GB2228955A

GB2228955A - Joist hangers

Info

Publication number: GB2228955A
Application number: GB8926321A
Authority: GB
Inventors: Charles Edward Harris; Ronald Charles Sammons
Original assignee: Individual
Current assignee: Individual
Priority date: 1989-03-10
Filing date: 1989-11-21
Publication date: 1990-09-12
Also published as: GB8905524D0; ZA901458B; GB8926321D0

Abstract

Upper, horizontal bearing plate 42 or 53 is connected to the vertical back plate 43 or 61 by a bend including a radius profile 44 or 52 whereby no pressure is applied to the edge of supporting wall 41 along the length of the radius profile. The profile 44, 52 may extend the full width of the hanger or only over a part, the remainder 57, 58 having right angled bends. The hanger may be formed from a single metal blank and may include drainage and ventilation holes. <IMAGE>

Description

JOIST HANGERS This invention relates to joist hangers and their method of manufacture.

Wooden joists are frequently used in domestic and other building construction. Such joists extend from wall to wall inside a building and are supported by the walls.

The joists are used in turn to support floorboards laid across them.

The ends of the joists may be located in cavities made in the supporting wall or on ledges fixed to the walls. In modern building practice the joists are often carried by metal hangers which are fixed in the supporting wall.

These hangers are substantially 'Z' shaped with an upper flange portion, the masonry flange, which lies in the wall and a lower stirrup portion which carries and retains the joist. The hangers are normally fabricated from stainless or galvanised steel to avoid rust. In most designs joist hangers are made in two parts which are welded together.

The use of joist hangers for supporting joists has a number of advantages over the earlier practice of locating the ends of hoists in a supporting wall. These include reduction in the length of joists, saving timber, and prevention of rot in the supporting ends due to damp from the supporting wall.

The use of joist hangers is well known and described in textbooks such as Construction Technology by R. Chudley, Volume I and The Construction of Buildings by R. Barns.

In many buildings cavity walls are used to increase thermal insulation. Joist hangers to support the floors are usually mounted on the inner wall which, for reasons of economy, is seldom made from brick or a similar hard materials but from concrete blocks. Currently the most frequently used concrete blocks are formed from light weight aerated concrete which has a low density and low thermal conductivity. These blocks have poor compressive strength and can easily be chipped or caused to crumble.

It is found that joist hangers frequently cause them to crumble at the edge where the masonry flange joins the stirrup portion. This may lead to movement of the supported joist and require expensive repairs.

It is an object of the present invention provides a joist hanger which avoids damage to supporting concrete block walls.

It is a further object to provide joist hangers formed from a single piece of metal which eliminates the need for welding and the consequent possibility of collapse due to welding faults or corrosion.

According to the present invention there is provided a joist hanger comprising a masonry flange, adapted to lie on the upper surface of a supporting wall, connected through a right angle to a stirrup portion, adapted to carry the end of a joist, characterised in that a formed radius profile is used to join the masonry flange to the stirrup portion whereby the pressure on the edge of the supporting wall caused by any load on the stirrup portion is reduced.

The formed radius profile ensures that the weight of the joist in the stirrup portion is transmitted only to the central and rear portion of the upper surface of the supporting wall; no pressure is applied to the inner edge of the wall. Preferably the inside of the formed radius profile provides a clearance of from 3 mm to 40 mm between the edge and the upper surface of the wall when the joist hanger is in its supporting position.

The masonry flange of the joist hanger may be a flat strip pierced with one or more fixing holes or it may be split into strips with a central space. Flanges, humps and butterflies may be stamped into the flange, in known manner, to assist keying into mortar and fabric of the wall. The end of the flange portion furthest from the stirrup portion may be bent downwardly so that it abuts the rear face of the wall. In an alternative embodiment, for use with internal walls in buildings, the masonry flange may carry a stirrup portion at both ends allowing joists to be supported on opposite sides of the wall by a single hanger.

The stirrup portion has a base section which carries the lower surface of a joist and two side walls which retain the joist in position on the base. The base and/or side walls may be pierced with fixing holes. The retaining action of the side walls may be augmented by wing sections near the flange which also prevent the retained joist twisting.

