Patent Publication Number: US-9404262-B1

Title: Standing seam metal panel recover for shingled roofs

Description:
FIELD OF THE INVENTION 
     The present invention relates to metal panel roof covers and, more particularly, to metal panel roof covers for installation over an existing shingled roof. 
     BACKGROUND OF THE INVENTION 
     Shingled roofs utilize individual, overlapping units of prepared roofing materials referred to as shingles. Roofing shingles most commonly are made out of asphalt or wood, such as cut or split cedar and redwood. They also may be fabricated from stone, fiber cement, metal, and plastic. Shingled roofs utilize various flashing and other components where the fields of a roof terminate or intersect, such as the eaves, gables, valleys, ridges, and hips of a roof. Even in roofs having many different intersecting or overlapping fields, however, the basic construction of shingled roofs across the major expanse of a roof is fairly standard. 
     Most commonly, the roof substructure includes rafters. The rafters typically are dimensional wood boards which run vertically, i.e., along the pitch of the roof from the eaves to the ridges. Sheathing is installed on the rafters to provide a deck. The deck provides the structural support for the roof cover. The sheathing typically is plywood, oriented, strand board (OSB), or wooden planks. Spaced boards also may be used to provide a deck. 
     An underlayment, usually consisting of asphalt-saturated felt (tar paper), is generally installed to protect the deck. Other barrier webs may be installed both above and below the deck, such as reflective barriers or moisture barriers. Ice and water barriers often will be installed along the eaves and valleys of the roof. 
     The shingles provide the cover for the roof. For example, so-called strip or 3-tab asphalt shingles are in widespread use. They are have a somewhat elongated, rectangular shape. A pair of cutouts run partially across the shingle from its lower or butt edge to define the three tabs. The shingles may incorporate a factory-applied strip or spots of heat sensitive adhesive on their upper, lap portions. A starter strip also typically will be installed along the eaves to cover portions of the deck that otherwise would be exposed by the cutouts in the shingles. 
     The shingles are installed on the deck in overlapping rows or “courses” that run horizontally, i.e., across the pitch of the roof. The shingles are installed with their longer ends parallel to the eave. The first course is installed along the eave of the roof, typically over a starter strip. Successive courses are then laid up the slope of the roof. Typically, the shingles are installed without overlaps as they run along a course, but may be provided with Dutch laps at their ends. If the shingles are not self-sealing, adhesive may be applied to the upper, lap portion of the shingles as successive courses are installed. Overlapping courses of shingles will be more resistant to uplift in heavy wind if they are adhered to underlying course. 
     Overlapping courses are installed such that the butt edge of the course overlaps slightly more than half the width of the lower, underlying course of shingles. It will be appreciated that this installation pattern creates a head lap. That is, the pattern provides area of triple coverage: areas where the upper edge, mid portion, and butt edge of three courses overlap. 
     Roofs in general are designed to endure. Three-tab asphalt shingle roofs, for example, on average last 15 to 18 years. Eventually, however, they will deteriorate to the point where the cover is no longer weather proof. Removing and replacing the shingles has a number of advantages, especially where the roof is in serious disrepair. Stripping the old shingles will expose the roof deck and allow repair of any deteriorated underlayment and sheathing. Removing the old shingles also minimizes the load on the roof substructure. 
     On the other hand, removing an existing roof can be expensive and can disrupt occupants of a building. It also creates large quantities of waste that must be disposed of, and eliminates not only the existing roof, but whatever insulation value the existing roof may have provided. It also is quicker and cheaper to simply install new shingles over the existing shingles. 
     For example, new courses may be nested into existing courses by butting the top edge of the new shingles against the butt edge of the old shingles. Tapered wood filler strips or “feathering” strips also may be used, especially with thicker shingles. The feathering strips will be placed along the butt edge of the old shingles to create a level surface for installing new shingles. Recovering existing shingles with new shingles, however, greatly increase the load on the roof substructure. 
     Metal panel covers also have been used to “recover” deteriorated shingle roofs. A new metal cover, or “recover” over an existing cover will add much less weight to the roof as compared to simply installing new shingles over the old. Metal panel recovers also offer significantly longer service life—up to 40 years or more. That extended service life, however, often comes with a much greater cost. Metal panel recovers can be at a significant disadvantage relative to cheaper alternatives such as simply re-shingling the roof. 
     Metal panel covers, whether a new installation or a recover, utilize rather elongated metal panels installed along the slope of a roof. Each cover panel is typically about a foot to three feet in width. Though they may be cut to any length, they commonly are 30 to 40 feet long and may run as long as 200 feet. The lateral edges of the panels are bent in various configurations to form upwardly extending sides and a trough in the middle. The trough is where most of the water will be shed from the roof. 
     Adjacent panels are joined along their upwardly extending sides to create relatively narrow seams which are elevated above the trough. The panels are laid out such that the seams run vertically, i.e., with the slope of the roof. The panels also may have one or more ridges running vertically through the trough, and it is those vertically oriented seams and ridges that create the distinctive appearance that consumers associate with metal roofs. More importantly, however, since the seams between adjacent panels are formed a few inches above the troughs where most rain will be shed, metal panel roofs can be very resistant to leaking. 
     Raised-seam, metal panels may be classified according to the manner in which they are installed. So called “through panel” or “exposed” fastener panels are installed with screws or other fasteners that penetrate through the cover panels. The panels typically are laid over a roof so that their sides overlap and form a raised, often trapezoidal shaped seam or “lap” rib. The panels then are joined together along the lap rib by, e.g., gasketed screws. Gasketed screws also are driven through the trough. When used to recover a shingled roof, the through-panel fasters will be driven in the shingles and sheathing. Leakage around the fastener, at least initially, is not a significant problem. Over time, however, the elastomeric material from which the screw gaskets are fabricated can deteriorate, and leaks tend to develop around penetrating fasteners. 
