[0001] 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.
[0002] 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.
[0003] 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.
[0004] The latter method is unsatisfactory as it is expensive and can cause distortion.
However, up-grading of building standards mean that a thin galvanic coating is unacceptable.
[0005] Additionally, the width of the metal strip forming the lazy Z section is equivalent
to the width of the joist and therefore forms a relatively narrow bearing portion
resting on the load bearing wall. It does not spread the load substantially along
the length of the wall nor does it offer much lateral restraint to the joist.
[0006] Two-part hangers have been proposed but may give rise to jointing problems even where
welding is not used.
[0007] It is an object of the present invention to provide a new or improved joist hanger
which overcomes or reduces these disadvantages and which is economical to produce.
[0008] According to the invention there is provided a joist hanger comprising a strip of
material formed to provide a stirrup portion; a pair of abutment portions adapted
to abut a forward face of a supporting element; and a pair of bearing portions adapted
to rest on a horizontal top face of the supporting element in use; characterised in
that; the stirrup portion has a base and a pair of integral side walls extending upwardly
away from the base; the abutment portions are each integrally connected to respective
side walls at a substantially upright fold line so as to lie at least partly within
the boundary of the stirrup defined by the base and side walls; and the bearing portions
are each integrally connected to respective abutment portions at a substantially horizontal
fold line.
[0009] It will be appreciated that, for convenience of description, terms such as "upwardly"
and "horizontal" are used in this description to denote the positions of parts of
the joist hanger considered in use in supporting a timber.
[0010] The material of the strip may be slit at its forward edges to define the tops of
each of the side walls. The portion of the strip immediately above the slit may be
coplanar with the associated abutment portions.
[0011] The side walls may extend generally rearwardly and upwardly from the base.
[0012] A shoe plate may be secured to the base of the stirrup portion to enlarge its effective
area. The shoe plate may extend rearwardly of the base and may have a rear edge portion
substantially coplanar with the abutment portions.
[0013] The rear edge portion of the shoe plate may be rolled or folded to provide an enlarged
bearing area adapted to abut the supporting element.
[0014] The shoe plate may be secured to the base by cooperating inter-engaging formations,
for example slot and lug formations or hook formations, which may be permanently secured
by deforming the material of the strip.
[0015] The shoe plate may have location means to enable the shoe plate to be correctly positioned
relative to the base. The location means may be pressed formations also adapted to
stiffen the shoe plate.
[0016] The stirrup portion may include a rear edge flap integrally connected with the base
and folded to lie generally coplanar with the abutment portions. The flap may be folded
upwardly to lie within the stirrup or may be folded downwardly to provide an enlarged
bearing area, adapted to abut the supporting element.
[0017] The invention further provides a return type joist hanger comprising a joist hanger
as set out in the foregoing statements of invention characterised in that each bearing
portion has a locking formation and in that a return member of angle shape is provided
having at least one pair of cooperating locking formations, the return member being
integrally secured to the bearing portions by interlocking and permanently deforming
the respective locking formations, so as to be adapted to hook over said supporting
element in use.
[0018] According to a further aspect of the invention there is provided a straddle type
joist hanger comprising a pair of joist hangers according to any of the foregoing
statements of invention characterised in that each bearing portion of each of said
joist hangers has a locking formation and in that a straddle member is provided having
at least two pairs of cooperating locking formations,the straddle member being integrally
secured to the bearing portions by interlocking and permanently deforming the respective
locking formations, so as to be adapted to straddle said supporting element in use.
[0019] Viewed from a further aspect, the invention also provides a method of making a blank
for a joist hanger as set out above, wherein a pair of opposed cropping tools are
used to crop opposite ends of the blank from sheet metal, the method being characterised
in that the spacing of the opposed cropping tools can be selectively varied to produce
blanks for differently sized hangers.
[0020] The width of the blank may also be varied for different tool separations.
[0021] A joist hanger embodying 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 blank from which joist hangers of various sizes can be formed.
FIGURE 2 is a side elevational view of a joist hanger embodying the invention.
FIGURE 3 is a plan view of the joist hanger of Figure 2.
