GB2511155A

GB2511155A - Joist end cap

Info

Publication number: GB2511155A
Application number: GB1320152.0A
Authority: GB
Inventors: Scott Mcandrew
Original assignee: Illinois Tool Works Inc
Current assignee: Illinois Tool Works Inc
Priority date: 2013-02-25
Filing date: 2013-11-14
Publication date: 2014-08-27
Anticipated expiration: 2033-11-14
Also published as: GB201320152D0; GB2511109A; GB201303261D0; GB2511155B

Abstract

A joist end cap for limiting thermal conductivity between adjacent storeys of a building comprises a face 3 and two protrusions 5 extending therefrom and defining a space therebetween. The space is adapted to receive an end of an I-joist web, the face being configured to extend between the top and bottom chords of the I-joist, wherein the protrusions each comprise a cavity 13 therein. The cavity provides a thermal break in the end cap. The end cap may be friction fit with the I-joist. A plurality of fins may be provided on the protrusions. One or more supports 19 may extend across the cavity between first and second portions of a protrusion. Tabs 21, 27, 121, 127 may also be provided on the protrusions.

Description

JOIST END CAP

The present invention relates to an end cap for an I-joist. In particular, though not exclusively, the present invention relates to an end cap for an I-joist intended to mitigate air leakage at an end of an I-joist web and to minimize thermal bridging through joists.

Thermal loss in buildings is a problem for which many solutions have been proposed. Thermal loss occurs, for example, when timber I-joists are built into masonry walls or the like as there is a void between the masonry blocks situated at each side of the I-joist and the central web of the I-joist, which must be filled up with mortar. When the mortar is applied, it has a tendency to shrink or slump downwards leaving air gaps through which thermal loss may occur. In addition, the end cap itself, applied to the end of the I-joist to prevent air leakage at the end of the I-joist, may be formed ofa material which is thermally conductive thereby forming a thermal bridge between the I-joist and the masonry. Such a thermal bridge allows heat to escape from the building.

It is desirable to build joists into masonry walls to mitigate the problems associated with utilising metal joist hangers. It is further desirable to ensure that the connection between the joist and the masonry wall is air tight and has a low thermal conductivity to avoid thermal losses at or around the connection point An end cap for I-joists is disclosed in GB 2406343. The end cap is configured to limit air leakage where the joist is mortared into a wall. However, the material of the end cap itself provides a thermal bridge through which heat loss may occur as heat is conducted through the end cap. Particularly, the end cap described will provide a thermal bridge between the upper and lower extent of the I-joist allowing heat loss between adjacent levels in the building comprising the I-joist.

Utilising thermally conductive materials to provide an end cap for an 1-joist, the maximum possible conductive energy transfer is provided across the 1-joist between the adjacent flooring and/or roof structures, despite insulating material that maybe placed in the space between the chords of the I-joist. This energy loss is also known as "thermal bridging".

"Thermal bridging" is created when materials that are poor thermal insulators come into contact allowing heat to flow from a higher temperature environment to a lower temperature environment through the path of least thermal resistance leading to significantly increased heat losses.

It would therefore be desirable to provide a joist end cap that is capable of minimizing the "thermal bridging" affect and improve the general energy efficiency of structural buildings assemblies, such as any heated or cooled building enclosure or building envelope.

It is an object of the present invention to provide an improved end cap for I-joists.

It is a further object of the present invention to provide an end cap for 1-joists limiting the thermal bridging between the upper and lower extent of the I-joist and between the interior of a building structure and the exterior masonry.

According to a first aspect the present invention provides a joist end cap for limiting thermal conductivity between adjacent storeys of a building, the end cap comprising a face and two protrusions extending therefrom and defining a space therebetween, said space being adapted to receive an end of an 1-joist web, the face being configured to extend between the top and bottom chords of the I-joist, wherein the protrusions each comprise a cavity therein, wherein the cavity provides a thermal break in the end cap.

The cavity in each protrusion provides a thermal break in the material of the end cap. In this way, the thermal bridging between the interior of a structure comprising an I-joist having an end cap of the present invention at an end thereof and the exterior masonry into which the I-joist is mounted is reduced. The cavity in each protrusion reduces thermal conduction through the end cap.

