GB2156398A

GB2156398A - Two-part joist-hanger

Info

Publication number: GB2156398A
Application number: GB08505317A
Authority: GB
Inventors: Richard George Walker; Michael Douglas Hoyland
Original assignee: PRESS BAT HOLDINGS Ltd
Current assignee: PRESS BAT HOLDINGS Ltd
Priority date: 1984-03-28
Filing date: 1985-03-01
Publication date: 1985-10-09
Also published as: GB2156398B; IE56406B1; GB8505317D0; IE850534L

Abstract

The hanger has a bearing flange 14 or 113, and a downwardly depending abutment 15 or 114. A pair of arms 19 or 118 is formed from the abutment bent away from the supporting masonry in parallel with each other. Arms 19 are slotted to receive outward turned and pressed hooks 24 on the side walls 22 of a one part shoe 12 in which a joist is received. Arms 118 are pressed from a central portion of abutment 114 leaving windows 119. The shoe 112 has outward turned lugs 126 deformed to crimp them over arms 118. The shoes may be made in a range of different depths to accommodate different joist sizes. As no welding is performed, each part may be made from thickly galvanized steel. <IMAGE>

Description

SPECIFICATION Joist hanger This invention relates to a joist hanger.

It is customary building practice to provide a metal hanger for supporting a generally horizontal structural timber or timber assembly from a load bearing wall of a building. The structural timber may be a joist or a roof truss for example. Such a hanger will be referred to in this description under the generic term "joist hanger"irrespective of what type of timber or timber assembly it is intended to support.

A conventional form of joist hanger employs a generally lazy Z section of thin gauge galvanised steel, having side straps welded between the upright and lower horizontal part of the section. In use, the joist sits in the shoe formed by the upright and lower horizontal part and the straps. The upper horizontal part forms a bearing portion which rests on top of a masonry element such as a brick or block of the load bearing wall.

Joist hangers of this general type have been in use for many years but they have certain disadvantages. Firstly, the welding required to form the shoe can only be achieved if the zinc coating on the metal is relatively thin or if the hanger is galvanised after welding.

The latter method is unsatisfactory as it is expensive and can cause distortion. However, upgrading of building standards mean that a thin galvanic coating is unacceptable.

Additionally, the width of the metal strip forming the lazy Z section is equivalent to the width of the joist. It therefore forms a relatively narrow bearing portion resting on the load bearing wall. This means that the load of the joist is transferred to a relatively small bearing area of the masonry.

Where the masonry is of brick, this may be satisfactory but increasing use is being made of very lightweight insulating building blocks which have a low crushing strength. If the whole joist load is transferred to a small bearing area, this may result in the block being crushed, particularly about its forward edge. The joist hanger is therefore insecure.

Other problems arise out of the variation in the sizes of timbers which need to be coped with. Both the height and the width of the joist hanger need to suit the joist dimensions so a large range of differvent joist hangers needs to kept by a stockist.

There have previously been suggestions of two part joist hangers, for example those shown in British patents specifications numbers 1,431,122 and 2,047,320. These prior proposals have not been wholly acceptable since they have required a large amount of metal and have involved on site assembly. Additionally, patent number 1,431,122 describes a fabricated shoe which is relatively expensive to produce.

It is an object of the present invention to produce a two piece joist hanger which overcomes or reduces many of the disadvantages of both the conventional and prior two piece joist hangers.

According to the invention there is provided a joist hanger comprising an attachment part adapted to be supported by a supporting wall and comprising an abutment disposed generally upright in use and abutting said wall and a pair of arms extending away from the abutment; and a shoe part including a base and a pair of side abutments adapted to receive a joist, the side abutments of the shoe part and the arms having cooperating formations capable of securing the shoe part and attachment part together.

The attachment part and the shoe part can therefore be formed without welding, for example as pressings and can therefore be made in thickly galvanised steel.

The attachment part may comprise a bearing flange adapted to bear on a supporting wall and said abutment may be disposed at right angles to the bearing flange.