FIGURE 4 is a front elevational view of the joist hanger shown in Figures 2 and 3.
FIGURE 5, FIGURE 5 & FIGURE 7 are'views similar to Figures 2 to 4 of a smaller sized
joist hanger embodying the invention.
FIGURE 8 is a plan view of the shoe plate of the hanger shown in Figures 2 to 4.
FIGURE 9 is a side elevational view of the shoe plate of Figure 8.
FIGURE 10 is a plan view of a blank for making a joist hanger.
FIGURE 11 is a joist hanger made from the blank of Figure 10 shown in side elevation,
in use.
FIGURE 12 is a front elevational view of the hanger only, taken on the arrow A of
Figure 11.
FIGURE 13 is a front elevational view of a smaller size of joist hanger.
FIGURE 14 is a detail view of a bearing portion of a joist hanger.
FIGURE 15 is a plan view of a return type joist hanger.
FIGURE 16 is a vertical part sectional view of the return hanger.
FIGURE 17 is a similar view to Figure 16 of a straddle type joist hanger.
[0022] Referring firstly to Figures 2 to 4 of the drawings, a joist hanger generally indicated
at 10 comprises a main part formed from a single sheet metal blank 11 shown in more
detail in Figure 1, together with an optional shoe plate 12 shown in Figures 8 and
9.
[0023] The blank 11 is formed into a stirrup part generally indicated at 13 which includes
a base 14 and a pair of substantially upright side walls 15 spaced to form a seating
for a joist of a specific size. It will be appreciated that a range of joist hangers
of varying widths and depths will be provided to accommodate different sizes of joist
(or other timber) and the manufacture of such hangers using the same basic blank shown
in Figure 1 will be referred to later.
[0024] Each of the side walls 15 will be seen to extend upwardly and rearwardly as shown
at 16, away from the base 14. In use, the base 14 is positioned away from the supporting
element 17 which may be a masonry wall, timber, concrete beam or the like. This means
that the positioning of the joist within the hanger can clearly be seen and the end
of the joist can be ventilated through the opening behind the inclined edge 16 of
the side walls. Fastenings to secure the joist in the stirrup portion 13 are made
through the fastening holes 17 shown in Figure 2.
[0025] Each side wall 15 is integrally contacted at a generally upright fold line-18, to
an abutment portion 19 which lies against the forward face of the supporting element
17 in use. The abutment portions are turned inwardly towards each other so as to lie
at least partly within the boundary of the stirrup defined by the base and side walls.
The abutment portion 19 has an enlarged surface area at the top of the joist hanger
where a slit 20 in the forward edge of the blank enables the part above the slit to
extend laterally outwardly so as to provide the enlarged portions 19a of the abutment
portions.
[0026] Finally, each of the abutment portions 19 is integrally connected by a horizontal
fold line 21 to a bearing portion 22 which rests on the supporting element 17. This
may be secured in any suitable manner to the supporting element, for example by being
embedded in a mortar coursing joist where the supporting element is a masonry wall,
or being bolted or nailed in place to timber.
[0027] For use in face fixing, the bend 21 can be omitted so that the bearing portion is
aligned with the abutment portion to enable the hanger to be secured by bolting to
the face of a concrete or metal beam.
[0028] In addition to the main sheet metal blank 11, the joist hanger shown in Figures 2
to 4 also includes a shoe plate 12 which is secured by cooperating inter-engaging
formations in the form of a pair of projecting lugs 23 engaging in corresponding slots
of the base of the base 14. Correct positioning of the shoe plate in the stirrup 13
is assisted by location ribs 24 which also serve to stiffen the rearwardly projecting
part of the shoe plate 12. The extreme rear edge 25 of the shoe plate 12 is bent downwardly
to provide an enlarged bearing area abutting the supporting element 17 and substantially
coplanar with the abutment portions 19.
