GB2641092A

GB2641092A - A joist

Info

Publication number: GB2641092A
Application number: GB2406935.3A
Authority: GB
Inventors: Richard John Whale Luke
Original assignee: Staircraft Group Ltd
Current assignee: Staircraft Group Ltd
Priority date: 2024-05-16
Filing date: 2024-05-16
Publication date: 2025-11-19
Also published as: GB202406935D0

Abstract

The joist 10 comprises: a first flange 20 having a groove 22 along at least a portion of the length of the first flange 20 parallel to the first axis 12. A second flange 30 having a groove 32 along at least a portion of the length of the second flange 30 parallel to the first axis 12. A central web 40 is affixed between the flanges within the respective grooves. One or more reinforcement webs 60, located at a first discontinuity 52 in the central web 40, and affixed between the first flange 20 and the second flange 30. A first portion 62 of a first reinforcement web 60 is affixed to the first flange, and a second portion 64 of the first reinforcement web 60 is affixed to the second flange 30, and wherein the first portion 62 of the first reinforcement web 60 is offset, along the first axis 12, from the second portion 64 of the first reinforcement web 60. The discontinuity may be at the end of the joist or form one end of an aperture 50 within for passing through cables.

Description

A JOIST

TECHNICAL FIELD

The present disclosure relates to joists. Particularly, but not exclusively, the present disclosure relates to a hybrid timber I-joist that can be used in the construction of flooring in a building.

Aspects of the invention relate to a joist.

BACKGROUND

Joists are commonly used in residential, commercial and industrial building construction for structurally framing and supporting floors, roofs and walls. Traditionally, joists, especially in residential construction, have been formed of solid timber. Such joists can however be prone to shrinkage and distortion, have low weight bearing capacity, and are limited by the natural variability of wood. Because of these shortcomings of traditional timber joists, within the last twenty years two alternative types of joist have taken over a large market share of the UK residential construction market.

The first of these alternative types of joist are timber I-joists. Timber I-joists are engineered wood products that are commonly used in residential and some commercial construction. They are known for their high strength-to-weight ratio, dimensional stability, and long continuous spans. Timber I-joists comprise a top and bottom flange formed of solid timber or laminated timber connected by a solid vertical central web formed from plywood, hardboard or oriented strand board (OSB). This design allows them to carry heavy loads over longer spans than traditional solid timber joists.

The second of these alternative types of joist are metal-webbed joists. Metal-webbed joists are formed with timber upper and lower flanges separated by and connected via pre-formed metal webs which are affixed to each flange via integral teeth which can be pressed into the sides of the flanges to ensure that the flanges are rigidly fixed in a separated arrangement relative to each other. The metal webs are pressed into the sides of the flanges on both sides to form a lattice beam. This shape is structurally efficient and can span similar distances to I-joists, have limited shrinkage/distortion, are lightweight and well suited to passing services, such as pipes, ducts or wires, therethrough.

Although small apertures through the central web of an I-joist may be cut for passing individual services through, when there are significant services to be run through I-joists, this can be time consuming and error prone as it can be difficult to locate the apertures in the correct positions. Metal webbed joists may be traditionally used in those circumstances requiring the passage of significant services as these provide an open framework to pass such services through more easily, without affecting the structural integrity of the joist, but they are more expensive to manufacture than I-joists It is an aim of the present invention to address one or more of the disadvantages associated

with the prior art.

SUMMARY OF THE INVENTION

Aspects and embodiments of the invention provide a joist as claimed in the appended claims.

According to an aspect of the present invention there is provided a joist having a length along a first axis for spanning a gap between two support structures, the joist comprising: a first flange having a groove along at least a portion of the length of the first flange parallel to the first axis; and a second flange having a groove along at least a portion of the length of the second flange parallel to the first axis, the second flange being separated from the first flange in a second axis, perpendicular to the first axis; a central web affixed between the first flange and the second flange, the central web having a first side located in the groove of the first flange and a second side, opposite the first side, located in the groove of the second flange; and one or more reinforcement webs, located at a first discontinuity in the central web, and affixed between the first flange and the second flange; wherein a first portion of a first reinforcement web is affixed to the first flange, and a second portion of the first reinforcement web is affixed to the second flange, and wherein the first portion of the first reinforcement web is offset, along the first axis, from the second portion of the first reinforcement web.

An advantage of this aspect of the invention is that the joist can provide support for floors, roofs and walls along with an improved facility to run services around the building without being hindered by the mechanical limitations of traditional wooden joists or I-joists, or by the cost limitations of metal-webbed joists. These joists therefore minimise the impact of the joists on the overall cost and complexity of the construction of a building.

The first discontinuity in the central web may form a first end of the central web at a first end of the joist. The first flange may extend beyond the central web and the second flange along the first axis at the first end of the joist.

The first portion of the first reinforcement web may extend beyond the first end of the central web along the first axis.

The joist may comprise the first reinforcement web, located at the first discontinuity in the central web, on a first side of the joist, and a second reinforcement web, located at the first discontinuity in the central web, on a second side of the joist, opposite the first side of the joist.

A first portion of the second reinforcement web may be affixed to the first flange, and a second portion of the second reinforcement web may be affixed to the second flange. The first portion of the second reinforcement web may be offset, along the first axis, from the second portion of the second reinforcement web.

The first portion of the second reinforcement web may extend beyond the first end of the central web along the first axis.

The first reinforcement web and the second reinforcement web may be located at the same longitudinal position along the first axis.

The orientation of the first reinforcement web may mirror the orientation of the second reinforcement web in the plane defined by the first axis and second axis.

The first reinforcement web may have an opposing orientation to the second reinforcement web.

The first discontinuity in the central web may form a first end of an aperture through the central web. The aperture may provide access from a first side of the joist to a second side of the joist.

One of the first portion of the first reinforcement web or the second portion of the first reinforcement web may extend beyond the first discontinuity in the central web to overlap the aperture in the central web along the first axis.

A second discontinuity in the central web may form a second end of the aperture through the central web. The second end of the aperture may be separated from the first end of the aperture along the first axis.

The joist may comprise a second reinforcement web, located at the second discontinuity in the central web, and affixed between the first flange and the second flange. A first portion of the second reinforcement web may be affixed to the first flange, and a second portion of the second reinforcement web may be affixed to the second flange. The first portion of the second reinforcement web may be offset, along the first axis, from the second portion of the second reinforcement web.

One of the first portion of the second reinforcement web or the second portion of the second reinforcement web may extend beyond the second discontinuity in the central web to overlap the aperture in the central web along the first axis.

The aperture in the central web may be configured to receive services such as water and drainage pipes, ducts, and electrical wires.

The joist may comprise the first reinforcement web, located at the first discontinuity in the central web, on a first side of the joist, the second reinforcement web, located at the second discontinuity in the central web, on a first side of the joist, a third reinforcement web, located at the first discontinuity in the central web, on a second side of the joist, opposite the first side of the joist, and a fourth reinforcement web, located at the second discontinuity in the central web, on the second side of the joist.

The first reinforcement web and the third reinforcement web may be located at the same longitudinal position along the first axis, and the second reinforcement web and the fourth reinforcement web may be located at the same longitudinal position along the first axis.

The orientation of the first reinforcement web may mirror the orientation of the third reinforcement web in the plane defined by the first axis and second axis, and the orientation of the second reinforcement web may mirror the orientation of the fourth reinforcement web in the plane defined by the first axis and second axis.

The first reinforcement web may have an opposing orientation to the third reinforcement web and the second reinforcement web may have an opposing orientation to the fourth reinforcement web.

A further reinforcement web may be located adjacent, and on the same side of the joist to, one or more of the one or more reinforcement webs.

The further reinforcement web may comprise a first portion affixed to the first flange, and a second portion affixed to the second flange. The first portion of the further reinforcement web may be offset, along the first axis, from the second portion of the further reinforcement web.

The, or each, reinforcement web may comprise a third portion between the first portion of the reinforcement web and the second portion of the reinforcement web. The third portion of the reinforcement web may be at an angle between 30 and 60 degrees relative to the first axis.

The third portion of the reinforcement web may be at an angle of 45 degrees relative to the first axis.

For at least one of the one or more reinforcement webs, the first portion of the reinforcement web may comprise a first set of teeth projecting perpendicular to both the first axis and the second axis. The teeth may be configured to be pressed into the first flange for fixing thereto. The second portion of the reinforcement web may comprise a second set of teeth projecting perpendicular to both the first axis and the second axis. The teeth may be configured to be pressed into the second flange for fixing thereto.