In certain embodiments, the cavity in each protrusion permits air flow vertically through the end cap. The cavity in each protrusion mitigates the thermal conductivity of the end cap vertically of the device and also horizontally of the end cap and therefore between the inside of a structure to the external masonry into which the joist having the end cap fitted thereto is to be mounted.

In this way a thermal break in the end cap is provided, whereby the cavity provides a break in the thermally conductive material of the end cap. The cavity provides a thermal break between the top and the bottom chords of an I-joist onto which the end cap is located and also between the I-joist and the external masonry into which the I-joist is to be mounted.

In preferred embodiments, the first and second protrusions are each formed of a first and second portion, the first and second portions being parallel and spaced apart from one another and defining a cavity therebetween.

In embodiments of the invention, the first and second portions of the protrusions are planar portions. The planar portions are parallel and spaced apart from one another. It is much preferred that each of the first and second portions is a rectangular planar portion.

More specifically, the first and second portions of each protrusion are vertically planar portions having a rectangular footprint.

The first and second portions of each protrusion are preferably configured to extend between the top and bottom chords of an I-joist.

In exemplary embodiments, the first and second protrusions are each closed at their opposing ends. In this way, horizontal air flow through the end cap is prevented. It is much preferred that when the end cap is in position about the end of an I-joist air leakage through and about the end cap is prevented.

In a preferred embodiment, the cavity defined by the first and second portions of a protrusion is closed at opposing ends. In an exemplary embodiment, at a first end, the cavity is dosed by the face of the end cap and at the opposing end there is provided an end face of the protrusion. In an alternative embodiment, at a first end, the cavity is dosed by a forward end face and at the opposing end the cavity is closed by a rearward end face. The end face(s) of the protrusion extends between the edges of the first and second portions of the protrusion. It is much by preference that the end face(s) extends the entire height of the protrusion forming a complete end surface. In this way, the protrusions each define a cavity, open at top and bottom faces so as to allow air flow vertically therethrough, and closed at the end faces and front and rear faces so as to prevent horizontal air flow.

In alternative exemplary embodiments, the first and second protrusions are each closed at their top and bottom ends. In this way, vertical air flow through the end cap is prevented.

In exemplary embodiments, the cavity defined by the first and second portions of a protrusion is also closed at the end faces and front and rear faces of the protrusion.

In certain embodiments, the end face of each protrusion of the end cap may have a width dimension configured to extend transversely from the central web of the I-joist to the edge of the upper and thwer chords of the I-joist. More specifically, when the end cap is in position at the end of an I-joist, the end face of each protrusion extends from the central web of the I-joist to the edge of each chord of the joist between a side surface and an upper and/or lower surface thereof

S

It is much preferred that the lace of the end cap is a face of an end wall of the end cap. The end wall has a predetermined thickness in a direction parallel to the direction of extension of the two protrusions from the face. In an exemplary embodiment, the end wall conveniently forms an end wall of each of the two protrusions of the end cap.

The end wall of the end cap is preferably vertically planar and having a rectangular footprint.

In much preferred embodiments, the plane including the face of the end wall of the end cap and each of the planes including the first and the second portions of each protrusion are perpendicular to one another.

In exemplary embodiments, the joist end cap further comprises at least one elongate fin extending outwardly from a front face of the first and second protrusions.

Preferably, the joist end cap comprises a plurality of elongate fins.

Each protrusion comprises air passages vertically therethrough to provide a thermal break between the uppermost extent and the lowermost extent of the end cap. That is to say, by providing a vertically open cavity in each protrusion, thermal loss resulting from heat conduction through the material of the end cap is reduced.

Horizontal air flow from the I-joist web to the adjacent masonry is prevented by the end face of each protrusion. The air passages in each protrusion also provide a horizontal thermal break between the end wall of each protrusion and the face of the end cap. In this way, heat transfer by conduction through the material of the end cap between the internal space in which the I-joist is located and the surrounding masonry is reduced.