[0029] The joist hanger provides a firm seating for the joist ai.d provides a very considerable
bearing area on which the joist load can be transmitted to the supporting structure
17. This bearing area is provided by the enlarged bearing portions 22, each of which
is the full width of the metal strip blank. It will also be seen that these bearing
elements extend laterally of the main body of the hanger in use and hence will spread
the load along the supporting element 17 over a considerable distance. In addition
to reducing localised loading of the supporting element, which may cause crumbling
if it is for example light-weight blockwork, the increased width of the bearing area
also assists in providing lateral restraint to the joist. A floor made up on joists
supported in this manner tends to act as a rigid diaphragm which in turn can be used
to give lateral support to associated walls to increase the structural stability of
a building.
[0030] Additionally, the face of the supporting structure 17 is contacted by the abutment
portions 19, 19a over a substantial area which may assist in protecting the supporting
structure, particularly where this is made of relatively soft light-weight building
blocks. End loading on the joists is also spread over a substantial area and the length
of the fold lines 21 which act as stiffeners also tends to increase the rigidity of
the joist support.
[0031] In a conventional lazy Z type joist hanger, there is a tendency for the metal of
the Z shaped main supporting element to straighten out under joist loading which may
tend to cause the shoe part of the hanger to droop and the bearing part to pull out
of the masonry. The present hanger, however, is much less prone to this type of deformation
because the load carrying stirrup 13 is spaced forwardly away from the supporting
structure 17 and any load tending to "straighten" the joist hanger is carried as a
reaction load on the downwardly turned rear edge 25 of the shoe plate.
[0032] The long upright fold lines 18 at which the bearing portions 19 meet the side walls
15 tend to stiffen and rigidify the hanger and improve lateral restraint of the joist
and also ensure that the whole bearing portion 19 is substantially in contact with
the supporting structure 17.
[0033] The shoe plate could be omitted for some applications. It would then be necessary
to use a stirrup which made contact at its rear edge with the supporting structure
In this case, the blank shown in Figure 1 would need to be modified to provide a broader
central portion. This would not achieve the same economy in the use of metal as can
be obtained using the blank shown in Figure 1, to which reference will now be made
in more detail.
[0034] In order to manufacture the hanger, a sheet metal blank as shown in Figure 1 is used.
This is pre-galvanised and it will be appreciated that, because the hanger is entirely
free of welding, the galvanised coating can be thick and durable, and corrosion resistance
of the material is retained throughout manufacture of the hanger. A series of blanks
can be cut side-by-side from a metal sheet without substantial wastage.
[0035] The blank 11 includes a central part 26 which provides the base 14 and the lower
upright sections of the side walls 15. The strip then comprises a pair of obliquely
angled parts 27 which form the rearwardly inclined parts of the side walls 15 having
their inclined edges 16, and which also form the lowermost regions of the abutment
portions 19.
[0036] The opposite edge of the strip is notched at 20 to provide the dividing position
between the upper edges of the side walls 15 and the lateral projecting parts 19a
of the abutment portions. The fold line 21 can also be seen.
[0037] In the central region 26 of the strip, folding at the fold lines 26a defines a stirrup
portion suitable for making the joist hanger shown in Figures 2 to 4 of the drawings.
The slots 28 are punched out of the material in the central region, to receive the
corresponding lugs 23 of the shoe plate.
[0038] However, in order to make a joist hanger of a smaller size such as that shown in
Figures 5 to 7 of the accompanying drawings, the central part 26 of the blank 11 is
folded about the alternative fold lines 29 and, instead of the two slots 28 being
punched, a single slot 30 is punched from the central part 26 of the strip. The slots
20 are not provided but are replaced by alternatively positioned slots 31, closer
to the central part of the strip. However, the blank is folded along the same upright
fold line 18.
[0039] Because of the width of the blank, this would cause the abutment portions 19 and
bearing portions 21 to overlap so the shaded region 32 of the strip is angled outwardly
as best seen in Figures 6 and 7 of the drawings. The ends of the blank 11 can be cropped
off so that the bearing portions 22 are of suitable size.
[0040] This avoids the other possible way of ensuring that the abutment and bearing portions
do not meet which would be to enlarge the length of the slot 31 in the edge of the
blank 11 and alter the position of the corresponding fold line 18. This is undesirable
because it would weaken the hanger.