For at least one of the one or more reinforcement webs, the first portion of the reinforcement web may comprise one or more fixing apertures for receiving first fixing means in a direction perpendicular to both the first axis and the second axis. The first fixing means may be configured to affix the first portion of the reinforcement web to the first flange. The second portion of the reinforcement web may comprise one or more fixing apertures for receiving second fixing means in a direction perpendicular to both the first axis and the second axis. The second fixing means may be configured to affix the second portion of the reinforcement web to the second flange.

The first flange and the second flange may be formed of timber or laminated timber.

The central web may be formed of engineered wood.

The central web may be located, in use, in a vertical orientation.

The, or each, reinforcement web may be formed of metal.

The, or each, reinforcement web may be formed of a composite material.

Within the scope of this application, it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure la illustrates a perspective view of a joist according to an embodiment of the invention; Figure lb illustrates a side view of a first side of the joist of Figure 1 a; Figure lc illustrates a side view of a second side of the joist of Figure 1 a; Figure 2a illustrates a side view of a first side of a joist according to an embodiment of the invention; Figure 2b illustrates a side view of a second side of the joist of Figure 2a; Figure 3a illustrates a side view of a first side of a joist according to an embodiment of the invention; Figure 3b illustrates a side view of a second side of the joist of Figure 3a; Figure 4a illustrates a perspective view of a joist according to an embodiment of the invention; Figure 4b illustrates a side view of a first side of the joist of Figure 4a; Figure 4c illustrates a side view of a second side of the joist of Figure 4a; Figure 5a illustrates a side view of a first side of a joist according to an embodiment of the invention; Figure 5b illustrates a side view of a second side of the joist of Figure 5a; Figure 6a illustrates a perspective view of a joist according to an embodiment of the invention; Figure 6b illustrates a side view of a first side of the joist of Figure 6a; Figure 6c illustrates a side view of a second side of the joist of Figure 6a; Figure 7a illustrates a side view of a first side of a joist according to an embodiment of the invention; Figure 7b illustrates a side view of a first side of the joist of Figure 7a; Figure 8a illustrates a side view of a first side of a joist according to an embodiment of the invention; Figure 8b illustrates a side view of a second side of the joist of Figure 8a; Figure 9a illustrates a side view of a first side of a joist according to an embodiment of the invention; Figure 9b illustrates a side view of a second side of the joist of Figure 9a; Figure 10a illustrates a side view of a first side of a joist according to an embodiment of the invention; Figure 10b illustrates a side view of a second side of the joist of Figure 10a; Figure 11a illustrates a side view of a first side of a joist according to an embodiment of the invention; Figure 11 b illustrates a side view of a second side of the joist of Figure 11a; Figure 12a illustrates a side view of a first side of a joist according to an embodiment of the invention; Figure 12b illustrates a side view of a second side of the joist of Figure 12a; Figure 13 illustrates a side view of a first side of a joist according to an embodiment of the invention; Figure 14 illustrates a side view of a first side of a joist according to an embodiment of the invention; Figure 15 illustrates a metal web for use in a joist according to an embodiment of the invention; and Figure 16 illustrates a metal web for use in a joist according to an embodiment of the invention.

DETAILED DESCRIPTION

Examples of the present disclosure relate to a joist, which may be used in the construction of a residential, commercial or industrial building.

In some examples, the joist comprises an I-joist with reinforcing webs, also known as reinforcement webs, where the reinforcing webs are provided at discontinuities in the I-joist construction and are configured to ensure structural integrity of the joist during use.

The I-joist may be formed using high-strength upper and lower timber or laminated timber flanges with a thin central web formed from engineered wood, such as plywood, hardboard, or oriented strand board (OSB). Such I-joists are structurally efficient and can span further than traditional solid timber joists. I-joists having this type of construction are also less prone to shrinkage and distortion. I-joists are lightweight thereby saving on transportation costs and reducing handling issues.

In some embodiments, the I-joists may be formed to be bottom supported joists, that is, configured to be supported on a supporting structure via the lower timber flange. In other embodiments, the I-joists may be formed to be top hung joists, that is, configured to be supported on a supporting structure via the upper timber flange.

Non-limiting examples will now be described with reference to accompanying Figures la to 16, where the figures illustrate a joist 10 and a reinforcing web 60.

As illustrated in the example arrangements illustrated in Figures la to 14, the joist 10 of the present invention is formed to have a length along a first axis 12, which is a longitudinal axis of the joist 10, which is to be positioned, in use, in a horizontal, or substantially horizontal plane. The joist 10 is arranged or configured to span a gap between two supports, or supporting structures, such as opposing walls of a building.

As illustrated in Figure la, Figure lb, and Figure lc for a first example joist 10, the joist 10 comprises a first flange 20 having a groove, or channel, 22 along at least a portion of the length of the first flange 20 parallel to the first axis 12. The first flange 20 may be formed of timber, or laminated timber, and may, in use, form the upper flange of the joist 10. The joist 10 also comprises a second flange 30 having a groove, or channel, 32 along at least a portion of the length of the second flange 30 parallel to the first axis 12. The second flange 30 may be formed of timber, or laminated timber, and may, in use, form the lower flange of the joist 10. Alternatively, the flanges 20, 30 may be formed of laminated veneer timber or laminated veneer lumber.

The second flange 30 is arranged or configured to be separated from the first flange 20 in a second axis 14, the second axis 14 being perpendicular to the first axis 12. That is, the first flange 20 and the second flange 30 are spaced apart from each other. The groove 22 in the first flange 20 faces, and is parallel to, the groove 32 in the second flange 30. When the joist 10 is in use, the second axis 14 is a vertical axis, or substantially vertical axis.

A central web, or web material, 40 is located and affixed between the first flange 20 and the second flange 30. The central web 40 may be formed of engineered wood, such as plywood, hardboard, or Oriented Strand Board (OSB).

As illustrated in Figure 1 a, a first side, or edge, 42 of the central web 40 is located in the groove 22 of the first flange 20 and a second side, or edge, 44 of the central web 40 is located in the groove 32 of the second flange 30. The first side 42 of the central web 40 is an opposite side of the central web 40 to the second side 44 of the central web 40. The central web 40 may be configured such that, in use, it is positioned in a vertical, or substantially vertical, orientation along the second axis 14.

In the production of the joist 10, grooves are cut into the centre of a face of each of the first flange 20 and second flange 30 and the central web 40 is cut to the required depth, that is, cut to be of a size to ensure a desired separation of the first flange 20 from the second flange 30 when the central web 40 is connected to the first flange 20 and the second flange 30. The sides, or edges, of the central web are shaped to match the groove in the first flange 20 and the second flange 30. The sides, or edges 42, 44, of the central web 40 are then glued and inserted into the respective flanges 20, 30. A polyurethane or phenol resorcinol-based adhesive may be used to adhere the central web 40 to the flanges 20, 30. The sides, or edges, 42, 44 of the central web 40 may be of a thickness to provide a push fit, or an interference fit, with the grooves 22, 32 in the respective flanges 20, 30. The construction of the central web and the first flange 20 and second flange 30 provides an I-joist which forms part of the joist 10.

The central web 40 of the joist 10 comprises discontinuities, that is, sections where the central web 40 is no longer present or has a significant section missing.

In some embodiments, as illustrated in Figures 4a to 7b and 11a to 14, discontinuities may be found at the ends of the joist 10. Such discontinuities at the ends of the joist 10 may be provided by cutting the central web 40 of a manufactured I-joist, and the lower flange 30, by way of a saw or router, or by not positioning any central web 40 and lower flange 30 at the end of the joist 10 when manufacturing the I-joist. In some embodiments a length between eighty millimetres and one hundred and sixty millimetres of the central web 40 and lower flange 30 may be missing at the end of the joist 10. In one example one hundred and twenty millimetres of the central web 40 and lower flange 30 may be missing at the end of the joist 10.

In some embodiments, as illustrated in Figures 1a to 4c, Figure 6a to 6c, Figures 8a to 10b, Figure 13, and Figure 14, discontinuities may also, or alternatively, be present along the length of the joist 10, away from the ends of the joist 10, where an aperture 50 or apertures 50 in the central web 40 may be formed and configured to receive services such as water and drainage pipes, ducts, and electrical cables or wires, which commonly need to pass throughout a building. In some embodiments, such apertures 50 may be up to one metre long in order to accommodate all of the desired services, which can cause structural weakness in the joist 10 if not reinforced. In one example a 0.6 metre aperture can be formed to accommodate several rows of pipes. Such apertures 50 may be cut into the central web 40 of a manufactured I-joist by way of a saw or router, or by not positioning any central web 40 in some locations along the I-joist when manufacturing the I-joist.