Preferably, the two protrusions are resiliently biased towards each other so as to provide a friction fit with the I-joist web onto which it is to be fitted.

The end cap may further comprise one or more supports extending between the first and second portions of a protrusion. More specifically, the one or more supports extend across the cavity defined between the first and the second portion of a protrusion. Even more specifically, the one or more supports extend perpendicularly of the first and second portions of a protrusion to form a bridging support therebetween. The one or more supports of a protrusion are configured to maintain the cavity in the protrusion and to maintain the first and second portions in spaced apart relation to one another. In this way, the thermal break provided by the cavity in the protrusion is maintained when the end cap is in position about the end of an I-joist.

It is much by preference that the, or each, support extends the entire height of the protrusion.

In preferred embodiments, each protrusion comprises two supports extending between the first and the second portions thereof More specifically, the two supports are spaced apart from one another within the cavity.

The one or more support(s) within the cavity of a protrusion are preferably parallel to and spaced apart from the face of the end cap and the end face of the protrusion.

In certain embodiments a, or each, protrusion is provided with at least one tab extending outwardiy of the protrusion and adapted to engage with a chord of the I-joist More specifically, the at least one tab extends substantially vertically outwardly of the protrusion and is adapted to engage with a lower or an upper surface of a chord of an I-joist.

Even more specifically, the at least one tab projects outwardly of the upper or lower open face of the protrusion. The atieast one tab may extend at an acute angk to the upper or lower face of the protrusion such that the free end of the tab faces rearwardly of the end cap towards the face thereof. In this way, as the end cap is pushed into place on the end of the I-joist, the tab or tabs serve to grip the chord(s) of the I-joist and to fix the end cap in position.

In embodiments of the invention) the end face of each protrusion comprises a tab.

Preferably the tab extends upwardly and rearwardly from the upper edge of the end face. In certain embodiments) the end face of each protrusion additionally or alternatively comprises a further tab. Preferably the further tab extends downwardly and rearwardly of the end face from a lower edge of the end face of the protrusion.

The, or each, support of a protrusion may comprise a tab. Preferably the tab extends upwardly and rearwardly from the upper edge of the support. In certain embodiments, the, or each) support of the protrusion additionally or alternatively comprises a further tab. Preferably the further tab extends downwardly and rearwardly of the support from a lower edge of the support of the protrusion.

The, or each) tab is preferably formed of a planar protrusion. The, or each, tab may be tapered away from the edge of the protrusion from which it extends. Specifically) the) or each, tab is narrower at its free end than at its root The, or each, tab may be resiliently biased such that the tab deflects whilst the end cap is located onto the end of the I-joist and grips a chord of the I-joist once the end cap is in its operating position. In this way, the end cap prevents air leakage between the I-joist and the masonry into which the I-joist is built.

It is preferred that the end face of each protrusion is dimensioned such that the cross section of the end of the I-joist including the end cap is substantially rectangular. That is to say, the protrusions of the end cap, when in position, fill the gap between the chords at the end of the I-joist The side surfaces of the upper and lower chords of the I-joist and the front faces of the protrusions are thus coplanar when the end cap is in position.

B

The joist end cap may be formed of a steel material. More specifically, the joist end cap may be formed of stainless steel or galvanised steel.

Alternatively, the joist end cap may be formed of pkstic or other suitable polymer material.

In exemplary embodiments, the end cap further comprises one or more shelves extending outwardly from a surface thereof The one or more shelves, are adapted to prevent mortar sag in use.

According to a second aspect of the invention, there is provided a blank suitable for forming a joist end cap in accordance with the invention.

In preferred embodiments, the blank is in the form of a ready-to-assemble piece.

Preferably, the ready-to-assemble piece comprises a pair of spaced apart grooves along a edge of the inner surface of the face to facilitate the assembly of the blank into a joist end cap in accordance with the invention.

Throughout the description and claims of this specification, the words "comprise" and "contain" and variations of the words, for example "comprising" and "comprises", means "including but not limited to", and is not intended to (and does not) exdude other components, integers or steps.

Throughout the description and claims of this specification, the singukr encompasses the plura' unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemphting plurality as well as singularity, unless the context requires otherwise.

While the terms "upwardly", "downwardly", "rearwardly", "vertically", "horizontally", "upper", "lower", "top" and "bottom" are used within the specification, they should be considered as no more than relative, as the end cap of the present invention may be used in any orientation to suit the location of one or more joists.

In order that the present invention be readily understood and easily carried into effect, reference will now be made, by way of example only, to the accompanying drawings in which: Figure 1 shows an end cap according to a first embodiment of the present invention; Figure 2 shows the end of an I-joist in plan view; Figure 3 shows in side plan view, the end cap of Figure 1 in place on the end of the I-joist of Figure 2; Figure 4 shows in end plan view, the end cap of Figure 1 in place on the end of the I-joist of Figure 2; Figure 5 shows, in top plan view, an end cap according to an embodiment of the invention on an I-joist having its upper chord removed to assist clarity, itself mounted onto a masonry wall; Figures 6a and 6b show an end cap according to a second embodiment of the present invention; Figures 7a and 7b show an end cap according to a third embodiment of the present invention; Figures Sa to Sc shown an end cap according to a fourth embodiment of the present invention; Figures 9 and 10 show an end cap according to a fifth embodiment of the present invention; and Figures 11 and 12 show an embodiment of a blank adapted to form the end cap in accordance with the fifth embodiment of the invention.

Throughout the drawings, like reference numera's denote like features.

Referring to Figure 1, there is depicted an end cap 1 for an I-joist [not shown). The end cap 1 having a face 3 and a first protrusion S extending perpendicukrly from the face 3. The first protrusion 5 comprises a planar front face 7 parafl& to and spaced apart from a pknar rear face 9. An end face 11 of the first protrusion S extends between the vertical edges of the front face 7 and the rear face 9, and is parall& and spaced apart from the face 3 of the end cap 1. Cavity 13 is defined in the first protrusion 5 by the face 3 of the end cap 1 and the front face 7, the rear face 9 and the end face 11. The cavity 13 is open at its top and bottom faces (15, 17) to allow air flow vertically therethrough.

The first protrusion 5 further comprises vertical supports 19 extending between the front face 7 and the rear face 9. The supports 19 extend the full height of the cavity 13 between the open top and bottom faces (15, 17) of the protrusion 5.

In the depicted embodiment, the supports 19 and the end face 11 each comprise a tab 21 depending from an upper edge thereof. Each tab 21, extends upwardly and rearwardly of the protrusion towards the face 3. Tab 21 is tapered towards its free edge 23 such that its uppermost edge 23 is of smaller length dimension than its root 25. Each tab 21 is resiliently biased such that it may deflect about its root 25 as the end capt is pushed into position on the end of an I-joist. Deflection of the tab 21 is caused as the tab contacts the lower surface of the upper chord of the I-joist as the end cap 1 is pushed into place on the end of the I-joist Once in position, each tab 21 is caused to bear onto the lower surface of the upper chord of the I-joist by way of its resilient bias. In this way, the tabs 21 grip the surface of the chord of the I-joist so as to maintain the end cap 1 in position.

The first protrusion 5 further comprises tabs 27 depending from the lower edges of supports 19 and the end face 11. Each tab 27, extends downwardly and rearwardly of the protrusion towards the face 3. Each tab 27 is tapered towards its free edge 29 such that its lowermost edge 29 is of smaller length dimension than its root 31.

Each tab 27 is resiliently biased such that it may deflect about its root 31 as the end cap 1 is pushed into position on the end of an I-joist. Deflection of the tab 27 is caused as the tab contacts the upper surface of the lower chord of the I-joist as the end cap 1 is pushed into place on the end of the I-joist Once in position, each tab 27 is caused to bear onto the upper surface of the lower chord of the I-joist by way of its resilient bias. In this way, the tabs 27 grip the surface of the chord of the I-joist so as to maintain the end cap 1 in position.

