roofing panels matched to the size of a typical solar panel to create a roof where some or all of the roofing panels may be solar panels. 
         FIGS.  22  and  23    illustrate the concept of a living roof using roofing panels of the present disclosure and which can be interlocked or inter-connected to enable removal and replacement or substitution thereof. 
         FIGS.  24  -  26    illustrate the use of full-length water troughs as part of a sidelap water shedding strategy for roofing panels according to the present disclosure. 
         FIGS.  27  and  28    illustrate the use of extruded or sheet metal water troughs as part of a sidelap water shedding strategy for roofing panels according to the present disclosure. 
         FIG.  29    illustrates roofing panels in the form of rolled out water troughs extending beneath sidelap edges of roofing panels according to the present disclosure. 
         FIGS.  30  and  31    illustrate vertical underlayment strips with adhered or covered edges that together form a standing seam for water shedding features. 
         FIGS.  32   a  and  32   b    illustrate roofing panels according to the present disclosure with hooked side edges providing water containment and shedding properties. 
         FIG.  33    illustrates a possible headlap edge of the hooked side edge roofing panels according to the present disclosure of  FIGS.  32   a  and  32   b   . 
         FIGS.  34  and  35    illustrate a roofing panel according to the present disclosure with micro corrugations for water containment and shedding. 
         FIG.  36    shows the location of a headlap seam on a roof with roofing panels of the present disclosure. 
         FIG.  37    shows the location of a sidelap seam on a roof with roofing panels of the present disclosure. 
         FIGS.  38  and  39    show headlapped roofing panels forming a simple mechanical water shedding feature. 
         FIGS.  40  and  41    show side-lapped roofing panels forming a simple mechanical water shedding feature. 
         FIGS.  42  and  43    suggest the need for windblown rain testing of the lapped roofing panels of  FIGS.  38 - 41   . 
         FIGS.  44  -  46    suggest the use of overlaps between roofing panels, for preventing windblown rain infiltration. 
         FIGS.  47 ,  48 ,  49 , and  50    illustrate roofing panels according to the present disclosure with extended back sheets on 2 or more sides as water shedding features. 
         FIG.  51    illustrates the use of panel-tite sealing screws for attaching roofing panels to a roof. 
         FIGS.  52   a  -  52   d    illustrate an installation sequence for a “hook-and-rock-in” headlap attachment for roofing panels according to the present disclosure. 
         FIG.  53    illustrates one embodiment of flashing that may be used with a roofing panel as shown in  FIG.  2   b   . 
         FIG.  54    illustrates one embodiment of flashing that may be used with a roofing panel as shown in  FIG.  5   d   . 
         FIG.  55    illustrates trapezoidal-shaped roofing panels with sidelap overlaps that form mechanical water shedding features. 
         FIGS.  56   a  -  56   f  and  57    illustrate roofing panels according to the present disclosure available in various shapes to accommodate angles at hips and valleys. 
         FIGS.  58   a  -  58   l    show how roofing panels according to the present disclosure of various shapes can be combined to cover a variety of roof plane shapes. 
         FIGS.  59   a  and  59   b    illustrate how roofing panels according to the present disclosure may be oriented in a landscape or a portrait orientation. 
         FIG.  60   a    illustrates roofing panels according to the present disclosure installed on the roof of a home in a portrait orientation. 
         FIG.  60   b    illustrates roofing panels according to the present disclosure installed on the roof of a home in a landscape orientation. 
         FIG.  61    illustrates roofing panels according to the present disclosure installed in combinations of portrait and landscape orientations on the roof of a home. 
         FIG.  62   a    is an isometric view of roofing panels according to still further embodiments of the present disclosure, illustrating the overlapping installation of the roofing panels in adjacent courses and the use of water shedding accessories for water shedding between adjacent panels. 
         FIG.  62   b    is a side elevational view of two installed panels illustrating the overlap of the upper panel over the headlap portion of the lower panel. 
         FIG.  62   c    is an isometric view showing four roofing panels of an installation of roofing panels on a roof deck using water trough accessories between horizontally adjacent panels. 
         FIG.  63   a    is an isometric view of a roofing panel system according to still another embodiment, with overlying accessory caps to shed water along horizontally adjacent panels. 
         FIG.  63   b    is a front elevational view of the panels shown in  FIG.  63   a    illustrating attachment of an overlying accessory cap to adjacent panels. 
         FIG.  63   c    is an isometric view of four roofing panels of an installation of roofing panels according to the embodiment of  FIG.  63   a    installed on a roof deck. 
     
    
    
     DETAILED DESCRIPTION 
     General Discussion 
     This disclosure is directed to roofing panels that, once installed, form water shedding features that waterproof and shed water from the roof. The roofing panels are distinct and separate from materials chosen for a roofing system. They can be components that are inherent to the roofing material design, components that are added onto a selected roofing system on the top, bottom, or edge of a chosen roofing material. Since the roofing panels are distinct from the roofing material, the panels can be used with many current and future roofing systems, including roofs designed from panels, tiles, shingles, etc. 
     The roofing panels include, in numerous embodiments, features for waterproofing and shedding rainwater from sidelap seams of horizontally adjacent roofing panels and headlap seams of roofing panels in vertically adjacent courses. The water shedding features formed when the roofing panels are installed may be applied to the roofing panels at a manufacturing facility (prefab) or they may be applied to roofing panels in the field. The waterproofing and water shedding features disclosed herein can be applied to a variety of roofing systems including but not limited to panels, tiles, or metal roofing just to name a few. 
     The water shedding features disclosed in the numerous embodiments discussed below may be segregated into a number of main categories. These include (1) roofing panels with top layer water shedding features, (2) roofing panels with bottom layer water shedding features, (3) roofing panels with combination top and bottom layer water shedding features, (4) edge accessory water shedding features, and (5) other water shedding features. 
