GB2062058A

GB2062058A - Joist hanger

Info

Publication number: GB2062058A
Application number: GB8032093A
Authority: GB
Original assignee: PRESS BAT HOLDINGS Ltd
Current assignee: PRESS BAT HOLDINGS Ltd
Priority date: 1979-10-10
Filing date: 1980-10-06
Publication date: 1981-05-20

Abstract

A joist hanger is made in two parts which are secured together by mechanical interengagement without welding. A stirrup-shaped joist supporting part (11) is secured to a broad generally angle section bearing part (12) by means of interengaging projections (18) and apertures (19). The projections (18) are on the rear edges (17) of the joist supporting part (11) and may either comprise plane projections which are bent over after insertion through the apertures or single or double hook formations having undercuts (29, 30), which hook over the borders of the slots. The slots then have an enlarged part (27) to receive the tongue (18), the undercuts (29, 30) then being slid laterally to engage with upper and lower borders of a smaller sized part of the slots. The limbs (15) of the joist supporting member are resilient to allow this movement. <IMAGE>

Description

SPECIFICATION Joist hanger This invention relates to joist hangers for use in building.

Where the context allows, the expression "joist" includes all forms of structural timber elements such as roof trusses for example, as well as the timbers conventionally referred to as joists and intended to support floors and ceilings.

Conventional joist hangers usually take the form of a lazy Z-shaped metal strip having a width equivalent to the width of a joist (approximately 50 millimetres for most joists), the lower horizontal flange of the strip being connected to the upright by means of gusset plates or strips and the whole assembly being prefabricated by welding, frequently spot welding. The material of which joist hangers are conventionally made is pregalvanised sheet steel. In order to spot weld pregalvanised sheet, it is necessary that the galvanic coating of zinc is relatively thin, since a thick coating prevents the making of a satisfactory weld. Additionally, the use of welded joints means that very rigorous quality control standards have to be applied to ensure the safety of the resulting joist hanger.

These problems could be avoided by the use of ungalvanised sheet steel which was made into a joist hanger and subsequently galvanised by hot dipping but this alternative is not satisfactory because of the excessive stresses and distortions of the joist hanger which tend to result from the hot dipping process.

It is an object of the present invention to provide a joist hanger which overcomes or reduces some or all of these disadvantages.

According to the invention there is provided a joist hanger comprising a sheet metal bearing part and a sheet metal joist supporting part, these parts being secured together by mechanical interengagement without the use of welding.

The mechanical inter-engagement may be provided by one or more projections interengaging with one or more apertures. Where more than one projection and aperture are provided, it is preferred that one part has all the projections and the other part has all the apertures, The projections may be formed from rearwardly directed edges of the joist supporting part. In this case, the apertures will be provided in the bearing part.

At least some of the apertures and projections may be elongate and upright in use.

The projections may be undercut at the upper and/or lower edges to form a single or double hook formation. In this case, the or each undercut may be of a sufficient size to receive as a firm frictional fit a portion of the border of the associated aperture.

Thus, the projections may for example form downwardly directed hooks engageable gravitationally with the lower border of an associated aperture.

Where the or each projections is undercut at both upper and lower edges, the associated aperture may have an enlarged part through which the projection can be inserted and a smaller sized part affording upper and lower border portions with which the upper and lower hook formations engage.

In this case, the projection will be slid laterally into position in the aperture. The projection may be resiliently mounted by virtue of the resilience of one of both of the sheet metal parts forming the joist hanger. For example, where the projections are provided on a rearwardly directed edge of the joist supporting part, that part may comprise a generally U-shaped sheet metal member with the projections provided at or near the outer ends of the limbs, whereby the limbs may be sprung together against the resilience of the material to engage the projections in the enlarged parts of the respective apertures, the limbs then being permitted to spring apart to engage the hook members with the upper and lower borders of the smaller sized parts of the apertures.