The joist 10 further comprises one or more reinforcement webs, illustrated in more detail in Figure 15 and Figure 16, to ensure structural integrity of the joist 10 at the location of a discontinuity in the central web 40. In some embodiments, the, or each, reinforcement web may be formed of metal. Alternatively, the, or each, reinforcement web may be formed of a composite material, such as fibre-reinforced polymers. Such fibre-reinforced polymers include carbon fibre reinforced polymers, glass fibre reinforced polymers, and metal fibre reinforced polymers. In some embodiments of the joist 10, some of the reinforcement webs may be formed of metal and some may be formed of composite materials, the use of which may depend on the type and extent of the discontinuity in the central web 40.

As illustrated in Figures la to lc, a first reinforcement web 60, is located at, or in the proximity of, a first discontinuity 52 in the central web 40. The first reinforcement web 60 is affixed between the first flange 20 and the second flange 30.

As shown in Figure 1 b, the first reinforcement web 60 comprises a first portion 62, a second portion 64, and a third portion 66. The first portion 62 of the first reinforcement web 60 is affixed to the first flange 20. The second portion 64 of the first reinforcement web 60 is affixed to the second flange 30. The third portion 66 of the first reinforcement web 60 is located between the first portion 62 of the first reinforcement web 60 and the second portion 64 of the first reinforcement web 60.

The first portion 62 of the first reinforcement web 60 is offset, along the first axis 12, from the second portion 64 of the first reinforcement web 60. This helps to transmit tension forces applied to the joist 10 when the joist 10 is under load. These forces are transmitted between the first flange 20 and the second flange 30 via the first reinforcement web 60. This creates an alternative load path between the first flange 20, which in use is an upper flange, and the second flange 30, which is use is a lower flange, by bypassing the connection between the flanges 20, 30 and the intervening central web 40 at the location of the first discontinuity 52.

The third portion 66 of the first reinforcement web 60, between the first portion 62 of the first reinforcement web 60 and the second portion 64 of the first reinforcement web 60 is configured to be at an angle to the first axis 12. In some embodiments, the third portion 66 of the first reinforcement web 60 is at an angle between thirty and sixty degrees relative to the first axis 12. This equates to an angle between sixty and thirty degrees relative to the second axis 14. In some embodiments, the third portion 66 of the first reinforcement web 60 is at an angle of forty-five degrees, or substantially forty-five degrees, relative to the first axis 12, and therefore also relative to the second axis 14.

The first portion 62, second portion 64, and third portion 66, of the first reinforcing web 60 may be connected or formed to provide a smooth curved profile, thereby avoiding any angular joints that may provide a stress concentration point. As illustrated in Figures 15 and 16, the third portion 66 may comprise a straight section which also comprises ribs 78 projecting perpendicularly from the surface of the third portion 66 and running along the edge and/or centre of the third portion 66 in order to provide further strengthening of the first reinforcing web 60.

In some embodiments, for example the embodiment as illustrated in Figures la to 1c, the first discontinuity 52 in the central web 40 may form a first end 53 of an aperture 50 through the central web 40. The aperture 50 may provide access, for services such as pipes, cables, and wires for example, from a first side 18 of the joist 10 to a second side 19 of the joist 10.

One of the first portion 62 of the first reinforcement web 60 or the second portion 64 of the first reinforcement web 60 may extend beyond the first discontinuity 52 in the central web 40 to overlap part of the aperture 50 in the central web 40 along the first axis 12. The extent of the overlap of the aperture 50 by the first reinforcement web 60 may depend on the type and size of the services required to traverse the aperture 50. In other embodiments the first reinforcement web 60 does not overlap the aperture 50.

A second discontinuity 152 in the central web 40 may form a second end 55 of the aperture 50 through the central web 40, the second end 55 of the aperture 50 being separated along the first axis 12 from the first end 53 of the aperture 50.

The joist 10 may comprise a second reinforcement web 80, located at the second discontinuity 152 in the central web 40, and affixed between the first flange 20 and the second flange 30. A first portion 82 of the second reinforcement web 80 may be affixed to the first flange 20, and a second portion 84 of the second reinforcement web 80 may be affixed to the second flange 30.

The second reinforcement web 80 comprises a first portion 82, a second portion 84, and a third portion 86. The first portion 82 of the second reinforcement web 80 is affixed to the first flange 20. The second portion 84 of the second reinforcement web 80 is affixed to the second flange 30. The third portion 86 of the second reinforcement web 80 is located between the first portion 82 of the second reinforcement web 80 and the second portion 84 of the second reinforcement web 80.

The first portion 82 of the second reinforcement web 80 is offset, along the first axis 12, from the second portion 84 of the second reinforcement web 80. This helps to transmit tension forces applied to the joist 10 when the joist 10 is under load. These forces are transmitted between the first flange 20 and the second flange 30 via the second reinforcement web 80. This creates an alternative load path between the first flange 20, which in use is an upper flange, and the second flange 30, which is use is a lower flange, by bypassing the connection between the flanges 20, 30 and the intervening central web 40 at the location of the second discontinuity 152.

The third portion 86 of the second reinforcement web 80, between the first portion 82 of the second reinforcement web 60 and the second portion 84 of the second reinforcement web 80 is configured to be at an angle to the first axis 12. In some embodiments, the third portion 86 of the second reinforcement web 80 is at an angle between thirty and sixty degrees relative to the first axis 12. This equates to an angle between sixty and thirty degrees relative to the second axis 14. In some embodiments, the third portion 86 of the second reinforcement web 80 is at an angle of forty-five degrees, or substantially forty-five degrees, relative to the first axis 12, and therefore also relative to the second axis 14.

The first portion 82, second portion 84, and third portion 86, of the second reinforcing web 80 may be connected or formed to provide a smooth curved profile, thereby avoiding any angular joints that may provide a stress concentration point. The third portion 86 may comprise a straight section which also comprises ribs 78 projecting perpendicularly from the surface of the third portion 86 and running along the edge and/or centre of the third portion 86 in order to provide further strengthening of the second reinforcing web 80.

One of the first portion 82 of the second reinforcement web 80 or the second portion 84 of the second reinforcement web 80 may extend beyond the second discontinuity 152 in the central web 40 to overlap part of the aperture 50 in the central web 40 along the first axis 12. The extent of the overlap of the aperture 50 by the second reinforcement web 80 may depend on the type and size of the services required to traverse the aperture 50. In other embodiments the second reinforcement web 80 does not overlap the aperture 50.

Figure 1b illustrates a first arrangement of the first reinforcement web 60 and the second reinforcement web 80 at the location of an aperture 50 through the central web 40 of a joist 10. In this arrangement the first portions 62, 82 of the respective first reinforcement web 60 and the second reinforcement web 80 are further away from the aperture 50 than the second portions 64, 84 of the respective first reinforcement web 60 and the second reinforcement web 80. Such an arrangement provides opposing reinforcement webs 60, 80, which allows for even transmission of forces between the first flange 20, positioned as the upper flange, and the second flange 30, positioned as the lower flange.

Alternative arrangements of the first reinforcement web 60 and the second reinforcement web 80 at the location of an aperture 50 through the central web 40 of a joist 10 are shown in Figures 2a and 3a.

In Figure 2a the first portions 62, 82 of the respective first reinforcement web 60 and the second reinforcement web 80 are closer to the aperture 50 than the second portions 64, 84 of the respective first reinforcement web 60 and the second reinforcement web 80. Such an arrangement provides opposing reinforcement webs 60, 80, which allows for even transmission of forces between the first flange 20, positioned as the upper flange, and the second flange 30, positioned as the lower flange.

In Figure 3a the first reinforcement web 60 and the second reinforcement web 80 are not in opposing orientations, but are in the same orientation. In these arrangements the transmission of forces may not be even around the position of the aperture 50 in the central web 40, but the joist 10 is still able to take an increased load over a joist without such reinforcement webs 60, 80.

According to various embodiments, the joist 10 may comprise, as described above, a first reinforcement web 60, located at the first discontinuity 52 in the central web 40, on a first side 18 of the joist 10, and a second reinforcement web 80, located at the second discontinuity 152 in the central web 40, on a first side 18 of the joist 10.

