Abstract:
A roof insulation fastening system employs a fastener and a compression plate with a tube which interacts with the compression plate to permit the plate to vertically move relative to the head of the fastener when the adjacent area and/or plate is subject to excessive compression. The tube includes a retainer shoulder and a pair of tabs wherein the plate captures the tube. The tube includes a throat and a tapered portion with a throughbore. The fastener is inserted into the tube and secured in place so that the head is retained at the intersection of the throat and the tapered portion and the shank is secured into the roofing substrate.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority of U.S. Provisional Patent Application No. 61/366,006 filed on Jul. 20, 2010, the disclosure of which is incorporated by reference in its entirety. 
    
    
     BACKGROUND 
     This disclosure relates generally to fasteners and fastener assemblies which are employed for securing roof insulation to a roof deck. More particularly, this disclosure relates to fastening assemblies which employ a metal plate to secure an overlying membrane and insulation to a roof deck. 
     In roof installations for which the present disclosure has particular applicability, battens or rolls of insulation are laid across a roof deck. A water-impermeable membrane is laid on top of the insulation. Metal plates clamp the membrane and insulation to the roof deck by means of fasteners which are inserted through central openings of the plates and threaded into the roof deck. 
     For some installations, which employ relatively thick insulation that is highly compressible, it is common to insert a tube into the central opening of the metal plate. The fastener is inserted into the tube. The underside of the head of the fastener engages an interior shoulder of the tube. The fastener is then driven into the roof deck so that the plate clamps against the membrane and insulation. The tube is vertically displaceable relative to the secured fastener. The plate can thus vertically move relative to the head of the threaded fastener when the adjacent area and/or plate is subject to excessive compression. 
     For some applications, the plate may also be affixed with a heat-activated adhesive. A water impermeable membrane covers the plates. An induction tool is passed over the plate to heat the adhesive which bonds with the membrane overlying the plate. 
     SUMMARY 
     Briefly stated, a fastening assembly for securing a membrane and insulation to a roof deck comprises a fastener, a compression plate and a clamp tube. The fastener has a drive head and a threaded shank extending from the drive head. The compression plate distributes the load of the fastener across the upper surface of the membrane and defines a central opening. The clamp tube has a retainer collar, a throat and a tapered portion with a fastener opening through which the shank extends. The fastener shank is inserted through the central opening so that the retainer collar engages the plate and is captured thereby. The tapered portion is traversed by at least one slot and preferably by a plurality of angularly disposed slots. The plate has an underside which preferably engages the membrane. 
     The clamp tube further comprises a retainer tab for engaging the underside of the plate. The tube preferably further comprises a second retainer tab opposite the first retainer tab for engaging the underside of the plate. A shoulder, which may have an annular form, is defined in an interior location adjacent the introduction of the tube adjacent the intersection of the throat and the tapered portion. 
     In one embodiment, the compression plate further comprises a plurality of angularly spaced prongs which surround the central opening. The prongs surround and resiliently engage against the throat at a peripheral exterior portion adjacent the retainer collar. The tube further comprises a pair of opposed tabs and at least two of the prongs engage against the retainer tabs. 
     A one-piece tube is seatable in a compression plate for receiving a fastener. The tube includes a circumferential retaining flange. A sleeve integrally extends from the flange and has a pair of tabs with shoulders spaced from the underside of the flange. The tabs have a peripheral ramp surface. The sleeve further defines a cutout adjacent each of the tabs. The sleeve interiorly forms a throat with an interior shoulder adapted for engagement by the fastener head. A tapered portion integrally extends from the sleeve and tapers toward a distal tip. A throughbore extends from the throat and is dimensioned for receiving the shank of the fastener. A plurality of angularly spaced slots extends to the tip to permit limited flexure in the tapered portion. There are preferably three slots in the tapered portion of the tube. The exterior surface of a conical portion of the tapered portion is defined by a plurality of angularly spaced gussets. 
     A plurality of ribs project inwardly into the throughbore at the tip. The ribs preferably project inwardly and extend arcuately at the tip. In another embodiment, a plurality of angularly spaced ribs extend longitudinally interiorly of the sleeve. A recess for receiving the head is defined at an interior location adjacent the intersection of the throat and the tapered portion. The tube is preferably manufactured from a plastic material. 