The bearing flange may have a return flange at its end remote from the abutment and disposed generally parallel to the abutment, so as to be capable of hooking over the supporting wall in use.

A further form of joist hanger may comprise an attachment part including a bearing flange and a pair of abutments disposed generally upright in use and at right angles to the bearing flange, each of said abutments having a pair of arms extending away from the abutment in a direction away from the bearing flange; and a pair of shoe parts adapted to be secured to respective pairs of arms to form a double or straddle hanger capable of supporting a joist at each side of the supporting wall.

In a further alternative, the abutment may be enlarged upwardly and provided with means for bolt attachment toan upright face of a supporting member such as concrete wall or beam.

The arms may be formed from portions of the material of the abutment deformed out of the plane thereof to leave one or a pair of openings in the central region of the abutment facing between the side abutments of the shoe part.

Preferably, a pair of generally -rectangular arms are provided, folded outwar.'ly in opposite directions away from said central region.

The arms may be spaced from the end portions of the attachment part in order to ensure that the rigidity of the abutment is not significantly reduced by the provision of the arms and their removal from the metal of the attachment part.

In an alternative form of hanger embodying the invention, the arms may be provided by folding opposite side edge portions of he abutment towards each other so as to extend away from the abutment.

Preferably, when a bearing flange is provided, the arms are disposed close to the junction between the bearing flange and the abutment.

The cooperating formations of 'e side abutments of the shoe may comprise inwardly or outwardly turned edges forming hooks or lugs.

The hooks or lugs may engage over the upper edges of arms.

Alternatively, each arm may have a horizontal slot and a lug of each side abutment of the shoe part may be passed through the slot.

The side abutments may be cranked to permit the joist to be snugly received in the shoe below the position of the arms, where the side abutments include the inwardly turned edges.

The cooperating formations on the attachment part and on the shoe part may be deformable by pressing to provide a permanent inter-engagement of the shoe part and attachment parts.

Preferably the width of the attachment part is substantially greater than the spacing of the side abutments of the shoe part.

Stiffening formations may be provided in the material of the attachment part. For example, where the attachment part includes a bearing flange at right angles to the abutment, these stiffening formations may comprise one or more pressed darts or ribs extending into both the bearing flange and the abutment. Two such darts or ribs may be formed adjacent respective opposite ends of the attachment part. Where a return flange is provided on the bearing flange, further darts or ribs may be provided between the bearing flange and the return flange.

Where a further abutment is provided to form a straddle type hanger, further darts or ribs may be formed at the junction between the bearing flange and the further abutment.

Two embodiments of joint hanger according to the invention will now be described in more detail by way of example only with reference to the accompanying drawings in which: Figure lis a perspective view of a two piece joist hanger embodying the invention, shown in position on a load bearing wall and having a joist shown in chain dotted outline; Figure 2 is a side elevational view of the joist hanger in use in supporting a joist from a load bearing wall; Figure 3 is an end elevation, partly in section, taken on the line 3-3 of Figure 2; Figure 4 is a plan view of the joist hanger in position on a load bearing wall; Figure 5 is a front elevation of an alternative form of joist hanger embodying the invention; Figure 6 is a side elevation of the joist hanger of Figure 5; Figure 7 is a plan view of the joist hanger of Figure 5;; Referring firstly to Figure 1 of the drawings, a two piece joist hanger 10 comprises an attachment part generally indicated at 11 and a shoe part generally indicated at 12 which receives a joist shown in chain dotted outline at 13.

The attachment part 11 comprises a main bearing flange 14 which is planar and rectangular. The forward edge of the attachment part 11 is bent at right angles to the bearing flange 14 to form an abutment 15 which abuts the forward edge of a masonry element 16 such as a building block or brick. A central part 17 of the abutment 15 extends downwardly a short distance against the forward face of the block 16. However, the blank from which the bearing part 11 is formed is slotted at 18 at each side to define two arms 19, which are bent forwardly out of the plane of the abutment 15.

