Abstract:
A flexible roofing fastener is provided for securing water resistant material to a substrate such as wood and preventing leaks through holes created in the material by the roofing fastener. The roofing fastener includes a resilient disk having a flat lower surface, a thick central region and an annular region having a thickness that tapers downwardly from a central area toward a periphery. The disk central region has a plurality of evenly spaced apart flat-headed nails extending downwardly there through. The annular region having plurality of holes through which sealing material can flow. A flexible disk, when upload flexes in a cup shape causing wedge effect on the anchoring points in the substrate, allowing this fastener to perform better when under a simulated wind uplift testing of various modified bitumen Roof Systems.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 13/355,899 filed Jan. 23, 2012, the disclosure of which is hereby incorporated in its entirety by reference herein. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to a roofing fastener having a disk that distributes pressure over greater areas than do heads of nails alone when used to secure sheets of water-resistant materials to substrates such as wood and more specifically to roofing fasteners having resilient disks configured to moderate pressures along their peripheral edges to prevent damage to the material being supported by the roofing fasteners while preventing leaks through holes created in the material by the roofing fasteners. 
     2. Background Art 
     Roofing components are applied to the top of roofs for several reasons. First, the roofing materials prevent moisture from reaching an underlying support member such as concrete or plywood. Also, roofing materials serve to insulate a building from the outdoors. 
     With respect to underlying support members which are made of plywood or OSB, plywood, and about ½″ to ¾″ inches thick, a base ply sheet of felt-like material of fiberglass or organic material is commonly placed over the plywood. Roof fasteners are then installed through the base ply and into the plywood to hold the base ply to the support member. A layer of molten asphalt is then poured or brushed over the base ply and roofing fasteners. In some instances, a second layer of base ply sheets are placed over the first layer of asphalt while the asphalt it still hot. The asphalt thus holds the first and second layers of base ply sheet together. 
     In the event of high winds, it is important that the combination of the base ply sheet and asphalt be strongly anchored to the underlying roof substrate. With high winds, such as might accompany hurricanes, large relatively low-pressure conditions can be created above the asphalt/base ply roofing materials. This wind or low pressure can rip the asphalt/base ply sheet roofing materials off the underlying roofing substrate if not sufficiently anchored. 
     A common type of roofing fastener used today to hold plywood and asphalt roof materials to a roofing substrate is a nail with a disc 1″ to 1⅝ inches in diameter having a generally flat head. The fastener is pounded into the base ply and plywood. The nail penetrates the plywood and secures the disk, therefore securing the base-sheet to the plywood. 
     These cap nails have drawbacks. Often, they have limited capacity to secure the base sheet, because they will only provide 50-100 pounds of resistance. Tear out strength test results conducted on these roofing fasteners installed in plywood vary greatly from fastener to fastener due to inconsistency of plywood. Moreover, due to increasing losses in the insurance industry, pull out requirements for fasteners have been revised upward. Often these cap nails fail to meet the new and higher industry standards. Typically, these cap nails have pullout strength of about 50-100 pounds. 
     Problems exist with other fasteners as well. A roofing nail with a 1⅝″ metal disk adjacent to its head, have limited pull out rupture strength typically in the range of 70 to 100 pounds. Multiple component fasteners are also used which include a retaining disk with a central aperture, which receives a threaded fastener. This multiple piece construction increases the cost of making the fastener and complexity of installation. Further, even these multiple component fasteners also have difficulty in meeting today&#39;s desire for providing higher load values without pulling out or tearing the roofing material. 
     The present invention is intended to address deficiencies found in these above-described conventional fasteners. 
     SUMMARY 
     A roofing fastener is provided for nondestructively securing water resistant membrane material to a substrate; such as wood roof decking and preventing leaks through holes created in the membrane material by the roofing fastener. The roofing fastener includes a resilient, disk having a flat lower surface. The roofing fastener also includes a plurality of nails having an elongate, metal, senate shank bearing a flat head at a first end and a point at the second end. The second end and the shank of each nail extend fixedly downwardly through evenly spaced apart apertures formed in the disk central region having a sized to securely grip the nail. An annular region having plurality of openings there through sized to allow roof adhesive to pass there through surrounds the disk central region. The disk is formed of a tough resilient plastic material. A flexible disk, which has more than one anchoring point, which flexes in a cup shape causing wedge effect on the anchoring point in the substrate, allows this fastener to perform 300% better than the standard cap nail. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side, sectional view of a roofing fastener, taken along the section line  1 - 1  of  FIG. 2 , with the roofing fastener disk in an unattached, uncurled configuration; 
         FIG. 2  is a plan view of the disk of the roofing fastener of  FIG. 1  and illustrates a web bridging an exemplary, secondary opening in the roofing fastener disk; 
         FIG. 2A  is an enlarged fragmentary view of an alternative roofing fastener hole structure; 
         FIG. 3  is a side, sectional view of the roofing fastener of  FIG. 1 , shown attached through a water-resistant material to a wooden substrate under an upward wind load with deflection exaggerated for illustration purposes; 
         FIG. 4  is a side elevational view of yet another roofing fastener embodiment; 
         FIG. 5  is a side view of a roofing fastener being installed utilizing a magnetic hammer; 
         FIG. 6  is a cross-sectional side view of a multi-layer roof system adhered to a roof deck using a roofing fastener; 
         FIG. 7  is a top plan view of a second alternative roofing fastener embodiment; 
         FIG. 8  is a top plan view of a third alternative roofing fastener embodiment; and 
         FIG. 9  illustrates a method of building a multi-layer roof system. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention. 