[0041] Apart from this sloping of the side walls at 32, the hanger shown in Figures 5 to
7 is similar to that of Figures 2 to 4. It will be seen, however, that the shoe plate
12 is narrower, in order to fit within the narrow stirrup and only has a single lug
23 engageable within the single slot 30 of the stirrup base 14. A pair of location
formations 24 are, however, provided to ensure correct positioning of the shoe plate
in relation to the stirrup.
[0042] Figures 8 and 9 of the drawings show the shoe plate in more detail. The lugs 23 are
pressed from the material of the shoe plate 12 leaving windows 33. The location formations
24 are in the form of shallow channels having straight ends 34 which define the position
of the rear edge of the stirrup base 14 in use. Because the location formations are
pressed in the metal of the shoe plate, they tend to rigidify the rear part of the
shoe plate. The downwardly turned rear edge 25 also increases the stiffness of the
shoe plate but in the opposite, transverse, direction, as well as providing a slightly
enlarged bearing area for the shoe plate to abut against the supporting structure
17.
[0043] In use, the joist hanger embodying the invention offers security, lateral restraint
to the joist and considerable resistance to deformation. Its manufacture can be performed
economically in a range of sizes using the same main tooling and merely changing the
position of slots and bend lines according to the sizes required. The construction
of the hanger entirely without welding from its manufacture from pre-galvanised material
without damage to the corrosion resistance of the material.
[0044] An alternative embodiment of the joist hanger is shown in Figures 10 to 13 of the
drawings, this form of joist hanger using a blank which is of varying widths throughout
its length, rather than the constant width blank used for the first embodiment of
hanger.
[0045] Referring firstly to Figure 10 of the drawings, a blank 40 for making a joist hanger
is formed from a single piece of sheet metal. Whilst this may be stainless steel for
example, the hanger to be described can advantageously be made of heavily galvanised
mild steel since no jointing either by welding or mechanical means is required in
the construction of the hanger.
[0046] The blank 40 is cropped from sheet metal which may have a strip width as shown in
full lines or may terminate at the dotted lines 41 and 41a, for making small sizes
of hanger. The cropping operation is carried out using opposed cropping tools and,
by selectively varying the spacing between the tools, blanks for different sizes of
hanger can be made without requiring different tooling for each size.
[0047] The blank comprises a central portion 42 which will form the shoe into which a joist
is inserted, and a pair of side strips 43 linked to the central portion by a gusset
44. A pair of opposed angular cut-outs 45 are provided in the longitudinal edge of
the blank, each cut-out 45 having its more central edge 46 angled at an obtuse angle,
typically 60
0, to the general longitudinal axis of the blank. The outer angled edge 47 of the cut-out
is more acutely angled, typically at 30°, so that the included angle of the cut-out
45 is 90°. These angles can be varied slightly if desired provided that the included
angle does not fall below 90
0. The edge 47 of the cut-out meets a further edge 48 which is at right angles to the
longitudinal axis of the blank. This edge 48 is omitted if a narrow blank having the
boundary 41a is used.
[0048] The cut-outs 45 effectively define between them the width of the joist receiving
shoe which is formed from the central part 42 of the blank by transversely folding
along the lines 49. A longitudinal fold line 50 links the apices of the cut-outs 45
and defines a rear flap 51 which can be turned upwardly to define part of the back
of the shoe or which can be turned downwardly in a modification.
[0049] The longitudinal fold line 50 continues at 52 into the side strips 43 and terminates
at a notch 53 in the upper edge of the blank as shown. The portions of the blank 54
beyond the notches 53 form the bearing portions of the hanger.
[0050] It will be seen that the blank 40 is symmetrical about the centre line 55. In order
to make smaller sizes of joist hanger, a strip of narrower width indicated by the
dotted lines 41 and 41a is used and the cropping tools are advanced towards each other
so that the cut-outs adopt the dotted line positions 45a. The transverse fold lines
defining the width of the shoe are then made at 49a. It will be appreciated that the
overall length of the blank is reduced by a corresponding amount and that the gussets
44 and notches 53 at either end of the blank will be positioned inwardly from those
illustrated in full lines in the drawing.