While the tabs 21,27 have been described as tapering towards their free end 23,29, it should be understood that it is not essential for the tabs 21,27 to taper. For example, the lateral edges of the tab 21,27 may be perpendicular to the free end 23,29 of the tab 21,27.

The end cap 1 furhter comprises face 3 and a second protrusion 33 extending perpendicularly from the face 3. The second protrusion 33 is identical to the first protrusion 5 in its features which are denoted by like numerals increased by 100, for example, the rear face of the protrusion which was indicated by the reference numeral 9 for the first protrusion 5 will be indicated by the reference numeral 109 for the second protrusion 33.. The second protrusion 33 extends from the opposing vertical edge of face 3 to the first protrusion S and is parallel thereto. The second protrusion 33 comprises a planar front face 107 parallel to and spaced apart from a planar rear face 109. An end face 111 of the second protrusion 33 extends between the vertical edges of front face 107 and rear face 109 and is parallel and spaced apart from the face 3 of the end cap 1. Cavity 113 is defined in the second protrusion 33 by the face 3 of the end cap 1 and front face 107, the rear face 109 and the end face 111. The cavity 113 is open at its top and bottom faces 115,117 to allow air flow vertically therethrough.

The second protrusion 33 further comprises vertical supports 119 extending between the front face 107 and the rear face 90. The supports 119 extend the full height of the cavity 113 between the open top and bottom faces 115,117 of the protrusion 33.

In the depicted embodiment) the supports 119 and the end face 111 each comprise a tab 121 depending from an upper edge thereof Each tab 121, extends upwardly and rearwardly of the protrusion towards the face 3. Tab 121 is tapered towards its free edge 123 such that its uppermost edge 123 is of smaller length dimension than its root 125. Each tab 121 is resiliently biased such that it may deflect about its root as the end cap 1 is pushed into position on the end of an I-joist. Deflection of the tab 121 is caused as the tab contacts the lower surface of the upper chord of the I-joist as the end cap 1 is pushed into place on the end of the I-joist Once in position, each tab 121 is caused to bear onto the lower surface of the upper chord of the I-joist by way of its resilient bias. In this way, the tabs 121 grip the surface of the chord of the I-joist so as to maintain the end cap 1 in position.

The second protrusion 33 further comprises tabs 127 depending from the lower edges of supports 119 and the end face 111. Each tab 127, extends downwardly and rearwardly of the protrusion towards the face 3. Each tab 127 is tapered towards its free edge 129 such that its lowermost edge 129 is of smaller length dimension than its root 131. Each tab 127 is resiliently biased such that it may deflect about its root 131 as the end cap us pushed into position on the end of an I-joist. Deflection of the tab 127 is caused as the tab contacts the upper surface of the lower chord of the I-joist as the end cap 1 is pushed into place on the end of the I-joist. Once in position, each tab 127 is caused to bear onto the upper surface of the lower chord of the I-joist by way of its resilient bias. In this way, the tabs 127 grip the surface of the chord of the I-joist so as to maintain the end cap 1 in position.

Protrusions 5, 33 are resiliently biased towards one another such that they deflect outwardly away from one another as the end cap 1 is pushed onto the end of an I-joist. The inner surface 37 of face 3 contacts the end surface of the web of the I-joist (not shown] when the end cap 1 is fully located onto the end of the I-joist. The bias of the protrusions 5, 33 towards one another causes the rear surfaces 9, 109 of the protrusions 5, 33 of the end cap 1 to grip the faces of the web of the I-joist so as to provide an air tight seal therebetween.

Figure 2 depicts the end of an I-joist 40 having an upper flange/chord 42, a lower flange/chord 44 and a web 46 extending therebetween. The end cap of Figure 1 is dimensioned to provide a frictional fit onto the end of the I-joist 40 and to prevent air leakage from the web 46 area of the I-joist to the masonry into which the I-joist 40 is to be mounted. Cavities 13, 113 in the end cap 1 reduce the thermal bridge provided by the end cap 1 between the upper and lower chords (42, 44) of the I-joist 40 whilst allowing vertical airflow within the end cap 1.

Figures 3 and 4 depict an end cap 1 in position at the end of I-joist 40. Tabs 21, 27, 121, 127 engage with the lower surface of upper chord 42 and the upper surface of the lower chord 44 to hold the end cap 1 in position at the end of the I-joist 40. The end wall 3 of the end cap 1 abuts the end of the central web 46 of the I-joist 40.

As seen in Figure 4, the front faces 7,107 of end cap 1 are co-planar with the side surfaces of chords 42, 44 when the end cap is located at the end of the I-joist 40.

The end of the I-joist 40 with end cap 1 in place has a substantially rectangular footprint. The rear faces 9, 109 (see Figure 1) of the end cap 1 grip either side surface of the central web 46 of the I-joist. Horizontal air flow from the region of the central web 46 to the adjacent masonry (not shown) is prevented whilst air passages in the form of cavities 13, 113 provide a thermal break vertically and horizontally of the end cap 1. In this way, thermal conductivity through the end cap from the upper chord 42 to the lower chord 44 of I-joist 40 is mitigated. Further, thermal conductivity through the end cap from the web region 46 of the I-joist 40 to the surrounding masonry into which the end of the I-joist is mounted is reduced.

As best seen in Figure 5, once the end cap 1 is in position on the end of I-joist 40, the space about the web 46 may be filled with mortar 48 to further reduce air leakage at the end of the I-joist 40.

Figure 5 shows a joist 40, having its upper removed to assist with clarity of understanding, may be mounted to masonry 50 and a mortar joint 52 provided on either side of the joist and end cap assembly. Together, the mortar 48, 52 and the end cap 1 and joist 40 provide a mounting which is resistant to air leakage whilst the cavities 13, 113 in the end cap 1 reduce the thermal bridging provided by the end cap between the upper and lower surfaces of the joist 40 and between the mortar regions 48, 52 and the masonry 50. In the depicted embodiment) tabs 21 and 121 have been removed for clarity. It will be understood that, in use, tabs 21 and 121 would bear onto the lower surface of the upper chord [not shown] of the joist 40 to retain the end cap 1 in position at the end of the joist 40.

Referring to Figures 6a and 6b, an end cap 201 according to a second embodiment of the invention is shown.

The same reference numerals have been used to identify the same features to those as in the first embodiment. The reference numerals for similar features have been increase by a factor of 200 for convenience. For example, the face which was indicated by the reference numeral 3 in the first embodiment is now indicated by the reference numeral 203.

As in the first embodiment) the end cap 201 comprises a face 203, a first protrusion 205 extending perpendicular from the face 203 and a second protrusion 233 extending perpendicular from the face 203.

The first protrusion 205 comprises a planar front face 207 parallel to and spaced apart from a planar rear face 209. Unlike in the first embodiment) the front face 207 of the first protrusion 205 does not extend to and connect to the face 203.

Similarly, the second protrusion 233, which is identical to the first protrusion 205, comprises a planar front face 207 parallel to and spaced apart from a planar rear face 209, and the front face 207 of the second protrusion 233 does not extend to and connectto the face 203.

A top face 215, 315 of the first and second protrusions 205,233 extends between the uppermost horizontal edges of front face 207,307 and rear face 209,309 of the respective protrusions and is parallel and spaced apart from the face 203 of the end cap 201.

A bottom face 217, 317 of the first and second protrusions 205,233 extends between the lowermost horizonta' edges of front face 207,307 and rear face 209,309 of the respective protrusions 205,233 and is parallel and spaced apart from the face 203 of the end cap 201.

A cavity 214,314 is defined in the first and second protrusion 205,233 by the top face 215,315, the front face 207,307, the rear face 209,309 and the bottom face 217,317. The cavity 214,314 is open at the end faces 211, 311 of the first and second protrusions 205,233 to allow air flow horizontally therethrough.

The first and second protrusions 205,233 further comprise one or more horizontal supports 220,320 extending between the front face 207,307 and the rear face 209,309 thereof. In the embodiment shown, the first and second protrusions each comprise a single horizontal support 220,320 extending between the front face 207,307 and the rear face 209,309 thereof The supports 220,320 extend the full length of the cavity 214,314 between the open end faces 211,311 of the protrusions 205,233.