       FIG. 1  shows a side, sectional view of a first roofing fastener embodiment  10 , taken along the section line  1 - 1  of  FIG. 2 . The roofing fastener  10  comprises a disk  12  having a flat lower surface  14  and has a generally flat upper surface  16 . Disk  12  has a relatively thick central region  18  surrounded by an annular region  20  which preferably tapers downwardly from the central region  18  toward a periphery  22 . The disk is formed of one of a tough flexible plastic material such as nylon, Lexan, acrylics and/or flexible metals or mixture of metals; such as tin, aluminum, zinc etc. The illustrated embodiment is formed of impact modified Nylon 66. 
     Extending through the central region  18  of the disk  12  is a plurality of evenly spaced apart apertures  24 . The annular region  20  is provided with a series of holes  26 . Apertures  24  receive and firmly support a plurality of nails  28  and  28 ′. The series of holes  26  contribute to the flexibility of the disk  12  and enable an adhesive  30 , such as asphalt or tar, to flow through the holes  26  and adhere to a water-resistant first layer of roofing material  32  as shown in  FIG. 3  such as roofing felt or tar paper disposed below. Optionally, each the series of holes  26  provided with one or more webs  33  spanning the holes as shown in  FIG. 2A  allowing sealing material to flow through the holes  26  while preventing the tip of a nail of another roofing fastener from becoming entangled therein pro to use or when shipped in bulk. 
     The nails  28  and  28 ′ extend downwardly through apertures  24  the central region  18  in a perpendicular manner. The diameter of apertures  24  are slightly smaller than the diameter of the nail shank  34  to retain the nail  28 , once inserted. Apertures  24  can be preformed when the disk is molded or formed in situ as the nails are driven through the central region  18 . The nails  28  have a shank  34  with a flat head  36  located at a first end and a point  38  located at an opposed second end. The nail head  36  is preferably of the flat head design, and the shank  34  is preferably serrated to form a ringed shank or a screw shank. 
       FIG. 2  is a plane view of the first roofing fastener embodiment  10  illustrating the positions of the central region  18 , nails  28  and  28 ′ and of a typical arrangement of holes  26  in annular region  20 . Also shown is the disposition of the centerline  40 . 
       FIG. 3  is a cross-sectional side view of the roofing fastener  10  attached to a substrate  44  and shows the disk  12  in a curled, partially inverted configuration as it would appear when being flexed by an upward wind load. The inversion of the disk  12 , which is exaggerated for illustration purposes, moderates shear forces applied to the multilayer roof system  42  by the peripheral edge  22  of the disk  12 , reducing the likelihood of the first layer of roofing material  30  being damaged by the peripheral edge of the disk. 
     The illustrated multilayer roof system  42  has first layer  32  applied directly over the roof deck  44  and affixed thereto by a series of roofing fasteners  10 . On top of the first layer  32  held to the roof deck  44  by roofing fasteners  10  is a layer of roofing adhesive  30  such as tar or other roof sealant is applied. The roof adhesive penetrates through the holes  26  in a disk and bonds to the first layer  32 . A second membrane  48  is applied over the adhesive layer to form a water impervious multilayer roof system  42 . An example of a roof system of this type is referred to a 30/90 hot mop roof. 
       FIG. 3  illustrates the pair of nails  28  and  28 ′ extending through the central region  18  of disk  12 . Disk  12  is preferably made of a very tough plastic material, an example of which is impact modified Nylon 66. Nails  28  and  28 ′ are preferably ring groove type nails having a length of 1/1 to 1 1/1 inches so that the nails can extend through the roof deck  44  to which it is affixed as illustrated in  FIGS. 3 and 6 . The nails  28  and  28 ′ preferably form a very tight fit with the apertures  24  through which they extend. The holes can be formed by the nails themselves as they are driven through the center region of the disk or small pallet holes may be provided. 