     “Standing seam” covers can provide better resistance to leakage over longer periods of time and, in the eyes of many beholders, provide a more beautiful roof. In a standing seam cover, the metal panels are secured with concealed clips instead of unsightly and leak-prone penetrating fasteners. Most commonly, a plurality of relatively small panel clips are installed in a fairly widely spaced, array running vertically (along the slope of the roof) in what will become a seam line between adjacent panels. Panels are then installed between the vertical lines of clips, with the upturned seam edges of the panels abutting and mating with the clips and each other. There are no penetrations through the panels when clips are used. Moreover, all gaps between the panels and the clips are elevated well above the trough through which most water runoff occurs. Thus, standing seam panel covers provide better, longer resistance to leakage as compared to covers using screws or other “through panel” fasteners that penetrate the panels. 
     There are many conventional systems that use non-penetrating clips with standing seam metal panels for new installations. In new installations, the clips typically are mounted to an array of spaced, elongated support members or “purlins” which are mounted across the structural rafters of a roof substructure. The purlins run horizontally across the rafters, i.e., across the slope of the roof. 
     Such systems are disclosed in U.S. Pat. No. 4,575,983 to H. Lott, Jr. et al. Panel clips are mounted on purlins, and the metal panels secured to the clips. The panels disclosed therein are asymmetrical standing seam panels. Asymmetrical panels have mating male-female connections, each panel having a male connection formed in one side and a female connection formed in its other side. Thus, installation must proceed in a certain direction across the roof, and removal for repair must proceed in the opposite direction. 
     Symmetrical standing seam panels, however, have sides which are identical and are joined with a separate seam cover. Symmetrical panels, therefore, may be installed in either direction. A damaged panel also may be removed for replacement without removing any adjacent panels. Examples of new installation, symmetrical standing seam roof covers where non-penetrating individual clips are mounted on purlins are disclosed in U.S. Pat. No. 4,649,684 to L. Petree et al. Other covers, such as those disclosed in U.S. Pat. No. 6,354,045 to M Boone et al. and U.S. Pat. No. 5,737,892 to P. Greenberg, utilize individual and elongated, “continuous” clips that are mounted to and span adjacent purlins. While they are more costly than covers using asymmetrical panels, such symmetrical panel covers can offer improved leak protection, better uplift resistance, and longer service life. 
     U.S. Pat. No. 8,887,464 to C. Smith and U.S. Pat. No. 8,938,924 to C. Smith disclose standing seam metal panel recovers for installation over existing metal panel roofs. Those systems include systems where the panels are installed using a combination of individual and continuous clips. The individual clips are arranged in linear arrays, each individual clip being mounted on a single purlin. Thus, the base of the clip has a very limited span, typically only a few inches, just long enough to run across the width of the purlin with some play. The continuous clips are extremely elongated—up to 30 feet long—with each continuous clip spanning at least two, or more typically, many purlins. 
     The upper surface of a shingled roof, however, is by its nature quite uneven. It is unsuited for use with individual clips such as those disclosed in the &#39;464 and &#39;924 patents. Moreover, extremely long continuous clips are difficult to work with during installation. Thus, when metal panels have been used to recover deteriorated shingled roofs, various supporting structures have been provided to provide a more even surface upon which the metal panels may be installed. 
     For example, a new underlayment may be laid over the existing shingles and new, exposed fastener metal panels installed over the underlayment. Alternately, wood boards or “battens” may be nailed into the existing deck and running horizontally across the existing shingles. Exposed fastener panels then may be installed on the battens. See Tri County Metals,  Can You Install Metal Roofing Over Shingles?  (http://tricountymetals.com/can-you-install-metal-roofing-over-shingles/); and D. Chasar,  Metal Roof Retrofit on a Hurricane Damaged Home  (Copyright 2014 Florida Solar Energy Center) (http://www.ba-pirc.org/CASESTUD/hdh_roof/index.htm). 
     Alternatively, wood batten and counter-batten systems have been used to provide a supporting structure upon which metal panels may be installed. Such systems are disclosed, for example, in Houston Cool Metal Roofs,  The Texas Smart Roof™: The Coolest Roof in Texas  (http://www.houstoncoolmetalroofs.com/cool-roof-information/cool-roof-design-texas/). Similar metal batten-counter-batten systems have been devised for installation of metal tiles and shingles. Cool Roof Canada,  Radiant Ventilated Cool Roofing: Metal ‘ASV’ Batten Ventilation System for Stone Coated Steel Roofing  (http://www.coolroofcanada.com/cool-roof-batten.html). 
     Such systems employ horizontally oriented battens and vertically oriented “cross-battens.” That crisscrossing pattern not only elevates the recover well above the existing shingles, it allows for above sheathing ventilation (ASV). That is, convective air currents caused by the heating of the roof have a path allowing flow of heated air from the eave toward the ridge. 
     Above sheathing ventilation can dramatically reduce the amount of heat transmitted through the roof into a structure. It will be appreciated, however, that convective flow paths created by batten-counter-batten systems are somewhat tortuous. In addition, and while metal systems are lighter weight than wood and are said to be less expensive, batten-counter-batten systems typically will add both cost and weight to a recover system. 
     The statements in this section are intended to provide background information related to the invention disclosed and claimed herein. Such information may or may not constitute prior art. It will be appreciated from the foregoing, however, that there remains a need for new and improved systems, apparatus and methods for installing metal panels over existing shingled roofs. Such disadvantages and others inherent in the prior art are addressed by various aspects and embodiments of the subject invention. 
     SUMMARY OF THE INVENTION 
     The subject invention, in its various aspects and embodiments, is directed generally to metal panel standing seam roof “recovers” that are installed over an existing shingled roof. One aspect of the invention provides for a metal panel standing seam roof recover system installed over an existing shingled roof having a pitch. The existing shingled roof comprises a support frame that includes an array of elongated roof support members extending along the pitch of the existing roof. A deck is installed on the roof support members, and a cover is installed on the deck. The cover comprises a plurality of shingles installed in overlapping rows running across the pitch of the existing roof. The rows of shingles have a covered upper edge and an exposed lower edge. 
     The metal panel standing seam roof recover system comprises a plurality of panel clips mounted to the existing roof and arranged in linear arrays running along the pitch of the existing roof. The panel clips have a base that extends across and is supported by the lower edges of a first row of shingles and an adjacent second row of shingles. A recover is attached to the panel clips. The recover comprises a plurality of elongated metal panels having upstanding sides defining lateral edges with a trough therebetween. The metal panels are interconnected along adjacent lateral edges by seams formed on the panel clips. 
     Other aspects provide such recovers where the panel clips support the metal panels above the cover such that clearance is provided between the top side of the cover and the bottom side of the recover. Another aspect provides such recovers where the clearance is sufficient to allow convection air flow between the top side of the cover and the bottom side of the recover. 
     Preferred embodiments also include recovers where the panel clips are installed by a fastener extending through the shingles and into the deck. Other embodiments provide recovers where the panel clips are installed by a fastener extending through the shingles proximate to the lower edges thereof and into the deck. 
     Yet other aspects and embodiments provide such recovers where the shingles are asphalt shingles or other types of shingles, where the shingles have an exposure of from between about 4 to about 6 inches or between about 4 to about 8 inches, or where the length of said base of said clips is about 8 inches or from about 6 to about 18 inches. 
     Further embodiments provide such recovers where the base of the panel clips extends across and is supported by two lower edges of shingle courses, or by three lower edges, or by four lower edges. 
     Still other embodiments provide recovers where the panel clips comprise a vertical body and a horizontal bottom flange. The bottom flange provides the base of the panel clips and the panel clips are installed by a clip fastener extending through the bottom flange, through the shingles proximate to lower edges thereof and into the sheathing. 
     Various aspects and embodiments will utilize recovers where the metal panels are symmetrical or asymmetrical panels. 
     Yet other aspects and embodiments provide recovers that comprise an eave assembly. The eave assembly comprises a vent strip extending along an eave of the recover between the bottom side of the recover and the top side of the cover. The eave vent strip has openings therein which are adapted to allow convection air flow into the clearance between the cover and recover. Preferably, the eave vent strip is formed from perforated sheet metal. 
     Further embodiments and aspects provide recover systems where the eave vent strip has a first portion which is installed on the top side of the cover, a second, intermediate portion in which are provided the openings, and a third portion which is installed on the bottom side of the recover. 
     In still other aspects, the invention is directed to metal panel standing seam roof recover systems installed over an existing shingled roof which comprises a ridge assembly. The ridge assembly comprises a vent strip extending along a ridge of the recover. The ridge vent strip has openings and is mounted such that the openings are spaced above the troughs of the metal panels. The ridge assembly also includes a ridge cap mounted on the ridge vent strip. The ridge cap extends over and above the openings in the ridge vent strip whereby convection air flow from the clearance between the cover and recover may flow under the ridge cap and out the openings in the ridge cap. 
     In another aspect the invention provides such recovers where the ridge assembly comprises a trough closure extending vertically between the seams of the metal panels, and wherein the ridge vent strip is mounted on the closure. 
     Other preferred embodiments include such recovers where the ridge assembly comprises a panel support extending along the ridge. The panel support is attached to the cover and has corrugations supporting the metal panels. The corrugations run along the pitch of the roof thereby allowing convection air flow through the panel support. 
     Yet another aspect and embodiment provides such recovers where the ridge assembly comprises a trough closure which is fastened to the corrugated panel support. 
     The subject invention also includes methods for installing a metal panel standing seam recover over an existing shingled roof. The existing shingled roof comprises a support frame that includes an array of elongated roof support members extending along the pitch of the existing roof. A deck is installed on the roof support members, and a cover is installed on the deck. The cover comprises a plurality of shingles installed in overlapping rows running across the pitch of the existing roof. The rows of shingles have a covered upper edge and an exposed lower edge. 
     The method comprises installing an array of panel clips on the existing roof. The panel clips are installed such that they extend across and are supported by the lower, exposed edge of a first row of shingles and by the lower, exposed edge of an adjacent second row of shingles. Elongated metal panels then are attached to the clips by forming seams on the panel clips. 
     Other aspects provide such methods where the panel clips support the metal panels above the cover such that clearance is provided between the top side of the cover and the bottom side of the recover. Another aspect provides such recovers where the clearance is sufficient to allow convection air flow between the top side of the cover and the bottom side of the recover. 
     Preferred embodiments also include methods where the panel clips are installed by a fastener extending through the shingles and into the deck. Other embodiments provide methods where the panel clips are installed by a fastener extending through the shingles proximate to the lower edges thereof and into the deck. 
     Yet other aspects and embodiments provide such methods where the shingles are asphalt shingles or other types of shingles, where the shingles have an exposure of from between about 4 to about 6 inches or between about 4 to about 8 inches, or where the length of said base of said clips is about 8 inches or from about 6 to about 18 inches. 
     Further embodiments provide such methods where the panel clips extend across and are supported by two lower edges of shingle courses, or by three lower edges, or by four lower edges. 
     Still other embodiments provide methods where the panel clips comprise a bottom flange, a vertical body, and a horizontal bottom flange. The bottom flange provides a base of the panel clips and the panel clips are installed by a clip fastener extending through the bottom flange, through the shingles proximate to tower edges thereof and into the sheathing. 
     Various aspects and embodiments of the methods will utilize metal panels which are symmetrical or asymmetrical panels. 
     Yet other aspects and embodiments provide methods which includes installing an eave assembly which includes a vent strip. The eave vent strip is installed along an eave of the recover between the bottom side of the recover and the top side of the cover. The eave vent strip has openings therein which are adapted to allow convection air flow into the clearance between the cover and recover. Preferably, the eave vent strip is formed from perforated sheet metal. 
     Further embodiments and aspects provide methods where the eave vent strip has a first portion which is installed on the top side of the cover, a second, intermediate portion in which are provided the openings, and a third portion which is installed on the bottom side of the recover. 
     In still other aspects, the invention is directed to methods of installing metal panel standing seam roof recover systems over an existing shingled roof which also includes installing a ridge assembly. A vent strip is installed along a ridge of the recover. The ridge vent strip has openings and is mounted such that the openings are spaced above the troughs of the metal panels. A ridge cap is installed on the ridge vent strip. The ridge cap extends over and above the openings in the ridge vent strip whereby convection air flow from the clearance between the cover and recover may flow under the ridge cap and out the openings in the ridge cap. 
     In another aspect the invention provides such methods where installation of the ridge assembly includes installation of a trough closure extending vertically between the seams of the metal panels. The ridge vent strip is mounted on the closure. 
     Other preferred embodiments include such methods where installation of the ridge assembly includes installation of a panel support extending along the ridge. The panel support is attached to the cover and has corrugations supporting the metal panels. The corrugations run along the pitch of the roof thereby allowing convection air flow through the panel support. 
     Yet another aspect and embodiment provides such methods where a trough closure is fastened to the corrugated panel support. 
     Finally, still other aspect and embodiments of the invention will have various combinations of such features as will be apparent to workers in the art. 
     Thus, the present invention in its various aspects and embodiments comprises a combination of features and characteristics that are directed to overcoming various shortcomings of the prior art. The various features and characteristics described above, as well as other features and characteristics, will be readily apparent to those skilled in the art upon reading the following detailed description of the preferred embodiments and by reference to the appended drawings. 
     Since the description and drawings that follow are directed to particular embodiments, however, they shall not be understood as limiting the scope of the invention. They are included to provide a better understanding of the invention and the manner in which it may be practiced. The subject invention encompasses other embodiments consistent with the claims set forth herein. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a plan view, including partial tear-away views, of a conventional shingled roof  1  which has been recovered with a first preferred embodiment  10  of the metal panel roof recovers of the subject invention; 
         FIG. 2  is a perspective, partially exploded, partial tear-away view of a portion of novel roof recover  10  which has been installed along an eave E of conventional shingled roof  1  (certain components of novel roof recover  10  and conventional roof  1  having been omitted or truncated to better show underlying components); 
         FIG. 3  is a cross-sectional view, taken generally across lap ridges  21  of novel roof recover  10  shown in  FIGS. 1-2 ; 
         FIG. 4  is an enlarged, detailed view of portion  4  of the view shown in  FIG. 3 ; 
         FIG. 5  is a cross-sectional view, taken generally along a lap ridge  21  in the eave area of novel roof recover  10  shown in  FIGS. 1-4 ; 
         FIG. 6  is a perspective, partially exploded, partial tear-away view of a portion of novel roof recover  10  which has been installed along a ridge R of conventional shingled roof  1  (certain components of novel roof recover  10  and conventional roof  1  having been omitted or truncated to better show underlying components); 
         FIG. 7  is a cross-sectional view, taken generally along a lap ridge  21  in the ridge area of novel roof recover  10  shown in  FIGS. 1-6 ; 
         FIG. 8  is a perspective view of a preferred embodiment  30  of panel clips of the subject invention, panel clip  30  being used in novel roof recover  10  shown in  FIGS. 1-7 ; 
         FIG. 9  is a perspective view of a preferred embodiment  40  of eave vent strips of the subject invention (showing the upper side thereof), eave vent strip  40  being used in novel roof recover  10  shown in  FIGS. 1-7 ; 
         FIG. 10  is a perspective view of a preferred embodiment  50  of panel supports of the subject invention, corrugated panel support  50  being used in novel roof recover  10  shown in  FIGS. 1-7 ; 
         FIG. 11  is a perspective view of at preferred embodiment  60  of trough closures of the subject invention, trough closures  60  being used in novel roof recover  10  shown in  FIGS. 1-7 ; and 
         FIG. 12  is a perspective view of a preferred embodiment  70  of ridge vent strips of the subject invention (showing the upper side thereof), ridge vent strip  70  being used in novel roof recover  10  shown in  FIGS. 1-7 . 
     
    
    
     In the drawings and in the description that follows, like parts are identified by the same reference numerals. The drawing figures are not necessarily to scale. Certain features of the invention may be shown exaggerated in scale or in somewhat schematic form and some details of conventional design and construction may not be shown in the interest of clarity and conciseness. 
     DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS 
     The present invention generally relates to metal panel roof covers for installation over an existing roof, that is, to metal panel roof “recovers.” The novel metal panel roof recovers may be installed over many types of conventional shingled roofs, such a gabled, hip, mansard, and gambrel roofs, or roofs incorporating several basic designs. For example, novel metal panel recover  10  is installed over prior art shingled roof  1  as shown in  FIGS. 1-7 . 
     Existing shingled roof  1  is a typical gabled roof, that is, it has two roof fields F that slope upwards from their eaves E and intersect at a ridge R. The roof support frame (not shown in large part) typically will provide each field F in roof  1  with a pitch of at least 2:12 (2 inches of vertical rise for every 12 inches of horizontal reach). A shingled cover usually is designed to be hydrokinetic. That is, they are designed to shed water, and a minimum pitch must be maintained to ensure water flow off the roof. 
     The roof support frame includes an array of spaced support members or “rafters”  2 . Rafters  2  typically are made from relatively large dimensional wood boards, such as 2×10s or 2×12s, but they also may be metal. As will be appreciated from  FIG. 1 , rafters  2  run “vertically” through the roof. That is, they run along the pitch of fields F of roof  1 , as opposed to running “horizontally” or across the pitch. 