In the preferred embodiments the hanger is fabricated from a single sheet of metal. This may take the form/ of a central portion which abuts the end of the joist, a lower portion which is folded through a right angle to support the base of the joist having side portions which are bent through a right angle to enclose and retain the sides of the joist. The two supporting flaps attached to the side walls are folded behind the lower end of the central portion and attached to it so as to retain the base portion in its folded position. The upper portion of the sheet is folded through a right angle having the opposite sense to that of the lower portion to form the supporting flange.

In one preferred embodiment the supporting flaps are attached to the central portion of the hanger by means of a self-locking method, such as a a swaged or plunged joint.

The metal surrounding the periphery of each hole pierced in the rear wall of the hanger is forced into the corresponding hole in each flap to form a rigid joint. This prefered method of attachment eliminates the need for welding or the use of fastening devices such as rivets.

In an alternative preferred embodiment the stirrup portion may consist of a strip of metal whose edges have been folded through a right angle to form side walls and whose base has been bent through a right angle to form the base of the stirrup. Such an arrangement is mechanically extremely robust and avoids the need for locking folds to hold the base of the stirrup in position.

The joist hanger is preferably formed from sheet steel having a thickness in the range 2.5 mm to 6 mm. In order to avoid corrosion the hanger is preferably formed from galvanised steel sheet or stainless steel alloy sheet.

Alternatively the metal may be surface treated and coated with a water impervious coating.

Joist hangers are made in a series of sizes to fit the various standard sizes of timber uses as joists. The width of the stirrup portion may range from 38 mm to 125 mm and the distance between the base and the upper fold may lie in the range 76 mm to 500 mm. The metal sheet used to form the larger hangers may be of a heavier gauge that that used for the smaller hangers.

In order that the invention may be clearly understood it will now be described with reference to the accompanying drawings in which: Figure 1 is a perspective view of one form of a joist hanger according to the invention, Figure 2 is a plan view of a metal sheet prior to fabrication into a joist hanger as shown in Figure 1, Figure 3 is a side view of one form of the formed radius profile used in a joist hanger according to the invention, Figure 4 is a side view of an alternative form of the formed radius profile, Figure 5 is a side view of the form of the formed radius profile used in the joist hanger shown in Figure 1, Figure 6 is a perspective view of an alternative form of a joist hanger according to the invention, Figure 7 is a perspective view of a form of a joist hanger according to the invention avoiding locking folds, Figure 8 is a plan view of a the flange portion of the joist hanger shown in Figure 7, Figure 9 is a side view of the joist hanger shown in Figure 7 and Figure 10 is a front view of the joist hanger shown in Figure 7.

A joist hanger according to the invention, see Figure 1, comprises a stirrup portion 1 connected to a masonry flange 2 through a formed radius profile 3. The masonry flange 2 is shown as a flat plate 4 pierced with fixing holes 5.

The flange 4 also carries a locating hump 6 and two 'butterfly' folds 7 to assist location and retention in masonry. The plate 4 is connected to the rear face 8 of the stirrup portion 1 through the formed radius profile 3.

The angle between the plane of the plate 4 and the face 8 is substantially 90 degrees. The rear face 8 is joined by a substantially 90 degree fold 9 to the base plate 11 of the stirrup 1. The upper portion of the rear face 8 carries wing elements 12 on each side pierced with fixing holes 13. The base plate 8 carries vertical retaining walls 14 pierced with fixing holes 15 on each edge.

Each of the walls 14 carries a rearward folded portion which provides a flap 16 whose inner surface abuts the rear surface of the face 8. Each flap 16 is pierced with an attachment hole, not shown, to allow rigid fastening to the face 8 through a cooperating attachment hole 17 in the face 8. So as to ensure that the rear surface of the joist hanger is substantially flat the flaps 16 are accomodated by a joggle formed in the face 8. The joggle comprises two double bends. 18 and 19. forming a cavity having a depth equal to the thickness of the sheet metal. The vertical height of the flaps 16 is less than that of the walls 14 so that an aperture 18 is formed at the rearward edge of each of the retaining walls 14.

The flaps 16 are preferably attached to the face 8 by means of a swaged or plunged joint formed by driving the peripheral metal from one attachment hole into the cooperating hole.

The formed radius profile comprises an extended fold between the stirrup 1 and the flange 2 combined with a triangular hump 10 formed by pressing. The hump 10 increases the rigidity of the fold and reduces the edge contact area of the masonry flange 4.