     Preferably, a total area of the array of holes  26  formed in disk  12  is about 10% to 30% of the total plan view area of the disk assuming no holes and most preferably, the area of the holes  26  is approximately 15% of the disk area assuming not holes. The illustrated disk of  FIGS. 3 and 6  has the diameter of approximately 3 inches. The central region  18  is approximately 1.2 inches in diameter. The disk central region has thickness of 0.06-0.15 inches and preferably about 0.1 inches. The surrounding annular region  20  has a thickness which tapers from a maximum of the thickness of the central region to 0.05 inches less than the central region has thickness to 0.1-0.03 inches at periphery  22 . Of course, material thickness will be dependent upon the properties of the plastic selected. The tougher the plastic, the larger diameter and the thinner the disk can be fabricated. If the disk is made larger or if a less tough plastic material is utilized, the disk accordingly will be thicker. Preferably, disk  12  is made utilizing an injection molding process. As previously indicated, nails  28  and  28 ′ may fit in a small diameter preform pilot holes or the disk center region can be made without pilot holes and the nails simply driven through the disk after the disk is molded. In the embodiment illustrated, only two nails are provided per disk, however, three or more nails may be used with the nails spaced generally evenly out from the disk center and circumferentially from one another. The three nail embodiment is illustrated in phantom outline in  FIGS. 1 and 2  and shown in the  FIG. 8  embodiment. In most instances, two nails are sufficient to securely adhere the disk to a roof deck. 
     When there is an upward wind load on the building roof system made using described fastener and assembly method the resilient disk flexes becoming slightly cup shaped causing the heads of the plurality of nails to be urged inward toward one another binding in the holes in the roof deck. The deflection of the resilient disk and the movement of the plurality of nails is shown in  FIG. 3  is exaggerated for illustration purposes. By loading the two nails spaced from each other and the central axis using the resilient disk as shown pull out strength has increased to over 300% of that of a single centrally located nail of similar size and construction. 
     If a large number of roofing fasteners are placed in bulk in a shipping box, there is a risk that the nails of one roofing fastener will become entangled in the holes  26  of another disk. To reduce this risk, it is possible to mold a series of webs across the holes as illustrated in  FIG. 2A , the webs are sufficiently close to prevent a nail of an adjacent roofing fastener to go through the aperture, yet, sufficiently open to allow roof sealant to past there through. An alternative structure to reduce entanglement to reduce entanglement is shown in  FIG. 4 . A tape bridge  50  is provided spanning the ends of nails  28  and  28 ′. This tape bridge can be left in place when the roofing fastener is installed, the tape simply tearing away as the nails are driven through a membrane and the adjacent roof deck. A short length of conventional adhesive tape or the like can be folded over on its self to grip and span between two or more nails as illustrated. 
     An alternative way of preventing roofing fasteners from becoming entangled is to carefully nest the adjacent nails with nails of one roofing fastener oriented within the holes of another. By placing the nested rows of roofing fasteners in a box and separated by sheets of paper or plastic film, roofing fasteners can be densely packed and easily removed from a shipping container. 
     A building roof system can be easily installed using roofing fasteners  10  and a magnetic hammer  52  as illustrated in  FIG. 5 . The first membrane  32  is applied to the roof deck  44 . Roofing fastener  10  is placed on the head of the hammer  52  and preferably, driven in place with a single blow. Roofing fasteners should be generally uniformly spaced along the surface of the first membrane  32  to achieve the desired anchored strength for the expected wind loads on the building. On top of the first membrane  32 , which is held to the roof deck  44  by roofing fasteners  10 , a layer of roof adhesive  30  such as tar or the like is applied to the desired thickness. The roof adhesive penetrates the holes  26  in the disks  12  to securely bonded to the first membrane  32 . On top of the roof adhesive layer  30 , a second membrane  48  is applied as illustrated in  FIG. 6 . The method of building a multi-layer roof system is further described in the flow chart of  FIG. 9 . 
     Alternatively, roofing fastener  60  as shown in  FIG. 7 , has a disk  62  which is oval or elliptical in shape with two spaced apart two nails  64  and  64 ′. Another roofing fastener  70  has a disk  72  with a three lobe shaped disk  72 , as shown in  FIG. 8 , with three nails  74 ,  74 ′ and  74 ″ The nails are evenly spaced apart from one another and the center of the disk. In two nail designs, the nails would be spaced approximately 180° apart, in a three nail design the nails would be spaced approximately 120° apart, and in a four nail design the nails would be spaced approximately 90° apart. Preferably the nails are spaced an equal distance from the disk center by about 10-20% of the maximum radial dimension of the disk, most preferable about ⅙th of the maximum radial dimension of the disk. Alternatively, the nails are spaced 20-45% of the maximum radial dimension of the disk. By spacing the nails away from the center of the disk pull out strength is improved and is more than twice that of a single nail or two nails adjacent the center. It is believed that flexing of the disk as shown in  FIG. 3  causes the shanks of the nails to be side loaded binding in the hole formed in the roof deck  44 . 
     While embodiments of the invention have been illustrated and described, it is not intended that these embodiments illustrate and describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention.