GB2400384A

GB2400384A - Joist hanger provided with a bottom flange

Info

Publication number: GB2400384A
Application number: GB0324445A
Authority: GB
Inventors: Ian Harrison
Original assignee: Simpson Strong Tie International Inc
Current assignee: Simpson Strong Tie International Inc
Priority date: 2003-10-20
Filing date: 2003-10-20
Publication date: 2004-10-13
Anticipated expiration: 2023-10-20
Also published as: GB2400384C; GB0324445D0; US20050120669A1; GB2400384B

Abstract

A joist hanger 10 for use in the construction industry comprises first and second side flanges 30, 40, a seat 50, at least one back flange 61 and at least one bottom flange 80; wherein the seat is provided between the first and second side flanges 30, 40 to form a stirrup for supporting a first joist 1, 2, 3. A back flange adjoins at least one of the side flanges 30, 40 in a plane approximately perpendicular to planes including the adjoining side flange 30, 40 and the seat 50. A bottom flange 80 adjoins the back flange 61 proximal to the seat 50 and in a plane approximately parallel to a plane including the seat 50. The back flange 61 and the bottom flange 80 together form a bracket for abutting a lower surface and a side surface of a second joist. A top flange (62, fig 5a) may adjoin the back flange 61. A lower return leg (91), and upper return leg (90) may adjoin the bottom flange 80 and the top flange (62) respectively (figures 6-8). Each of the flanges may have apertures for fixing. The stirrup may be tapered in width from the mouth.

Description

Bottom Flange Hanger The present invention relates to a joist hanger for

use in the construction industry.

Within the context of this specification the word "comprises" is taken to mean "includes, among other things". It is not intended to be construed as "consists of only".

A known method of floor or roof construction in residential buildings typically comprises the step of providing a number of approximately parallel supporting joists.

Thereafter flooring or roofing is positioned atop the supporting joists. However, there are many situations during the construction of a floor or roof in which it is necessary to create an aperture, usually rectangular, through the floor or roof e.g. for a staircase or roof light. In these situations it is known to split the span of one or more supporting joists thereby forming trimmed joist(s). The cut ends of the À trimmed joist(s) are supported by trimmer joist(s) positioned adjacent the aperture and the trimmer joists are usually supported between adjacent supporting joists. À

This is illustrated in Figure 2. Joist hangers are generally provided at the junction between (a) one end of a trimmer joist and a supporting joist; or (b) one end of a trimmed joist and a trimmer joist. À. À À À Àe

A traditional joist hanger is shown in Figure 11 wherein the joist hanger 10, comprises a joist bearing slot 20 formed by opposed approximately parallel spaced apart side flanges 30, 40 and a joining bottom flange 50, the side flanges are joined to an angle bracket 60 by weld lines 70. The angle bracket 60 is arranged such that a first face thereof provides a back flange 61, attached to the joist bearing slot, whilst a second face thereof, provides a top flange 62 arranged at a right angle to the back flange 61. In use, the joist hanger 10, is set with the back flange 61 tight against a support. The top flange 62, is of course at this point resting on a top surface of the support.

Hangers folded from a single piece of metal are also known. An example of a hanger produced of a single piece of metal is the well known ITT _ hanger sold by Simpson Strong Tie.

There are a number of different forms of floor joist used in construction, three main types being: i) Traditional rectangular solid sawn timber; ii) Engineered timber "l" shaped joists comprising a narrow web and rectangular top and bottom flanges; and iii) Engineered timber truss joists comprising rectangular timber top and bottom flanges which are spaced apart by a lattice work of metal webs.

Known joists of solid timber suffer from the problem that they are prone to shrinkage and distortion. To address this problem 'I' joists have been developed which typically consist of two rectangular flanges attached by a web. A cross À . sectional view of an 'I'joist is shown in Figure t. The flanges are usually either solid À sawn or composite laminated timber and the web is usually manufactured from panel timber such as plywood or oriented strand board (OSB). In the case of À flooring, the I joists are provided with their flanges lying in horizontal planes and their webs positioned vertically. À.- À À Àe

However, as disclosed in GB2376700 (sullen Building Products Limited), it is difficult to make an orthogonal junction of 'I' joists because connection to one or both flanges of an 'I' joist can cause rotation of the flange(s) relative to the web and this limits the load bearing capacity of the joist. In the past, as shown in Figures 3A and 3B, this has been facilitated by packing the gap between the web and the flanges of the 'I' joist with a backer block, thereby limiting rotation. However, it has been found that the backer blocks are costly, time consuming and difficult to install correctly often resulting in inadequate installation. In addition, if the backer blocks have high moisture content when installed they can subsequently shrink on drying and create a gap to the underside of the top flange enabling rotation to take place.

GB2376700 suggests that this problem should be addressed by a hanger having a first bracket having first and second side members with an intermediate member therebetween capable of supporting a flange of one end of a first 'I' joist, and a second bracket having first and second side members and an intermediate member therebetween adapted in use to overlie the upper flange of a second 'I' joist. Fixing apertures are provided in all the side members particularly to facilitate connection of the upper flange of the end of the first 'I'joist to the first bracket.

A need exists for new equipment for facilitating the erection of a building structure which can be used easily, which reduces the burden required to secure a first joist to a second joist, which is strong and which facilitates the use of all known joists including joists of"I" shaped section.

It is an aim of preferred embodiments of the invention to solve or reduce at least one of the problems set out above.

Remarkably, an embodiment of a joist hanger which is the subject of this invention, À addresses or solves one or more problems of the prior art by inclusion of a bottom À. flange which can be fixed (eg by one or more nails) to the underside of the supporting joist bottom flange. Advantageously, it has been found that this feature À creates a connection capable of resisting rotation.

À : Accordingly, in a first aspect the invention provides a joist hanger which comprises : first and second side flanges, a seat, at least one back flange and at least one À Àe bottom flange; wherein the seat is provided between the first and second side flanges to form a stirrup for supporting a first joist; a back flange adjoins at least one of the side flanges in a plane approximately perpendicular to planes including the adjoining side flange and the seat; a bottom flange adjoins the back flange proximal to the seat and in a plane approximately parallel to a plane including the seat; and the back flange and the bottom flange form a bracket for abutting a lower surface and a side surface of a second joist.

Preferably, at least one of the side flanges defines one or more fixing apertures for receiving a fixing (eg a nail or screw). Preferably, the fixing apertures are positioned to facilitate fixing to the flange(s) of an 'I' joist. In addition, preferably the fixing apertures are staggered to minimise the risk of splitting wooden flanges of en 'I' joist.

Preferably, the seat defines one or more fixing apertures for receiving a fixing (eg a nail or screw). Preferably, the fixing apertures are positioned to facilitate fixing to the flange(s) of an 'I' joist. In addition, preferably the fixing apertures are staggered to minimise the risk of splitting wooden flanges of an 'I' joist.

Preferably, at least one of the back flanges defines one or more fixing apertures for receiving a fixing (eg a nail or screw). Preferably, the fixing apertures are positioned to facilitate fixing to the flange(s) of an 'I' joist. In addition, preferably the fixing apertures are staggered to minimise the risk of splitting wooden flanges of en 'I' joist. À-e.

À Preferably, the bottom flange(s) define(s) one or more fixing apertures for receiving À. a fixing (eg a nail or screw). Preferably, the fixing apertures are positioned to facilitate fixing to the flange(s) of an 'I' joist. In addition, preferably the fixing À apertures are staggered to minimise the risk of splitting wooden flanges of en 'I' Àe À joist. À.

In use, an embodiment of a joist hanger according to the invention can be fixed to a supporting joist wherein the bottom flange abuts a bottom surface of the supporting joist and the back flange abuts a side surface of the supporting joist. The stirrup of the joist hanger projects from the supporting joist and is capable of receiving and supporting a further joist.

Accordingly, in a second aspect the invention provides a method for connecting a first and second joists which comprises the step of fixing a joist hanger according to a first aspect of the invention to the second joist and fixing the first joist to the joist hanger.

Advantageously, it has been found that when a first joist is connected to a second joist according to an embodiment of the method, the ability of the bottom flange of an 'I' joist to rotate relative to the web of the 'I' joist is greatly reduced.

Preferably the stirrup is tapered in width from the mouth. A taper provides the advantage of taking account of tolerance in the dimensional width of a joist and allows a joist to be tightly gripped as it is driven into the hanger.

A preferred embodiment of a joist hanger according to the invention additionally comprises at least one top flange which adjoins a back flange distal to the seat and in a plane approximately parallel to a plane including the seat; the bottom flange, back flange and top flange forming a bracket for abutting a lower surface, a side surface and an upper surface of a joist.

Preferably, at least one of the top flanges defines one or more fixing apertures for receiving a fixing (eg a nail or screw). Preferably, the fixing apertures are positioned À. to facilitate fixing to the flange(s) of an 'I' joist. In addition, preferably the fixing À.' apertures are staggered to minimise the risk of splitting wooden flanges of an 'I' joist . e À A further preferred embodiment of a joist hanger according to the invention : additionally comprises at least one lower return leg which adjoins the bottom flange; . the back flange, bottom flange and the lower return leg forming a bracket for ..

abutting a joist.

A further preferred embodiment of a joist hanger according to the invention additionally comprises at least one upper return leg which adjoins the top flange; the back flange, top flange and the upper return leg forming a bracket for abutting a joist.

Preferably the upper and/ or lower return legs lie in a plane or planes approximately parallel to a plane including the back flange(s).

Preferably, the upper and/ or lower return leg(s) define(s) one or more fixing apertures for receiving a fixing (eg a nail or screw). Preferably, the fixing apertures are positioned to facilitate fixing to the flange(s) of an 'I' joist. In addition, preferably the fixing apertures are staggered to minimise the risk of splitting wooden flanges of an 'I' joist.

Embodiments of the invention will now be described in detail with reference to the drawings in which: Figure 1 shows a cross sectional view of a typical I joist.

Figure 2 shows a schematic view of a typical arrangement of supporting joists, trimmer joists and trimmed joists. The possible position of a joist hanger is shown.

Figures 3A and 3B show schematic views of rotation of the flanges of an 'I'joist and how this rotation can be restricted by the positioning of backer blocks.

A: Figures 4A and 4B show views of a preferred embodiment of a joist hanger B'..

À . according to the invention with and without 'I' joists.

Àcc cec À . À Figures 5A and 5B show views of an alternative embodiment of a joist hanger À according to the invention with and without 'I' joists. The length of top flanges (62) corresponds to the width of the flange (1) of en 'I' joist. Be Be À

Figures 6A and 6B show views of a further alternative embodiment of a joist hanger according to the invention with and without 'I'joists. The length of top flanges (62) corresponds to the width of the top flange of an 'I' joist and return legs (90) adjoin the top flanges.

Figures 7A and 7B show views of a further alternative embodiment of a joist hanger according to the invention with and without 'I' joists. Top flanges (62) are absent.

Figures 8A and 8B show views of a further alternative embodiment of a joist hanger according to the invention with and without 'I' joists. The length of bottom flanges (80) corresponds to the width of the flange of an 'I'joist and return legs (91) adjoin the bottom flanges.

Figures 9A and 9B show views of a further alternative embodiment of a joist hanger according to the invention with and without'I'joists. Bottom flange (80) is coplanar with and extends from seat (50).

Figures 10A and 10B show views of a further alternative embodiment of a joist hanger according to the invention with and without 'I' joists. Back flanges (61) project inwardly toward each other from side flanges (30, 40) .

Figure 11 shows an embodiment of a typical known joist hanger (10).

For the purposes of clarity and a concise description features are described herein as part of the same or separate embodiments, however it will be appreciated that the scope of the invention may include embodiments having combinations of all or some Àe..

: of the features described. À. À Àe

Referring to Figures 4A and 4B, a preferred embodiment of a joist hanger (10) Àec.e À À according to the invention is formed/ folded from a single piece of metal (eg steel).

À:. Therefore, it is more economic and efficient to manufacture compared to the known joist hangers. In addition, unlike a welded two part hanger it does not require secondary protective coatings such as hot dip galvanising for durability, because À À À. unlike the known products an embodiment of the invention can be produced of steel sheet which is pre-galvanised. Alternatively the hanger (10) is formed from multiple pieces which are connected by for example welding, riveting etc. An embodiment of a hanger (10) may be formed of plastics material or timber.

The hanger (10) comprises first and second side flanges (30, 40), a seat (50), two back flanges (61) and two bottom flanges (80).

The seat (50) is provided between the first and second side flanges (30, 40) to form a stirrup for supporting a first joist (1, 2, 3).

The back flanges (61) adjoin the side flanges (30, 40) in a plane approximately perpendicular to planes including the adjoining side flanges (30, 40) and the seat (so).

The bottom flanges (80) adjoin the back flanges (61) proximal to the seat (50) and in a plane approximately parallel to a plane including the seat (50).

The back flanges (61) and the bottom flanges (80) form a bracket for abutting a lower surface and a side surface of a second joist.

The back flanges (61) project outwardly from the side flanges (30, 40).

Alternatively, the back flanges (61) project inwardly from the side flanges (30, 40) as shown in Figures 10A and JOB. In one embodiment, a single back flange (61) adjoins both side flanges (30, 40). In yet another embodiment, the back flange (61) adjoins both side flanges (30, 40) and the seat (50).

Fixing apertures are defined by the top flanges (62), bottom flanges (80), side flanges (30, 40) and back flanges (61). The apertures receive fixings (not shown) À and facilitate connection to the upper and lower flanges (1, 3) of one or more'I' joists. À

À:. The hanger (10) can be used to provide restraint of the supported joist (1,2,3) against rotation/lateral movement at its upper flange (1). The hanger side flanges À À (30, 40) are therefore preferably of sufficient height in relation to the supported joist À À À height to enable the supported joist top flanges (1) to bear against the inner faces of the side flanges (30, 40). This obviates the need for timber blocking pieces (7) to be installed to the supported joist web (2) to create the required contact with the side flanges (30, 40) to resist lateral movement of the upper part of the supported joist (1) An embodiment (10) can also be used for, and gives similar benefits, on open web beams which have a top and bottom flange connected by metal webs/struts (2).

The joist hanger (10) can be applied to solid rectangular timber joists where the benefits of reduced flange rotation and load sharing between the flanges are not required.

A preferred embodiment (10) is sized to receive a standard size of joist. Preferably, an embodiment of a hanger (10) according to the invention can accommodate any type of joist and a range of sizes allows joists of different types and sizes to be accommodated.

Although the stirrup (30, 40, 50) is described as enclosing the end part of a joist (1, 2, 3), it will be appreciated that there may be gaps or holes formed in the joist hanger such that the stirrup (30, 40, 50) only partially encloses the joist end.

Referring to Figures 5A, 5B, 6A, 6B, 7A and 7B, the top flange(s) of an embodiment of the invention are part or full width of the supporting joist top flange (1) as shown in Figures 5A and 5B or they extend over the full width of the supporting joist top flange and adjoin upper return legs (90) as shown in Figures 6A and 6B. The upper return legs (90) project downwardly from the top flange (62) for abutting the side of a joist flange (1) distal to the stirrup of the hanger (10). Alternatively, as show in À.- : Figures 7A and 7B, an embodiment of the hanger (10) has no top flange(s) (62). À. À ..

Referring to Figures 7A, 7B, 8A, 8B, 9A and 9B, the bottom flange(s) of an He À À embodiment of the invention are part or full width of the supporting joist bottom flange (3) as shown in Figures 7A and 7B or they extend over the full width of the supporting joist bottom flange and adjoin return legs (91) as shown in Figures 8A l and 8B. The lower return legs (91) project upwardly from the bottom flange (80) À À. for abutting the side of a joist flange (3) distal to the stirrup of the hanger (10). In an embodiment the bottom flanges (80) extend from the back flanges (61) proximal to the seat (50) as shown in Figures 7A, 7B, 8A and 8B. Alternatively, as shown in Figures 9A and 9B, an alternative embodiment of the hanger (10) has a single bottom flange (80) which is coplanar with and extends from the seat (50) of the stirrup.

Referring to Figure 10, back flanges (61) of an embodiment of a hanger (1) according to the invention project inwardly toward each other from side flanges (30, 4o).

It will be apparent that, in a preferred embodiment of the invention, the top flange(s) (62), back flange(s) (61) and bottom flanges (80) together define a 'C' shape. However the embodiments of the invention include within their scope any combination of the top and bottom flange variations described herein.

In a preferred embodiment the top flange(s) (62), upper return leg(s) (90) , back flange(s) (61), side flange(s) (30, 40), bottom flange(s) (80) and lower return legs (91) define fixing apertures for receiving fixings. However, it will be apparent that the fixing apertures could be absent or present. The fixing apertures are optional and any combination is possible. The fixings (not shown) facilitate connection to one or more joists (1, 2, 3). A preferred embodiment has locations of fixing apertures, but not necessarily number of fixing apertures, as shown in Figure 4.

Tests carried out demonstrate that an embodiment of a hanger according to the invention has a significantly higher failure load compared to hangers which fall outside the scope of the invention. À:- À.

À In one test, performance of an embodiment of the invention as shown in Figure 4 was compared to a similar joist hanger having no bottom flanges. Àec.e À

: In the test, a joist hanger having no bottom flanges having a thickness of about 1.5mm was fixed to appropriate joists and subjected to a load in a downward direction for a period of 10 minutes. The test was repeated a number of times and À '. the mean failure load was 11.66kN.

Thereafter, an embodiment of a hanger according to the invention as shown in Figure 4 having a thickness of about 1.5mm was fixed to appropriate joists. One nail was used to fix each bottom flange to a supporting hoist. The embodiment was subjected to a load in a downward direction for a period of 10 minutes. The test was repeated a number of times and the mean failure load was 13.91kN.

The test demonstrates that the tested embodiment had a failure load 20% higher than a similar joist hanger falling outside the scope of the invention.

The reader's attention is directed to all papers and documents which are referred to herein or filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

It will be appreciated that there are many different variations of hanger which may be envisaged incorporating the teachings of the present invention. Wherever joists are referred to in this description, the skilled man will realise that such a term is used by way of example only and that other forms of supporting structure may be used in conjunction with embodiments of the invention.

Each feature disclosed in this specification (including any accompanying claims, I abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features. In addition, all of the features disclosed in Àeae : this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or . À steps are mutually exclusive.

It should be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. À À

À Such changes and modifications can be made without departing from the spirit and scope of the present invention and without diminishing its attendant advantages. It is therefore intended that such changes and modifications are covered by the appended claims.

