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You are an expert at summarizing long articles. Proceed to summarize the following text: 
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention generally relates to metal roofs. More particularly, the invention relates to a metal roof system for use over an existing low slope modified bitumen, single ply rubber or built up roof.  
         [0003]     2. Description of the Related Art  
         [0004]     Many structures utilize low slope modified bitumen, single ply rubber or built up roofs to protect the interior of the structure from exposure to the elements, including sun, rain, snow, and the like. Modified bitumen, single ply rubber or built up roofs are utilized on metal, brick, wood, and other structures. Generally, the structure is built with interior columns that support a series of rafters or beams attached at the top of the columns. The roof rafters or beams are typically attached in a low-sloped manner with a ridge at the top to provide downward drainage. Spanning the rafters or beams is a wooden deck or a light gauge metal deck which is in turn covered with insulation and modified bitumen, single ply rubber or built up roofing. The decking generally runs perpendicular to the rafters or beams and is configured to be interconnected providing structural support for the overlying low slope modified bitumen, single ply rubber or built up roof. The low sloped roof usually consists of a layer of insulation board covered by either a multi-layer built up roof, a single ply rubber membrane or a modified bitumen membrane and are secured to a roof deck structure by nails, screws, clips, or other type fasteners. These low slope roofs find applications in many building constructions, such as commercial and industrial buildings.  
         [0005]     Over time, due to wear and other factors, the existing low slope modified bitumen, single ply rubber or built up roof is either removed and replaced with another modified bitumen, single ply rubber or built up roof or re-roofed by placing a new metal roof on top of the existing low slope modified bitumen, single ply rubber or built up roof. Re-roofing of such roofs with metal is difficult since the reroofing operation typically requires additional support structure to add slope to the existing low sloped modified bitumen, single ply rubber or built up roof or insulation layers or possibly a wood layer to accept the new roof. The addition of a typical support structure makes this system difficult and expensive to apply effectively. Additionally, reroofing of low sloped roofs with metal is typically hard to effectively weatherproof due to the slope of the roof which results in a less then optimum downward drainage. Furthermore, the metal panels in the new roof are subject to considerable movement together with the building due to the expansion and contraction of the panels by heat, cold, wind, etc. making it extremely difficult to provide a satisfactory weatherproof seal along the seams and at the fastener locations since over time the panels and their seams tend to become loose and create a potential leak path.  
         [0006]     A need therefore exists for a reliable and a weatherproof metal roof system for use to re-roof an existing low slope modified bitumen, single ply rubber or built up roof without adding slope.  
       SUMMARY OF THE INVENTION  
       [0007]     The present invention generally relates to a metal roof system. In one aspect, a method of placing a roof system over an existing low slope modified bitumen, single ply rubber or built up roof is provided. The method includes measuring a slope plane of the existing low slope modified bitumen, single ply rubber or built up roof to determine the location of irregularity points. Thereafter, at least one shim member is placed proximate each low irregularity point and at other predetermined locations. Next, an air space is formed between the existing low sloped roof and the roof system and then the roof system is operatively attached to the existing low sloped roof.  
         [0008]     In another aspect, a method of placing a roof system over an existing low sloped roof is provided. The method includes placing at least one shim member proximate each irregularity point on the existing low sloped roof and at other predetermined locations. The method further includes reducing the heat transfer from the roof system to a building or structure below by forming an air space between the roof system and the existing low sloped roof. Further, the method includes operatively attaching the roof system to the existing low sloped roof.  
         [0009]     In yet another aspect, a method of placing a roof system over an existing low sloped roof is provided. The method includes measuring a slope plane of the existing low sloped roof to determine the location of irregularity points and then placing at least one shim member proximate each low irregularity point and at other predetermined locations. The method also includes directing the thermal movement of the roof system by employing a plurality of fixed and floating clips at predetermined locations between the roof system and the existing low sloped roof and then operatively attaching the roof system to the existing low sloped roof. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]     So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.  
         [0011]      FIG. 1  is a view illustrating a sidewall arrangement of a roof system in accordance with the present invention.  
         [0012]      FIG. 2  is a view illustrating a headwall arrangement and a curb arrangement of the roof system in accordance with the present invention.  
         [0013]      FIG. 3  is a view illustrating the headwall arrangement.  
         [0014]      FIG. 4  is a view illustrating the curb arrangement.  
