AUSTRALIA ORIGINAL COMPLETE SPECIFICATION INNOVATION PATENT Invention Title: Strutting Beam for use in Roofing Structure Name of Applicant: Wesbeam Holdings Ltd Actual Inventors: Denis Cullity Boris Iskra Address for service: WRAYS Ground Floor, 56 Ord Street West Perth WA 6005 Attorney code: WR The following statement is a full description of this invention, including the best method of performing it known to me:- 1A Strutting beam for use in roof structures Field of the invention The present invention relates to strutting beams used in roof structures in the building industry, and particularly to beams manufactured from laminated veneer lumber (LVL). 5 Background of the invention Pitched roofs that are constructed one beam at a time, rather than being prefabricated, are commonly termed stick roof frames. In stick roof frames approximately eight strutting beams are used per house. Strutting beams are used to support other load bearing elements in the roof structure, such as standard strutting beams, strutting 10 counter beams and strutting hanging beams. Of the eight strutting beams used in the average stick roof frame house, approximately six are steel universal beams and two are laminated veneer lumber (LVL) beams. Laminated veneer lumber beams are lengths of timber that are constructed from a plurality of timber veneer sheets laminated together to form the beam of the required 15 dimensions. Laminated veneer lumber beams are often used in situations where solid hardwood was previously used, however, given the decrease in availability of hardwood, hardwood is no longer used regularly in the building industry. The benefits of laminated veneer lumber beams are that they can be provided in any length, have the consistency of steel, and are lighter than steel in most instances. 20 Laminated veneer lumber has reliable and consistent structural properties, and has strength and stiffness capabilities greater than the individual veneer sheets from which it is manufactured. The maximum effect of a single natural feature (for example a knot) in an LVL beam is very small as the veneer sheets are so thin compared with the thickness of the whole beam. In terms of structural performance, this achieves a reliable 25 and consistent LVL product. LVL has a co-efficient of variation that is similar to Australian-produced hot rolled steel sections. In relation to strutting beams, the co efficient of variation is a measure of the variability in a particular structural property, 2 such as bending, tension or compression. A low variability gives a more reliable product. Most builders have a preference for laminated veneer lumber over steel due to the increased costs associated with steel universal beams. These include the need for a 5 crane to lift the universal beams into position. Crane drivers routinely delay work, which results in subsequent roof carpentry work being delayed. The cost to hire the crane and operator is also significant. If modification of the fixing positions is required, an on-site welder is required to perform rectification work on the universal beams to reposition mounting brackets and cut new holes for fixing. The cost of steel is also increasing 10 appreciably relative to timber. In contrast, laminated veneer lumber beams are, on average, lighter than steel universal beams and can frequently be lifted into position by the roof carpenters, removing the need for crane operators in most situations. The roof carpenters are able to use conventional fixing techniques involving nail guns and power saws to fix and modify 15 laminated veneer lumber beams, eliminating the need for on-site rectification welding. With steel roof frames, pitched roofs are able to be built with the rafters meeting the walls at a variety of pitch angles. At the point where the strutting beam intersects the wall plate beam on the top of the brick wall, the strutting beam must include a chamfer at the end so that it can fit between the wall plate and the top surface of the rafter or 20 roof cladding. Laminated veneer lumber beams cannot have a chamfer cut that is more than a third of the depth of the beam (see Figure 1) without compromising the structural integrity of that portion of the beam. For this reason steel universal beams are always used where the beams require a chamfer portion having a depth that is greater than a third of the 25 beam depth.
3 Summary of the invention Accordingly, the present invention provides a strutting beam, including: an elongate member of laminated veneer lumber, wherein at least one end of the member has a portion having a chamfer cut on one side; an elongate reinforcement means for reinforcing the chamfer cut portion, the elongate reinforcing means being located on the opposite side of the elongate member and extending along the member's length from at or adjacent said at least one end; and at least one attachment means attaching the reinforcement means to the member; whereby the structural integrity of the chamfer cut portion with reinforcement means is equal to or greater than the member's structural integrity at a location remote from the chamfer cut portion. Advantageously, the depth of the chamfer cut is greater than a third of the depth of the beam. A compromise to the structural integrity of the beam may include a reduction in the strength of the material, such that the beam would fail under application of a load. Such failure may result in the beam shearing. Preferably, the chamfer cut ends in a tip; this may be a chisel edge. The angle of the chamfer cut is variable, but is typically 20*. The strutting beam is preferably rectangular in cross-section and may have a length between 3.0 m and 8.1m. The width is typically between 35-75mm and the depth is between 200-450mm. The elongate reinforcement means is typically 700mm in length and 90mm in depth. The attachment means is preferably nail plates and may be dimensioned 150m by 4 150mm. Two spaced apart attachment means are preferably provided on either side of the reinforcement means. The face of the chamfer cut is preferably along the narrower width of the beam and advantageously the veneer sheets are orientated to line up along the width, such that 5 the face of the chamfer cut is across the ends of all of the veneer sheets. Advantageously, the strutting beam will be pre-fabricated with the chamfer cut and reinforcement means. However, it will be appreciated that the strutting beam may be manufactured on-site to suit the roof requirements for the particular building. The strutting beam may be installed as a standard strutting beam, a strutting hanging 10 beam, a strutting counter beam or another type of strutting beam for supporting underpurlins, ceiling joists, hanging beams, or similar. Where only one end of the beam includes a chamfer cut and reinforcement means, the other end may be raised with a block. The laminated veneer lumber is preferably manufactured from plantation pine, such as, 15 for example, Maritime pine and/or Radiata pine. The veneer sheets typically have a nominal thickness of 3.2mm to 4.2mm. The density of the laminated veneer lumber beam may be approximately 660 kg/M 3 . The reinforcement means may also be manufactured from laminated veneer lumber or from another suitable material, such as solid timber or steel. 