     A roof installation comprises a roof deck insulation disposed on the roof deck and a membrane overlying the insulation. A compression plate which has a central opening is disposed on the upper surface of the membrane. A clamp tube having a retainer collar, a throat and a tapered portion with a fastener opening is captured by the plate. A fastener which has a drive head and a threaded shank extends from the drive head. The fastener shank extends through the fastener opening and engages with the deck. The retainer collar of the tube engages the plate, and the tube is captured by the plate. The tube and plate are displaceable as a unit from a first position under a compressive load and return to the first position as a unit when the compressive load is removed while the fastener remains engaged with the deck. 
     The plate has an underside which engages the membrane and the clamp tube further comprises a pair of opposed retainer tabs for engaging the underside of the plate. The tapered portion is traversed by a plurality of angularly disposed slots. A shoulder defined by an interior location of the tube adjacent the intersection of the throat and the tapered portion is positioned so that the fastener head is seated against the shoulder. The compression plate further comprises a recessed portion surrounding the central opening and the retainer collar is received in the recess portion. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side elevational view of an assembled fastening assembly including a plate, a tube and a fastener; 
         FIG. 2  is a central sectional view of the fastening assembly of  FIG. 1 ; 
         FIG. 3  is a sectional view of the fastening assembly of  FIG. 1  as installed in a roof installation shown in section for securing insulation to a roof deck; 
         FIG. 4  is a top plan view of a plate, a tube and a fastener for the fastening assembly of  FIG. 1 ; 
         FIG. 5  is an enlarged perspective view of a tube which may be employed in the fastening assembly of  FIG. 1 ; 
         FIG. 6  is a central sectional view of the tube of  FIG. 5 , taken along line  6 - 6  thereof; 
         FIG. 7  is a top plan view of the tube of  FIG. 5 ; 
         FIG. 8  is a cross-sectional view of the tube of  FIG. 5 , taken along line  8 - 8  thereof; 
         FIG. 9  is a cross-sectional view of the tube of  FIG. 5 , taken along line  9 - 9  thereof; 
         FIG. 10  is a bottom plan view of the tube of  FIG. 6 ; 
         FIG. 11  is an enlarged side elevational view of another embodiment of a tube which may be employed for the fastening system of  FIG. 1 ; 
         FIG. 12  is a central sectional view of a second alternate embodiment of a tube; 
         FIG. 13  is a central sectional view of a third alternate embodiment of a tube; 
         FIG. 14  is a perspective half-sectional view of the tube of  FIG. 11 ; 
         FIG. 15  is a top plan view of the tube of  FIG. 11 ; 
         FIG. 16  is an enlarged perspective view of a plate for the fastening assembly of  FIG. 1 ; 
         FIG. 17  is an enlarged central sectional view, partly in diagram form, of the plate of  FIG. 16 ; 
         FIG. 18  is an enlarged side view, partly in diagram form, of a fastener that may be employed in the fastening assembly of  FIG. 1 ; 
         FIG. 19  is a side view, partly in diagram form, of a second fastener that may be employed in the fastening assembly of  FIG. 1 ; 
         FIG. 20  is a central sectional view, partly in diagram form, of the tube of  FIG. 5 ; 
         FIG. 21  is a perspective view of an alternative embodiment of a plate which may be employed in a fastening assembly; 
         FIG. 22  is a sectional view of the plate of  FIG. 21 ; 
         FIG. 23  is a bottom perspective view of the plate of  21  assembled with a tube as employed for the fastening assembly; 
         FIG. 24  is a sectional view of the assembled plate and tube of  FIG. 23 ; 
         FIG. 25  is a top plan view of an alternative embodiment of a tube which may be employed in the fastening assembly; 
         FIG. 26  is a perspective view of the tube of  FIG. 25  and looking into the tube interior; and 
         FIG. 27  is a central sectional view of the tube of  FIG. 25 . 
     
    
    
     DETAILED DESCRIPTION 
     With reference to the drawings wherein like numerals represent like parts throughout the several figures, a fastening assembly designated generally by the numeral  10  is employed to secure insulation  12  and a water impermeable membrane  14  to a roof deck  16  and to maintain the connection between the membrane and the roof deck. In the illustrated installation of  FIG. 3 , the roof deck  16  has a corrugated steel form, and the insulation  12  is typically a highly compressible insulation which may have a thickness which varies, for example, from 8 to 12 inches. 