     Discussions of Embodiments 
     Reference will now be made to the drawing figures. Roofing panels according to embodiments of the present disclosure can be configured to be installed on a roof in a variety of configurations. For example, a non-structural roofing panel can be attached atop of a plywood roof deck. Alternatively, a roofing panel can replace the plywood deck if it satisfies applicable structural requirements. A structural roofing panel can replace the plywood deck and supporting rafters and trusses like a structural insulated panel (SIP), or reduce the number of rafters required by supplementing the structural integrity. As also indicated in the figures, the roofing panels can comprise a body or base having upper and lower surfaces and a series of peripheral portions or side edges, and further can be formed with various shapes or configurations. 
       FIG.  1   a    shows an embodiment of a roofing panel  10  that can be placed over and/or mounted to rafters  11  of a roof structure  12 , with the roofing panel having a base  13  with a thick upper layer of a waterproof material  14  applied thereto. For example, a thermoplastic polyolefin (TPO) membrane can be applied over an upper surface  13 A of the base  13 , with a lower surface  13 B of the base  13  being configured to engage the rafters  11 . In  FIG.  1   b   , a roofing panel  10  having a base  13  with a thin upper waterproofing layer  14 , including a polymer material that can be melted or fused to the upper surface  13 A of the roofing panel, is shown resting atop rafters  11 .  FIG.  1   c    shows a roofing panel  10  with a base  13  with one or more framed peripheral edges  16 , e.g. having a frame formed from a metal, plastic or other substantially rigid waterproof material attached to and protecting the peripheral edges of the base, can be used in a manner wherein the base  13  is resting atop rafters  11 . While the roofing panels  10  are shown in  FIGS.  1   a - 1   c    as a single roofing panel supported by two rafters  11 , the roofing panels  10  can be mounted on the rafters  11  in such a manner that at least an edge portion of two adjacent roofing panels are supported on a common rafter  11 . In  FIG.  1   d   , a roofing panel  10  meeting required structural requirements is shown resting directly on rafters  11  and replacing at least a portion of a roof deck or substrate.  FIG.  1   e    illustrates an embodiment including a non-structural roof panel  10  applied to a traditional roof deck or substrate  18 . 
       FIG.  1   f    illustrates a structural insulated panel (SIP) type roofing panel  21  with a base  22  having a core  23 , a bottom structural layer  24 , mid-top structural layer  25 , and a waterproof top layer  26 . Here, the SIP type roofing panel can have sufficient strength to replace the rafters and the roof deck or substrate of a roof. For example, such a roofing panel can be extended across a span or roof section between a peak or ridge of a roof and a roof eave or structure wall (e.g. as illustrated in  FIG.  20   ) without rafters or a roof deck or substrate required so as to be substantially self-supporting. Furthermore,  FIG.  1   g    shows a structural roofing panel with a core  23 , a bottom layer of structural material such as plywood  24 , structural foam or other structural material, and which can have a waterproof top layer  26  applied or formed thereon. In this example, the roofing panel may be extended across a roof section or a span, such as extending the full length between the peak or ridge and an eave of the roof, or at least partially therebetween. Such panels may not sufficiently structurally robust to replace the rafters  11 , but may allow for the reduction of the number of required rafters by enabling spacing of the rafters wider than the traditional 16 inch on center spacing. 
       FIGS.  2   a  -  2   c    show three general categories or types of roofing panels according to aspects of the present disclosure. The roofing panels can be of varying sizes, configurations and constructions; for example, including structural and/or self-supporting panels adapted to extend along a section of span of the roof such as extending a full length between a peak of the roof and an eave of the roof or to a wall of a building structure as generally illustrated in  FIG.  20   .  FIG.  2   a    shows a roofing panel  50 A that consists of a waterproof base  51  with edge features  52  and trough accessories  53  for water shedding. For example, the waterproof base  51  can be formed from a waterproof material such as metal or polymer or synthetic polymer, or composite materials, or can have a core that is encapsulated and/or sealed so as to be substantially waterproof. Such a roofing panel  50  might typically be attached directly to a roof deck or substrate such as shown in  FIG.  1   e   . In addition, a vapor barrier also can be applied below the substrate or roof deck. 
       FIG.  2   b    shows a roofing panel  50 B comprising a base  55  with a waterproof layer  54  that can be formed or applied as a top layer or a bottom layer of the base material which roofing panel can be used as a replacement for a portion of a roof deck or substrate. Water shedding features  56  are formed by edge structures  52  and trough accessories  53  to receive and direct water along a drainage path. In  FIG.  2   c   , a roofing panel  50 C having base is shown that is inherently waterproof and employs a ridged edge frame  57  with trough accessories  58  and/or flexible edge seals  59  for water shedding. In various embodiments, the base of such panels may comprise oriented strand board (OSB), polyisocyanurate (ISD) plywood, foam board including structural foams, polystyrene, polyvinyl chloride (PVC) plastic, concrete, a solar panel, a solar tile, pressed recycled materials, structural insulated panel materials, or other materials and combinations of any of the foregoing. These examples are, of course, not exhaustive, nor are they limiting. 
       FIG.  3    illustrates a further embodiment of roofing panels  100  formed from various materials with top layer waterproofing according to aspects of the present disclosure. The roofing panels  100  may comprise a base or core  101  that can be oriented strand board (OSB), polyisocyanurate (ISD) plywood, foam board including structural foams, polystyrene, polyvinyl chloride (PVC) plastic, concrete, a solar panel, a solar tile, pressed recycled materials, structural insulated panel materials, or other materials and combinations of any of the foregoing. These examples are, of course, not exhaustive, nor are they limiting. The waterproof layer  102  (shown on top here) may be a thermoplastic polyolefin (TPO) membrane, sheet, or layer, a plastic extrusion, rolled aluminum or an aluminum extrusion, bent or rolled sheet metal, a waterproof coating or sealant, shingles of all types including solar shingles, tiles of all types including solar tiles, or any other appropriate material. The term “waterproof layer” should be construed to include all such variations of liquid resistant materials configured to substantially resist or block penetration of liquid there through. Furthermore, roofing accessories such as solar arrays, ventilation fans, attic or plumbing vents, or any other roofing accessory may be pre-installed on a roofing panel to save time and effort in the field. 
     Water shedding features  103  in this example embodiment can include downturned lips  103 A positioned or defined along the peripheral portions or side edges  101 A- 101 D of the waterproof layer  102  or that overlie a water trough accessory  104 . The water trough accessory  104  may be a plastic extrusion, an aluminum extrusion, bent or rolled sheet metal, or an appropriate flexible waterproof sheet material, and generally will be configured to receive and direct water along a drainage path. In addition, it should be understood that many of the water shedding features discussed herein may be applied to various configurations and constructions of roofing panels as disclosed herein. 
       FIG.  4    illustrates a roofing panel  106  with bottom layer waterproofing  107  according to aspects of the present disclosure. Here, the roofing panel  106 , which is exposed, may be easily replaceable and/or can be made of a sacrificial protective material and/or any of the various materials discussed herein. The roofing panel may have core or base  108  of a porous and relatively inexpensive material that has aesthetic features and/or energy absorbing features for resisting hail impacts. The roofing panel  106  also may have ultraviolet blocking properties, which can enable the use of less expensive material for the underlying waterproofing layer  107 . In this example, the waterproofing layer  107  has upturned edges  107 A that are capped between roofing panels by a water shedding cap  109 . 
     With the forgoing background in mind,  FIGS.  5   a - 5   g    show various embodiments of water shedding features  110  for roofing panels  50 B ( FIG.  2 B ) and roofing panels  100  ( FIG.  3   ) with top layer waterproofing.  FIG.  5   a    shows side-by-side roofing panels with waterproof top layers  111  and with seams  112  between the roofing panels being sealed with a watertight sealing tape.  FIG.  5   b    illustrates a T-extrusion  113  with flexible lip seals  113 A between adjacent roofing panels, while  FIG.  5   c    shows a waterproof top layer  111  with drip edges  114  overlying the peripheral edges of the roofing panels for collecting and directing water into a water trough accessory  115 A below. In  FIG.  5   d   , the waterproof top layer  111  of each roofing panel has upturned edges  116  forming water stops with ancillary water cap accessories  117  connecting two adjacent upturned edges  116 . 
       FIG.  5   e    shows roofing panels  100  having top layers  111  with recessed edge features  119  covered by accessory water caps  117  to form an installation in which the water caps  117  are flush with or below the surfaces of the waterproof layer  111 .  FIG.  5   f    shows roofing panels with over-under, left-right sidelap joint forming water shedding features  121  between roofing panels, wherein each waterproof layer  111  forms a trough  121 A and a drip edge  121 B on opposite sides thereof.  FIG.  5   g    shows roofing panels wherein alternating panels have waterproofing layers  111  that form troughs  122  and the other panels have waterproofing layers that form drip edges  123 . 
       FIGS.  6   a  -  6   f    show various embodiments of water shedding features  130  for roofing panels  131  with bottom layer waterproofing  132 .  FIG.  6   a    shows roofing panels  131  having a construction as illustrated in  FIG.  4   , with waterproof bottom layers  132 , and with taped seams  133  along joints (e.g. handle p or side p joints) between the roofing panels.  FIG.  6   b    shows roofing panels  131  with bottom layer projections  134  that are overlapped by adjacent roofing panels and  FIG.  6   c    shows a similar concept with the roofing panels having a sealed overlap  136 , which sealing can include adhesives or other sealant materials  137  applied as a strip, patch or layer applied between the roofing panels along the overlapping portions  136  thereof.  FIG.  6   d    shows roofing panels  131  with bottom layer waterproofing  132  and a folded extension  138  overlapped by adjacent panels. The bottom waterproofing layer can include a TPO or similar polymer membrane, sheet, a metal layer or sheet, or other material sheet, the folded portion  138  of which forms a water trough  139 . 
     In  FIG.  6   e   , waterproof bottom layers  141  of roofing panels  131  have upturned portions  142  shaped to form interacting water troughs  143  between adjacent roofing panels.  FIG.  6   f    illustrates roofing panels  131  with bottom layer waterproofing  146  wherein the waterproofing layer  146  has extension portions or projections  147  that extend beyond opposed peripheral or side edges  148  of the roofing panel and are upturned at  149 . The upturned edges  149  of the projections  148  projecting between adjacent panels are sealed with an overlapping cap accessory  152 . 
       FIGS.  7   a  -  7   g    illustrate concepts for sidelap sealing between adjacent roofing panels  160  that can comprise a waterproof layer  161  as shown in  FIG.  2   a    (e.g. the panels can be formed from a metal or polymer waterproof material).  FIG.  7   a    illustrates adjacent roofing panels  160  with taped seams  162 , and  FIG.  7   b    illustrates adjacent roofing panels  160  with a water trough  163  having flexible lip seals  164  contacting the bottom or undersides  166  of adjacent roofing panels  160 .  FIG.  7   c    shows a water trough  163  beneath two adjacent roofing panels  160  having drip edges  167  formed along the bottoms or undersides  166  of the roofing panels, and  FIG.  7   d    shows adjacent roofing panels  160  with a thin water trough  163  with inwardly bent edges  168  beneath a seam defined between adjacent ones of the roofing panels. 
       FIG.  7   e    shows adjacent roofing panels  160  with a thin water trough  163  formed by hat-shaped ridges  169  on the water trough  163 .  FIG.  7   f    illustrates adjacent roofing panels  160  that overlap as indicated at  171  to form a water barrier. The width of the overlap will be sufficient to prevent water migration between the roofing panels. Finally,  FIG.  7   g    region  173  shows overlapped roofing panels  160  with a sealant or adhesive  172  applied between the overlapped edges  174 , and which can include, for example, a peal-and-stick tape or pressure sensitive adhesive joining the panels in the region of overlap  173 . 
       FIGS.  8   a  -  8   g    illustrate embodiments of water shedding features for roofing panels  180  having side edge frames  181  with profiles or configurations that form water shedding features  182 , such as shown in  FIG.  2   c   . In  FIG.  8   a   , the side edge frames  181  form drip edges  183  and a water trough  184  that is shown disposed beneath the drip edges.  FIG.  8   b    shows a water trough  184  beneath adjacent side edge frames  186  with the water trough spanning substantially across the width of the adjacent extrusions.  FIG.  8   c    shows adjacent roofing panels  180  with side edge frames  181  that form upturned flanges  187  and with a cap or cover strip  188  spanning adjacent upturned flanges. 
