AU2007202286B1 - A Truss Bracket With Indication Means - Google Patents

Description

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O A TRUSS BRACKET WITH INDICATION MEANS FIELD OF THE INVENTION C"l This invention is directed to a truss bracket to attach a roof truss to a wall and which is provided with alignment means to ensure that the bracket correctly aligned to the truss after the bracket has been concreted or CN1 otherwise fixed into position.

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BACKGROUND ART

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During severe windstorm events, large uplift forces are generated on the roofs of houses. Therefore, it is now a legal requirement in many regions to have the roof truss properly secured to the wall.

One type of house uses a timber wall frame and the roof truss is secured to the top of the timber wall frame and typically to the upper horizontal wall beam. Steel threaded rods extend from the top wall beam and into the concrete floor slab.

Another type of house uses a concrete wall and the roof truss needs to be secured to the top of the concrete wall. The concrete wall is typically made of concrete blocks (known in Australia as Besser blocks). These blocks are hollow and concrete can be poured down the blocks to form a masonry wall.

There are various known arrangements by which the roof truss can be attached to a masonry wall but each suffer from disadvantages being lack of adjustability, the relatively large number of parts required, lack of proper anchoring, and the rather longer assembly and securing time required to fix the roof truss to the masonry wall.

Typically, the uppermost course of concrete blocks is provided

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O with a channel to allow reinforcement rods (also known as bond beam (-i reinforcement) to be laid horizontally in the upper course of blocks. Figure 2 tillustrates a typical known concrete block having this channel. This upper course of blocks is known as a masonry lintel.

One very well-known truss attachment system uses a steel plate 110 (known as a cleat). The cleat is substantially rectangular and typically has a oO CN1 length of 200 millimetres, a width of 50 millimetres and a thickness of five O millimetres.

0 O Figure 1 illustrates such a cleat.

The cleat is provided with an opening at the lower end to allow the cleat to be threaded on to one of the reinforcement rods. Concrete is then poured into the uppermost course of concrete blocks and about the reinforcement to anchor the cleat into the top of the masonry wall. At this stage, the top of the cleat projects from the top of the wall and this is illustrated in figure 1 which shows this type of conventional arrangement. The upper part of the cleat is also provided with a large hole to accommodate a bolt.

A roof truss is then placed against the steel cleat, and a hole is drilled through the roof truss, this hole needing to be carefully aligned with the hole in the upper part of the cleat. A bolt is then pushed through the aligned holes and a nut is attached to anchor the roof truss to the wall. One disadvantage with this arrangement is the time taken to secure the cleat into the wall, the rather large number of tools that are required which will include a drill, the need to carefully drill a hole through the truss to align with the hole in the cleat, a spanner, and need to tighten the nut (it being appreciated that a typical house will have many roof trusses each of which will need to be secured). Another disadvantage is that each truss needs to be temporarily held in place during the attachment process. A further disadvantage with the cleat arrangement is that the "hold down value" is different between different regions.

Therefore, if a larger hold down value is required, a larger bolt is used which now requires a different hole to be drilled through the truss. It is also known to attach an over strap to the cleat. The over strap is attached at one end to the bolt, extends over the top of the truss and is attached to the same bolt at the other side of the truss.

0 Another type of attachment arrangement which is not very common

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N and not particularly popular is to use a threaded rod on either side of the truss. The

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,N bottom of the threaded rod is embedded in the concrete of the masonry wall and a r- 0 timber top plate is placed on top of the bond beam.

0 In my earlier patent AU2003235057 I provided an improved truss bracket which was particularly suited to a masonry wall (although not necessarily limited thereto), and which could attach a roof truss in a manner which used less tools and which was less labour-intensive.

My earlier truss bracket consisted of a substantially U-shaped member which had a bottom wall, a first upstanding sidewall and a second upstanding sidewall, each said sidewall being provided with an opening to allow a reinforcing rod to extend through each said sidewall, one sidewall in use extending along one side 0 of the truss and the other sidewall in use extending along the other side of the truss, each sidewall being long enough to allow it to be bent over the top of the truss and down the other sidewall of the truss, each sidewall adapted to be nailed to the truss.

An advantage of my bracket was that the bracket could secure a roof truss using a hammer and nails only (or a nail gun) and therefore did not require a hole to be drilled through the truss and a nut and bolt to secure the truss. Also, each sidewall could be secured to the masonry wall to provide two anchor points instead of a single anchor point as is the case with the cleat system.

A disadvantage with the bracket as described in my earlier patent was that inexperienced trade persons could attach the bracket incorrectly which

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O could result in a reduction of the hold down strength of the bracket. This can be visualised in figure 3.

Referring to figure 3, there is illustrated a bracket 10 which has (Ni been attached incorrectly in that the over straps are not snugly positioned against the top wall 51 of top chord 11. On the other hand, bracket 12 (the rear 110 bracket) has been attached correctly in that the over straps extend snugly over oO (Ni chord 11. It is important that the over straps are always attached in the manner O illustrated by bracket 12 as this ensures that the maximum hold down strength of the bracket is achieved. Any significant misalignment (as illustrated by

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O bracket 10) can significantly reduce the hold down strength and cause the bracket to fail under high load conditions. The possible misalignment (e.g.

bracket 10) is caused by the angle of top chord 11.

To further explain and again with reference to figure 5, the typical building steps is that the top row of blocks contains the reinforcement rod (illustrated in figure 5) and the rod is held in the correct position using spaced V shaped wires (also illustrated in figure 5) this being entirely conventional. A number of brackets then threaded onto the rod (the number of brackets corresponding to the number of trusses) and are spaced apart relative to each other by the correct spacing to enable the trusses to be spaced correctly as well. Concrete is then poured into the top block to cover the reinforcing rod, most of the V shaped wire and the bottom part of the bracket. Therefore, once the concrete has cured, the bracket is fixed in position and can no longer be adjusted. Clearly, if the bracket is wrongly positioned, it cannot be fixed once the concrete is cured.

Therefore, there would be a significant advantage if it were possible to design a truss bracket in such a manner that proper alignment of the bracket can be quickly achieved even by inexperienced people. Put differently, when the brackets are initially spaced on the reinforcing rod and concrete is poured into the upper course of blocks, there would be a significant advantage if the brackets could be correctly and quickly angled (even by

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o inexperienced people) while the concrete is still wet, so that when the concrete hardens the brackets will be locked in the correct position to maximise the hold tdown strength of each bracket.

It will be clearly understood that, if a prior art publication is referred to herein, this reference does not constitute an admission that the forms part of the common general knowledge in the art in Australia oO or in any other country.

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(Ni OBJECT OF THE INVENTION

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It is an object of the invention to provide a roof truss bracket which may at least partially overcome some of the above-mentioned disadvantages or provide the consumer with a useful or commercial choice.

In one form, the invention resides in a roof truss bracket, the bracket comprising a first upstanding sidewall and a second upstanding sidewall, each said sidewall being provided with an opening to allow a reinforcing rod to extend through each said sidewall, one sidewall in use extending along one side of the truss and the other sidewall in use extending along the other side of the truss, each sidewall being long enough to allow it to be bent over the top chord of the truss and down the other sidewall of the truss, each sidewall adapted to be nailed to the truss, the sidewalls being attached relative to each other, and a visual alignment means being provided on at least one (and preferably both) sidewalls to enable the bracket to be positioned against the truss in such a manner that the sidewalls are substantially at right angles to the top chord of the truss prior to being bent over the top chord of the truss.

The visual alignment means may comprise at least one, and preferably a plurality of scribed lines or markings on a said sidewall and preferably adjacent an edge of the sidewall. A non-limiting example of a marking is illustrated as reference numeral 53 in figure 4. The marking may be 0 o formed by any suitable means. For instance, the marking may be stamped into the side wall, etched into the side wall, cut into the side wall etc. Alternatively, tthe marking may be printed or drawn onto the side wall in such a manner that it is not easily rubbed off or otherwise smudged or removed. Alternatively, the

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marking may comprise a small rib or bead. The marking may also comprise a series of small aligned openings, or dimples, or small projections, or a small 11 cutout in the side wall.

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O The alignment means preferably uses a said marking as one 10 alignment point and another part of the bracket as the other alignment point.

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O The other part of the bracket may be an upper edge, and figure 4 illustrates as reference 100 a non-limiting example of the other alignment point.

Therefore, in an embodiment of the invention, and referring to figure 4, when the bracket is positioned such that an imaginary line between 100 and 53a is vertical the imaginary line being illustrated as 50 for the purposes of understanding the invention only, but usually not actually present on the bracket), the bracket is correctly positioned to properly clamp a truss having a pitch of 150).

Similarly, if the manufactured truss has a pitch of say 200, the bracket is positioned such that an imaginary line between reference numeral 100 and marking 53c is substantially vertical.

Similarly, if the manufactured truss has a pitch of say 22.50, the bracket is positioned such that an imaginary line between reference numeral 100 and marking 53d is substantially vertical.

The bracket will typically be provided with markings that correspond to all the popular truss pitches and, in Australia at least, the popular truss pitches are 150, 17.50, 200, 22.50 and 250. Therefore in a particularly preferred embodiments of the invention there will be markings in respect of each of these angles this being illustrated in a nonlimiting embodiments of the 0 o invention illustrated in figure 4.

It is preferred that a line is provided on each side wall and Cadjacent an edge of the side wall.

Cl A typical truss will have a substantially inverted V shaped 0configuration and will comprise a bottom horizontal chord 60 see figure 5) and 00 a first and second inclined top chord 11 which are attached together at the 0apex. Various strengthening struts may be provided. Nail plates are commonly used to nail the various chords to each other.

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It is common for there to be a relatively few truss designs with the main difference being in the pitch of the truss which will determine the pitch of the roof. Thus, a truss having a higher pitch will have the top chord inclined more steeply than a truss having a lower pitch.

The pitch of the truss determines the correct positioning of the bracket against the side wall of the truss. If the bracket is tee lew is at the incorrect angle relative to the pitch of the truss. then the over straps (sidewalls) may not properly extend over the top of the chord and against the opposed side wall see figure 3).

An advantage of the system is that the bracket can secure a roof truss using a hammer and nails only (or a nail gun) and therefore does not require a hole to be drilled through the truss and a nut and bolt to secure the truss. Also, each sidewall can be secured to the masonry wall to provide two anchor points instead of a single anchor point as is the case with the cleat system.

The visual alignment means will allow all the brackets to be quickly and accurately rotated relative to the reinforcing rod to the correct angle (which will be determined by the pitch of the roof truss) while the concrete is still wet such that when the concrete dries and the brackets are locked in position,

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O all the brackets will be at the correct angle to enable the over straps to fit (-i snugly about the top chord of the truss.

The bracket typically comprises a metal strap and the strap will typically be galvanised or otherwise made corrosion resistant. However, the strap need not be made of metal and may also be made of other strong 110 materials such as plastic composite materials, metal composite materials and o0O tCq the like.

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10 The bracket will typically be substantially U-shaped although no

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O specific limitation is meant thereby. For instance, the bracket could be V shaped or have other shapes provided that a reinforcement rod can extend through each sidewall to secure the bracket to the masonry wall. It is also envisaged that the bracket may comprise a pair of separate sidewalls which need not be connected to each other at their lower ends and each sidewall can be attached to the reinforcement rod and embedded into the masonry wall. It is also envisaged that the bracket may be H shaped. However, it is convenient for the bracket to be formed of a single strap of metal bent into a substantial Ushape.

Each sidewall will have a length, a width and a thickness to suit the purpose. For a typical roof truss attached to a masonry wall, it is considered convenient for each sidewall to have a length of between 200-800 millimetres and preferably between 300-500 millimetres, with a typical example being a length of about 410 millimetres. Each sidewall may have a width of between 10-200 millimetres and preferably between 20-100 millimetres, with a typical example having a width of about 50 millimetres. The thickness of the material can be between 0.5-10 millimetres with a typical example having a thickness of between 1-3 millimetres.

The spacing between each sidewall may vary to suit but the spacing will typically be about the same or larger than the thickness of the roof truss. A typical spacing will be between 20-200 millimetres and a typical 0 o example will be approximately 40 millimetres. If the sidewalls are interconnected by a bottom wall, the dimensions of the bottom wall will typically Cbe between 20-200 millimetres long with a typical example being approximately 40 millimetres, between 10-200 millimetres wide with a typical example being

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the same width as the sidewall, and a thickness of between 1-10 millimetres with a typical example being the same thickness as each sidewall.

0O Each sidewall is provided with an opening to allow a Oreinforcement rod to extend through the sidewall. The opening will typically be ("i circular and will have a diameter sufficient to allow the reinforcement rod to

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O pass through the opening. As the reinforcement rod will typically have a diameter of about 15 millimetres, the opening will have a diameter of 15-20 millimetres with a typical example being 18 millimetres. More than one opening may be provided if considered necessary.

The opening will typically be in a lower part of the sidewall such that this part of the sidewall will be anchored in the concrete. The opening may therefore be positioned between 10-50 millimetres above the lower edge of the sidewall with a typical position having the centre of the opening approximately 30 millimetres from the bottom of the sidewall.

Each sidewall can be bent over the top of the truss to extend over at least the top and preferably some of the opposed sidewall of the truss. To enable each sidewall to do this without overlapping each other, each sidewall may have a cutout portion or a portion of reduced width to enable the two sidewalls to extend over the truss in a side-by-side relationship as opposed to a totally overlapping relationship. This can provide greater strength to the bracket hold down ability. Thus, the top portion of each sidewall and typically the top 100-200 millimetres of the sidewall will have a reduced width or cutout portion. It is preferred that this cutout portion reduces the normal width of the sidewall by between 40-60%.

It is preferred that the cutout portion contains a tapered edge (see ~IVl

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o reference numeral 101 in figure 4) to provide extra strength and to prevent the reduced portion from being torn away from the remainder of the bracket Cespecially under extremely high load conditions a cyclone/hurricane).

