GB1572865A

GB1572865A - Joist hangers

Info

Publication number: GB1572865A
Application number: GB873277A
Authority: GB
Original assignee: BAT BUILDING
Current assignee: BAT BUILDING
Priority date: 1978-01-25
Filing date: 1978-01-25
Publication date: 1980-08-06

Description

(54) IMPROVEMENTS RELATING TO JOIST HANGERS (71) We, BAT BUILDING & BR< ENGINEERING PRODUCTS LIMITED, formerly Automatic Pressings Limited, a British Company, of Halesfield 9, Telford, Shropshire, do hereby declare -this invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to joist hangers for buildings.

It was particularly devised for use in the type of hanger used to suspend a timber joist from brickwork or blockwork (hereinafter referred to as "masonry"). However, the invention could be adapted for use in connecting timber to timber, steel or concrete.

Joist hangers are conventionally used in connecting timber joists to masonry so that the timber does not penerate the masonry of a partition wall which might allow fire to spread through the wall. The joist is secured in a metal hanger which extends into the masonry.

Such hangers may be at one side of the masonry or may extend completely through a partition wall with means being provided for a joist to be fixed at each side of the wall to the same "saddle" hanger.

In the fitting of joist hangers, it is conventional practice to take a joist and nail or otherwise fix the hangers to each end of the joist. The joist and hangers are then presented to the masonry which has been built up to the correct horizontal level and then further bricks or blocks are added in courses above the hanger to hold it firmly in position.

Since the tolerances in building work tend to be large, the joists are usually cut slightly short for the gap between the two opposed walls which are intended to support them, to enable them to be maneouvred into position. This means that the load on the joist hangers is generally speaking somewhat spaced away from the masonry, thus reducing the effective bearing surface of the hanger on which the joist is resting and tending to exert some turning moment on the hanger which may tend to pull it away from the masonry.

If, as is sometimes the case, insufficient masonry is built up above the joist hanger before the joist is loaded, it is possible for the part of the hanger which is built into the masonry to tend to slip out slightly. Furthermore, such joist hangers tend to be of the same width as the joist so that the bearing surface in the masonry exerts a concentrated load on the edge of the immediatley supporting brick or block. This can cause crushing and yielding of the extreme edge of the block and hence loosening of the hanger.

It is an object of the present invention to provide a joist hanger and a method of making such a hanger which enables some or all of these disadvantages to be overcome or reduced.

According to the invention there is provided a joist hanger integrally formed from a single sheet of material and comprising a generally horizontal top bearing surface and, spaced therefrom, a generally horizontal lower bearing surface, an intermediate portion also being formed integrally with said bearing surfaces and including a pair of straight side straps disposed generally parallel to and aligned edgewise with each other, the rear of the lower bearing surface being substantially vertically directly below the forward end of the top bearing and the straps extending forwardly and downwardly from a position substantially vertically directly below the forward end of the top bearing surface to a region adjacent the forward end of the lower bearing surface.

A generally vertically directed back member may extend from the rear of the lower bearing surface. This back member may extend upwardly from the lower bearing surface towards the top bearing surface.

It will be appreciated that the terms "upwardly" and "lower" for example refer to the position of the joist hanger in use. The expression "rear" refers to portions closest to or within the masonry in use whereas the term "forward" refers to portions closer to the centre of the joist in use.

The invention also provides a method of making a joist hanger comprising taking a sheet metal blank of elongate form, parting the metal to provide a pair of longitudinally disposed and laterally spaced straps, each integrally connected at both its ends to the remainder of the blank, transversely parting the metal blank between the straps, and form ing the blank to provide a generally planar top bearing surface and a generally parallel, forwardly and downwardly spaced lower bear ing surface, the rear of which is disposed substantially directly vertically below the for ward end of the top bearing surface, the straps being straight and inclined forwardly and downwardly from a position substantially directly vertically below the forward end of the top bearing surface to a region adjacent the forward end of the lower bearing surface.

A generally vertically disposed back mem ber may be formed at the rear of the lower bearing surface and may extend upwardly from the lower bearing surface towards the top bearing surface.

The sheet metal blank may be of substan tially rectangular shape.

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 perspective view of a joist hanger embodying the invention.

FIGURE 2 is a front elevational view of a partly formed blank used in the manufacture of the joist hanger.

Referring first to Figure 2, it will be seen -that the hoist hanger is made from a rect angular sheet metal blank 10 which may be of stainless or galvanised steel for example.

This blank can be parted off, substantially without any waste, from a larger sheet of metal.