The arms 19 extend generally parallel in a direction away from the bearing flange 14. Each arm 19 is provided with a horizontal slot 20.

The shoe part 12 is formed from a single metal blank. It comprises a base 21 and a pair of side abutments 22 which are dimensioned to receive the joist 13. The shoe part is open adjacent the wall.

The side abutments 22 each have a narrowed upper extremity 23 formed with a notch 24 so that the rear edge of the shoe can lie against the forward face of the block 16. The thickness of the abutment 15 is accomodated within the notch 24.

The extremities of the side abutments 22 are bent outwardly through the slots 20 in the arms 19 and are then deformed downwardly to form hooks 25, securing the shoe part 12 to the attachment part 11.

It will be appreciated that no welding is required to secure the parts together and therefore the galvanic coating can be as thick as desired. Furthermore, the width of the bearing flange 14 can be considerably wider than that of the shoe 12 so as to give a large bearing area to distribute the load of the joist on the block 16.

In use, the joist tends to force the forward end of the shoe downwardly which brings the rear edge into firm abutment with the block 16. Coupled with the slight "play" in the hook and slot connections, this reduces the cantilever effect on the bearing flange of the hanger, compared with that which acts on the bearing portion of the conventional one piece joist hanger. In the latter case, the joist loading tends to pull the bearing portion out of the masonry because the joist load acts at a substantial distance below the bearing portion and therefore exerts considerable leverage.

Figures 2 to 4 show the joist hanger in use. The width of the bearing flange 14 can particularly be noted from Figures 3 and 4.

The joist hanger can be made with considerable economy both on materials and on assembly costs. Each part is formed as a blank in sheet metal such as pre- galvanised mild steel sheet and can be formed by pressing. In particular, the attachment part uses a relatively small amount of metal, considering the very large bearing flange area provided which distributes the joist load over a large area of the supporting masonry. It is envisaged that different depths of shoe part 12 could be used with the same size of attachment part, reducing the amount of stock which needs to be held to accomodate different joist sizes.

Various modifications are possible within the scope of the invention, particularly as regards the form of the cooperating formations of the arms and of the side abutments of the shoe part. For example, the arms might have vertical slots engaged by upright hooks on the side abutments or the upright hooks might be hooked over the upper edges of the arms. It is preferred that a single pair of cooperating formations is provided, one at each side of the joist. The use of several connection posi tions spaced from each other would reduce the "pla'j'between the two parts of the hanger and hence would contribute to excessive leverage on the hanger, resulting in loosening from the masonry.

An alternative form of joist hanger is illustrated in Figures 5 to 7 of the drawings.

The joist hanger is generally indicated at 110 and comprises an attachment part 111 and a shoe part 11, connected together in a permanent fashion to form a single unit.

The attachment part 111 comprises a bearing flange 113 and an abutment 114 disposed at right angles to each other. The bearing flange 113 is intended to rest on a masonry support (not shown) and is provided with openings 115,116 which can be used to promote a key with the mortar of a conventional masonry wall. Alternatively,the joist hanger may be mounted on a timber wall plate, in which case suitable nails are used to secure it in position through nail holes 117 provided in the bearing flange.

In alternative forms of joist hanger (not all illustrated) modifications to the attachment part may be made. In one form, the bearing flange 113 may be provided with a return flange 109 which is parallel to the abutment 114 and spaced from it by a distance equivalent to the width of a standard masonry block. The bearing flange and the return flange are effectively "hooked" over the masonry element. Where it is intended to support two joists at opposed faces of the supporting masonry wall, the return flange is replaced by a further abutment, in order to suport a second Shoe part similar to that described below. In a further embodiment, the abutment 114 is extended upwardly and provided with suitable bolt holes for making a "fair face fixing". This involves bolting the attachment part upright against the face of for example a concrete wall or beam.

The abutment 114 abuts the face of the wall in use. Two arms 118 of generally rectangular shape are formed by piercing the material of the abutment, leaving a pair of rectangular "windows" 119 in the central region of the abutment. The arms 118 are bent out at right angles to the plane of the abutment 114 and are used to support the shoe part 112 of the hanger.