In order to provide a more even distribution of forces throughout the joist 10, at the site of the aperture 50 in the central web 40, the joist 10 may comprise further reinforcement webs as illustrated in Figure 1c, Figure 2b, and Figure 3b. As illustrated in Figure lc, which is the second side of the joist 10 shown in Figure 1a and Figure 1 b, Figure 2b, which is the second side of the joist 10 shown in Figure 2a, and Figure 3b, which is the second side of the joist 10 shown in Figure 3a, the joist may further comprise a third reinforcement web 160, located at the first discontinuity 52 in the central web 40, on a second side 19 of the joist 10, opposite the first side 18 of the joist 10, and a fourth reinforcement web 180, located at the second discontinuity 152 in the central web 40, on the second side 19 of the joist 10.

The third reinforcement web 160 comprises a first portion 162, a second portion 164, and a third portion 166. The first portion 162 of the third reinforcement web 160 is affixed to the first flange 20. The second portion 164 of the third reinforcement web 160 is affixed to the second flange 30. The third portion 166 of the third reinforcement web 160 is located between the first portion 162 of the third reinforcement web 160 and the second portion 164 of the third reinforcement web 160.

The first portion 162 of the third reinforcement web 160 is offset, along the first axis 12, from the second portion 164 of the third reinforcement web 160. This helps to transmit tension forces applied to the joist 10 when the joist 10 is under load. These forces are transmitted between the first flange 20 and the second flange 30, at least in part, via the third reinforcement web 160. This creates an alternative load path between the first flange 20, which in use is an upper flange, and the second flange 30, which is use is a lower flange, by bypassing the connection between the flanges 20, 30 and the intervening central web 40 at the location of a discontinuity.

The fourth reinforcement web 180 comprises a first portion 182, a second portion 184, and a third portion 186. The first portion 182 of the fourth reinforcement web 180 is affixed to the first flange 20. The second portion 184 of the fourth reinforcement web 180 is affixed to the second flange 30. The third portion 186 of the fourth reinforcement web 180 is located between the first portion 182 of the fourth reinforcement web 180 and the second portion 184 of the fourth reinforcement web 180.

The first portion 182 of the fourth reinforcement web 180 is offset, along the first axis 12, from the second portion 184 of the fourth reinforcement web 180. This helps to transmit tension forces applied to the joist 10 when the joist 10 is under load. These forces are transmitted between the first flange 20 and the second flange 30, at least in part, via the fourth reinforcement web 180. This creates an alternative load path between the first flange 20, which in use is an upper flange, and the second flange 30, which is use is a lower flange, by bypassing the connection between the flanges 20, 30 and the intervening central web 40 at the location of a discontinuity.

The first reinforcement web 60 and the third reinforcement web 160 may be located at the same position, or substantially the same position, along the first axis 12, and the second reinforcement web 80 and the fourth reinforcement web 180 may be located at the same position, or substantially the same position, along the first axis 12.

In some embodiments, the orientation of the third reinforcement web 160 may be such that it mirrors the orientation of the first reinforcement web 60 in the plane of the joist 10 defined by the first axis 12 and second axis 14. The orientation of the fourth reinforcement web 180 may be such that it mirrors the orientation of the second reinforcement web 80 in the plane of the joist 10 defined by the first axis 12 and second axis 14. However, other orientations of the reinforcement webs 60, 80, 160, 180 can be provided.

In some embodiments the reinforcement webs at either side of the joist 10 at a discontinuity 52, 152 in the joist 10 may define a crossed arrangement, that is they have opposing orientations at the discontinuity 52, 152. In an example, on the first side 18 of the joist 10 the first portion 62 of the first reinforcement web 60 is offset, along the first axis 12, from the second portion 64 of the first reinforcement web 60, to be further away from the first discontinuity 52, and on the second side 19 of the joist 10 the first portion 162 of the third reinforcement web 160 is offset, along the first axis 12, from the second portion 164 of the third reinforcement web 160, to be closer to the first discontinuity 52. A similar arrangement may be provided for other reinforcement webs, such as for the second reinforcement web 80 and fourth reinforcement web 180 described above.

By having reinforcement webs 60, 80, 160, 180 on either side of the joist 10, in such an arrangement, the loads transmitted from the first flange 20 to the second flange 30 are shared through the multiple reinforcing webs 60, 80, 160, 180, and may, in some arrangements, be shared evenly between the multiple reinforcing webs 60, 80, 160, 180.

As illustrated in Figures 4a to 4c and 6a to 6c, in some embodiments, the joist 10 may comprise apertures 50, as previously described, and reinforcement webs 60, 80, 160, 180, as previously described in various combinations, and also comprise further discontinuities, such as third discontinuity 252 in the central web 40 which may form a first end 54 of the central web 40 at a first end 16 of the joist 10. The first end 16 of the joist 10 is configured to be proximal to a first supporting structure. In these embodiments, the first flange 20 extends beyond the central web 40 and the second flange 30 along the first axis 12 at the first end 16 of the joist 10. In this way, the joist 10 forms a top hung joist with the first flange 20 being configured to be supported by a first supporting structure. The other end of the joist 10 can provide a similar arrangement, where a second end of the central web 40 can form a further discontinuity and the first flange 20 extends beyond the central web 40 and the second flange 30 along the first axis 12 at the second end of the joist 10, the first flange 20 being configured to be supported by a second supporting structure.

In some embodiments, as illustrated in Figure 4a, showing a perspective view of the first end 16 of a joist 10, Figure 4b, showing a side view of a first side 18 of the first end 16 of the joist 10, and Figure 4c, showing a side view of a second side 19 of the first end 16 of the joist 10, the first portion 62 of the first reinforcement web 60 does not extend beyond the first end 54 of the central web 40 along the first axis 12. This ensures that timber which is positioned between adjacent joists, to improve air tightness, can be positioned without interference from the reinforcement web 60.

In alternative embodiments, as illustrated in Figure 5a, showing a side view of a first side 18 of the first end 16 of the joist 10, and Figure 5b, showing a side view of a second side 19 of the first end 16 of the joist 10, the only discontinuities in the joist 10 may be at the ends of the joist 10, for example the first end 16 of the joist 10 as shown in Figure 5a and Figure 5b, and the opposite end along the first axis 12. That is, the joist 10 may have no apertures 50 therethrough that significantly affect the structural integrity of the joist 10. The discontinuity at the first end 16 of the joist 10 may be the same as the third discontinuity 252 as illustrated in Figures 4a, 4b, and 4c. This discontinuity 252 in the central web 40 may form a first end 54 of the central web 40 at a first end 16 of the joist 10. The first end 16 of the joist 10 is configured to be proximal to a first supporting structure. In this embodiment, the first flange 20 extends beyond the central web 40 and the second flange 30 along the first axis 12 at the first end 16 of the joist 10. In this way, the joist 10 forms a top hung joist with the first flange 20 being configured to be supported by a first supporting structure. The other end of the joist 10 can provide a similar arrangement, where a second end of the central web 40 can form a further discontinuity and the first flange 20 extends beyond the central web 40 and the second flange 30 along the first axis 12 at the second end of the joist 10, the first flange 20 being configured to be supported by a second supporting structure.

As illustrated in Figure 5a, a first reinforcement web 60, is located at, or in the proximity of, a discontinuity 252 in the central web 40 which forms a first end 54 of the central web 40 at a first end 16 of the joist 10. The first reinforcement web 60 is affixed between the first flange 20 and the second flange 30.

As shown in Figure 5a, the first reinforcement web 60 comprises a first portion 62, a second portion 64, and a third portion 66. The first portion 62 of the first reinforcement web 60 is affixed to the first flange 20. The second portion 64 of the first reinforcement web 60 is affixed to the second flange 30. The third portion 66 of the first reinforcement web 60 is located between the first portion 62 of the first reinforcement web 60 and the second portion 64 of the first reinforcement web 60.

The first portion 62 of the first reinforcement web 60 is offset, along the first axis 12, from the second portion 64 of the first reinforcement web 60. This helps to transmit tension forces applied to the joist 10 when the joist 10 is under load. These forces are transmitted between the first flange 20 and the second flange 30, at least in part, via the first reinforcement web 60.

This creates an alternative load path between the first flange 20, which in use is an upper flange, and the second flange 30, which is use is a lower flange, by bypassing the connection between the flanges 20, 30 and the intervening central web 40 at the location of the discontinuity 252.