20 Brief description of the drawings The invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a side view of a standard strutting beam having a chamfer cut with a depth equal to a third of the depth of the beam; 5 Figure 2 is a side view of a steel strutting beam having a chamfer cut with a depth greater than a third of the depth of the beam, showing where the beam intersects with the wall, according to the prior art, when installed in a roof structure; Figure 3 is a side elevation of an end portion of a strutting beam shown according to the 5 present invention; Figure 4 is a side view (from the other side) of a strutting beam manufactured from laminated veneer lumber with a chamfer cut according to another embodiment of the present invention, showing the beam where it intersects with the wall when installed in a roof structure; 10 Figure 5 is a perspective view of the strutting beam according to Figure 4, installed in a roof structure as a standard strutting beam; and Figure 6 is a perspective view of the strutting beam according to Figure 4, installed in a roof structure as a strutting hanging beam. Detailed description of the embodiments 15 Figure 1 shows a standard strutting beam 8 that has a chamfer cut 9. The depth (d) of the chamfer cut 9 is equal to a third of the depth (D) of the beam. This is the maximum permissible depth. Figure 2 shows a strutting beam 10 manufactured in steel, typically a steel universal beam having an I-shaped cross-section. Strutting beams are used as beams that 20 support other load bearing elements such as strutting hanging beams. In the illustrated building, a double cavity brick wall is used, having an inner wall 12 and an outer wall 14. At the top of the inner wall a wall plate 16 is located, which is typically manufactured in pine. The strutting beam 10 rests on top of the wall plate 16 and must fit in the limited vertical space between the wall plate 16 and the top of the rafter 18 to allow the roof 25 cladding (not shown) to be fixed above. The pitch of the roof determines the angle of the rafter 18 and therefore the vertical space defined for the end of the strutting beam 10.
6 To be accommodated in the space defined, the end portion 20 of the beam includes a chamfer cut to a tip. Laminated veneer lumber beams cannot include a chamfer cut that has a depth greater than a third of the depth of the beam, without compromising the beam's structural 5 integrity. For this reason, steel universal beams are used where beams require any chamfer cut where the height is required to be greater than a third of the height of the beam. The present invention provides a solution to this problem, which will allow builders to reduce the number of, or remove entirely, steel universal beams and therefore all of the 10 problems associated with their use. According to the invention, strutting beam 100 is provided that includes an elongate member 110 of laminated veneer lumber. At least one end of the elongate member 110 has a chamfer cut 112 ending in a tip 114, which is preferably a chisel edge. The face of the chamfer cut runs across the veneers on the narrower dimension of the beam. In the 15 embodiment illustrated in the Figure 3, the depth of the chamfer cut 112 is equal to the depth of the beam 100. The strutting beam 100 includes an elongate reinforcement means 116 located on the opposite side 118 of the elongate member 110 to the chamfer cut 112 at or adjacent the end of the beam, or tip 114, and extends along the beam length. The reinforcement 20 means 116 is typically a length of timber and may extend further than the splayed portion 112 (Figure 4) or less than it (Figure 3). Two attachment means 120 are spaced along the two sides of the reinforcement means 116 to attach the reinforcement means 116 to the elongate member 110. In the illustrated embodiment the attachment means 120 are metal nail plates measuring 25 150mm by 150mm. They are spaced apart approximately 120mm. It will be appreciated that only one attachment means may be used. The structural integrity of the portion having the chamfer cut 112 of the beam 100 with reinforcement means 116 is equal to or greater than the structural integrity of the beam 7 100 at a location remote from the chamfer cut portion, ie any location where the depth of the beam is not reduced. This means that, under equal loads, the structural performance of the chamfer cut portion is not compromised by the depth of the chamfer cut being greater than a third of the depth of the beam. 5 As shown in Figure 4, when in position, the chamfer cut portion 112 fits in the vertical space above the wall plate 124 located on top of the inner wall 126 and below the top of the rafter 122. The height of the reinforcement means 116 is typically the same as the ceiling joists. As can be seen from Figure 5, the strutting beam 100 spans from a wall plate 132 to a 10 bearer 134 and is used to support underpurlin 136 via struts 138. The beam 100 can be put at an angle so as to avoid loads falling over window openings 139, as illustrated in Figure 5. Figure 6 shows the strutting beam 100 extending from one bearer 140 to another 142 and being used to support underpurlin 144 via strut 146. As shown in Figure 5, to raise the other end of the beam 100, a block 130 is used. 15 By providing a practical solution that allows laminated veneer lumber to be used for strutting beams beyond the current dimensional restraints, laminated veneer lumber beams will be able to be specified in many more applications. Builders are looking for opportunities to reduce the number of steel beams used due to the complications involved. The present invention provides the builders with a solution that will allow them 20 to eliminate the use of steel in roof constructions, which was previously not possible.