In use the masonry flange 4 is located on the upper surface of a wall. not shown. and retained in position by means of fastening devices driven through the fixing holes 5 into the wall. The rear surface of the rear face 8 of the stirrup portion 1 abuts the vertical face of the wall.

The formed radius profile 3 between the portions 1 and 2 together with the hump 10 ensures that no pressure is applied to the inner edge of the upper surface of the wall.

One end of a wooden joist. not shown. is placed in the stirrup portion 1 so that its lower edge is carried by the base plate 11. The joist is held in position by the retaining walls 14 and prevented from twisting by the wings 12. The fixing holes 13 and 15 allow fastenings to be inserted so that the joist is firmly retained in the stirrup. The aperture 18 provides ventilation and prevents the accumulation of moisture at the end of the joist.

In a preferred embodiment of the invention the joist hanger is fabricated from a single sheet of metal by cutting followed by folding. A suitable form of such a metal sheet is shown in Figure 2. The sheet has a rectangular masonry flange 21 connected by a narrower neck 22 to a rectangular plate portions 23 and 24. The plate 23 carries wing plates 26 on each side. The plate 24 carries side plates 27 having flap portions 28. Before folding the masonry flange 21 is pierced with fixing holes 29, the plate portion 23 is pierced with attachment holes 31 and the wing plates 26 with fixing holes 32. The side plates 27 are pierced with fixing holes 33 and the flap portions with attachment holes 34.

The neck portion 22 is pressed so as to create a formed radius profile providing a 90 degree angle between the portions 21 and 23 with the masonry flange 21 directed downwards. Further pressing on the triangular area 30 provides a hump which, as explained earlier, increases the efficiency of the profile. The wing plates 26 are folded upwards along the dashed lines 35 to form the wing elements for the hanger. The flaps 28 are folded upwards along the dashed lines 36. The plates 27 are folded upwards along the lines 37 so that the flaps 28 face inwardly. Finally the plate portion 24 is folded upwards through 90 degrees along the line 38 so that each attachment hole 34 on the flap 28 is positioned over an attachment hole 31 in the plate 23. The plate 23 and the flaps 28 are preferably fastened to each other by swageing the edges of the attachment holes 31 into the attachment holes 34.

In the preferred embodiment illustrated a locating hump is formed by pressing the area 39 and butterflies are formed similarly by pressing the edge portions 40.

It will thus be seen that the joist hanger illustrated in Figure 1 can be fabricated from the sheet of metal shown in Figure 2.

The formed radius profile between the masonry flange and the stirrup portion of a joist hanger according to the invention is shown in greater detail in Figure 3. A concrete block 41 forms the upper portion of a wall. The masonry flange 42 of a joist hanger lies on the upper surface of the block 41 and the rear face 43 of the stirrup portion of a joist hanger rests against the vertical surface of the block 41. It will be seen that a formed radius profile joining the portions 42 and 43 ensures that contact with the block 41 only takes place on the central and rear portion of the upper face. the edge 45 is not in contact with the joist hanger and does not receive the damaging pressure produced by prior joist hangers.

The formed radius profile is shown in Figure 3 as having a substantially circular cross-section. It is however possible to use other profiles according to the fabricating methods employed. An alternative rectangular fold is shown in Figure 4 in which the same reference numerals are used as in Figure 3 to denote the same features.

A cross section of the central portion of the formed radius profile 3 shown in Figure 1 is shown in cross section in Figure 5. The important feature of any formed radius profile used is that when the joist hanger rests on a wall no pressure is exerted on the edge portion. A hump portion 46 extends the distance D between the point where the lawer surface of the masonry flange 42 and the upper suface of the block 41 are out of contact. The distance D may be up to 40 mm or more at the central portion of the masonry flange.

An alternative embodiment of the joist hanger in shown in Figure 6 where like reference numerals have the same meaning as those shown in Figure 1. In this embodiment a rectangular hump 46, formed by pressing, joins the formed radius profile 3 to the flange 2. The longer side of the hump 46 is parallel to the axis of the extended fold. The hump 46 increases the rigidity of the fold and reduces the edge contact area of the masonry flange 4. Slots 47 between the flange 4 and the hump 46 provide extra flexibility and assist location the upper surface of block walls.