[0051] Referring now to Figures 11 and 12 of the drawings, these illustrate a large size
joist hanger made from the blank of Figure 10. The base 56 of the stirrup portion
57 corresponds to the central part 42 of the blank between the fold lines 49, the
position of which is indicated. The stirrup portion 57 of the hanger also has side
walls 58 and the position of the gusset 44 and notch 53 can be seen. The longitudinal
fold lines 52 of the blank are also indicated.
[0052] The central flap 51 can be seen at the rear of the shoe portion bent upwardly along
the fold line 50. Abutment portions 59 are formed from the parts of the side members
43 of the blank which are shown below the fold line 52. These abutment portions are
coplanar with the flap 51 and it will be appreciated that, when a right angled fold
is made at 52 and at 49 on the blank 40, the edges 46 and 47 of the cut-outs come
into close proximity at the rear of the shoe as shown.
[0053] The abutment portions 59 become wider, taking up the full width of the strip, above
the position of the notches 53 and are folded transversely at 60 to form bearing portions
61 to rest on a supporting structure such as a wall. As a final stage of manufacture,
stiffening ribs 62 are pressed into the material of the hanger linking the abutment
portions 59 and bearing portions 61.
[0054] In a modification, which is shown in dotted lines in Figure 12, the flap 51 is bent
downwardly at the fold line 50 to provide a rear abutment 51a which is again coplanar
with the abutment portion 59 of the side straps. The presence of such a lower abutment
51a effectively increases the vertical height of the hanger against the supporting
wall and hence may tend to reduce the leverage acting on the bearing portions 61.
[0055] It will be seen that the joist hanger again has a much greater width than the joist
to give lateral restraint and this is also assisted by the presence of the transverse
folds 60 and 50 and the stiffening rib 62. The large bearing area of the bearing portions
reduces the localised loading on the supporting structure which may be advantageous
where this of lightweight blockwork of low load bearing capacity, or of timber for
example.
[0056] Any tendency for the forward or open end of the shoe to sag downwardly under load
is resisted by the long, relatively stiff angled sections formed between the side
walls 58 and the abutment portions 59, linked by the long fold line 52. The hanger
is therefore extremely rigid compared with conventional hangers.
[0057] Figure 13 shows a small sized joist hanger made from a blank using the same tooling
as the large sized hanger but acting on a narrower strip of metal between the dotted
line 41 and the lower dotted line 41 a of the blank shown in Figure 10. The two part
cropping tools are moved so that the cut-outs adopt the position shown at 45a and
the blank is then folded in precisely the same manner as before resulting in the hanger
shown in front elevation in Figure 13. It will be noted that the lesser width of the
strip results in the absence of the edges 48 to prevent overlap of the abutment portions
59 in the smaller size of hanger. The reduction in the amount of metal does not give
rise to strength problems since the load bearing capacity of the smaller joist is
of course less than a larger joist and therefore the hanger loading is correspondingly
reduced.
[0058] Figures 14 to 17 illustrate some modified forms of the joist hanger used in conditions
where a return or straddle type joist hanger is required.
[0059] A return type joist hanger is particularly used in circumstances where there are
not many courses of masonry above the position of the joist hanger in a masonry wall.
It is therefore necessary for the hanger to be provided with a return member to hook
over the masonry and hold it steady.
[0060] Figure 14 of the drawings shows in detail the portions 61 of the blank at the extreme
free ends, which form the bearing portions of the hanger. Each bearing portion 61
is provided with a longitudinal stiffening rib 62 and is also provided with an upturned
tab 64 in its inwardly facing edge. Where a return or straddle type hanger is to be
produced for use with a wall of narrow width, the end of the bearing portion may be
cropped off at one of the dotted lines 63 or 63a, depending on the width to be provided
for. Where a narrow bearing width is to be catered for, the position of the tab 64
may be moved to the dotted line position 64a, that is when the end of the bearing
portion is cropped off too short to accomodate the tab in the position 64.
[0061] A return hanger is formed by combining a single joist hanger with a return plate
65 of angle shape, shown in Figures 15 and 16. The return member 65 is provided with
a number of pairs of slots 66 which can receive the respective tabs 64 of the bearing
portions 61 of the hanger. These tabs are then peened over as shown in Figure 16 so
as to mechanically interlock the return member to the bearing portions of the hanger.