     In installations for which the fastening assembly  10  has particular application, battens or rolls of the insulation are laid onto the roof deck. The roof is typically a “flat” type of roof. A membrane covers the insulation. The fastening assembly  10  functions to clamp the membrane and the insulation onto the roof deck to secure same therewith. Naturally, numerous such fastening assemblies are employed for a given installation and typically form a grid across the roof. 
     The fastening assembly comprises a plate  20 , a fastener  30  which is driven into the roof deck to provide the securing/clamping function, and a tube  40  which is inserted into the plate and receives fastener  30  which is inserted into the tube. The foregoing three components may be pre-assembled. 
     With additional reference to  FIGS. 16-17 , the plate  20  is typically made from galvanized steel or other metal and formed by a stamping process. The plate  20  typically has a stepped circular shape with a central circular opening  22  and a raised annular platform  24 . The plate includes an outer peripheral lower annular rim  26  and an inner stepped recess  28  which surrounds the opening  22  and tapers downwardly in two steps from the raised platform  24 . One or more stress cuts  27  may be formed in the plate portion defining the recess around the opening. For some embodiments, heat-activated adhesive (not illustrated) may be applied to the platform  24  for sealing and securing an overlying membrane. The plate  20  may also include a vent opening  29 . 
     The tube  40  is an integral, one-piece plastic member. The tube  40  is preferably formed from polyamide with 0 to 15% glass filler and 0 to 3% impact modifier or polypropylene with 0 to 20% glass filler and 0 to 10% impact modifier. Other materials may also be suitable. 
     The tube  40  includes an annular flange-like collar  42  configured to be received in the plate recess  28 . The collar underside  44  engages the plate portion defining the recess  28  surrounding the opening of the plate. The tube  40  functions to facilitate the clamping securement of the plate and in part as a relief structure to allow the installed fastening assembly to accommodate a downwardly compressive load applied at or adjacent the top of the plate without jeopardizing the integrity of the membrane and the clamp load supplied by the fastening assembly after the compressive load is relieved. The tube  40  includes a sleeve-like cylindrical throat portion  50  generally extending from the underside  44  of the collar and a quasi-conical distal tapered portion  60 . The tube  40  is especially configured to be compatible with and capable of accommodating fasteners of different dimensions. 
     The cylindrical throat portion  50  includes a pair of opposed, inverted quasi-U-shaped cutouts  52 . Each cutout surrounds a resilient tab  54  which projects upwardly. Each tab  54  has an upper shoulder  56  preferably having a top planar surface. Each tab  54  has a ramp surface  55  configured and dimensioned to slide over the edge of the plate opening  22  so that the shoulder  56  engages the underside  44  of the plate when the tube  40  is inserted through the central opening  22  and seated in the recess  28 . The outside diameter of the cylindrical throat portion  50  is generally dimensioned to be closely received in the opening  22  of the plate so that the collar  42  is seated in the recess  28 , and the opposed tab shoulders  56  engage the underside  44  of the plate whereby the tube may be vertically captured by the plate. The inner diameter of the inner cylindrical surface  58  of the throat portion is dimensioned so that the head  32  of the fastener  30  may be easily passed until the underside  33  of the fastener head  32  engages against an intermediate shoulder  62  or annular restriction formed at the bottom of the throat portion. 
     The tapered portion  60  includes an upper interior annular recess region at the interface with the throat portion  50 . The tapered portion  60  is configured so that the effective inside diameter is variable as a function of the thread/shank diameter of the associated fastener  30 . The tapered portion in a first mode is dimensioned to be approximately the outside diameter of a fastener having a first diameter. The axial end of the tapered portion includes an opening  70  through which the tip and end portion of the shank of the fastener passes. Angularly spaced vertical slots  66  are formed at the end of the tapered portion. The slots  66  function to allow the tapered portion to flex generally radially to accommodate fasteners with different diameters. 
     In addition, inwardly protruding crush ribs  68  are effectively displaced radially and/or at least partially destroyed when a larger diameter fastener is driven into the tube. Naturally, the tapered portion  60  has an effective fastener diameter range and has a limit for effectively accommodating fasteners of a given diameter. 
     The conical portion is traversed by angularly spaced gusset grooves  69  to provide reinforcement for the tube. The tapering and geometry of the tube facilitates the insertion of the tube into the insulation and the membrane. 
     The fastener  30  includes a head  32  with a hex head, a Phillips-type slot, a square drive recess or other configuration adapted for engagement by a driving tool for torquably driving the fastener. The shank  34  of the fastener includes a thread  36  which may be a buttress thread and terminates in a drill tip  38 . Two suitable fasteners  30 A and  30 B are illustrated in  FIGS. 18 and 19 , respectively. Other fasteners are also possible. 
     With reference to  FIG. 18 , fastener  30 A is a #15 RoofGrip™ fastener marketed by OMG, Inc. of Agawam, Mass. The head  32 A has a #3 Phillips recess. The major diameter D of the thread  36  is 0.250 to 0.275 inches and the minor diameter d of the thread is 0.165 to 0.175 inches. The thread  36 A is a buttress thread having a pitch of 13 TPI. The shaft length A may vary from 1¼ to 22 inches and the thread  36 B length B (including the drill tip  38 A) may vary from 1¼ to 4 inches. 
     Another suitable embodiment for the fastener is fastener  32 B illustrated in  FIG. 19 . The fastener  30 B is a RhinoBond™ heavy duty drill point fastener marketed by OMG, Inc. of Agawam, Mass. The head  32 B has a #3 square drive. The thread has a major diameter of D 0.226 to 0.230 inches and a minor diameter d of 0.175 inches. The thread  36 B is a single lead thread with a pitch of 20 TPI and is a type AB thread. The drill tip  38 B is a ¾ inch drill tip with a nominal diameter N of 0.208 to 0.212 inches. The shaft length L varies from 4 inches to 10 inches and the thread length Λ (including the drill tip  38 B) is approximately 3.860 inches. 
     With reference to  FIGS. 11-15 , the tube may assume a number of alternative forms. Tube  140  illustrated in  FIGS. 11 ,  14  and  15  has a shorter axial dimension. Four slots  166  are employed. The crush rib  168  structure is employed at the intermediate interior. 
     Tube  240  illustrated in  FIG. 12  employs horizontal crush ribs  265  at or slightly below the cylindrical/tapered portion interface and longitudinally tapered and extending crush ribs  267  at the interior of the tapered portion  260  of the tube. The interior wall at the distal end of the tapered portion includes a dual conical surface  261 . An additional set of inwardly tapered ribs  266  are engageable into the surface  261  in a first position for one diameter and are forced away from the surface for a second diameter. The horizontal crush ribs  265  tend to deflect and engage the minor diametral surface of the fastener in a friction type fit. The longitudinal ribs  267  and, to some extent, ribs  261 , tend to be damaged and/or sheared off by the fastener. The interior of the throat prior to the restriction may also include tapered surfaces  251  to accommodate the multi-dimensioned fasteners. 
     Tube  340  illustrated in  FIG. 13  employs inwardly extending axial ribs  361  adjacent the terminal end of the tapered portion. The ribs cause the exterior tapered portion  360  of the tube to flex outwardly if a larger diameter fastener is employed. Four slots  366  are employed to allow for the terminal tube flexure to accommodate the enlarged diameter fastener. 
     With reference to  FIGS. 25-27 , tube  440  employs inwardly extending axial ribs  461  which extend interiorly from the upper portion of the tube and extend longitudinally to the interface with the tapered portion of the tube  460 . Three slots  466  are employed to allow the terminal tube flexure to accommodate an enlarged diameter fastener. With additional reference to  FIG. 25 , it should be appreciated that the upper cutouts  452 , which allows for the formation of the resilient tabs  454  are configured so that the tabs may be molded with the tube without employing slides and gates in the molding process. This latter configuration significantly simplifies the manufacturing of the tube. 