It will be seen from figures 5 and 7 of the drawings in particular that the attachment part 111 of the hanger is considerably wider than the width of the shoe part 112. The shoe part is selected so as to conform to the width of a joist which is inserted in the shoe in use. However, it will be noted that the shoe is open at the top and therefore the depth of the joist can vary within a certain range.

The shoe part is of generally squared-off U shape having a base 120 and a pair of side walls 121, within which the joist (not shown) is located.

The base 120 has a forward projecting part 122 which provides an extra bearing length, without unnecessarily impeding the placing of the joist into the shoe 112. Nail holes 123 are provided forse- curing the joist in position in the shoe part 112.

A small notch 124 is provided in the rear edge of the side wall 121 of the shoe part 112. The purpose of this notch is to allow fitment, flush with the back of the shoe, of a tie bracket which is provided with a bolt hole. This tie bracket can be used to provide extra lateral restraint to the hanger shoe part 112.

It is particularly used where a fair face fixing is made. To ensure rigidity of the hanger two bolt holes are provided in the extended abutment 114 and a further bolt hole is provided in the tie bracket (not shown), the three bolt holes being disposed in a triangle.

A similar notch 125 is provided at the upper ends of the side walls, to accomodate the thickness of the metal of the abutment 114, forming part of the attachment part of the hanger.

At the extreme upper ends of the side walls 121 a pair of tabs or hook 126 are provided, which hook over the tops of the arms 118. As shown in Figures 5 to 7 of the drawings, the tabs or hook$ 126 are turned outwardly away from each other.

However, they could equally well be turned inwardly to hook over the tops of the arms 118, with the side walls 121 formed into a cranked shape near the tip. This would mean that the side walls 121 would lie directly below the arms 180 to provide a snug seating for the joist, whilst the hooks 126 would tend to embed into the timber of the joist in a direction opposing withdrawal of the joist.

Although it is possible merely to assemble the parts together, this would not give the desired degree of securing and so a deforming operation is performed where indicated at 127, to secure the parts together permanently.

It will be appreciated that the same attachment part 111 can be used with shoe parts 112 of varying depths, reducing tooling and stock costs. The same blank can be used for the attachment part shown and the extended abutment used for fair face fixing. The bearing flange 113 is broader than the shoe part 112 and therefore spreads the loading of the joist hanger and the timber which it supports across a length of wall which is substantially greater than the width of the joist. This is particularly important in view of the mo 4ern trend towards using relatively light weight insulating blocks, of low crushing strength for the internal leaf of a cavity wall.

In order further to assist in spreading the load across the whole area of the attachment flange 113, a pair of stiffening darts 12û are provided in the bearing part, extending from the bearing flange 113 to the abutment 114. These stiffening darts 128 tend to stiffen the fold line between ,hm bearing flange 113 and the abutmen; '6!. so as to distribute the load of the joist hanger and its accompanying joist over the entire area of the bearing flange 113. If flexing were to occur about the fold line between the bearing flange 113 and the abutment 114, this could result in excessive loading at the forward edge of the supporting masonry and hence crumbling of the masonry, ma', .ng the joist hanger insecure.

Where a return flange 109 or a second abutment is provided, further stiffening darts my be formed so as similarly to stiffen the junction between the return flange or further abutment and the bearing flange 113.

The position of the arms inwardly of the side edges of the abutment 114 means that these edges can contribute to the rigidity of the bearing part.

The arms are loaded in shear.

It will be seen that, between the notches 124 and 125 of the rear edge of the shoe part 112, there is a projecting edge 129 which is aligned with the abutment 114 and hence abuts the masonry directly. A similar projecting edge 113 is formed at the base of the shoe part 112. The edges 120 and 130 help to support the shoe part 112 upright and reduce leverage on the bearing part 111.

The joist hanger described and illustrated can be made in heavy gauge steel and thickly galvanised, since it is not welded at any part of its structure.