     
    
     DETAILED DESCRIPTION  
       [0015]     The present invention generally relates to a metal roof system for use on an existing low sloped modified bitumen, single ply rubber or built up roof. The metal roof system is comprised of clips, shims, roof panels, and other components. Prior to installing the metal roof system, the existing low sloped modified bitumen, single ply rubber or built up roof must be examined to determine if it is suitable for a retrofit. For example, the existing roof decking is examined to determine if the decking is capable of holding fasteners. Additionally, the structure of the existing roof is examined to determine if the structure is capable of holding additional weight. After the existing low sloped roof has been completely examined and has met certain criteria, the metal roof system of the present invention may be employed in accordance with the method described herein. To better understand the novelty of the apparatus of the present invention and the methods of use thereof, reference is hereafter made to the accompanying drawings.  
         [0016]      FIG. 1  is a view illustrating a sidewall arrangement  150  of a roof system  100  in accordance with the present invention. Generally, the sidewall arrangement  150  is a portion of the roof system  100  adjacent a wall  155  on an existing roof  10 . The sidewall arrangement is constructed of various components to ensure that there is a weatherproof relationship between the wall  155  and the roof system  100 .  
         [0017]     The sidewall arrangement  150  includes a plurality of shims  165  or bearing plates positioned at predetermined locations along on top of the existing roof  10 . Prior to positioning the shims  165 , the slope of the existing roof  10  is measured by a level device (not shown). The level device is used to determine the amount of shimming that will be required to make the roof system  100  straight and true. Next, the shims  165  are used to fill low spots or irregularities and other predetermined locations on the existing roof  10  to ensure that the roof system  100  is substantially without dips which typically hold water. It should be noted that a plurality of shims may be employed at any one location without departing from principles of the present invention. In one embodiment, the shims  165  are constructed from a plastic or composite material. Additionally, the shims  165  or bearing plates are used to increase the contact surface area between a clip  120  and the existing roof  10 . Furthermore, the shims  165  are used to create an airspace  135  between the existing roof  10  and the roof system  100 .  
         [0018]     The airspace  135  is generally used as insulation to reduce the amount of heat transferred from the roof system  100  through the existing roof  10  into the building or structure below (not shown). In reducing the amount of heat transferred into the building or structure below the roof system  100 , the energy required to heat or cool the building or structure is subsequently reduced. In one embodiment, a radiant barrier may be disposed in the airspace  135  to further reduce the amount of heat transfer between the roof system  100  and the building or structure below. It should be understood, however, that any form of insulation may be employed in the airspace  135  without departing from principles of the present invention  
         [0019]     The sidewall arrangement  150  further includes a plurality of clips  120  positioned on top of the shims  165 . The clips  120  are secured to the existing roof  10  by a plurality of fasteners  130 . The primary function of the clips  120  is to secure the roof system  100  to the existing roof  10 . More particularly, the clips  120  provide a means of supporting a roof panel  125  and holding new roof panels together. The clips  120  may be a fixed clip which is secured at one location or a floating clip which is capable of moving a predetermined distance. The floating clip allows the panel  125  to move as the panel  125  expands or contracts due to heat, cold, etc. Therefore, the placement of the fixed and floating clips at predetermined locations on the existing roof controls the direct thermal movement of the roof system  100 . In one embodiment, the fixed clips will be used in the middle area or top area of the roof system  100  and all other clips will be floating clips installed in such a manner where a sliding mechanism is in the center of the clip allowing the panel to move in either direction. Another function of the clips  120  adjacent the wall  155  is to support a sidewall cleat  110 .  
         [0020]     As illustrated in  FIG. 1 , the sidewall cleat  110  is attached both to a seam of the panel  125  and to the clips  120  by a fastening member  170 . Typically, a tape seal  140  is disposed between the panel  125  and the sidewall cleat  110  to create a watertight sealing relationship therebetween. The tape seal  140  is generally an elastomeric material that is capable of forming a fluid seal between two members. The sidewall cleat  110  or extension member is used to raise the perimeter of the roof system  100  along the wall  155  to ensure a weatherproof arrangement between the roof system  100  and the building or structure below. The sidewall arrangement  150  also includes a sidewall trim  105  that extends downwardly over the sidewall cleat  110 . The sidewall trim  105  is used to direct particles, such as water, toward the roof panel  125 . It should be noted that the sidewall trim  105  is not operatively attached to the roof panel  125 , thereby allowing the roof panel  125  to expand or contract without affecting the sidewall trim  105 . Additionally, the panel  125  is sloped in the direction indicated by arrow  115  to facilitate the downward drainage of the particles, such as water.  