     Sheathing is installed on rafters  2  to provide a deck  3 . A shingled cover, by itself, is incapable of supporting any significant load. Thus, deck  3  provides a support for and a surface onto which shingles  4  may be installed. Deck  3  as illustrated in  FIGS. 1-7  is made from plywood or OSB sheets and provides a more or less continuous support surface. Many conventional shingled roofs, however, have spaced dimensional boards, such as 1×4s or 1×6s, which run horizontally across the fields of the roof. In other roofs, shingles may be installed on sheet metal decks 
     Shingles  4  are conventional 3-tab asphalt shingles having rectangular tabs of uniform size and exposure. It will be appreciated, however, that the novel recover systems may be installed over covers utilizing other types of shingles. They may be installed, for example, over covers having no-cutout shingles, which lack tabs, or random-tab shingles, which have tabs of varying sizes and exposure. They also may be used with covers having shingles made from other materials, such a cut or split wood. As will be appreciated from the description that follows, some modifications may be necessary depending on the type of shingles present in an existing roof, but such modifications are well within the skill of the art. 
     Shingles  4  are installed in overlapping courses running horizontally across fields F of roof  1 . Starting at eaves E, each course of shingles partially overlaps the course below it. In particular, each course of shingles commonly will be installed such that its butt edge overlaps slightly more than half the width of the lower course of shingles. Thus, an area of triple coverage is created where the upper edge, mid portion, and butt edge of three courses overlap. That overlap is best seen in  FIGS. 5 and 7 , although it will be appreciated that as in all the accompanying figures that the components illustrated therein are not necessarily to scale. In particular, the proportions and arrangement of shingles  4  in  FIGS. 5 and 7 , are intended to exaggerate somewhat the overlap areas for the sake of better illustrating the preferred embodiments. 
     The novel roof recover systems, however, may be installed over shingled roofs with other installation patterns. It also will be appreciated that shingled roofs incorporate other components which for the sake of clarity have been omitted from the drawings. Roof  1 , since it incorporates asphalt shingles  4 , almost certainly will be provided with an underlayment of tar paper to protect the underside of shingles  4  from the deteriorating effects of repeated thermal expansion. Ice and water barriers commonly will be incorporated as well, as may be reflective barriers or other types of barriers. 
     The novel metal panel roof recovers will be described in relation to existing shingled roof  1 . It is to be understood, however, that the novel roof recovers may be installed over other types of existing shingled roofs without departing from the principles of the present invention. 
     Various preferred embodiments of the novel metal panel standing seam roof recovers will generally comprise a plurality of panel clips mounted to the existing roof and a plurality of elongated metal panels which are interconnected on the panel clips. The panel clips are arranged in linear arrays running along the pitch of the existing shingled roof. The panel clips have a base that extends across and is supported by the lower edge of a row of shingles and the lower edge of an adjacent row of shingles. A recover is attached to the panel clips. The recover comprises a plurality of elongated metal panels having upstanding sides defining lateral edges with a trough therebetween. The metal panels are interconnected along adjacent lateral edges by seams formed on the panel clips. 
     For example, preferred novel roof recover  10  generally comprises roof recover metal panels  20  and panel clips  30 . As best appreciated from  FIGS. 1, 2, and 6 , metal panels  20  run vertically and are interconnected along their lateral edges by standing seams  21 . Standing seams  21  define troughs  22  through which water is shed from recover  10 . The upper ends of metal panels  20  extend under a ridge cap  80  installed along ridge R of recover  10 . Preferably, each metal panel  20  runs down the entire slope of recover  10  to its eave E, but the troughs may be provided by two or more panels overlapped at their ends. It also will be appreciated that the panels may terminate in a hip ridge or in a valley depending on the design of the existing roof, such as where there are intersecting gabled roofs. Shingled roofs may have many different or intersecting fields, and the novel roof recovers may be adapted accordingly. 
     The panels used in the novel recover metal roofs are the same type of standing seam panels as are conventionally used in metal panel roof covers. Thus, they may be fabricated from materials and by methods as are commonly employed in the art. Typically, such panels are fabricated from roll stock of painted or unpainted coated steel, such as Galvalume™ steel, zinc, copper, or aluminum. The roll stock is fed into a roll former which shapes the metal sheet into the desired configuration and cuts it to a desired length. Preformed panels may be used for a particular installation and cut as necessary, or a former may mounted on a trailer or truck so that panels may be fabricated on a job site. 
     It also will be appreciated that the novel metal panel roof recovers will be exemplified as using symmetrical metal panels of a particular configuration. Other types of symmetrical panels may be used, however, as may be asymmetrical metal panels. A variety of conventional symmetrical and asymmetrical panels are known and may be adapted for use in the subject invention. For example, 138T and 238T symmetrical metal panels sold by McElroy Metal may be used. Asymmetrical, “mechanically seamed,” and “snap-in” standing seam metal panels also may be used. Panels of this type are available commercially from a number of manufacturers, such as the Maxima and Medallionlock standing seam panels sold by McElroy Metal. 
     Panel clips are used to secure recover metal panels to an existing shingled roof and to facilitate the formation of standing seams between the metal panels. Panel clips  30 , for example, are used to secure metal panels  20  over existing shingled roof  1  and to facilitate the formation of seams  21  between laterally adjacent panels  20  as seen best in  FIGS. 2-4 . As described in further detail below, panel clips  30  are installed in linear arrays. The arrays of panel clips  30  run vertically through field F of existing roof  1  along what will become the seam lines for metal panels  20 . Thus, the linear arrays of clips  30  are separated horizontally by a distance substantially equal to the width of metal panels  20 . 
     More particularly, as seen best in  FIG. 8 , panel clips  30  include a bottom flange  32 , shelf flanges  33 , and top flanges  34  that extend generally horizontally from a vertically oriented web or body  35 . In accordance with the invention, and as best appreciated from  FIGS. 2, 5, and 7 , it will be appreciated that the length of bottom flange  32  is sufficient to enable panel clips  30  to span the butt edges of adjacent courses of shingles  4 . Thus, panel clips  30  will be supported substantially only on the butt edges such that the horizontally extending shelf flanges  33  and top flanges  34  in the array of clips  30  will be substantially parallel to each other and to the slope of existing roof  1 . 
     A typical 3-tab asphalt shingle, for example, has an exposed area of from about 5 to about 5.5 inches, and more comprehensively, will have an exposed area of from about 4 to about 6 inches or from about four to eight inches. Thus, clips having a base of about 8 inches will be preferred and adequate for most asphalt shingle installations. In most installations, clips of that length will span at least two butt edges and, therefore, will allow more precise alignment with the slope of the existing roof as described above. They also may be spaced along the pitch so as to effectively support and connect the metal panels, and they generally will provide savings in material costs and easier installation as compared to longer clips. 
     The base of the panel clips will span at least two butt edges, and thus for some installations shorter clips may be used. Somewhat longer clips also may be provided which span more than two butt edges, but preferably the clips will span no more than four butt edges. Thus, clips having a base of from about 6 to about 18 inches are preferred. It will be appreciated that optimum or preferred lengths may differ depending on the particular shingle present in the existing roof. 
     In contrast, conventional individual panel clips used in other metal panel systems are too short to span the butt edges of conventional shingled roofs. The base of such clips has a very limited span, typically only a few inches, given that it is just long enough to run across the width of relatively narrow purlins. On the other hand, extremely long, continuous clips which are used in recover installations over other types of roofs, require considerably more material and may be somewhat cumbersome to install and work with on a job site. 
     Panel clips  30  are attached to existing roof  1  by fasteners, such as a pair of screws  39 , extending through bottom flange  32  of clips  30  and shingles  4  into deck  3  of existing roof  1 . Preferably, as exemplified, panel clips  30  are placed on existing roof  1  such that each of screws  39  extend into the overlap area of shingles  4  just slightly above the butt edges, that is, the head lap areas of adjacent courses. 
     It will be appreciated, however, that a greater or lesser number of screws  39  or other fasteners may be used to mount panel clips  30  to existing roof  1 . Typically at least two fasteners will be used to resist torque about the connections and to provide greater stability for clips  30 . Where wind uplift is of minimal concern, however, it may be possible to mount panel clips  30  with a single fastener. Conversely, additional screws  39  or other fasteners may be installed through base  32  when more stability and strength is required in the connection between panel clips  30  and existing roof  1 . 
     Preformed round apertures  36  preferably are provided in base  32  of panel dips  30  to accommodate screws or other fasteners. If desired, however, slots may be provided, or screws may be driven through base  32 . The exact length of dips  30  and base  32  thereof, as well as the placement, configuration, and number of apertures  36 , preferably are coordinated to allow for some imprecision in placement of clips  30  during installation. 
     Shelf flanges  33  of panel clips  30 , along with top flanges  34 , provides support for metal panels  20 . Top flanges  34  also facilitate the formation of standing seams  21  between metal panels  20 . That is, as best appreciated from the cross-sectional views of  FIGS. 3-4 , the lateral edges of panels  20  are bent upwards to provide upwardly extending sides  23  on both sides of trough  22 . The upper portion of panel sides  23  is doubled over horizontally to form a narrow u-shaped channel  24  running vertically on top of each side  23  of panels  20 . It will be noted that metal panels  20  are symmetrical, that is, their sides  23  are mirror images. 
     As metal panels  20  are installed, therefore, sides  23  of panels  20  will be supported on the top surfaces of shelf flanges  33  in adjacent lines of clips  30 . At the same time, u-shaped channels  24  in the upper portion of sides  23  of panels  20  are slipped over top flanges  34  of clips  30 . A seam cover  25  then is provided over and around the exterior of channels  24  to secure panels  20  to each other and to clips  30 . Preferably, a sealant, such as a bead of silicone caulk or elastomeric tape, is provided between seam cover  25  and the exterior of channels  24  to enhance the weather tightness of seams  21 . A seamer also may, and preferably is used to securely connect and seal seam cover  25  to panel sides  23 . 
     While panel clips  30  are used in preferred embodiments of the novel roof recovers, the invention is not limited thereto. Other clip configurations may be used if desired. For example, panel clips  30  in novel roof recover  10  are a unitary component, but panel clips suitable for use in other embodiments of the subject invention may be assembled from multiple pieces. For example, the various flanges in the exemplified clip  30  are integral with the clip body. If desired, however, various flanges may be provided as separate components affixed to a clip body, e.g., by welding. 
     The exact dimensions of shelf flanges and top flanges in the novel panel clips also are not especially critical and may be varied somewhat to provide as much or as little support surface as may be desired or necessary for a particular installation. Likewise, clips  30  have four shelf flanges  33  and four top flanges  34 , two flanges  33  and  34  extending in each direction. Other clips, however, may be provided with an number of shelf flanges and top flanges extending in opposite directions. 
     The clips used in the novel metal panel roof recovers preferably are made from steel, such as 16 to 24 gauge galvanized steel sheets that may be easily formed and bent and cut into a desired configuration by conventional metal forming equipment. Such materials provide a rugged, weather resistant clip that may be manufactured easily and economically. Other metals, such as extruded aluminum, may be used to fabricate the panel clips, however, as well as rigid, moldable or extrudable plastics. 
     It also will be appreciated that the configuration of the panel clips will be coordinated with the choice of panels used in the novel recover systems. Though similar in many respects, clips for other symmetrical or asymmetrical metal panels may have somewhat different configurations as are suitable for the panel. It is believed that a wide variety of panel clips for a variety of metal panels may be adapted for use in the subject invention. 
     Preferred embodiments of the panel clips will provide clearance between the existing roof and the recover. For example, as best appreciated from the cross-sectional views of  FIGS. 3-5 and 7 , when panel clips  30  are installed on existing roof  1  shelf flanges  33  are situated somewhat above the surface of existing roof  1 . Thus, when metal panels  20  are attached to panel clips  30 , a clearance or space  11  is created between shingles  4  of existing roof  1  and the bottom side of metal panels  20 . 
     Preferably, the clearance provided between an existing roof and the recover is sufficient to allow convection air flow in space created thereby or, what is referred to in the industry as above sheathing ventilation (ASV). For example, as air in space  11  is heated to temperatures above the ambient temperature, it will rise and recover  10  will tend to direct it up the slope of existing roof  1  toward ridge R. Movement of hot air up the slope will allow cooler ambient air to enter space  11  from the eave E, as described in further detail below. Given the fluid properties of hot air, sonic movement up the slope will occur if there are any flow paths available, and any movement of hot air from space  11  to a cooler ambient will remove a certain amount of heat from the roof system. Preferably, however, clearance  11  between existing roof  1  and recover  10  is sufficiently large to allow significant flow of air through space  11  when existing roof  1  and recover  10  are heated significantly above ambient temperature. By establishing convection air flow through space  11 , large quantities of heat may be removed from the roof system instead of being transferred into the structure. That, in turn, may significantly reduce the cost of cooling the structure during warm weather. 
     Thus, clips  30  are configured to provide a clearance  11  of approximately 0.75″ between existing roof  1  and recover  10 . A clearance of 0.75″ is expected to allow convective air flow through the clearance in most installations. Preferably, a clearance of from about 0.5 to about 2 inches is created. Lesser clearances may provide some benefits, but may not be sufficient to allow movement of substantial quantities of air. Higher clearances may provide greater airflow, but may not provide meaningfully greater benefits and may comprise the aesthetics of a structure. Regardless, however, workers in the art will be able to adapt embodiments of the invention to provide desired levels of ASV for particular installations. 
     With that in mind, it will be appreciated that the novel recover systems also comprise embodiments providing eave and ridge assemblies that allow air flow and, especially, convective air flow into and out of the clearance between the existing roof and the recover. For example, as seen in  FIGS. 2 and 5 , recover  10  comprises eave vent strip  40 . Eave vent strip  40 , as seen best in  FIG. 9 , includes a generally flat body portion  41 . A vent portion  42  angles up and out from body  41 , and a lip portion  42  extends from vent portion  42  in a plane generally parallel to the plane of body portion  41 . Vent  42  is provided with a plurality of openings. Although not readily apparent from  FIG. 9 , eave vent strip  40  preferably is rather elongated to facilitate installation and typically will be provided in lengths of from about 10 to about 20 feet which may be overlapped or cut to length as required. 
     As seen in  FIGS. 2 and 5 , typically, as in preferred recover  10 , an eave trim  44  is first installed on existing shingles  4  along eave E of existing roof  1 . Eave trim  44  may be mounted on existing roof  1  by fasteners, e.g., screws  48  extending through eave trim  44 , shingles  4 , and into deck  3 . A portion of eave trim  44  is folded over and, when installed, runs down along the face of existing fascia board  5 . The lower portion of eave trim may be secured, for example, by trim cleats  45 . Trim cleats  45  are installed on existing fascia board  5  by fasteners, e.g., screws  47 . Eave trim  44  provides a neater, cleaner finish for the recover installation and, since the overhanging portions of shingles  4  in existing roof  1  typically will be trimmed to allow installation of recover  10 , impedes the flow of water under shingles  4 . 
     Eave vent strip  40  then is installed on eave trim  44  and along eave E of existing roof  1  such its vent portion  42  and lip  43  extend out over existing eave E. Eave vent strip  40  may be mounted on existing roof  1  by fasteners, e.g., screws  49  extending through eave vent strip  40 , eave trim  44 , shingles  4 , and into deck  3 . As may be seen in  FIG. 5 , the ends of metal panels  20 , once panels  20  are installed, may be bent around and under lip  43  of eave vent strip  40 . In any event, clearance  11  between existing, roof  1  and recover  10  thus is substantially closed along eaves E, but holes in vent portion  42  of eave vent strip  40  will allow air flow into clearance  11 . The size, number, and pattern of openings in vent portion  42  may be varied widely. Preferably, that is coordinated with the other features of the recover such that the openings allow convective air flow through the clearance between the existing roof and the recover. 
     Preferred embodiments of the novel roof recover systems also comprises a ridge assembly that facilitates air flow and, especially, convective air flow out of the clearance between the existing roof and the recover. For example, as seen in  FIGS. 6 and 7 , recover  10  has a ridge assembly that generally comprises a panel support  50 , a trough closure  60 , a ridge vent strip  70 , and ridge cap  80 . Initially, it will be noted that fields F of existing roof  1  extend toward, but stop short of intersecting at ridge R. Thus, there is an elongated opening  6  running along ridge R between the upper edges of fields F. If not present in existing roof  1  as originally installed, deck  3  and shingles  4  of existing roof  1  may be trimmed to create opening  6  if desired. The ridge assembly also may be installed on existing roof  1  without providing an opening  6 . As will be appreciated from the description that follows, elongated opening  6  allows hot air to rise out of the attic space underneath existing roof  1  and flow towards the ambient. 
     Panel support  50 , which is shown in isolation in  FIG. 10 , has corrugations  51  running across the body and, when installed, along the pitch of existing roof  1 . Although not necessarily apparent from  FIG. 10 , panel support  50  preferably is somewhat elongated to facilitate installation and typically will be provided in lengths of from about 16 to about 36 inches and in widths of from about 8 to 12 inches which may be overlapped or cut to length as required. 
     As may be seen best in  FIGS. 6 and 7 , panel support  50  is installed on existing roof  1  along and proximate ridge R of existing roof  1  and opening  6  therein. Panel support  50  may be mounted on existing roof  1  by fasteners, e.g., screws  59  extending through the lower corrugations  51  in panel support  50 , shingles  4 , and into deck  3 . The upper ends of metal panels  20 , when installed, will extend over panel support  50 . The height of panel support  50  is coordinated with the height of shelf flanges  33  on panel clips  30  to provide support for panels  20  at more or less the same height. The width of panel support  50  preferably is sufficient to allow it to span butt edges of adjacent rows of shingles  4 . It will be appreciated that panel support  50  provides support for metal panels  20  along ridge R while at the same time allowing air flow out of space  11 . 
     After metal panels  20  are installed over panel support  50 , trough closures  60  are installed. As shown in  FIG. 11 , trough closures  60  are somewhat elongated, z-shaped components having a horizontal base  62 , a vertical extension  63 , and a horizontal shelf  64 . A pair of tabs  65  extend from the end of vertical extension  63 . As best seen in  FIG. 6 , trough closures  60  are installed in troughs  22  of metal panels  20  proximate to ridge R and above panel support  50 . They may be secured thereto by fasteners, such as screws  69  extending through openings  66  in base  61  of trough closure  60 , through trough  22  of metal panels  20 , and into panel support  50 . Metal panels  20  will also thereby be secured to panel support  50 . Tabs  64  of trough closures  60  are bent backward (towards ridge R) along seams  21  of metal panels  20 . The length of trough closures  60  is such that trough closures  60  will extend substantially across the entire width of trough  22  and, when ridge vent strip  70  is installed as described below, will substantially prevent water from being blown up troughs  22 . 
     Ridge vent strip  70  then is installed on trough closures  60 . As may be seen in  FIG. 12 , ridge vent strip  70  has a generally flat body  71 . A vent portion  72  having a plurality of openings runs along one side of body  71 . An extension  73  extends vertically from body  71 . A shelf  74  extends more or less horizontally from vertical extension  73 . Although not necessarily apparent from  FIG. 12 , ridge vent strip  70  preferably is rather elongated to facilitate installation and typically will be provided in lengths of from about 10 to about 20 feet which may be overlapped or cut to length as required. 
     As shown in  FIGS. 6 and 7 , ridge vent strip  70  is installed on shelves  63  of trough closures  60  such that vent portion  72  of ridge vent strip  70  extends beyond (downslope of) trough closures  60 . It also will be appreciated that vertical extension  63  of trough closures  60  preferably, as exemplified in  FIG. 6 , extends somewhat above the top of seams  21  in panels  20 . Thus, vent portion  72  of ridge vent strip  70  will also be spaced well above troughs  22  in panels  20 . Ridge vent strip  70  may be secured to trough closures  60  by fasteners, such as screws  79  extending through body  71  of ridge vent strip  70  into shelves  63  of trough closures  60 . 
     Ridge cap  80  then may be installed. As appreciated from  FIGS. 6-7 , ridge cap  80  has a conventional peaked design. The sides of ridge cap  80  are folded down and then out to provide a narrow fascia and a narrow sill. Ridge cap  80  may be installed on ridge vent strips  70  by fasteners, e.g., screws  89  extending through the fascia of ridge cap  80  into vertical extension  73  of ridge vent strip  70 . Thus, it will be appreciated that the ridge assembly substantially restricts water from falling, flowing, or being blown into opening  6  running along ridge R or into space  11  between existing roof  1  and recover  10 . Importantly, the ridge assembly also allows convective air flow from space  11 , through panel support  50 , under ridge cap  80 , and out through ridge vent strip  70 . With that in mind, the configuration of panel support  50  and the size, number, and pattern of openings in vent portion  72  of ridge vent strip  70  may be varied widely. Preferably, such features are coordinated with the other features of the recover such that convective air flow may be established in space  11  allowing air to enter space  11  through eave vent strip  40  and exit through ridge vent strip  70 . 
     The components of the exemplified eave and ridge assemblies preferably are made from steel, such as 16 to 24 gauge galvanized steel sheets that may be easily formed and bent and cut into a desired configuration by conventional metal forming equipment. Such materials provide durable, weather resistant components that may be manufactured easily and economically. Other metals, such as extruded aluminum, may be used to fabricate the components, however, as well as rigid, moldable or extrudable plastics. 
     It is believed the exemplified eave and ridge assemblies may be used in the novel recover systems to provide effective above sheathing ventilation. The individual components may be fabricated and installed easily and economically, and when installed, effectively minimize the ingress of water into the existing roof or through the recover system. On the other hand, the components of the exemplified assemblies individually or the assemblies as a whole may be varied considerably in accordance with other embodiments of the invention. For example, the corrugations  51  in panel support  50  provide relatively flat upper and lower surfaces. Flat surfaces facilitate installation of the assembly, but corrugations of other shapes may be provided. A plurality of individual spacers, for example, I-shaped spacers may be used instead of a corrugated panel support. Eave and ridge vent strips also may be bent into different configuration, for example, to allow for different installation methods or for other functional reasons and for aesthetic reasons. They also may be assembled from separate components if desired. Various embodiments of the subject invention may incorporate different eave and ridge assemblies including different components. 
     It also will be appreciated that the novel standing seam roof recovers almost invariably require the use of other components to complete certain portions of a recover installation either for functional purposes, such as weather sealing, or for aesthetic purposes. For example, the roof may incorporate skylights, vent stacks or other projections, and special components may be required for their installation. Similarly, flashing and sealants may be installed in roof valleys, around projections, and elsewhere through the roof. Fascia and soffit components also may be installed along the eaves and gables of the roof. A wide variety of such components and installation methods are known in the art and may be used in the novel roof recovers. 
     While this invention has been disclosed and discussed primarily in terms of specific embodiments thereof, it is not intended to be limited thereto. Other modifications and embodiments will be apparent to the worker in the art.