     In  FIG.  8   d   , two adjacent roofing panels  180  can have edge frames  181  that are abutting, and a cover strip  189  can span the width of both adjacent frame members.  FIG.  8   e    shows roofing panels  180  with edge frames  181  that have extension portions that form upturned flanges  187 , recessed below the top or upper surfaces  190  of the roofing panels, and which can be covered with a cover strip  191  so that the cover strip is substantially flush with the top surfaces  190  of the panels. In  FIG.  8   f   , the edge frames  181  along the peripheral edges of the roofing panels can form over-under left-right sidelap joints  192 , wherein each of the edge frames  181  has extension portions forming a water trough  194  and an opposing drip edge  196 . The water troughs  194  and the drip edges  196  of adjacent roofing panels are paired to form the sidelap joints  192 .  FIG.  8   g    shows edge frames  181  with extension portions that form alternating over-under joints  193 , wherein one roofing panel can have two water troughs  194  along opposite peripheral edges and the other has two drip edges  196  along opposite peripheral edges of the roofing panel. 
       FIGS.  9   a  -  9   e    illustrate embodiments of roofing panels  200  that use compressible seals  201  as part of the waterproofing layer/features and water shedding features.  FIG.  9   a    shows edge frames  202  with integral horizontally compressible bubble seals  203  positioned along the peripheral edges of the roofing panels, and which form a seal when the bubble seals are compressed together.  FIG.  9   b    shows vertically compressible seals  204  that are compressed against a water trough  206 , and  FIG.  9   c    shows compressible seals along edges of water troughs  206  that are compressed against a bottom surface of drip edges of adjacent roofing panels.  FIG.  9   d    shows seal strips or spray foam seals  208  received in channels  209  that are compressed against a flat water channel strip  211  to form waterproof drainage troughs or pathways.  FIG.  9   e    shows two roofing panels joined by a single flexible and compressible extrusion  212  that is configured to be applied or engaged along peripheral edges of adjacent roofing panels. Roofing panels may be assembled according to this embodiment on site. 
     The forgoing embodiments are particularly useful in sidelap joints between horizontally adjacent roofing panels, although some are usable for headlap joints between vertically adjacent roofing panels as well. Following are descriptions of embodiments particularly useful for headlap joints. 
       FIGS.  10   a -  10   f    show embodiments of headlap joints between vertically adjacent roofing panels with waterproof top layers. In  FIG.  10   a   , the roofing panels  220  have a waterproof top layer  221  with taped headlap seams  222  and in  FIG.  10   b    a top layer extension portion or projection  223  of the upper roofing panel overlaps the top layer  221  of the lower roofing panel.  FIG.  10   c    shows an overlapping top layer projection  223  with a drip edge  224  downslope of a water stop  226  along a back peripheral edge  227 A of the lower roofing panel. In  FIG.  10   d   , a portion of the upper roofing panel is overlapped with or positioned onto the lower roofing panel to create a stepped profile.  FIG.  10   e    illustrates roofing panels that have a stepped-down water ramp  228  along their upper or back edges  227 A and a drip edge  224  along their lower or front edges  227 B. These features cooperate to shed water from the upper roofing panel onto the lower roofing panel. In  10   f , the stepped-down water ramp  228  is shown as a separate transition feature that is adhered to and extends along the upper edges of roofing panels. 
       FIGS.  11   a  -  11   e    show embodiments of headlap joints between vertically adjacent roofing panels  230  with waterproof bottom layers  231 .  FIG.  11   a    shows a roofing panel with a bottom layer projection  232  that is overlapped by a vertically adjacent roofing panel. In this embodiment, water is diverted from the headlap joint or seam  233  over to the sidelap seams or joints.  FIG.  11   b    shows the region of overlap  234  between the vertically adjacent roofing panel and bottom projection layer is sealed, e.g., with a sealing material or portion. In  FIG.  11   c   , the waterproof bottom layer  231  is formed with a drip edge  236  along the front peripheral edge  237 A of a panel and a water stop  238  along the back peripheral edge  237 B of the panel. The front and back edges overlap to form a water shedding trough  239 . In  FIG.  11   d   , the waterproof bottom layers of vertically adjacent roofing panels are sealed along their seams with peel-and-stick tape or pressure sensitive adhesive material  241 , and in  FIG.  11   e   , the upper vertically adjacent panel has a waterproof bottom layer  231  that forms a water ramp  242  up to the top surface  243  of the lower vertically adjacent panel. 
       FIGS.  12   a  -  12   e    illustrate embodiments of headlap water shedding features for an edge framed roofing panel  250 , such as that shown in  FIG.  2   c   . In  FIG.  12   a   , an extension  251  formed along the downslope edge frame  252 A forms an overlap that directs water toward the top surface  253  of the lower vertically adjacent roofing panel. In  FIG.  12   b   , an extension portion  254  on the downslope edge frame  252 A forms a drip edge  256  and the upslope edge frame  252 B forms a water stop. 
       FIG.  12   c    shows entire roofing panels overlapped to form vertical water barriers, and  FIG.  12   d    shows downslope and upslope edge frames  252 A/ 252 B that overlap and form a drip edge  256  and a water stop respectively.  FIG.  12   e    shows flush mounted roofing panels with the downslope edge frames  252 A including an extension  257  with a drip edge  256  and with the upslope edge frames  252 B forming a water stop and a water ramp  259  to direct vertically flowing water onto the lower roofing panel. 
       FIGS.  13   a  -  13   d    illustrate embodiments of headlap sealing features utilizing flexible seals  260  for water containment and shedding. The roofing panels  261  in  FIG.  13   a    have compressible bubble seals  260  along their upslope and downslope edge frames  262 A/ 262 B that compress together to form a seal. In  FIG.  13   b   , a downslope edge frame  262 B on each roofing panel forms includes an extension  263  with drip edge  264  and the upslope edge frame  262 A has a flexible lip seal  265  that seals against the bottom of the overlapping extension and forms a water stop. 
       FIG.  13   c    illustrates an embodiment with a downslope edge frame  262 B that forms an extension  263  with a drip edge  264  and an upslope edge frame  262 A that forms a water trough  266 . A flexible bulb seal  260  is disposed along the back of the water trough and compresses against the bottom of the extension of a vertically adjacent roofing panel to form a seal.  FIG.  13   d    shows an embodiment wherein a sealant bead or spray foam  267  seals a channel  268  on the underside of roofing panels to an underlying flat water channel strip  269  to direct water horizontally. 
       FIGS.  14   a  -  14   g    show embodiments of headlap water shedding features  271  for a waterproof layer only panel  272 , such as that shown in  FIG.  2   a   .  FIG.  14   a    shows vertically adjacent panels with taped seams  273 ,  FIG.  14   b    shows overlapping panels, and  FIG.  14   c    shows overlapping panels with a sealing adhesive  274  in the regions of overlap  275 .  FIG.  14   d    shows panels with overlapping edges  276 A/ 276 B that form a drip edge  277  and a water stop  278 .  FIG.  14   e    shows a transition feature  279  between vertically adjacent panels that directs water to the top surface of a next lower vertically adjacent panel. 
       FIG.  14   f    shows roofing panels  280  wherein a top rib or bump  281 A is formed along the upper edge portion  282 A of each panel and forms a water stop  283 , while a bottom rib or bump  281 B along the lower edge portion  282 B of each panel forms a drip edge  284 . In some embodiments, each of the top and bottom ribs or bumps  281 A/ 281 B can be created by a bead of caulk or an adhesive.  FIG.  14   g    illustrates roofing panels with under-turned hooks  286  along their downslope edges and overturned hooks  287  along their upslope edges. The edges hook together so that the under-turned edges form drip edges and the overturned edges form water stops. 
       FIGS.  15 - 61    illustrate various example enhancements of roof installations or roof structures that can be constructed utilizing various types of roofing panels with watershedding features according to any of the foregoing embodiments disclosed above with respect to  FIGS.  2   a - 14   g   . The roofs constructed with the various types of roofing panels according to the present disclosures are illustrated for use with sloped roofs, including, but not limited to, residential or other steep sloped roofs. Other types of roofs also can be constructed. 
       FIG.  15    illustrates an example roofing panel installation wherein some roofing panels at the top of the drawing are installed in parallel relationships to each other and other panels at the bottom of the image are installed in offset relationships to each other. In addition, the roofing panels can be installed in an interlocking or coupled engagement, which can enable removal and replacement or interchanging of roofing panels of different types or panels having varying configurations. Either is possible and within the scope of the present disclosure.  FIG.  16    shows a plurality of roofing panels installed in offset relationships with both ends angled. This is primarily beneficial for roof sections with a hip and/or valley on both ends as on the left in  FIG.  18   .  FIG.  17    shows an offset panel installation with half panels filling gaps at one end. Such a configuration is beneficial for a roof section with a hip or valley on one end and a rake on the other end. 
       FIG.  18    shows a house with an installation of offset panels on a right roof section having a valley on one side and a hip on the other.  FIG.  19    shows a house with installations of parallel aligned roofing panels on each section of the roof. In each case, gaps are left along angled edges of the installations, which can be filled with partial and/ or specially shaped roofing panels as discussed in more detail below. 
       FIG.  20    illustrates the use of very large roofing panels  10 / 100  that can have a construction and/or configuration according to one or more of the foregoing embodiments, and can be formed with a length sufficient to extend across or over a span or roof section from the ridge or peak of the roof structure all the way to the eave of the roof structure or to an upper end portion of a wall of the building (i.e., along or across substantially the entire distance between eave and peak), as shown in  FIG.  20   . The panels  10 / 100  can be constructed to be substantially self-supporting, for example, SIP or other structural roofing panels can be used, configured to and extend along the slope of the roof and across a span or roof section of the roof, as a replacement for portions of the roof deck or substrate and at least a portion of the supporting rafters of the roof, enabling formation of a roof that incorporates the water shedding features of various embodiments of the present disclosure, without requiring supporting rafters, beams or a roof deck or substrate thereunder. The panels  10 / 100  can be structural, self-supporting panels secured to the ridge or peak of the roof at a first or upper end and to the eave of the roof structure at a second or lower end, and can be coupled to adjacent panels, such as by sealants or adhesives, or by fasteners or other connectors that can enable attachment and detachment of and interchangeability of panels as desired. 
     The use of such panels can provide numerous benefits including, but not limited to, the elimination of headlaps and consequently the need for headlap water shedding features. Horizontal seams, which may seem unsightly, also can be eliminated. Many of the sidelap water shedding feature embodiments described above may be used between horizontally adjacent panels in this embodiment. Another benefit is that these large roofing panels can be made sufficiently strong to provide their own structural support thus substantially eliminating or greatly reducing the need for trusses, rafters, and/or roof decks. 
       FIG.  21    illustrates an embodiment wherein the roofing panels can be sized or configured to match the size or configuration of a typical solar panel, for example, 3.25 feet by 6.5 feet for a 72 cell panel. Any or all of the water shedding feature embodiments described above may be used. In addition, the panels can include a frame with releasable connectors, such as clips, snaps, magnets, hooks, fasteners, brackets/battens, or other connectors, enabling removal and replacement or change-out as needed. With such a sizing strategy, a waterproofing layer on the top of a panel can be replaced by a solar panel without changing or disturbing the water shedding capabilities of the installation. 
       FIGS.  22  and  23    illustrate adaptation of the water shedding feature concepts disclosed herein to a green or living roof, which traditionally has been limited to low slope roofs. A roofing panel  290  forming a framework  291  or a tray sized to contain a layer of biological or vegetative, living material such as grass allows green roofs to be used on the steep slope roofs of residential houses as well. The growing material of each panel can be changed or replaced without disturbing the water shedding features and functions of the roof panel installation. For example, as indicated in  FIGS.  22 - 23    the panel framework  291  can include connectors  292  ( FIG.  22   ) that engage brackets, battens or other cooperative connectors arranged along the underlying roof structure  295  (e.g. a roof deck or substrate, or rafters or other support beams), and also can include connectors  294  ( FIG.  23   ) configured to connect or interlock with adjacent panels. Such connectors can include, but are not limited to hooks, snap, magnets, clips, locking connectors, fasteners and/or other engageable and disengageable connectors. 
     In addition, the vegetative or “green” panels shown are to be understood as examples of various types of panels, which panels further can be made interchangeable, i.e., they can be snapped or changed by a homeowner, etc..., and various other types of panels, including various types of “smart” or functional/decorative panels such as (but not limited to) energy panels configured to collect solar, wind, and heat energy, i.e. solar panels; panels configured for water collection and filtration; panels adapted to provide or configured with an antenna array; illuminating panels or panels with pre-installed lights; panels configured to enable roof access equipment, containing items such as a retractable ladder; skylight panels; panels configured for digital sensing/communications; decorative panels in solid colors, textures, patterns and/ or customizable print options; panels incorporating traditional roofing materials and aesthetics; panels with storage chamber for parts and tools for easy repair/replacement; and/or various combinations thereof, can be exchanged or substituted therefor. 
       FIGS.  24 ,  25 ,  26    illustrate an embodiment of roofing panels  25  such as illustrated in  FIGS.  2   a - 2   c    (or any of the other embodiments discussed above), including a full length water trough  26 . The water trough is roof profiled with two raised hill features  26 A/ 26 B that form a water trough  26 C between them. Edge flanges  30  extend outwardly from the hill features to accommodate attachment to a roof deck  31  with screws or other appropriate fasteners. The roof panels  25  can also have a caps, drip edges, or other water shedding features along their peripheral edges to direct rainwater to openings to be collected by the troughs and moved along a drainage path. This embodiment of a full length water trough can enable multiple water troughs can be nested for storage and shipment. 
       FIG.  27    illustrates another embodiment of a water trough in the form of an extruded or bent sheet metal strip with up and in turned edges to form water containment features. These extruded or bent sheet metal water troughs can be installed in nested sections on a roof deck beneath where horizontally adjacent roof panels will meet. 
       FIG.  28    illustrates an embodiment of an extruded plastic or film material water trough with in-turned edges that can be rolled into a roll for shipping and unrolled and cut to size on a job site. 
     In  FIG.  29   , the water trough, such as shown in  FIGS.  27 - 28   , has a peel-and-stick backing for attaching it to a roof deck. Here, roofing panels are mounted to the roof deck in overlapping courses, with the water trough along sidelap seams defined between the roofing panels. Fasteners for overlying roofing panels can pierce anywhere in the dry zones as shown in the drawing. Fasteners along the headlap edge are driven through the roofing panel or solar panel grommets. 
       FIGS.  30  and  31    illustrate another embodiment of a water management system beneath an installation of roofing panels. Here, vertically extending underlayment sheets are installed on a roof from a ridge to an eave. The material of the underlayment may be an appropriate membrane such as TPO and the strips abut one another at a standing seam. The abutting seams may be sewn or crimped together or they may be stuck together with an adhesive such as peel and stick strips.  FIG.  31    illustrates the option of crimping the standing seams together with long strips of plastic or metal to prevent water migration between adjacent strips. 
       FIGS.  32   a  and  32   b    illustrate another embodiment of water shedding. Here, mating hems on the left and right edges of roofing panels block water penetration between horizontally adjacent panels. Headlap edges can be nailed to the underlying deck and overlapped by vertically adjacent panels by, for example, one to four inches or more to prevent water penetration. The roofing panels of this embodiment may be fabricated of roll formed metal, which can be rolled from the back of a truck on site in a manner similar to the roll forming of seamless gutters. 
       FIG.  33    illustrates roofing panels with overlapped headlap sections for providing mechanical water shedding along or across the roofing panels. 
       FIGS.  34  and  35    illustrates another embodiment of a water shedding feature in the form of micro corrugated panels. Here, headlap edges may be overlapped by, for example, one to four inches or more after panels are nailed and sealed. The micro corrugated panels may be roll formed or stamped metal, extruded plastic, or formed plastic. They may be made of recycled regrind materials and material choices are not limited by a seam melting operation. As with the previous embodiment, the micro corrugated panels may be roll formed on site from the back of a roll forming truck. 
     Generally,  FIGS.  36  through  46    illustrate features of roofing panels with trapezoidal shapes that embody principles of the present disclosure.  FIGS.  36 ,  37   , (as well as  FIG.  55   ) show the roof of a home with trapezoidal roofing panels installed and indicate the locations of headlap seams ( FIG.  35   ) and sidelap seams ( FIG.  36   ). 
       FIGS.  38  and  39    show vertically adjacent trapezoidal roofing panels with a simple headlap overlap for water management at the headlap. Advantages are that the overlapped regions are substantially flat and bent lips or water dams are not required to make a water stop or a drip edge. 
       FIGS.  41  and  42    illustrate an embodiment wherein horizontally adjacent trapezoidal roofing panels are overlapped at their side edges to form simple mechanical water shedding features. Advantages are that the installation is substantially flat and there is no need for bent lips to create water stops or drip edges. As suggested in  FIGS.  42  and  43   , windblown rain testing is needed to ensure that the side-lapped ends do not leak under such conditions. 
       FIGS.  44  -  46    illustrate embodiments of possible selected overlaps at both the headlap and sidelap of trapezoidal roofing panels. For example, a two-inch overlap between vertically and horizontally adjacent panels generally should be sufficient to prevent water penetration; however, the overlap can be as little as one inch or as great as 4 inches or more if windblown rain testing so indicates. 
       FIGS.  47  -  50    illustrate another embodiment of a water shedding feature for roofing panels. Here, each panel is provided with a back sheet that extends beyond the edges of the roofing panels on two or three sides or even all four sides. One of the back sheet projections or extensions, in one embodiment the back sheet extension along the top edge of the roofing panel, may have fastening locations as shown in  FIG.  49    for securing the panel to a roof deck with fasteners. 
       FIG.  51    shows one embodiment for attaching roofing panels according to the present disclosure to a roof deck. Here, “panel-tite” sealing screws similar to those used to fasten tin roofs to buildings are driven through the roofing panels and into the rafters. The resulting screw head will be visible, but this may be acceptable in some cases. 
       FIGS.  52   a  -  52   d    show another embodiment for inter-attaching vertically adjacent roofing panels together. This embodiment is referred to as the “hook and rock-in” embodiment. The top water shedding features of panels are formed with a downturned lip along the forward edges of the panels and an upturned hook along the rear edges of the panels. With one panel installed, the next lower panel may be inter-attached to the installed panel as illustrated in sequence in these figures. First, the lower panel is slid upwardly until its hook moves beneath the downturned lip of the next higher panel ( FIGS.  50   a  and  50   b   ). Then the panel is progressively rocked down until its hook resides behind the downturned lip of the next higher panel ( FIGS.  50   b ,  50   c   , and 50d). This forms an interacting drip edge and water dam that sheds water away from the junction between the two panels. 
       FIG.  53    shows an embodiment of an installation of roofing panels according to one or more of the embodiments discussed above, such as illustrated in  FIGS.  2   b ,  3 ,  5   a - 5   g , and  10   a - 10   f   , for example. In  FIG.  53   , the roofing panels  65  are provided with water troughs as discussed with flashing  66  configured to form a water trough  67  along a protrusion in the roof or other structure such as a chimney. In this embodiment, roofing panels can be replaced without disturbing the water troughs or the flashing. Counter flashings typically are caulked into a groove that is cut into a chimney or other protrusion. In  FIG.  54   , roofing panels with upturned lips and caps are shown with flashing configured to direct water onto the top of an adjacent roofing panel. Here, the flashings are easily replaceable or reparable without disturbing the roofing panels. 
       FIG.  55    shows another embodiment wherein roofing panels are fabricated with a trapezoidal shape. These panels can make use of simple overlaps at the headlap edges and at the sidelap edges to obtain mechanical water shedding at a lower cost. In one embodiment, the angled side edges of the panels match the hip and valley angles of the roof and the roofing panels are flippable to reduce the number of panel SKUs needed. 
       FIGS.  56   a  -  56   f    show potential panel shapes to accommodate angles at hips and valleys of a roof plane. For example,  FIG.  57    shows a roofing panel installation with trapezoidal panels along the right side of the installation to accommodate an adjacent roof valley. 
       FIGS.  58   a  -  58   l    show various roofing panel installations for accommodating various shapes of roof deck planes.  FIGS.  58   a ,  58   d , and  58   g    show example installations using trapezoidal panels and rectangular panels for roofs of different pitches.  FIG.  58   a    shows an installation on a relatively lower pitched roof and  FIGS.  58   d  and  58   g    shows similar installations on increasingly higher pitched roofs.  FIGS.  58   b ,  58   e , and  58   h    show an installation on increasing pitched parallelogram-shaped roof decks using trapezoidal roofing panels of different configurations.  FIGS.  58   c ,  58   f  and  58   i    show example installations non-parallel trapezoid-shaped roof decks of increasing pitch. 
       FIG.  58   j    illustrates a roofing panel installation with a running bond brick layout configuration.  FIG.  58   k    shows an installation with a row and column panel configuration and  FIG.  58   l    shows an installation with an offset panel configuration. Installations other and different from these are of course possible and within the scope of the present disclosure. 
       FIGS.  59   a  and  59   b    illustrate that roofing panels according to this disclosure can be installed in landscape orientation or in portrait orientation as desired.  FIG.  60   a    shows a house with roofing panels installed in portrait orientation and  60   b  shows a house with roofing panels installed in landscape orientation.  FIG.  61    illustrates a house with a hybrid roofing panel installation wherein some panels are installed in landscape orientation and others are installed in portrait orientation. 
       FIGS.  62   a - 63   c    illustrate still further embodiments of a roof system or roof structure  300  that can be constructed using roofing panels  311  installed in overlapping courses  301 A/ 301 B ( FIGS.  62   b - 62   c   ) and that can incorporate various water shedding features  302 , including any of the water shedding features and panel constructions discussed above with respect to any of the foregoing embodiments. For example,  FIG.  62 A  illustrates two roofing panels  311  and  312  of the roofing system  300  according to one embodiment. 
     The roofing panels may be formed of a thermoplastic or thermo-formable, or compression moldable polymer sheet material, which may or may not include additives such as UV blockers, fire retardants, and compatibilizers as well as organic or inorganic fillers. For example, the roofing panels can comprise a base or sheet formed from a glass mat, a fabric base sheet, binders, adhesives, starch, lignin, virgin or recycled plastics such as low density polyethylene (LDPE) film, agricultural film, high density polyethylene (HDPE), polypropylene (PP), and polyvinylbutyral (PVB), sand, granules, shredded asphalt shingles, dust byproduct, cement, aggregates, bentonite clay, rice hulls, perlite, hemp, foaming agent, cellulose, among others. The roofing panels also may be formed of pressed sheet metal if desired. 
     Each roofing panel  311 A/ 311 B ( FIG.  62 A ) is formed to define a substantially flat main exposure region  313  flanked on its side edges by upwardly projecting V-shaped ridges  317  and  318 . An upwardly projecting lip  319  extends transversely between the V-shaped ridges  317  and  318  along the top of the main exposure region  313 . The thickness of the panel could range from 0.1 inches to 0.75 inches, from 0.1 inches to 0.65 inches, 0.1 inches to 0.55 inches, 0.1 inches to 0.45 inches, 0.1 inches to 0.35 inches, 0.1 inches to 0.25 inches, 0.2 inches to 0.020 inches, 0.2 inches to 0.30 inches, 0.2 inches to 0.40 inches, 0.2 inches to 0.50 inches, 0.2 inches to 0.60 inches, or 0.2 inches to 0.70 inches. Other thicknesses also can be used. The size of the panels could range from a small panel the size of a 12″ × 36″ shingle or the size of a clay tile, to a large panel approximately 48″ × 96″, and/or various other sizes and/or configurations, for example, ranging from approximately 20″ × 44″ to 50″ × 100″, although other sizes also can be used. 