As illustrated in Figure 5a, the first portion 62 of the first reinforcement web 60 does not extend beyond the first end 54 of the central web 40 along the first axis 12. Because the first portion 62 of the first reinforcement web 60 does not extend beyond the first end 54 of the central web 40 along the first axis 12, timber can be positioned between adjacent joists, to improve air tightness, without interference from the reinforcement web 60.

In order to provide a more even distribution of forces throughout the joist 10, at the first end 54 of the central web 40, the joist 10 may comprise a further reinforcement web as illustrated in Figure 5b. As illustrated in Figure 5b, which is the second side of the joist 10 shown in Figure 5a, the joist 10 may comprise a second reinforcement web 80, located at the first end 54 of the central web 40, on a second side 19 of the joist 10, opposite the first side 18 of the joist 10.

As shown in Figure 5b, the second reinforcement web 80 comprises a first portion 82, a second portion 84, and a third portion 86. The first portion 82 of the second reinforcement web 80 is affixed to the first flange 20. The second portion 84 of the second reinforcement web 80 is affixed to the second flange 30. The third portion 86 of the second reinforcement web 80 is located between the first portion 82 of the second reinforcement web 80 and the second portion 84 of the second reinforcement web 80.

The first portion 82 of the second reinforcement web 80 is offset, along the first axis 12, from the second portion 84 of the second reinforcement web 80. This helps to transmit tension forces applied to the joist 10 when the joist 10 is under load. These forces are transmitted between the first flange 20 and the second flange 30, at least in part, via the second reinforcement web 80. This creates an alternative load path between the first flange 20, which in use is an upper flange, and the second flange 30, which is use is a lower flange, by bypassing the connection between the flanges 20, 30 and the intervening central web 40 at the location of the discontinuity 252.

The first reinforcement web 60 and the second reinforcement web 80 may be located at the same longitudinal position, or substantially the same longitudinal position, along the first axis 12.

In some embodiments, the orientation of the second reinforcement web 80 may be such that it mirrors the orientation of the first reinforcement web 60 in the plane of the joist 10 defined by the first axis 12 and second axis 14. However, other orientations of the reinforcement webs 60, 80 can be provided.

In some embodiments the reinforcement webs at either side of the joist 10 may define a crossed arrangement, that is they have opposing orientations at the discontinuity 252. In an example, on the first side 18 of the joist 10 the first portion 62 of the first reinforcement web 60 is offset, along the first axis 12, from the second portion 64 of the first reinforcement web 60, to be further away from the discontinuity 252, and on the second side 19 of the joist 10 the first portion 82 of the second reinforcement web 80 is offset, along the first axis 12, from the second portion 84 of the second reinforcement web 80, to be closer to the discontinuity 252.

By having reinforcement webs 60, 80 on either side of the joist 10 at the first end 54 of the central web 40, the forces transmitted from the first flange 20 to the second flange 30 due to loading of the joist 10 are shared through the multiple reinforcing webs 60, 80, and may, in some arrangements, be shared evenly between the multiple reinforcing webs 60, 80.

In some embodiments, as illustrated in Figure 6a, showing a perspective view of the first end 16 of a joist 10, Figure 6b, showing a side view of a first side 18 of the first end 16 of the joist 10, and Figure 6c, showing a side view of a second side 19 of the first end 16 of the joist 10, the first portion 62 of the first reinforcement web 60 extends beyond the first end 54 of the central web 40 along the first axis 12. In this alternative embodiment, the joist 10 may be able to withstand a higher load, but at the expense of interference with timber that may be positioned between adjacent joists for the purpose of improving air tightness.

In alternative embodiments, as illustrated in Figure 7a, showing a side view of a first side 18 of the first end 16 of the joist 10, and Figure 7b, showing a side view of a second side 19 of the first end 16 of the joist 10, the only discontinuities in the joist 10 may be at the ends of the joist 10, for example the first end 16 of the joist 10 as shown in Figure 7a and Figure 7b, and the opposite end along the first axis 12. That is, the joist 10 may have no apertures 50 therethrough that significantly affect the structural integrity of the joist 10. The discontinuity at the first end 16 of the joist 10 may be the same as the third discontinuity 252 as illustrated in Figures 4a, 4b, and 4c. This discontinuity 252 in the central web 40 may form a first end 54 of the central web 40 at a first end 16 of the joist 10. The first end 16 of the joist 10 is configured to be proximal to a first supporting structure. In this embodiment, the first flange 20 extends beyond the central web 40 and the second flange 30 along the first axis 12 at the first end 16 of the joist 10. In this way, the joist 10 forms a top hung joist with the first flange 20 being configured to be supported by a first supporting structure. The other end of the joist 10 can provide a similar arrangement, where a second end of the central web 40 can form a further discontinuity and the first flange 20 extends beyond the central web 40 and the second flange along the first axis 12 at the second end of the joist 10, the first flange 20 being configured to be supported by a second supporting structure.

As illustrated in Figure 7a, a first reinforcement web 60, is located at, or in the proximity of, a discontinuity 252 in the central web 40 which forms a first end 54 of the central web 40 at a first end 16 of the joist 10. The first reinforcement web 60 is affixed between the first flange 20 and the second flange 30.

As shown in Figure 7a, the first reinforcement web 60 comprises a first portion 62, a second portion 64, and a third portion 66. The first portion 62 of the first reinforcement web 60 is affixed to the first flange 20. The second portion 64 of the first reinforcement web 60 is affixed to the second flange 30. The third portion 66 of the first reinforcement web 60 is located between the first portion 62 of the first reinforcement web 60 and the second portion 64 of the first reinforcement web 60.

The first portion 62 of the first reinforcement web 60 is offset, along the first axis 12, from the second portion 64 of the first reinforcement web 60. This helps to transmit tension forces applied to the joist 10 when the joist 10 is under load. These forces are transmitted between the first flange 20 and the second flange 30 via the first reinforcement web 60. This creates an alternative load path between the first flange 20, which in use is an upper flange, and the second flange 30, which is use is a lower flange, by bypassing the connection between the flanges 20, 30 and the intervening central web 40 at the location of the discontinuity 252.

As illustrated in Figure 7a, the first portion 62 of the first reinforcement web 60 extends beyond the first end 54 of the central web 40 along the first axis 12, towards the distal end of the joist 10, that is towards the free end of the joist 10. Because the first portion 62 of the first reinforcement web 60 extends beyond the first end 54 of the central web 40 along the first axis 12, increased loads may be applied to the joist 10 relative to joists in which the first reinforcement web 60 does not extend beyond the first end 54 of the central web 40 along the first axis 12, however this may affect air tightness of any construction since the reinforcement web 60 can interfere with the placement of timber between joists 10.

In order to provide a more even distribution of forces throughout the joist 10, at the first end 54 of the central web 40, the joist 10 may comprise a further reinforcement web as illustrated in Figure 7b. As illustrated in Figure 7b, which is the second side of the joist 10 shown in Figure 7a, the joist 10 may comprise a second reinforcement web 80, located at the first end 54 of the central web 40, on a second side 19 of the joist 10, opposite the first side 18 of the joist 10.

As shown in Figure 7b, the second reinforcement web 80 comprises a first portion 82, a second portion 84, and a third portion 86. The first portion 82 of the second reinforcement web 80 is affixed to the first flange 20. The second portion 84 of the second reinforcement web 80 is affixed to the second flange 30. The third portion 86 of the second reinforcement web 80 is located between the first portion 82 of the second reinforcement web 80 and the second portion 84 of the second reinforcement web 80.

The first portion 82 of the second reinforcement web 80 is offset, along the first axis 12, from the second portion 84 of the second reinforcement web 80. This helps to transmit tension forces applied to the joist 10 when the joist 10 is under load. These forces are transmitted between the first flange 20 and the second flange 30 via the second reinforcement web 80. This creates an alternative load path between the first flange 20, which in use is an upper flange, and the second flange 30, which is use is a lower flange, by bypassing the connection between the flanges 20, 30 and the intervening central web 40 at the location of the discontinuity 252.

In some embodiments, the orientation of the second reinforcement web 80 may be such that it mirrors the orientation of the first reinforcement web 60 in the plane of the joist 10 defined by the first axis 12 and second axis 14. However, other orientations of the reinforcement webs 60, 80 can be provided. In some embodiments the reinforcement webs at either side of the joist 10 may define a crossed arrangement, that is they have opposing orientations at the discontinuity 252.