A further modification of the joist hanger shown in Figure 6 consists of a hump 48, formed by pressing, which adds rigidity the the rear face 8 of the stirrup portion 1 and prevents bending about the upper fold 18 of the joggle.

A joist hanger according to the invention which avoids locking folds, see Figure 7, comprises a stirrup portion 50 connected to a masonry flange 51 through a formed radius profile 52. The profile 52 takes the form of an extended fold between the stirrup 50 and the flange 51. The masonry flange is shown as a plate 53 carrying butterfly folds 54 and 55 at each edge. The plate may be optionally pierced with one or more fixing holes. The profile 52 extends across the width of the stirrup 50. A rectangular hump 56 joins the central portion of the profile 52 to the plate 53 to increase its rigidity. The extended fold 52 reduces to a pair of right angle folds, 57 and 58, at each edge. These folds join flaps 59 and 60 to the plate 53.

The extended fold 52 ensures that the edges of a masonry block on which it is placed are not crushed as it carries the major portion of the load placed on the stirrup portion 50. The flaps 59 and 60 assist location of the joist hanger on a block or course.

The stirrup portion 50 consists of a rear face 61 and a base 62 formed by the folding of a sheet metal channel.

The sides 63 and 64 of the channel act as retaining walls locating a joist within the stirrup 50 and preventing twist. The sides may 63 and 64 may be pierced by one or more holes, not shown, to retain the joist within the stirrup using suitable fixing means.

In the embodiment of the invention shown in Figures 7 to 10 great strength is obtained without the use of folds or fixing devices to maintain the stirrup portion of the joist hanger in position.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.

Claims

1. A joist hanger comprising a masonry flange, adapted to lie on the upper surface of a supporting wall, connected through a right angle to a stirrup portion, adapted to carry the end of a joist. characterised in that a formed radius profile is used to join the masonry flange to the stirrup portion whereby the pressure on the edge of the supporting wall caused by any load on the stirrup portion is reduced.

2. A joist hanger according to claim 1 characterised in that the masonry flange and the stirrup portion are formed from a single sheet of metal.

3. A joist hanger according to any of the preceding claims characterised in that the edges of the formed radius profile provide a clearance of at least 6 mm from the point where the plane of the masonry flange crosses the rear surface of the stirrup portion.

4. A joist hanger according to claim 3 characterised in that the edges of the formed radius profile provide a clearance of from 3 mm to 40 mm from the point where the plane of the masonry flange crosses the rear surface of the stirrup portion.

5. A joist hanger according to any of the preceding claims characterised in that the base plate of the stirrup portion carries flaps attached to the rear face of the stirrup portion by a self-locking connection.

6. A joist hanger according to claim 5 characterised in that the flaps are attached to the rear face of the stirrup portion by means of a swaged or plunged joint.

7. A joist hanger according to either claim 5 or 6 characterised in that the flaps are accomodated within the rear face of the stirrup portion by means of a joggle pressed into the rear face.

8. A joist hanger according to any of the claims 1 to 4, characterised in that the stirrup portion consists of an upper portion and a base plate comprising a channel whose sides act as retaining walls.

9. A joist hanger according to any of the preceding claims characterised in that joist hanger is fabricated from galvanised or stainless steel having a thickness in the range 2.5 mm to 6mm.

10. A joist hanger according to any of the preceding claims characterised in that the width of the stirrup portion lies in the range 38 mm to 125 mm.

11. A joist hanger according to any of the preceding claims characterised in that the distance between the base and the upper fold lies in the range 76 mm to 500 mm.

12. A joist hanger according to any of the preceding claims characterised in that the formed radius profile comprises an extended fold between the stirrup portion and the masonry flange combined with a hump pressed into the masonry flange.

13. A joist hanger according to claim 12 characterised in that the hump is substantially triangular with one side parallel to the axis of the fold.

14. A joist hanger according to claim 12 characterised in that the hump is substantially rectangular with the longer side parallel to the axis of the fold.

15. A joist hanger according to any of the preceding claims characterised in that the rear face of the stirrup portion carries a strengthening bump.

16. A joist hanger according to any of the preceding claims characterised in that the masonry flange carries location flaps.

17. Joist hangers according to claim 1 and as herein described.

18. Joist hangers as herein described with reference to the accompanying drawings.