At the same time as parting off the blank 10, or subsequently, a pair of longitudinal slots are formed in the blank extending parallel to and spaced from the opposed longer sides of the blank. Again simultaneously, or in a subsequent operation, a transverse slot 12 and a plurality of fastening holes 13 and 14 are formed in the blank which is still in a flat condition. The slot 12 extends completely across the portion of the blank 10 between the slots 11.

The blank is then pressed to form it to the shape shown in Figure 1, which may be done in one or more stages.

It will be seen that the portion of the metal above the slots 11 is folded about a trans verse fold line 15 to provide a top horizontal bearing surface 16 having the holes 14. The metal extends downwardly from the fold line lj in one piece until the upper ends of the slots 11 are reached.

Below this, the metal at the sides of the blank forms a pair of straight straps 17. The metal between the straps 17 extends vertically downwardly from the fold line 15, but the folding operation separates the two edges 18 which were originally the boundaries of the slot 12.

At the lower end of the hanger, the full width of the metal blank is provided at the extreme forward end portion shown at 19.

Transverse ribs or corrugations 20 may optionally be provided by the pressing operation, to give this portion of the hanger added stiffness in the transverse direction where necessary.

The straps 17 meet the portion 19 at the region close to its forward end. The metal between the straps extends rearwardly at 21 to a position directly vertically below the fold line 15. At this position 22, there is another transverse fold line and a portion of metal 23 then extends vertically upwards towards the top bearing surface 16.

In particular, it will be seen that the straps 17 are substantially parallel and are aligned with each other edgewise with a spacing between which corresponds to the approximate transverse width of a joist to be fitted. The top bearing surface 16 is considerably wider than the joist width i.e. by the width of both straps. The fold line 15 is also wider than the joist. At the lower end of the hanger, the forward end of the lower bearing surface at 19 is also substantially wider than the joist and may be stiffened against bending by the ribs or corrugations, whereas the portion 21 of the lower bearing surface is of the same width as the joist In use, the joist hanger is secured by fastenings passing through the holes 13 to the underside of the end portions of a joist.The joist may extend right up to the back plate 23, but, on site, it is more likely to be slightly spaced from the back plate to give ease of positioning, particularly where a joist hanger is applied at each end of a joist.

The joist hanger is then abutted against a wall formed of masonry with the large top bearing surface 16 resting on the top of a course of masonry and the back plate 23 abutting the masonry lower down the wall.

The holes 14 form a key for mortar and further masonry is built up above the top bearing surface 16. Alternative forms of keying for example pressed ribs or dimples might be used instead of the holes.

Because the width of the top bearing surface is greater than has hitherto been provided in conventional joist hangers, there is less tendency for the weight of the joist and its loading to cause the masonry underneath to crumble, particularly adjacent the forward edge.

The fold line 15 at the forward edge is broad and this gives added stiffness which reduces the tendency in a conventional tie to straighten out at the equivalent bend.

The straps 17 prevent the joist from being dislodged sidewards, but makes it fully accessible so that air currents can pass around the joist and reduce the risk of damp or rot.

The joist itself is secured to a bearing surface which extends fully up to the brickwork which is particularly strengthened at the forward end which is subjected to the most loading in use. The broad and stiffened forward portion 19 transmits the load from the joist directly to the straps 17 which are straight metal strips in tension and hence extremely strong. This load is then transmitted directly to the top bearing surface 16. If the back plate 23 is not firmly braced against the wall, any load which acts on the joist hanger has the tendency of pulling downwardly on the straps 17 and any component of the load in the rearward direction will push the lower bearing surface rearwardly until the back plate 23 abuts the wall.In a conventional type of joist hanger, it is usual for the side straps to be aligned in face to face parallel relation and to be nailed or otherwise secured to the sides of the joist so that it is not possible for the side straps of a conventional joist hanger to move relative to the joist and hence if the back plate is not against the masonry, the loading of the hanger does not improve its positioning.

The back plate 23 is shown as extending upwardly towards the top bearing surface 16, but it could extend downwardly in the same plane (as shown in dotted outline) or part of the plate could extend upwardly and part downwardly if desired. However, by providing the back plate 23 projecting upwardly as shown, it can be used to guide the correct positioning of the joist relative to the hanger before the hanger is positioned in the masonry.

As a further alternative, the plate could extend straight into the masonry (as shown in chain dotted outline).

Joist hangers are usually formed from galvanised mild steel and this has presented problems in previously known types of joist hanger in which separate parts had to be welded together because the welding of galvanised steel to a satisfactory standard requires extreme care and high standards of quality inspection. In the joist hanger of the present invention, there are no welds necessary and hence quality can be expected to be more consistent and quality control becomes easier.