By having reinforcement webs 60, 80 on either side of the joist 10 at the first end 54 of the central web 40, the loads transmitted from the first flange 20 to the second flange 30 are shared through the multiple reinforcing webs 60, 80, and may, in some arrangements, be shared evenly between the multiple reinforcing webs 60, 80.

Figures 8a and 8b illustrate a similar arrangement to Figures lb and lc, with Figure 8a showing a first side 18 of the joist 10 and Figure 8b showing a second side 19 of the joist 10.

However, in the arrangement shown, rather than having one reinforcing web at each discontinuity, two or more reinforcing webs may be provided. In the arrangement of Figures 8a and 8b, two reinforcing webs are provided for each discontinuity on each side of the joist 10.

In the embodiment of Figures 8a and 8b, a first reinforcing web 60 is provided at a first discontinuity 52 on a first side 18 of the joist 10 and a second reinforcing web 80 is provided at a second discontinuity 152 on the first side 18 of the joist 10, as previously described in relation to Figure lb. Additionally, at the first discontinuity 52 a third reinforcing web 160 is provided on a second side 19 of the joist 10 and at the second discontinuity 152 a fourth reinforcing web 180 is provided on the second side 19 of the joist 10, as previously described in relation to Figure lc.

A further reinforcing web in the form of a fifth reinforcing web 260, is located or positioned on the first side 18 of the joist 10, more distal from the discontinuity 52 along the joist 10 than the first reinforcing web 60. The fifth reinforcement web 260 comprises a first portion 262, a second portion 264, and a third portion 266. The first portion 262 of the fifth reinforcement web 260 is affixed to the first flange 20. The second portion 264 of the fifth reinforcement web 260 is affixed to the second flange 30. The third portion 266 of the fifth reinforcement web 260 is located between the first portion 262 of the fifth reinforcement web 260 and the second portion 264 of the fifth reinforcement web 260. The first portion 262 of the fifth reinforcement web 260 is offset, along the first axis 12, from the second portion 264 of the fifth reinforcement web 260.

A further reinforcing web in the form of a sixth reinforcing web 280, is located or positioned on the first side 18 of the joist 10, more distal from the discontinuity 152 along the joist 10 than the second reinforcing web 80. The sixth reinforcement web 280 comprises a first portion 282, a second portion 284, and a third portion 286. The first portion 282 of the sixth reinforcement web 280 is affixed to the first flange 20. The second portion 284 of the sixth reinforcement web 280 is affixed to the second flange 30. The third portion 286 of the sixth reinforcement web 280 is located between the first portion 282 of the sixth reinforcement web 280 and the second portion 284 of the sixth reinforcement web 280. The first portion 282 of the sixth reinforcement web 280 is offset, along the first axis 12, from the second portion 284 of the sixth reinforcement web 280.

A further reinforcing web in the form of a seventh reinforcing web 360, is located or positioned on the second side 19 of the joist 10, more distal from the discontinuity 52 along the joist 10 than the third reinforcing web 160. The seventh reinforcement web 360 comprises a first portion 362, a second portion 364, and a third portion 366. The first portion 362 of the seventh reinforcement web 360 is affixed to the first flange 20. The second portion 364 of the seventh reinforcement web 360 is affixed to the second flange 30. The third portion 366 of the seventh reinforcement web 360 is located between the first portion 362 of the seventh reinforcement web 360 and the second portion 364 of the seventh reinforcement web 360. The first portion 362 of the seventh reinforcement web 360 is offset, along the first axis 12, from the second portion 364 of the seventh reinforcement web 360.

A further reinforcing web in the form of an eighth reinforcing web 380, is located or positioned on the second side 19 of the joist 10, more distal from the discontinuity 152 along the joist 10 than the fourth reinforcing web 180. The eighth reinforcement web 380 comprises a first portion 382, a second portion 384, and a third portion 386. The first portion 382 of the eighth reinforcement web 380 is affixed to the first flange 20. The second portion 384 of the eighth reinforcement web 380 is affixed to the second flange 30. The third portion 386 of the eighth reinforcement web 380 is located between the first portion 382 of the eighth reinforcement web 380 and the second portion 384 of the eighth reinforcement web 380. The first portion 382 of the eighth reinforcement web 380 is offset, along the first axis 12, from the second portion 384 of the eighth reinforcement web 380.

As illustrated in Figures 8a and 8b, adjacent reinforcing webs may be in the same orientation, but can in other embodiments be in opposing orientations whilst still providing structural reinforcement.

Figures 9a and 9b illustrate a similar arrangement to Figures 2a and 2b, with Figure 9a showing a first side 18 of the joist 10 and Figure 9b showing a second side 19 of the joist 10.

However, in the arrangement shown, rather than having one reinforcing web at each discontinuity, two or more reinforcing webs may be provided. In the arrangement of Figures 9a and 9b, two reinforcing webs are provided for each discontinuity on each side of the joist 10.

In the embodiment of Figures 9a and 9b, a first reinforcing web 60 is provided at a first discontinuity 52 on a first side 18 of the joist 10 and a second reinforcing web 80 is provided at a second discontinuity 152 on the first side 18 of the joist 10, as previously described in relation to Figure 2a. Additionally, at the first discontinuity 52 a third reinforcing web 160 is provided on a second side 19 of the joist 10 and at the second discontinuity 152 a fourth reinforcing web 180 is provided on the second side 19 of the joist 10, as previously described in relation to Figure 2b.

A further reinforcing web in the form of a fifth reinforcing web 260, is located or positioned on the first side 18 of the joist 10, more distal from the discontinuity 52 along the joist 10 than the first reinforcing web 60. A further reinforcing web in the form of a sixth reinforcing web 280, is located or positioned on the first side 18 of the joist 10, more distal from the discontinuity 152 along the joist 10 than the second reinforcing web 80.

A further reinforcing web in the form of a seventh reinforcing web 360, is located or positioned on the second side 19 of the joist 10, more distal from the discontinuity 52 along the joist 10 than the third reinforcing web 160. A further reinforcing web in the form of an eighth reinforcing web 380, is located or positioned on the second side 19 of the joist 10, more distal from the discontinuity 152 along the joist 10 than the fourth reinforcing web 180.

Figures 10a and 10b illustrate a similar arrangement to Figures 3a and 3b, with Figure 10a showing a first side 18 of the joist 10 and Figure 10b showing a second side 19 of the joist 10. However, in the arrangement shown, rather than having one reinforcing web at each discontinuity, two or more reinforcing webs may be provided. In the arrangement of Figures 10a and 10b, two reinforcing webs are provided for each discontinuity on each side of the joist 10.

In the embodiment of Figures 10a and 10b, a first reinforcing web 60 is provided at a first discontinuity 52 on a first side 18 of the joist 10 and a second reinforcing web 80 is provided at a second discontinuity 152 on the first side 18 of the joist 10, as previously described in relation to Figure 3a. Additionally, at the first discontinuity 52 a third reinforcing web 160 is provided on a second side 19 of the joist 10 and at the second discontinuity 152 a fourth reinforcing web 180 is provided on the second side 19 of the joist 10, as previously described in relation to Figure 3b.

Figures 11a and 11b illustrate a similar arrangement to Figures 5a and 5b, with Figure lla showing a first side 18 of the joist 10 and Figure 11 b showing a second side 19 of the joist 10. However, in the arrangement shown, rather than having one reinforcing web at the discontinuity 252 at the end 16 of the joist 10, two or more reinforcing webs may be provided. In the arrangement of Figures 11a and 11b, two reinforcing webs are provided at the discontinuity 252 on each side of the joist 10.

In the embodiment of Figures 11a and 11b, a first reinforcing web 60 is provided on a first side 18 of the joist 10 at the discontinuity 252, as previously described in relation to Figure 5a, and a second reinforcing web 80 is provided on a second side 19 of the joist 10 at the discontinuity 252, as previously described in relation to Figure 5b.

A further reinforcing web in the form of a third reinforcing web 460, is located or positioned on the first side 18 of the joist 10, more distal from the discontinuity 252 along the joist 10 than the first reinforcing web 60. A further reinforcing web in the form of a fourth reinforcing web 480, is located or positioned on the second side 19 of the joist 10, more distal from the discontinuity 252 along the joist 10 than the second reinforcing web 80.

The use of multiple reinforcing webs at the discontinuity 252 at the end 16 of the joist 10, where the joist 10 is connected to a supporting structure, provides an increased load bearing capacity for the joist 10.

