Structural timber floor assembly

Abstract

A method is described of forming a joint between the end of a timber I-beam joist and a transverse closure such as a rim-joist, in which two holes are formed a short distance from the end of the I-beam to be butt-jointed to the rim-joist, one in each of the upper and lower rails of the I-beam section, the two holes being coaxial and generally aligned with and parallel to the web of the I-beam section. The closure is positioned relative to the I-beam and two further holes are formed through the closure and into the ends of the upper and lower I-beam rails, generally perpendicular to and intersecting the first two holes. Two cross-dowels are inserted into the two first holes, each having a transverse threaded opening, and the dowels are inserted so as to align the openings with the holes which intersect the holes containing the cross-dowels, and threaded bolts are introduced into the intersecting holes and screwed into the threaded openings in the cross-dowels so as to draw the joist towards the closure, and thereby clamp the joist thereto. The cross-dowels may be formed from metal, or from a rigid plastics material or from a composite material and may have a smooth exterior or may be externally threaded or formed with one or more annular barbs for securing them in place. The technique may be applied on site, but more preferably in the course of constructing a roofing or flooring panel off-site, the joints serving to resist distortion or bending during handling of prefabricated panels, during storage, transportation, and/or final positioning on site.

1 . A method of forming a butt joint between one end of a timber, flanged I-beam joist and a transverse closure such as a rim-joist, wherein the I-beam joist is arranged so that the web of the joist is generally vertical and the flanges of the I-beam section are above and below the web, comprising the steps of: 
 1) forming two holes a short distance from the end of the I-beam which is to be butt-jointed to the closure, one hole in each of upper and lower flanges of the flanged I-beam section,    2) locating the closure in place and forming two further holes therethrough and into the abutting ends of the upper and lower flanges of the I-beam joist, the two further holes being generally perpendicular to, and intersecting, the first two holes,    3) inserting two cross-dowels into the two first holes, each having a transverse threaded opening, and aligning the threaded openings with the intersecting holes, and    4) inserting threaded bolts into the intersecting holes to engage in the threaded openings in the cross-dowels, and screwing the bolts into the dowels so as to draw the abutting end of the I-beam joist towards the closure, and thereby clamp it to the closure.    
     
     
         2 . A building panel comprised of at least two I-beam joists and at least one perpendicular closure, the I-beam joists forming a parallel spaced apart array, with ends of the I-beam joists abutting the perpendicular closure, with a butt joint between the end of each of the I-beam joists and the closure, characterised by: 
 1) two holes formed a short distance from the end of the I-beam which is to be butt-jointed to the closure, one hole in each of upper and lower flanges of the flanged I-beam section,    2) two further holes through the abutting ends of the upper and lower flanges of the I-beam joist, the two further holes being generally perpendicular to, and intersecting, the first two holes,    3) two cross-dowels located in the two first holes, each having a transverse threaded opening aligned with the intersecting holes, and    4) threaded bolts engaged in and screwed into the threaded openings in the cross-dowels, so that the abutting end of the I-beam joist is drawn towards the closure, thereby to clamp it to the closure.    
     
     
         3 . A building panel according to  claim 2  wherein a load spreading washer is located between the head of each bolt and the closure.  
     
     
         4 . A building panel according to  claim 2  wherein each bolt head includes an integral load spreading flange for increasing the area of the bolt head which is to make contact with the closure.  
     
     
         5 . A building panel according to  claim 2  wherein the holes through the closure through which the bolts pass into the I-beam are enlarged at one end to accommodate the heads of the bolts, so that the latter are at least partly contained within the thickness of the closure.  
     
     
         6 . A building panel according to  claim 2  wherein the upper and lower flanges of the I-beam joist are laminated, and the holes which are to receive the cross-dowels extend generally perpendicular to the laminations.  
     
     
         7 . A building panel according to  claim 6  wherein the holes in the upper and lower flanges are generally aligned with the web of the I-beam section.  
     
     
         8 . A building panel according to  claim 6  wherein the holes in the flanges are co-axial.  
     
     
         9 . A prefabricated timber building panel or deck, constructed from parallel spaced apart laminated timber I-beam joists butt-jointed to the side faces of perpendicularly extending rim-joists at opposite ends of the I-beam joists, wherein the joints between the ends of the I-beam joists and the rim-joists are formed by bolts and cross-dowels, wherein the latter extend perpendicularly to the laminations forming the upper and lower flanges of the I-beam joists, and the bolts extend transversely through the rim-joists and are threadedly engaged in the cross-dowels.  
     
     
         10 . A laminated timber I-beam joist comprising a web between upper and lower laminated flanges, having cross-dowels located therein transverse to the direction of the laminations close to at least one end thereof, to enable the I-beam to be butt-jointed to a transversely extending closure by means of bolts which in use extend through the closure and are threadly engaged in the cross-dowels in the I-beam joist.  
     
     
         11 . A cross-dowel adapted to be secured in a laminated flange of a timber I-beam joist to enable the I-beam joist to be secured to a closure in accordance with the method of  claim 1 , wherein the dowel is generally cylindrical in configuration, is formed with an external screw thread profile, and one end of the dowel includes tool engaging means to enable it to be screwed into a hole in the laminated flange of the I-beam joist.  
     
     
         12 . A cross-dowel according to  claim 11  wherein the external screw thread profile is a self-tapping thread.  
     
     
         13 . A cross-dowel according to  claim 11 , wherein the external diameter of the screw thread profile increases from the end of the dowel which is to be first introduced into the hole in the laminated flange, towards the other end which includes the tool engaging means.  
     
     
         14 . A cross-dowel adapted to be secured in a laminated flange of a timber I-beam joist to enable the I-beam joist to be secured to a closure in accordance with the method of  claim 1 , wherein the external surface of the dowel is formed with at least one annular barb for retaining the dowel in a hole in the laminated flange.  
     
     
         15 . A cross-dowel according to  claim 14  wherein the dowel is formed at one end with a tool engaging means such as a screwdriver slot whereby it can be rotated whilst embedded in the flange, to enable the transverse threaded opening therein to be aligned to receive a securing bolt.  
     
     
         16 . A flooring or roofing panel according to  claim 2  wherein the panel edges are formed by elongate closures, and a cross-dowel connection is formed between the end of one closure and an abutting face of an adjoining closure at each corner of the panel.