         [0021]      FIG. 2  is a view illustrating a headwall arrangement  200  and a curb arrangement  250  of the roof system  100  in accordance with the present invention. The headwall arrangement  200  is generally used to create a weatherproof relationship between a head wall  245  and the roof system  100 , as illustrated in  FIGS. 2 and 3 . The curb arrangement  250  is generally used to create a weatherproof relationship between a penetration, such as an AC unit or a sky light (not shown), and the roof system  100 , as illustrated in  FIGS. 2 and 4 . For convenience, the components in the sidewall arrangement  150  that are similar to the components in the headwall arrangement  200  and the curb arrangement  250  will be labeled with the same number indicator.  
         [0022]     As illustrated in  FIG. 3 , the headwall arrangement  200  includes a plurality of shim members  165  disposed on top of the existing roof  10 . Typically, a roof panel  225  that adjoins the head wall  245  will have extra shims  165  to support the top of the panel. Thereafter, a strip member  215  is placed on top of the shim members  165  adjacent the headwall  245 . In one embodiment, the strip member  215  is a 6″ wide, 16 gauge piece of sheet metal. A lower zee  210  is positioned inside the panel  225  and operatively attached to the strip member  215  by a plurality of fasteners  170 . The tape seal  140  is disposed between the strip member  215  and the panel  225  to create a fluid tight relationship therebetween. It should be noted that lower zee  210  and the strip member  215  are not attached to the existing roof  10 , thereby allowing the panel  225  to expand or contract without affecting the headwall arrangement  200 . Additionally, panel  225  is sloped in the direction indicated by arrow  230  to facilitate the downward drainage of the particles, such as water.  
         [0023]     The roof panel  225  and other main roof panels are typically continuous along their entire length from the ridge or headwall to the eave with no end laps. In one embodiment, the roof panel  225  and other roof panels (not shown) in the roof system  100  have different panel widths to ensure that the last panel seam lands at a predetermined distance from a penetration or a wall. Additionally, in another embodiment, the roof panel  225  and other panels in the roof system  100  have a vertical seam arrangement, thereby allowing versatility and more complex roof geometry.  
         [0024]     As shown, an upper zee  205  is attached to an upper end of the lower zee  210  by a plurality of fasteners  170 . Additionally, the tape seal  140  is disposed between the upper and lower zees  205 ,  210  to create a fluid tight relationship therebetween. The upper zee  205  is used to raise the perimeter of the roof system  100  along the headwall  245  or ridge to ensure a weatherproof arrangement between the roof system  100  and the building or structure below. The headwall arrangement  200  also includes a headwall trim  220  operatively attached to the upper zee  205  by fasteners  170 . The headwall trim  220  is used to direct particles, such as water, toward the roof panel  225 . Typically, a seal member (not shown) is employed between the headwall trim  220  and the headwall  245  to create a sealing relationship therebetween.  
         [0025]     Referring back to  FIG. 2 , the curb arrangement  250  is positioned adjacent the headwall arrangement  200 . It should be understood, however, that the curb arrangement  250  may be positioned at any location on the roof system  100 , without departing from principles of the present invention. As illustrated, a panel  255  on the curb arrangement  250  is raised in relation to the panel  225  and run substantially perpendicular to panel  225 , thereby allowing the panel  255  to direct particles, such as water, into the panel  225 . Additionally, panel  255  is sloped in the direction indicated by arrow  260  to facilitate the downward drainage of the particles.  
         [0026]     As illustrated in  FIG. 4 , shim  165  is placed on top of the existing roof  10 . A clip  280  is placed on top of the shim  165  and secured to the existing roof  10  by fastener  130 . Disposed on the upper end of the panel seam is a side cleat  275 . The side cleat  275  is used to raise the perimeter of the roof system  100  along curb arrangement  250  to ensure a weatherproof arrangement between the roof system  100  and the building or structure below. Additionally, the side cleat  275  is adjacent a structural zee member  270  disposed on top of the shim  165 . A transverse panel trim  265  is disposed adjacent the zee member  270 . The transverse panel  255  is secured to the transverse panel trim  265  by fasteners  170 . The transverse panel trim  265  and the zee member  270  are constructed and arranged to allow the panel  225  to expand or contract without affecting the curb arrangement  250 . Additionally, the tape seal  140  is typically disposed between the members of the curb arrangement  250  to ensure a fluid tight relationship therebetween.  
         [0027]     While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Summary:
The present invention generally relates to metal roofs. In one aspect, a method of placing a roof system over an existing low sloped roof is provided. The method includes measuring a slope of the existing low sloped roof to determine the location of irregularity points. Thereafter, at least one shim member is placed proximate each irregularity point and at other predetermined locations. Next, an airspace is formed between the existing low sloped roof and the roof system and then the roof system is operatively attached to the existing low sloped roof.