Furthermore, it will be seen that the method of manufacture substantially eliminates any waste metal.

The joist hanger shown is intended to secure a single joist at one side of a partition wall made of brickwork. However, a saddle joist hanger can also be formed by an extension of the method described so that the joists can be hung both sides of a partition wall from a single hanger.

WHAT WE CLAIM IS 1. A joist hanger integrally formed from a single sheet of material and comprising a generally horizontal top bearing surface and, spaced therefrom, a generally horizontal lower bearing surface, an intermediate portion also being formed integrally with said bearing surfaces and including a pair of straight side straps disposed generally parallel to and aligned edgewise with each other, the rear of the lower bearing surface being substantially vertically directly below the forward end of the top bearing surface and. the straps extending forwardly and downwardly from a position substantially vertically directly below the forward end of the top bearing surface to a region adjacent the forward end of the lower bearing surface.

2. A joist hanger according to Claim 1 wherein a generally vertically directed back member extends from the rear of the lower bearing surface.

3. A joist hanger according to Claim 2 wherein the back member extends upwardly from the lower bearing surface towards the top bearing surface.

4. A method of making a joist hanger comprising taking a sheet metal blank of elongate form, parting the metal to provide a pair of longitudinally disposed and laterally spaced straps, each integrally connected at both its ends to the remainder of the blank, transversely parting the metal blank between the straps, and forming the blank to provide a generally planar top bearing surface and a generally parallel, forwardly and downwardly spaced lower bearing surface, the rear of which is disposed substantially directly vertically below the forward end of the top bearing surface, the straps being straight and inclined forwardly and downwardly from a position substantially directly vertically below the forward end of the top bearing surface to a region adjacent the forward end of the lower bearing surface.

5. A method according to Claim 4 wherein a generally vertically disposed back member is provided at the rear of the lower bearing surface by said forming.

6. A method according to Claim 5 wherein the back member extends upwardly from the

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. The joist itself is secured to a bearing surface which extends fully up to the brickwork which is particularly strengthened at the forward end which is subjected to the most loading in use. The broad and stiffened forward portion 19 transmits the load from the joist directly to the straps 17 which are straight metal strips in tension and hence extremely strong. This load is then transmitted directly to the top bearing surface 16. If the back plate 23 is not firmly braced against the wall, any load which acts on the joist hanger has the tendency of pulling downwardly on the straps 17 and any component of the load in the rearward direction will push the lower bearing surface rearwardly until the back plate 23 abuts the wall.In a conventional type of joist hanger, it is usual for the side straps to be aligned in face to face parallel relation and to be nailed or otherwise secured to the sides of the joist so that it is not possible for the side straps of a conventional joist hanger to move relative to the joist and hence if the back plate is not against the masonry, the loading of the hanger does not improve its positioning. The back plate 23 is shown as extending upwardly towards the top bearing surface 16, but it could extend downwardly in the same plane (as shown in dotted outline) or part of the plate could extend upwardly and part downwardly if desired. However, by providing the back plate 23 projecting upwardly as shown, it can be used to guide the correct positioning of the joist relative to the hanger before the hanger is positioned in the masonry. As a further alternative, the plate could extend straight into the masonry (as shown in chain dotted outline). Joist hangers are usually formed from galvanised mild steel and this has presented problems in previously known types of joist hanger in which separate parts had to be welded together because the welding of galvanised steel to a satisfactory standard requires extreme care and high standards of quality inspection. In the joist hanger of the present invention, there are no welds necessary and hence quality can be expected to be more consistent and quality control becomes easier. Furthermore, it will be seen that the method of manufacture substantially eliminates any waste metal. The joist hanger shown is intended to secure a single joist at one side of a partition wall made of brickwork. However, a saddle joist hanger can also be formed by an extension of the method described so that the joists can be hung both sides of a partition wall from a single hanger. WHAT WE CLAIM IS

1. A joist hanger integrally formed from a single sheet of material and comprising a generally horizontal top bearing surface and, spaced therefrom, a generally horizontal lower bearing surface, an intermediate portion also being formed integrally with said bearing surfaces and including a pair of straight side straps disposed generally parallel to and aligned edgewise with each other, the rear of the lower bearing surface being substantially vertically directly below the forward end of the top bearing surface and. the straps extending forwardly and downwardly from a position substantially vertically directly below the forward end of the top bearing surface to a region adjacent the forward end of the lower bearing surface.

lower bearing surface towards the top bearing surface.

7. A method according to any one of Claims 4 to 6 wherein the sheet metal blank is of substantially rectangular shape.

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

9. A method of making a joist hanger according to Claim 4 and substantially as hereinbefore described.