Figures 12a and 12b illustrate a similar arrangement to Figures 7a and 7b, with Figure 12a showing a first side 18 of the joist 10 and Figure 12b showing a second side 19 of the joist 10. However, in the arrangement shown, rather than having one reinforcing web at the discontinuity 252 at the end 16 of the joist 10, two or more reinforcing webs may be provided.

In the arrangement of Figures 12a and 12b, two reinforcing webs are provided at the discontinuity 252 on each side of the joist 10.

In the embodiment of Figures 12a and 12b, a first reinforcing web 60 is provided on a first side 18 of the joist 10 at the discontinuity 252, as previously described in relation to Figure 7a, and a second reinforcing web 80 is provided on a second side 19 of the joist 10 at the discontinuity 252, as previously described in relation to Figure 7b.

As illustrated in Figure 12a, the first portion 62 of the first reinforcement web 60 extends beyond the first end 54 of the central web 40 along the first axis 12, towards the distal end of the joist 10, that is towards the free end of the joist 10. As illustrated in Figure 12b, the first portion 82 of the second reinforcement web 80 extends beyond the first end 54 of the central web 40 along the first axis 12, towards the distal end of the joist 10, that is towards the free end of the joist 10. Because the first portion 62 of the first reinforcement web 60 and the first portion 82 of the second reinforcement web 80 extend beyond the first end 54 of the central web 40 along the first axis 12, increased loads may be applied to the joist 10 relative to joists in which the first reinforcement web 60 does not extend beyond the first end 54 of the central web 40 along the first axis 12, such as the embodiment shown in Figure 1 1 a and Figure 11b, however this may affect air tightness of any construction since the reinforcement web 60 can, in some cases, interfere with the placement of timber between joists 10.

Figure 13 and Figure 14 illustrate particular embodiments where reinforcing webs may provide shared functionality in terms of reinforcing the joist 10 at multiple discontinuities. Only a first side 18 of the joist 10 is illustrated for these embodiments, though it will be understood that the second side 19 of the joist 10, opposite the first side 18 of the joist 10, may comprise components mirroring those of the first side 18 of the joist 10, as has been described above in relation to other embodiments.

In the embodiment illustrated in Figure 13, the joist 10 comprises both a discontinuity 252 at the end 16 of the joist 10 and an aperture 50, the aperture 50 comprising a first discontinuity 52 in the central web 40 and a second discontinuity 152 in the central web 40 as previously described. The first discontinuity 52 of the aperture 50 is closer to the end 16 of the joist 10 than the second discontinuity 152 of the aperture 50. The embodiment of Figure 13 comprises a first reinforcement web 60 at the discontinuity 252 at the end 16 of the joist 10, a second reinforcement web 80 at the second discontinuity 152 of the aperture 50, and a third reinforcement web 460 at the first discontinuity 52 of the aperture 50. In this embodiment, the third reinforcement web 460 provides both reinforcement of the joist 10 at the first discontinuity 52 of the aperture 50, as described above in relation to various embodiments, such as the embodiment of Figure lb, and reinforcement of the joist 10 at the end 16 of the joist 10, as described above in relation to the embodiment of Figure 1 la.

The third reinforcement web 460 comprises a first portion 462, a second portion 464, and a third portion 466. The first portion 462 of the third reinforcement web 460 is affixed to the first flange 20. The second portion 464 of the third reinforcement web 460 is affixed to the second flange 30. The third portion 466 of the third reinforcement web 460 is located between the first portion 462 of the third reinforcement web 460 and the second portion 464 of the third reinforcement web 460. The first portion 462 of the third reinforcement web 460 is offset, along the first axis 12, from the second portion 464 of the third reinforcement web 460. The second portion 464 of the third reinforcement web 460 overlaps the aperture 50 in the joist 10 to provide structural support at the aperture 50, and overlaps the first reinforcement web 60, in particular the second portion 64 of the first reinforcement web 60, to provide additional structural support at the connection between the joist 10 and a supporting structure upon which the joist 10 is configured to be positioned and at which the first reinforcement web 60 is positioned to provide structural support. Having the reinforcement webs orientated in the same direction allows such overlap of the reinforcing webs.

The first end 16 of the joist 10 is configured to be proximal to a first supporting structure. In this embodiment, the first flange 20 extends beyond the central web 40 and the second flange 30 along the first axis 12 at the first end 16 of the joist 10. In this way, the joist 10 forms a top hung joist with the first flange 20 being configured to be supported by a first supporting structure. The other end of the joist 10 can provide a similar arrangement, where a second end of the central web 40 can form a further discontinuity and the first flange 20 extends beyond the central web 40 and the second flange 30 along the first axis 12 at the second end of the joist 10, the first flange 20 being configured to be supported by a second supporting structure.

In the embodiment of Figure 13, the first reinforcement web 60 does not extend beyond the first end 54 of the central web 40 along the first axis 12. This ensures that timber which is positioned between adjacent joists, to improve air tightness, can be positioned without interference from the reinforcement web 60.

In the embodiment illustrated in Figure 14, the joist 10 comprises both a discontinuity 252 at the end 16 of the joist 10 and an aperture 50, the aperture 50 comprising a first discontinuity 52 in the central web 40 and a second discontinuity 152 in the central web 40 as previously described. The first discontinuity 52 of the aperture 50 is closer to the end 16 of the joist 10 than the second discontinuity 152 of the aperture 50. The embodiment of Figure 14 comprises a first reinforcement web 60 at the discontinuity 252 at the end 16 of the joist 10, a second reinforcement web 80 at the second discontinuity 152 of the aperture 50, and a third reinforcement web 460 at the first discontinuity 52 of the aperture 50. In this embodiment, the third reinforcement web 460 provides both reinforcement of the joist 10 at the first discontinuity 52 of the aperture 50, as described above in relation to various embodiments, such as the embodiment of Figure lb, and reinforcement of the joist 10 at the end 16 of the joist 10, as described above in relation to the embodiment of Figure 12a.

In the embodiment of Figure 14, the first portion 62 of the first reinforcement web 60 extends beyond the first end 54 of the central web 40 along the first axis 12. This allows increased loads to be applied to the joist 10 relative to joists in which the first reinforcement web 60 does not extend beyond the first end 54 of the central web 40 along the first axis 12, however this may affect air tightness of any construction since the reinforcement web 60 can interfere with the placement of timber between joists 10.

As illustrated in Figure 15, the first portion 62 of the first reinforcement web 60 may comprise a first set of teeth 67 projecting perpendicular to both the first axis 12 and the second axis 14. The first portion 62 of the first reinforcement web 60 may be flat, or substantially flat, in order to have a plane parallel to a side surface 24 of a first side 23 of the first flange 20 when the first reinforcement web 60 is joined or affixed to the first flange 20. The first set of teeth 67 may project from the first reinforcement web 60 and be configured to be pressed into the first flange 20, in particular the side surface 24 of the first side 23 of the first flange 20, for fixing thereto. The first set of teeth 67 may be pressed or hammered into the first flange 20.

Further, as illustrated in Figure 15, the second portion 64 of the first reinforcement web 60 may comprise a second set of teeth 68 projecting perpendicular to both the first axis 12 and the second axis 14. The second portion 64 of the first reinforcement web 60 may be flat, or substantially flat, in order to have a plane parallel to a side surface 34 of a first side 33 of the second flange 30 when the first reinforcement web 60 is joined or affixed to the second flange 30. The second set of teeth 68 may project from the first reinforcement web 60 and be configured to be pressed into the second flange 30, in particular the side surface 34 of the first side 33 of the second flange 30, for fixing thereto. The second set of teeth 68 may be pressed or hammered into the second flange 30. It will be understood that the various herein described reinforcement webs 60, 80, 160, 180, 260, 280, 360, 380, 460, 480 may take the same form as that described above.

In an alternative fixing arrangement to that illustrated in Figure 15, Figure 16 shows the use of other fixing means to affix the first reinforcement web 60 to the first flange 20 and the second flange 30.

As illustrated in Figure 16, the first portion 62 of the first reinforcement web 60 may comprise a first set of one or more fixing apertures 70 for receiving first fixing means 74 in a direction perpendicular to both the first axis 12 and the second axis 14. The first portion 62 of the first reinforcement web 60 may be flat, or substantially flat, in order to have a plane parallel to a side surface 24 of a first side 23 of the first flange 20 when the first reinforcement web 60 is joined or affixed to the first flange 20. The first fixing means 74 may be configured to affix the first portion 62 of the first reinforcement web 60 to the first flange 20. The first fixing means 74 may be, for example, screws or nails configured to be driven into the first flange 20 through the first set of one or more fixing apertures 70. Alternatively, the first fixing means 74 may be bolts arranged to pass through the first flange 20 and be secured at a second side surface 26 of a second side 25 of the first flange 20.