Claims

Claims I. A joist hanger which comprises first and second side flanges, a

seat, at least one back flange and at least one bottom flange; wherein the seat is provided between the first and second side flanges to form a stirrup for supporting a first joist; a back flange adjoins at least one of the side flanges in a plane approximately perpendicular to planes including the adjoining side flange and the seat; a bottom flange adjoins the back flange proximal to the seat and in a plane approximately parallel to a plane including the seat; and the back flange and the bottom flange form a bracket for abutting a lower surface and a side surface of a second joist.
2. A joist hanger according to claim wherein at least one of the side flanges defines one or more fixing apertures for receiving a fixing. À À.
3. A joist hanger according to claim or 2 wherein the seat defines one or more a:. : fixing apertures for receiving a fixing.
4. A joist hanger according to any preceding claim wherein at least one of the back flanges defines one or more fixing apertures for receiving a fixing. À À À.
5. A joist hanger according to any preceding claim wherein the bottom flange(s) define(s) one or more fixing apertures for receiving a fixing.
6. A joist hanger according to any preceding claim wherein the stirrup is tapered in width from the mouth.
7. A joist hanger according to any preceding claim which comprises at least one lower return leg which adjoins the bottom flange.
8. A joist hanger according to claim 7 wherein the lower return leg(s) define(s) one or more fixing apertures for receiving a fixing.
9. A joist hanger according to any preceding claim which comprises at least one top flange which adjoins a back flange distal to the seat and in a plane approximately parallel to a plane including the seat; the bottom flange, back flange and top flange forming a bracket for abutting a lower surface, a side surface and an upper surface of a joist.
10.A joist hanger according to claim 9 wherein at least one of the top flanges defines one or more fixing apertures for receiving a fixing.
ll.A joist hanger according to claim 8 or 9 which comprises at least one upper return leg which adjoins the top flange.
12.A joist hanger substantially as shown in any one of figures 4 to 10 of the accompanying drawings or as described herein with respect to figures 4 to 10 of the accompanying drawings.

12.A joist hanger according to claim 11 wherein the upper lower return leg(s) define(s) one or more fixing apertures for receiving a fixing. À:'.

I

13.A method for connecting first and second joists which comprises the step of fixing a joist hanger according to any preceding claim to the second joist and fixing the À:' : first joist to the joist hanger.

14.A joist hanger substantially as shown in any one of figures 4 to 10 of the accompanying drawings or as described herein with respect to figures 4 to 10 of À À À the accompanying drawings. / -

AmendmentS to the claims have been filed as follows Claims 1. A joist hanger which comprises first and second side flanges, a seat, at least one back flange and at least one bottom flange; wherein the seat is provided between the first and second side flanges to form a stirrup for supporting a first joist; a back flange adjoins at least one of the side flanges in a plane approximately perpendicular to planes including the adjoining side flange and the seat; a bottom flange adjoins the back flange proximal to the seat and in a plane approximately parallel to a plane including the seat; I the back flange and the bottom flange form a bracket for abutting a lower surface and a side surface of a second joist; and the seat and/or the bottom flange(s) define(s) one or more fixing apertures for receiving a fixing.

2. A joist hanger according to claim 1 wherein at least one of the side flanges defines one or more fixing apertures for receiving a fixing.

3. A joist hanger according to any preceding claim wherein at least one of the back flanges defines one or more fixing apertures for receiving a fixing.

4. A joist hanger according to any preceding claim wherein the stirrup comprises a mouth and it is tapered in width from the mouth.

5. A joist hanger according to any preceding claim which comprises at least one lower return leg which adjoins the bottom flange wherein the lower return leg comprises a flange; the back flange, bottom flange and lower return leg forming a bracket.

6. A joist hanger according to claim 5 wherein the lower return leg(s) define(s) one or more fixing apertures for receiving a fixing. I 7. A joist hanger according to any preceding claim which comprises at least one top flange which adjoins a back flange distal to the seat and in a plane approximately Is I; parallel to a plane including the seat; the bottom flange, back flange and top flange forming a bracket for abutting a lower surface, a side surface and an upper surface of a joist. i 8. A joist hanger according to claim 7 wherein at least one of the top flanges defines one or more fixing apertures for receiving a fixing.

9. A joist hanger according to claim 6 or 7 which comprises at least one upper return leg which adjoins the top flange wherein the upper return leg comprises a flange; the back flange, top flange and upper return leg forming a bracket.

10.A joist hanger according to claim 9 wherein the upper return leg(s) define(s) one i or more fixing apertures for receiving a fixing.

ll.A method for connecting first and second joists which comprises the step of fixing i a joist hanger according to any preceding claim to the second joist and fixing the,1 first joist to the joist hanger.