The bearing part may have a width substantially greater than that of the joist supporting part. The width is considered horizontally in a direction perpendicular to the axis of the joist to be supported.

The bearing part may be formed of sheet metal folded to a generally L-shape so as to have two flanges, one flange forming a bearing flange and the other being an attachment flange having one or more apertures or projections to which the joist supporting part is secured.

Where the attachment flange is provided with one or more apertures to receive projections of the joist supporting part, the attachment flange may have a cranked or inclined part so that the angle between the two flanges of the bearing part lies vertically above the rearmost edge of the joist supporting part in use.

The bearing flange of the bearing part may be extended to provide a return flange generally at right angles to the bearing flange and generally parallel to the attachment flange. The return flange may itself be provided with apertures or projections so as to afford a second attachment flange to which a second joist supporting part may be secured.

Preferably, all the parts of the joist hanger are made up of pregalvanised sheet steel.

The invention will now be described in more detail by way of example only with reference to the accompanying drawings in which: FIGURE 1 is a side elevational view of a first embodiment of joist hanger; FIGURE 2 is a rear elevational view of the joist hanger of Figure 1; FIGURE 3 is a top plan view of the joist hanger of Figure 1; FIGURE 4 is a front elevational view of a second embodiment of joist hanger; FIGURE 5 is an exploded side elevational view of the joist hanger of Figure 4.

Referring firstly to the embodiment shown in Figures 1 to 3 of the drawings, a joist hanger generally indicated at 10 is formed from two pregalvanised sheet steel parts, namely, a joist supporting part 11 and a bearing part 12. The two parts are mechanically interengaged as generally indicated at 13.

The joist supporting part 11 is in the form of a U-shaped metal stirrup having a base 14 and a pair of upright side walls 1 5. The spacing between the side walls is sufficient to receive a joist. This is done by lowering the joist into the stirrup formed by the base 14 and side walls 1 5. A cut-out 16 is formed in the rear edge 1 7 of each of the side walls 1 5. In use, the rear edge 1 7 will rest against the forward face of a masonry wall to which a joist is to be secured. Thus, the cut-out is spaced forwardly away from the wall.

A portion of the metal of the side walls 1 5 forms a tongue 18 which extends to a position level with the rear edge 1 7 within the cut-out.

The bearing member is provided with a pair of slots 1 9 extending upright in use, which receive the tongues 1 8 of the respective side walls 1 5.

The tongue will then occupy the dotted line position shown in Figure 1. Subsequently, the tongue 1 8 can be bent over against the rear face of the bearing part 12 as shown as 1 8a in the drawing. Thus, the joist supporting part is permanently mechanically interengaged with the bearing part.

The bearing member 12 has a width substantially greater than the width of the base 14 which supports the joist. The bearing part is generally L-shape as seen in side elevation and comprises a bearing flange 20 having two large circular holes 21 to form a mortar key and three smaller nail holes 22 which may be required in certain circumstances where the joist hanger is being secured to a wooden beam or wall plate.

The bearing part 12 additionally includes an attachment flange 23 on which the slots 1 9 are provided. The attachment flange 23 includes an inclined portion 24 which enables the fold at the forward edge of the bearing flange 20 to lie directly vertically above the rear edge 1 7 of the joist supporting part 11. This means that, in use, the joist supporting part lies against the forward face of a masonry wall and the entire bearing flange up to the fold which links it with the inclined portion 24 lies on top of the wall.

Nail holes 25 are provided on the joist supporting part 11 to enable the joist to be secured in place by nailing.

A second embodiment of the invention is shown in Figures 4 and 5 af the drawings. Where appropriate, the same reference numerals have been used for similar parts.

It will be seen that the joist supporting part 11 is generally triangular in side elevation, which enables the joist to be readily positioned in the stirrup shaped joist supporting part. Additionally, the upper portions 26 of the side walls 15 are relatively flexible so that they can be resiliently sprung together, This enables a modified form of tongue and slot engagement to be used. The slots in the attachment flange 23 of the bearing part 12 are generally indicated at 1 9 but will be seen to comprise an enlarged part 27 and a smaller sized part 28 communicating with each other. The enlarged part 27 of each of the slots 19 is disposed closest to the other slot.

The projecting tongues of the side walls 1 5 are again generally indicated at 1 8 but in this case each has an undercut 29, 30 at its upper and lower edges. The dimension a between the undercuts 29 and 30 is, within necessary tolerances, the same as the vertical dimension of the smaller sized part 28 of the slots. The external sizes of the tongue 1 8 is, within tolerances, the same as the vertical height of the enlarged part 27 of the slot or aperture 19.

The arrangement is such that the limbs 1 5 of the joist supporting part 12 are sprung together and the tongues 1 8 are pushed through the enlarged parts 27 of the slots. The limbs 1 5 are then allowed to separate resiliently, thereby engaging the undercuts 29 and 30 with the upper and lower borders of the smaller sized part 28 of the slots.

The mechanical inter-engagement is such that normal use of the joist hanger does not tend to disconnect the joist supporting part 11 from the bearing part 12 of the hanger. It will be appreciated that, once the joist is in position, the separation of the side walls 15 cannot be reduced sufficiently to remove the tongues 1 8 from the slots 19.

Instead of the provision of an inclined portion 24 as shown in Figure 1 , the hanger of Figures 4 and 5 has a cranked portion 31 so that the attachment flange 23 includes a lower vertical part 32 and an upper vertical part 33, the lower part 32 including the slots 1 9 and the upper vertical part 33 abutting against the forward face of a wall to which the joist hanger is being secured. In use, the upper vertical part 33 is aligned with the rear edge 1 7 of the joist supporting part.

The width of the bearing part 12 can be selected in accordance with the nature of the masonry of the wall. For example, where relatively hard materials such as brick are being used, the hanger need only be wide enough to enable the slots 19 to be provided to receive a joist support part, that is only a little wider than the joist supporting part. However, where very soft block work, for example insulating blocks, form the wall to which the joist is to be secured, the area of the bearing flange 20 can be made larger by increasing the width of the bearing part 12, to spread the load of the joist over a larger bearing area of the wall.

Similarly, the joist supporting part may be made to a suitable size for the depth and width of the joist being used. It is possible to provide a set of slots on the bearing part to receive various different widths of joist and/or the depth of the stirrup forming the joist supporting part can be selected to accommodate different depths of joist.

It will therefore be seen that a minimum stock of joist supporting parts and bearing parts needs to be kept to enable the whole range of building applications to be catered for. This means that a stockist can provide for all likely requirements with a reduced capital outlay compared with the case where whole individual hangers need to be provided for each appiication. Additionally, the component parts themselves may require less storage space than the equivalent number of conventional joist hangers.

It will be seen that the absence of any welding to mechanically inter-engage the joist supporting part and bearing part means that relatively thick galvanic coatings can be used to produce a greater degree of corrosion protection than is available with conventional hangers. Additionally, the absence of welds reduces the need for inspection and quality control which, in the past, has largely been concerned with the security of the welded connections.

Hangers can be pre-assembled at the suppliers for use in individual building operations from a stock of the necessary parts. Alternatively, the parts can be assembled on site to suit the joists, type of masonry and so on. This gives increased flexibility to the builders. Where joist supports are assembled from component joist supporting parts and bearing parts before being sent to the site, it may be desirabls to deform the tongues 1 8 to lock them in position in the slots 1 9 as shown in Figure 1 of the drawings for example. However this does not need to be done where the components are assembled on site.

Various modifications can be made within the scope of the invention. In particular, the mechanical inter-engagement may be provided by downwardly facing hook formations frictionally engaged with the lower border of the slots 1 9.

These hook formations can be provided by undercutting the tongue 1 8 at the position 30 but omitting the undercut 29 and, in this case, only plain upright slots of the type shown in Figures 1 to 3 need be provided in the bearing part. It will be appreciated that the joist hanger is normally heavily loaded in use by the supported joist, so that the connection is relatively stable.