Further, as illustrated in Figure 16, the second portion 64 of the first reinforcement web 60 may comprise a second set of one or more fixing apertures 72 for receiving second fixing means 76 in a direction perpendicular to both the first axis 12 and the second axis 14. The second portion 64 of the first reinforcement web 60 may be flat, or substantially flat, in order to have a plane parallel to a side surface 34 of a first side 33 of the second flange 30 when the first reinforcement web 60 is joined or affixed to the second flange 30. The second fixing means 76 may be configured to affix the second portion 64 of the first reinforcement web 60 to the second flange 30. The second fixing means 76 may be, for example, screws or nails configured to be driven into the second flange 30 through the second set of one or more fixing apertures 72. Alternatively, the second fixing means 76 may be bolts arranged to pass through the second flange 30 and be secured at a second side surface 36 of a second side 35 of the second flange 30. It will be understood that the various herein described reinforcement webs 60, 80, 160, 180, 260, 280, 360, 380, 460, 480 may take the same form as that described above.

It will be appreciated that various changes and modifications can be made to the present invention without departing from the scope of the present application. In particular, whilst the examples provided in Figures 1 to 14 illustrate various arrangements of an I-joist and reinforcing webs, and Figures 15 and 16 illustrate different reinforcing webs, it will be understood that the claimed invention is not limited to these specific examples but extends to other combinations of these arrangements as encompassed by the claims.

Claims

CLAIMS1. A joist having a length along a first axis for spanning a gap between two support structures, the joist comprising: a first flange having a groove along at least a portion of the length of the first flange parallel to the first axis; and a second flange having a groove along at least a portion of the length of the second flange parallel to the first axis, the second flange being separated from the first flange in a second axis, perpendicular to the first axis; a central web affixed between the first flange and the second flange, the central web having a first side located in the groove of the first flange and a second side, opposite the first side, located in the groove of the second flange; and one or more reinforcement webs, located at a first discontinuity in the central web, and affixed between the first flange and the second flange; wherein a first portion of a first reinforcement web is affixed to the first flange, and a second portion of the first reinforcement web is affixed to the second flange, and wherein the first portion of the first reinforcement web is offset, along the first axis, from the second portion of the first reinforcement web.
2. A joist according to claim 1, wherein the first discontinuity in the central web forms a first end of the central web at a first end of the joist, and wherein the first flange extends beyond the central web and the second flange along the first axis at the first end of the joist.
3. A joist according to claim 2, wherein the first portion of the first reinforcement web extends beyond the first end of the central web along the first axis.
4. A joist according to any preceding claim, wherein the joist comprises the first reinforcement web, located at the first discontinuity in the central web, on a first side of the joist, and a second reinforcement web, located at the first discontinuity in the central web, on a second side of the joist, opposite the first side of the joist.
5. A joist according to claim 4, wherein a first portion of the second reinforcement web is affixed to the first flange, and a second portion of the second reinforcement web is affixed to the second flange, and wherein the first portion of the second reinforcement web is offset, along the first axis, from the second portion of the second reinforcement web.
6. A joist according to claim 5 when also dependent on claim 2 or claim 3, wherein the first portion of the second reinforcement web extends beyond the first end of the central web along the first axis.
7. A joist according to any of claims 4 to 6, wherein the first reinforcement web and the second reinforcement web are located at the same longitudinal position along the first axis.
8. A joist according to claim 7, wherein the orientation of the first reinforcement web mirrors the orientation of the second reinforcement web in the plane defined by the first axis and second axis.
9. A joist according to claim 7, wherein the first reinforcement web has an opposing orientation to the second reinforcement web.
10. A joist according to claim 1, wherein the first discontinuity in the central web forms a first end of an aperture through the central web, the aperture providing access from a first side of the joist to a second side of the joist.
11. A joist according to any of claim 10, wherein one of the first portion of the first reinforcement web or the second portion of the first reinforcement web extends beyond the first discontinuity in the central web to overlap the aperture in the central web along the first axis.
12. A joist according to claim 10 or claim 11, wherein a second discontinuity in the central web forms a second end of the aperture through the central web, the second end of the aperture being separated from the first end of the aperture along the first axis.
13. A joist according to claim 12, comprising a second reinforcement web, located at the second discontinuity in the central web, and affixed between the first flange and the second flange, wherein a first portion of the second reinforcement web is affixed to the first flange, and a second portion of the second reinforcement web is affixed to the second flange, and wherein the first portion of the second reinforcement web is offset, along the first axis, from the second portion of the second reinforcement web.
14. A joist according to claim 13, wherein one of the first portion of the second reinforcement web or the second portion of the second reinforcement web extends beyond the second discontinuity in the central web to overlap the aperture in the central web along the first axis.
15. A joist according to any of claims 10 to 14, wherein the aperture in the central web is configured to receive services such as water and drainage pipes, ducts, and electrical wires.
16. A joist according to any of claims 13 to 15, wherein the joist comprises the first reinforcement web, located at the first discontinuity in the central web, on a first side of the joist, the second reinforcement web, located at the second discontinuity in the central web, on a first side of the joist, a third reinforcement web, located at the first discontinuity in the central web, on a second side of the joist, opposite the first side of the joist, and a fourth reinforcement web, located at the second discontinuity in the central web, on the second side of the joist.
17. A joist according to claim 16, wherein the first reinforcement web and the third reinforcement web are located at the same longitudinal position along the first axis, and the second reinforcement web and the fourth reinforcement web are located at the same longitudinal position along the first axis.
18. A joist according to claim 17, wherein the orientation of the first reinforcement web mirrors the orientation of the third reinforcement web in the plane defined by the first axis and second axis, and the orientation of the second reinforcement web mirrors the orientation of the fourth reinforcement web in the plane defined by the first axis and second axis.
19. A joist according to claim 17, wherein the first reinforcement web has an opposing orientation to the third reinforcement web and the second reinforcement web has an opposing orientation to the fourth reinforcement web.
20. A joist according to any preceding claim, wherein a further reinforcement web is located adjacent, and on the same side of the joist to, one or more of the one or more reinforcement webs.
21. A joist according to claim 20, wherein the further reinforcement web comprises a first portion affixed to the first flange, and a second portion affixed to the second flange, and wherein the first portion of the further reinforcement web is offset, along the first axis, from the second portion of the further reinforcement web.
22. A joist according to any preceding claim, wherein the, or each, reinforcement web comprises a third portion between the first portion of the reinforcement web and the second portion of the reinforcement web, the third portion of the reinforcement web being at an angle between 30 and 60 degrees relative to the first axis.
23. A joist according to claim 22, wherein the third portion of the reinforcement web is at an angle of 45 degrees relative to the first axis.
24. A joist according to any preceding claim, wherein, for at least one of the one or more reinforcement webs, the first portion of the reinforcement web comprises a first set of teeth projecting perpendicular to both the first axis and the second axis, the teeth being configured to be pressed into the first flange for fixing thereto, and the second portion of the reinforcement web comprises a second set of teeth projecting perpendicular to both the first axis and the second axis, the teeth being configured to be pressed into the second flange for fixing thereto.
25. A joist according to any preceding claim, wherein, for at least one of the one or more reinforcement webs, the first portion of the reinforcement web comprises one or more fixing apertures for receiving first fixing means in a direction perpendicular to both the first axis and the second axis, the first fixing means being configured to affix the first portion of the reinforcement web to the first flange, and the second portion of the reinforcement web comprises one or more fixing apertures for receiving second fixing means in a direction perpendicular to both the first axis and the second axis, the second fixing means being configured to affix the second portion of the reinforcement web to the second flange.
26. A joist according to any preceding claim, wherein the first flange and the second flange are formed of timber or laminated timber.
27. A joist according to any preceding claim, wherein the central web is formed of engineered wood.
28. A joist according to any preceding claim, wherein the central web is located, in use, in a vertical orientation.
29. A joist according to any preceding claim, wherein the, or each, reinforcement web is formed of metal.
30. A joist according to any of claims 1 to 28, wherein the, or each, reinforcement web is formed of a composite material.