     It will be appreciated that the geometry and position of the various inwardly protruding ribs  66 ,  166 ,  261 ,  265 ,  266 ,  361  and  461  may vary. The purpose of the ribs is to provide a stable engagement of the fastener having a minimal diameter and to allow the tube to expand or flex outwardly (radially) for larger diameter fasteners while still providing a tight semi-quasi-force fit relationship between the fastener and the tube so that during installation, both are essentially axially aligned about the central axis of the fastener and the tube. 
     With reference to  FIG. 20 , the tube employs inwardly protruding arcuate ribs structures inwardly adjacent the opening at the terminus of the tapered portion. As illustrated in the drawings, the tapered portions  60  may flex to accommodate fasteners of different diameters such as, for example, fasteners having 0.265, 0.274, 0.283, 0.288 inch diameters D 1 , D 2 , D 3  and D 4 . Diameter D 5  is slightly less than diameter D 6  ( FIG. 17 ) of the plate  20 . There is a slight taper, for example, of 1° at the interior upper portions of the throat portion  50  as well as at the terminal inner surface of the terminal tapered portion  60 . Naturally, other dimensions are also possible. 
     Upon installation, the tube  40  is inserted into the opening and a fastener  30  is inserted into the tube. The end of the fastener may project through the opening  70 . The foregoing components may be pre-assembled (typically loosely) prior to delivery to the installation site. The plate/tube/fastener is then positioned over the insulation, and in some installations, the membrane, at a pre-established anchoring location. It should be appreciated that for some installations, such as, for example, those that employ the OMG RhinoBond® system, the membrane is placed over the plates and bonded to the plate by heat activated adhesive. The tube penetrates the insulation and, in some installations, the membrane. The driving tool is coupled to the head  32  and the fastener torqued until the thread  36  engages into the roof deck  16  at a pre-established penetration depth. The underside of the fastener head engages the shoulder in the tube. The tabs  54  engage the underside of the plate. Downward displacement of the tube under the securement load of the fastener results in downward displacement of the plate until the proper securement by the fastener is attained. It will be appreciated that the insulation and overlying membrane are compressed or clamped between the plate and the roof deck for securing same. 
     With reference to  FIGS. 21-24 , an alternate embodiment of a plate which may be employed with respect to the connection with the fastening assembly is generally designated by the numeral  120 . The plate includes a plurality of angularly spaced, generally trapezoidal prongs  121  which project downwardly and inwardly from the inner stepped recess  128  which surrounds the opening  122 . The prongs  121  resiliently engage against the upper underside portion of the tube  40 , as best illustrated in  FIG. 23 . In addition, opposed prongs also engage the shoulders  56  of the resilient tabs  54 , as best illustrated in  FIG. 24 . 
     It should be appreciated that the configuration of the tube and the assembled relationship between the plate, the tube and the fastener cooperate to normalize the fracture area per unit of load carrying area of the tube between the conical transition and the flange transition. This latter relationship is implemented so that tensile stresses applied to the fastener system are applied along the length of the tube and any tensile failure would ultimately occur, if at all, at the strongest failure resistant structure. 
     The foregoing installation process is replicated for numerous fastening assemblies as required to properly secure the membrane and insulation. 
     For applications wherein an additional membrane is mounted over the plates and membranes, and the plates include a heat-activated adhesive, an induction tool (not illustrated) may be used to activate the adhesive and seal and secure the upper membrane to the plates. 
     If an excessive pressure is applied to the plate or adjacent the plate to compress the insulation so that the spacing between the plate and the deck is decreased, the tube is forced downwardly and slides along the shaft of the fastener. The head of the fastener remains fixed relative to the deck. Upon removal of the compressive load, the assembly resumes normal clamp engagement with the tube and the plate. 
     A heavy driller (not illustrated) for steel purlin applications is preferably employed for driving the fastener. One single tube  40  as described may provide a friction fit with multiple dimensional fasteners which may be either a #15 RoofGrip™ screw or an OMG Purlin Fastener screw, or a 14 HX or HD screw with a buttress thread marketed by OMG, Inc. of Agawam, Mass. 
     While preferred embodiments of the foregoing have been set forth for the purposes of illustration, the foregoing description should not be deemed a limitation of the invention herein. Accordingly, various modifications, adaptations and alternatives may occur to one skilled in the art without departing from the spirit and the scope of the present invention.