     A nailing flange  315  projects rearwardly from the lip  319  and may be configured with an array of holes  316  along a nail zone to accept fasteners such as roofing nails  320  ( FIGS.  62   b - 62   c   ) for fastening the panel to a roof deck  326  ( FIG.  62   b   ). Screws may be used instead of nails. Some materials allow nailing without pre-drilled holes. Alternative methods of fastening can include utilizing hooks, brackets or cleats. The forward edge of the exposure region  313  is characterized by a downturned lip  321 , which can form a drip edge  320 . The roofing panels also can include accessories that may include drain troughs  322  and  323  as shown in  FIG.  62   a   . The drain troughs are configured to be attached to a roof deck  326  underlying the V-shaped ridges of two horizontally adjacent roofing panels. In this way, rainwater that might seep between the horizontally adjacent roofing panels is captured and contained by the drain troughs and shed downslope to an eave of a roof deck where it is shed away from the roof. 
       FIG.  62   a    indicates via arrow  310  that during installation, a roofing panel  312  in one course  301 A is overlapped onto a previously installed roofing panel  311  in a next lower course  301 B and so on up the roof. As shown in  FIG.  62   b   , the panels are positioned so that the lower edge portion of the upper course panel overlaps the nailing flange  315  and the lip  319  of the lower course panel. A bead of adhesive or sealant  330  may be disposed between the lower edge of the upper course panel and the lower course panel to adhere the two roofing panels together and resist wind lift of the forward edges of the installed panels. 
       FIG.  62   c    illustrates sections of four roofing panels  311   a ,  311   b ,  312   a , and  312   b  installed on a roof deck  326  supported by rafters  327 . Roofing panels  311   a  and  311   b  are arranged horizontally adjacent to each other in a lower course  301 B of panels and roofing panels  312   a  and  312   b  are arranged horizontally adjacent to each other in an upper course  301 A of roofing panels. The forward edge portions of roofing panels  312  and  312   a  are seen to overlap the nailing flanges  315  and the transverse lips  319  of panels  311   a  and  311   b  as described above. In this way, drip edges  321  of the roofing panels  312   a  and  312   b  deposit rainwater onto the main exposure portions of roofing panels  311   a  and  311   b  to be shed down the roof  300 . Further, the raised lip  319  of roofing panels  311   a  and  311   b  form water shedding features  302 , here shown as water dams that reduce or prevent migration of rainwater to the roof deck  326 , especially during windblown rains. The nailing flanges  315  and fasteners also are covered and protected from corrosion by moisture and the elements. 
     With continued reference to  FIG.  62   c   , the forward edge portions of the V-shaped ridges  317  and  318  of horizontally adjacent roofing panels  312   a  and  312   b  overlap the rear edge portions of the V-shaped ridges  317  and  318  of roofing panels  311   a  and  311   b  respectively. This serves to reduce rainwater from seeping to the underlying roof deck in these regions. Further illustrated in  FIG.  62   c    are water shedding features  302  in the form of accessories that can be provided as part of a system or kit for forming the roof using the roofing panels. Such water shedding accessories can be in the form water troughs  322  disposed beneath the abutting V-shaped ridges of horizontally adjacent panels. The water troughs  322  may be attached to the roof in overlapping sections as shown in  FIG.  62   c   , or they may be a continuous length of formed material extending from the top of a roof deck to its eave, e.g. extending along or between substantially self-supporting panels such as illustrated in  FIG.  20   . The water troughs  322  capture and contain rainwater that seeps between horizontally adjacent roofing panels and sheds the captured water downslope to be shed away at the eave. 
       FIGS.  63   a - 63   c    illustrate another embodiment of the system and kit of this invention. In this embodiment, the roofing panels themselves are of the same configuration as the panels in the above embodiment. However, the accessories for managing rainwater at the junctions of horizontally adjacent panels are different. Referring to  FIG.  63   a   , roofing panel  312  has a main exposure portion  313 , V-shaped ridges along its side edges, a transverse lip  319 , and a nailing flange  315 . Water shedding features  302 , which can include accessories  331  and  332 , in this embodiment comprising caps, can be provided in positions that overlie the junctions between horizontally adjacent panels and overlie the abutting V-shaped ridges of the panels. 
     The sides of the caps are downturned to form drip edges that deposit rainwater falling on the caps onto adjacent exposure portions of panels inside their V-shaped ridges. The caps  331  and  332  are formed with depending splines  337  and  338  respectively. The splines  337  and  338  are sized and configured to be pressed into a space between horizontally adjacent panels. As shown in  FIG.  63   b   , once the splines are pressed into the space between panels, the barbs  340  of the splines spread out and become captured beneath the outermost edges of the V-shaped ridges. This secures the cap  331  in place with a mechanical interference fit. 
       FIG.  63   c    is an isometric view showing portions of four panels in two courses of panels on a roof deck that incorporate the cap accessories  331  according to the invention. The panels in the upper course overlap the panels in the lower course as discussed above and the panels in each course are horizontally adjacent to one another. Accessory caps  331  are pressed into spaces between horizontally adjacent roofing panels and held in place by splines  331 . In the illustration, the accessory cap of the upper course of roofing panels overlaps the accessory cap of the lower course of roofing panels for water shedding. It will be understood, however, that the accessory caps can comprise one long unitary extrusion that extends from the top of an installation to the bottom. The caps may also serve to hold down the roofing panels during wind, by virtue of the fact that the caps are trapping the edge of one roofing panel as well as the roofing panel directly uphill of that roofing panel. The downhill edge of a roofing panel can be held down by the caps, and the caps held down by the fact that they are hooked under the next panel which is directly fastened to the roof deck. This approach may be used to eliminate the aforementioned adhesive or sealant joining two neighboring roofing panels. 
     In addition, a kit or other pre-constructed or packaged roof system or structure can be provided. The kit can include a plurality of roofing panels constructed in accordance with one or more of the foregoing embodiments discussed above, and including one or more water shedding features or various combinations thereof as discussed above, that can be assembled and shipped as a roofing system for assembly on-site for construction of a building roof. 
     The present disclosure has been disclosed herein through various embodiments and examples that illustrate principles, aspects and features of the present disclosure. The skilled artisan will realize, of course, that a wide gamut of additions, deletions, and modifications, both subtle and gross, may be made to the illustrated embodiments without departing from the spirit and scope of the present disclosure of which they are examples.