As in the first embodiment, the end cap 201 comprises tabs 21,121, 27,127 extending from the top and bottom of the protrusions 205,233 (see Figure 6a).

The end cap 201 further comprises one or more elongate fins 238 extending outwardly from the front face 207,307 of each of the first and second protrusions 205,233. In the embodiment shown, each front face 207,307 comprises three e'ongate fins 238 extending outwardly therefrom.

The end cap 201 further comprises one or more shelves 239 extending from the rear face 209,309 of each of the first and second protrusions 205,233. In the embodiment shown, the end cap 201 comprises two sheh'es 239 on each of the rear faces 209,309 of the first and second protrusions 205,233.

The sh&ves 239, extend along the rear face 209,309 between a respective end face 211,311 and the face 203 as shown in Figure Sa. The shelves 539 act to prevent mortar sag during use. The sh&ves 539 extend outwardly from the rear face 509,309 up to a distance corresponding to the position of the front face 207,307 of the respective protrusion 205,233.

Referring to Figures 7a and 7b, an end cap 401 according to a third embodiment of the invention is shown.

The same reference numerals have been used to identify the same features to those as in the second embodiment The reference numerals for similar features have been increase by 200 for convenience. For example, the face which was indicated by the reference numeral 203 in the first embodiment is now indicated by the reference numeral 403.

The end cap 401 in accordance with the third embodiment is very similar to that of the second embodiment The only difference is that the cavity 413,513 is defined in the first and second protrusion 405,433 by the end faces 411,511, the front face 407,507 and the rear face 409,SO9. Unlike the second embodiment, the cavity 413,S13 is open at the top face 415,515 and bottom face 417,517 of the protrusions 405,433 to allow air flow vertically therethrough.

The first and second protrusions 205,233 further comprise one or more vertical supports 419,519 extending between the front face 407,507 and the rear face 409,509 thereof. In the embodiment shown, the first and second protrusions 405,433 each comprise a single vertical support 419,519 extending between the front face 407,507 and the rear face 409,509. The supports 419,519 extend the full length of the cavity 413,513 between the open top and bottom faces 415,515, 417,517 of the protrusions 405,433.

Referring to Figures Ba to Sc, an end cap 601 according to a fourth embodiment of the invention is shown.

The same reference numerals have been used to identify the same features to those as in the third embodiment The reference numerals for similar features have been increase by 200 for convenience. For example, the face which was indicated by the reference numeral 403 in the third embodiment is now indicated by the reference numeral 603.

The end cap 601 in accordance with the fourth embodiment is very similar to that of the third embodiment, the only difference is that rather than having a single vertical support extending between the front face 607,707 and the rear face 609,709, the end cap 601 comprises two vertical supports 619,719 extending between the front faces 607,707 and rear faces 609,709 of the first and second protrusions 605,633.

Referring to Figures 9 and 10, an end cap 801 according to a fifth embodiment of the invention is shown.

The fifth embodiment is similar to the third embodiment and the same reference numerals have been used to identify the same features to those as in the third embodiment The reference numerals for similar features have been increase by a factor of 400 for convenience. For example, the face which was indicated by the reference numeral 603 in the third embodiment is now indicated by the reference numeral 803.

As in the third embodiment, the end cap 801 comprises a face 803, a first protrusion 805 extending perpendicular from the face 803 and a second protrusion 833 extending perpendicular from the face 803.

The first protrusion 805 comprises a planar front face 807 parallel to and spaced apart from a planar rear face 809. As in the third embodiment, the front face 807 of the first protrusion 805 does not extend to and connect to the face 803.

The front face 807 and rear face 807 of the first protrusion do not overlap with each othen The rear face 809 of the first protrusion 805 extends between the face 803 and the forward end face 811a of the end cap 801 and the front face 807 of the first protrusion 805 extends between the forward end face 811a and the rearward end face Sub of the first protrusion 805.

The second protrusion 833 is identical to the first protrusion.

A cavity 813,913 is defined in the first and second protrusion 805,833 by the end faces 811,911 and the front face 807,907.

The cavity 813,913 is open at its top face 815,915 and bottom face 817,917 as well as directly opposite the front face 807,907. In use, the web 46 of the I-joist 40 will provide a wall directly opposite the front face 807,907 and close that side of the protrusion 805,833 such that air will only flow vertically through the cavity 813,913.

The end caps 1,201,401,601,801 in accordance with the invention when formed of plastic or other suitable polymer material may be cast moulded ready for use in the form shown in the above described embodiments.

Alternatively, the end caps may be moulded in the form of a ready-to-assemble piece which is assembled on-site prior to attachment to an 1-joist.

Referring to figures 11 and 12, an embodiment of a blank 1000 in the form of a ready-to-assemble piece suitable for forming an end cap in accordance with the fifth embodiment of the invention is shown.

The ready-to-assemlMe piece comprises a pair of spaced apart grooves 1100 along a edge of the inner surface 837 of the face 803 to facilitate the assembly of the blank into a joist end cap 801.

Claims

Claims 1. A joist end cap for limiting thermal conductivity between adjacent: storeys of a building, the end cap comprising a face and two protrusions extending therefrom and defining a space therebetween, said space being adapted to receive an end of an I-joist web, the face being configured to extend between the top and bottom chords of the I-joist, wherein the protrusions each comprise a cavity therein) wherein the cavity provides a thermal break in the end cap.
2. A joist end cap according to daim 1, wherein the cavity in each protrusion permits air flow vertically through the end cap.
3. A joist end cap according to claim 1 or claim 2, wherein the first and second protrusions are each formed of a first and second portion.
4. A joist end cap according to claim 3, wherein the first and second portions are parallel and spaced apart from one another and define a cavity therebetween.
5. A joist end cap according to claim 3 or claim 4, wherein the first and second portions of the protrusions are planar portions.
6. A joist end cap according to any one of claims 3 to 5, wherein the first and second portions of each protrusion are configured to extend between the top and bottom chords of an I-joist.
7. A joist end cap according to any one of claims 3 to 6, wherein the first and second protrusions are each closed at their opposing ends.
8. A joist end cap according to claim 7, when dependent directly or indirecdy on claim 4, wherein the cavity defined by the first and second portions of a protrnsion is closed at a first end by the face of the end cap and at the opposing end by an end face of the protrusion.
9. A joist end cap according w claim 7, when dependent directly or indirectly on claim 4, wherein the cavity defined by the first and second portions of a protrusion is also closed at the end faces and front and rear faces of the protrusion.
10. A joist end cap according to any one of the preceding claims further comprising at least one elongate fin extending outwardly from a front face of the first and second protrusions.
11. A joist end cap according to claim 10 comprising a plurality of elongate fins.
12. A joist end cap according to any one of the preceding claims, wherein the two protrusions are resiliently biased towards each other so as to provide a friction fit with the I-joist web onto which it is to be fitted.
13. A joist end cap according to any one of claims 3 to 9, further comprising one or more supports extending between the first and second portions of a protrusion.
14. A joist end cap according to claim 13, wherein the one or more supports extend across the cavity defined between the first and the second portion of a protrusion.
15. A joist end cap according to claim 13 or claim 14, wherein the one or more support(s) within the cavity of a protrusion are parallel to and spaced apart from the face of the end cap.
16. A joist end cap according to any one of the preceding claims, wherein a, or each, protrusion is provided with at least one tab extending outwardly of the protrusion and adapted to engage with a chord of the I-joist.
17. A joist end cap according to claim 17 when dependent on any one of daims 13 to 15, wherein the, or each, support of a protrusion comprises a tab.
18. A joist end cap according to claim 17, wherein the tab extends upwardly and rearwardly from the upper edge of the support
19. A joist end cap according to claim 17 or claim 18) wherein the, or each) support of the protrusion comprises a further tab extending downwardly and rearwardly of the support from a lower edge of the support of the protrusion.
20. A joist end cap substantially as hereindescribed with reference to the accompanying figures.