The deforming operation performed at 127 can be done before despatch of hangers from the factory or can be done on site using a power tool of generally known type.

The hanger described above conforms to British Standard BS.6178 Part 11982.

Claims

1. A joist hanger comprising an attachment part adapted to be supported by a supporting wall and comprising an abutment disposed generally upright in use and abutting said wall and a pair of arms extending away from the abutment; and a shoe part including a base and a pair of side abutments adapted to receive a joist, the side abutments of the shoe part and the arms halving cooperating formations capable of securing the shoe part and attachment part together.

2. A joist hanger according to Claim 1 wherein the attachment part comprises a bearing flange adapted to bear on a supporting wall and said abutment is disposed at right angles to the bearing flange.

3. A joist hanger according to Claim 2 wherein the bearing flange has a return flange at its end re mote from the abutment and disposed generally parallel to the abutment so as to be capable of hooking over the supporting wall in use.

4. A joist hanger according to Claim 2 wherein the attachment part includes a bearing flange and a pair of abutments disposed generally upright in use arJd at right angles to the bearing flange, each of said abutments having a pair of arms extending away from the abutment in a direction away from the bearing flange; and a pair of shoe parts adapted to be secured to respective pairs of arms to form a double or straddle hanger capable of supporting a joist at each side of the supporting wall.

5. A joist hanger according to Claim 1 wherein the abutment is enlarged upwardly and provided with means for bolt attachment to an upright face of a supporting member such as a concrete wall or beam.

6. A joist hanger according to any preceding claim wherein the arms are formed from portions of the material of the abutment deformed out of the plane thereof to leave one or a pair of openings in the central region of the abutment facing between the side abutments of the shoe part.

7. A joist hanger according to Claim 6 wherein a pair of generally rectangular arms are provided, folded outwardly in opposite directions from said central region.

8. A joist hanger according to Claim 6 or Claim 7 wherein the arms are spaced from the end portions of the attachment part.

9. A joist hanger according to any one of Claims 1 to 5 wherein the arms are provided by folding opposite side edge portions of the abutment towards each other so as to extend away from the abutment.

10. A joist hanger according to Claim 9 when appendent to Claim 2 wherein the arms are disposed close to the junction between the bearing flange and the abutment.

11. A joist hanger according to any preceding claim wherein the cooperating formations of the side abutments of the shoe comprise inwardly or outwardly turned edges forming hooks or lugs.

12. A joist hanger according to Claim 11 wherein the hooks or lugs engage over the upper edges of the arms.

13. A joist hanger according to Claim 11 wherein each arm has a horizontal slot and a lug of each side abutment of the shoe part is passed through the slot.

14. A joist hanger according to any one of Claims 11 to 13 wherein the side abutments are cranked to permit the joist to be snugly received in the shoe below the position of the arms, where the side abutments include inwardly turned adges.

15. A joist hanger according to any preceding claim wherein the cooperating formations on the attachment part and on the shoe part are deformable by pressing to provide a permanent inter-engagement of the shoe part and attachment part.

16. A joist hanger according to any preceding claim wherein the width of the attachment part is substantially greater than the spacing of the side abutments of the shoe part.

17. A joist hanger according to any one of Claims 2 to 16 wherein stiffening formations are provided, comprising one or more pressed darts or ribs extending into both the bearing flange and the abutment.

18. A joist hanger according to Claim 17 wherein two such darts or ribs are formed adjacent respective opposite ends of the attachment part.

19. A joist hanger according to Claim 17 or Claim 18 when appendant to Claim 3 wherein further darts or ribs are provided at the junction between the bearing flange and the return flange.

20. A joist hanger according to Claim 17 or Claim 18 when appendant to Claim 4 wherein further darts or ribs are formed at the junction between the bearing flange and the further abutment.

21. A joist hanger substantially as hereinbefore described with reference to and as illustrated in Figures 1 to 4 of the accompanying drawings.

22. A joist hanger substantially as hereinbefore described with reference to and as illustrated in Figures 5 to 7 of the accompanying drawings.