The bearing part itself could be modified by the provision of an additional return flange extending from the edge of the bearing flange remote from the attachment flange. This return flange (not shown) could merely provide a form of engagement behind the masonry of the type which may be desirable in eaves walls.

Alternatively, it could itself form a further attachment flange for the attachment of a further joist supporting part so as to form a straddle-type of double hanger intended to support two generally aligned joists on opposed sides of a partition wall.

Claims

1. A joist hanger comprising a sheet metal bearing part and a sheet metal joist supporting part, these parts being secured together by mechanical inter-engagement without the use of welding.

2. A joist hanger according to Claim 1 wherein the mechanical inter-engagement is provided by one or more projections inter-engaging with one or more apertures.

3. A joist hanger according to Claim 2 where more than one projection and aperture are provided, wherein ail the projections are provided on one part and all the apertures are provided on the other part.

4. A joist hanger according to Claim 3 wherein the projections are formed from rearwardly directed edges of the joist supporting part and the apertures are provided in the bearing part.

5. A joist hanger according to any one of Claims 2 to 4 wherein at least some of the apertures and projections are elongate and upright in use.

6. A joist hanger according to Claim 5 wherein the projections are undercut at the lower edges to form a hook formation.

7. A joist hanger according to Claim 6 wherein the projections are also undercut at the upper edges to form a double hook formation.

8. A joist hanger according to Claim 6 or Claim 7 wherein the or each undercut is of a sufficient size to receive a portion of the border of the associated aperture as a firm frictional fit.

9. A joist hanger according to Claim 7 wherein the or each projection is undercut at both upper and lower edges, the associated aperture having an enlarged part through which the projection can be inserted and a smaller sized part affording upper and lower border portions with which the upper and lower hook formations engage.

10. A joist hanger according to Claim 9 wherein the projection is resiliently mounted by virtue of the resilience of one or both of the sheet metal parts forming the joist hanger and is slid laterally into position in the aperture.

11. A joist hanger according to Claim 10 wherein the joist supporting part, comprises a generally U-shaped sheet metal member with a projection provided at or near the outer end of the limbs, on a rearwardly directed edge of the joist supporting part, the joist supporting part being resilient whereby the limbs may be sprung together to engage the projections in the enlarged parts of the respective apertures, the limbs then being permitted to spring apart to engage the hook members with the upper and lower borders of the smaller sized parts of the apertures.

1 2. A joist hanger according to any preceding claim wherein the bearing part has a width substantially greater than that of the joist supporting part, considered in a direction perpendicular to the axis of the joist to be supported.

13. A joist hanger according to any preceding claim wherein the bearing part is formed of sheet metal folded to a generally L-shape so as to have two flanges, one flange forming a bearing flange and the other being an attachment flange having one or more apertures or projections to which the joist supporting part is secured.

14. A joist hanger according to Claim 13 wherein the attachment flange is provided with one or more apertures to receive projections of the joist supporting part, and wherein the attachment flange has a cranked or inclined part so that the angle between the two flanges of the bearing part lies vertically above the rearmost edge of the joist supporting part in use.

15. A joist hanger according to Claim 13 or Claim 14 wherein the bearing flange of the bearing part is extended to provide a return flange generally at right angles to the bearing flange and generally parallel to the attachment flange.

1 6. A joist hanger according to Claim 1 5 wherein the return flange itself is provided with apertures or projections affording a second attachment flange to which a second joist supporting part may be secured.

1 7. A joist hanger according to any preceding claim wherein the parts of the joist hanger are made up of pregalvanised sheet metal.

1 8. A joist hanger substantially as hereinbefore described with reference to and as illustrated in Figures 1 to 3 of the accompanying drawings.

19. A joist hanger substantially as hereinbefore described with reference to and as illustrated in Figures 4 and 5 of the accompanying drawings.