[0062] Figure 17 illustrates a straddle type joist hanger for use where two joist hangers
are to be used at opposed sides of the same supporting wall in line with each other.
In principle this is similar to the return hanger except that a straddle member 70
of plate like form is provided with at least two pairs of slots 66 to receive respective
pairs of tabs 64 of the hangers which are arranged back to back. Again, the tabs are
peened over in the slots to mechanically interlock the two hangers with the straddle
member.
1. A joist hanger comprising a strip of material formed to provide a stirrup portion;
a pair of abutment portions adapted to abut a forward face of a supporting element;
and a pair of bearing portions adapted to rest on a horizontal top face of the supporting
element in use; characterised in that the stirrup portion has a base and a pair of
integral side walls extending upwardly away from the base; the abutment portions are
each integrally connected to respective side walls at a substantially upright fold
line so as to lie at least partly within the boundary of the stirrup defined by the
base and side walls; and the bearing portions are each integrally connected to respective
abutment portions at a substantially horizontal fold line.
2. A joist hanger according to Claim 1 further characterised in that the material
of the strip is slit at its forward edges to define the tops of each of the side walls.
3. A joist hanger according to Claim 2 further characterised in that the portion of
the strip immediately above the slit is coplanar with the associated abutment portions.
4. A joist hanger according to any preceding claim further characterised in that the
side walls extend generally rearwardly and upwardly from the base.
5. A joist hanger according to any preceding claim further characterised in that a
shoe plate is secured to the base of the stirrup portion to enlarge its effective
area.
6. A joist hanger according to Claim 5 further characterised in that the shoe plate
extends rearwardly of the base and has a rear edge portion substantially coplanar
with the abutment portions.
7. A joist hanger according to Claim 6 further characterised in that the rear edge
portion of the shoe plate is rolled or folded to provide an enlarged bearing area
adapted to abut the supporting element.
8. A joist hanger according to any one of Claims 5 to 7 further characterised in that
the shoe plate is secured to the base by cooperating inter-engaging formations such
as slot and lug formations or hook formations.
9. A joist hanger according to Claim 8 further characterised in that the inter-engaging
formations are permanently secured by deforming the material of the strip.
10. A joist hanger according to any one of Claims 5 to 9 further characterised in
that the shoe plate has location means to enable it to be correctly positioned relative
to the base of the stirrup.
11. A joist hanger according to Claim 10 further characterised in that the location
means are pressed formations also adapted to stiffen the shoe plate.
12. A joist hanger according to any one of Claims 1 to 3 further characterised in
that the stirrup portion includes a rear edge flap integrally connected with the base
and folded to lie generally coplanar with the abutment portions.
13. A joist hanger according to Claim 12 further characterised in that the flap is
folded upwardly to lie within the stirrup.
14. A joist hanger according to Claim 12 further characterised in that the flap is
folded downwardly to provide an enlarged bearing area adapted to abut the supporting
element.
15. A return type joist hanger comprising a joist hanger according to any one of Claims
1 to 14 characterised in that each bearing portion has a locking formation and in
that a return member of angle shape is provided having at least one pair of cooperating
locking formations, the return member being integrally secured to the bearing portions
by interlocking and permanently deforming the respective locking formations, so as
to be adapted to hook over said supporting element in use.
16. A straddle type joist hanger comprising a pair of joist hangers according to any
one of Claims 1 to 14 and further characterised in that each bearing portion of each
of said joist hangers has a locking formation and in that a straddle member is provided
having at least two pairs of cooperating locking formations, the straddle member being
integrally secured to the bearing portions by interlocking and permanently deforming
the respective locking formations, so as to be adapted to straddle said supporting
element in use.
17. A method of making a blank for a joist hanger according to any one of Claims 1
to 14 where a pair of opposed cropping tools are used to crop opposite ends of the
blank from sheet metal, the method being characterised in that the spacing of the
opposed cropping tools can be selectively varied to produce blanks for differently
sized hangers.
18. A method according to Claim 17 further characterised in that the .width of the
blank is also varied for different tool separations.