Each sidewall is typically provided with nail openings to allow each sidewall to be nailed to the truss. Typically, openings are provided entirely 11 through each sidewall. However, it is also envisaged that each sidewall may be 0o provided with depressions to act as guides for nails. It is also envisaged that Oeach sidewall may not be provided with openings and that a nail can be simply (Ni punched through the sidewall. However, the advantage of providing openings

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O or guides is that this ensures that the nails are spaced apart and that sufficient nails are used to provide an acceptable tie down.

BRIEF DESCRIPTION OF THE DRAWINGS An embodiment of the invention will be described with reference to the following illustrations in which: Figure 1. Illustrates a known type down arrangement using a cleat.

Figure 2. Illustrates a plan view of the bracket according to an embodiment of the invention.

Figure 3. Illustrates a pair of spaced apart truss chords with the front truss chord 11 containing a truss bracket 10 which has been incorrectly fixed and the rear truss chord containing a bracket 12 which has been correctly fixed.

Figure 4. Illustrates a truss bracket according to an embodiment of the invention and containing alignment means (markings).

Figure 5. Illustrates the attachment of the truss bracket to the reinforcing rod and again illustrates a wrongly attached bracket in the foreground and a correctly attached bracket in the background.

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(Ni Figure 6. Illustrates a plan view of a wrongly attached truss bracket on the Cleft-hand truss and a correctly attached bracket on the right-hand truss.

Figure 7. Illustrates the general design of the bracket.

SBEST MODE oO (Ni O Referring to the drawings and initially to figure 1, there is illustrated a known system. In this known system, a steel plate (known as a

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O cleat) 10 has one end embedded in the uppermost course 11 of a masonry wall. A timber truss 12 is then positioned against the cleat and must be temporarily held in place while a hole is drilled through the timber truss to coincide with a hole in cleat 10. A bolt 13 is then pushed through the aligned holes and a nut 14 is fastened to the bolt and rotated to tightly clamp truss 12 to cleat Referring now to figures 2-7 there is illustrated a roof truss bracket according to an embodiment of the invention. Referring initially to figure 7, truss bracket 15 is substantially U-shaped and has a bottom wall 16, a first upstanding sidewall 17 and a second upstanding sidewall 18. The bracket is made from a single strip of galvanised steel which is bent to shape. In this particular embodiment, the bracket has a thickness of between 0.8-6 millimetres. Bottom wall 16 has a length of 40 millimetres and a width of millimetres. Each sidewall 17, 18 is substantially identical and each sidewall has a length of 410 millimetres and a width of 50 millimetres in a lower part of the sidewall. In the bottom region of the sidewall is an opening 19 which has a diameter of 18 millimetres and which allows a reinforcement rod 20 (see figure two and figure three) to pass through each hole 19 to secure the bracket to the reinforcement rod 20 at two positions.

The upper part of each sidewall 17, 18 has a cutout 21 which extends along the top 150 millimetres of each sidewall and which effectively

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O halves the width of the sidewall at this part. The cutouts are on opposed sides of each sidewall as illustrated in figure 7 and are tapered 101. Each sidewall is tprovided with a plurality of nail openings 22.

In use, one or more reinforcing rods 20 are laid in the top row of blocks and the reinforcing rods 20 are supported by V shaped wire clips, the 110 clips being clearly illustrated in figure 5 and this arrangement being entirely oO conventional. The correct number of brackets are then threaded onto the O reinforcing rod. For instance, if there will be 20 roof trusses, there will be brackets on each wall and threaded onto the respective reinforcing rod. The

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O brackets are spaced apart by the regulatory distance (which will then determine the spacing between adjacent trusses). Concrete is then poured into the top row of blocks. While the concrete is wet, the brackets are pushed or pulled to be at the right angle depending on the particular type pitch) of truss. When the concrete is set, the trusses are usually lifted onto the roof and attached to each bracket.

A truss 12 can then be placed such that sidewalls 17, 18 extend up each side of the truss 12. Each sidewall 17, 18 can then be bent over the top and down the other sidewall of the truss, this being illustrated in figure 2 and figure 3. Each sidewall can then be nailed to the truss. Each sidewall 17, 18 can extend over the truss in a side-by-side relationship (best illustrated in figure 2) due to the cutout portion in each sidewall.

Referring now particularly to figure 4, there is illustrated a visual alignment means which in the particular embodiment comprises a number of spaced markings 53a-e. These markings correspond to the various popular truss designs (in particular the various popular truss pitches), and in the embodiment only (and not meant to be limiting on the invention) there are five markings 53a-e which correspond to trusses having a pitch of 150 (53a), 17.50 (53b), 20 0 (53c), 22.50 (53d) and 250 (53e). Of course, there is no need for the invention to be limited just to these particular markings and in Australia and other countries, there may be popular truss designs having different pitches.

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l Once the particular truss pitch is known, and the concrete has tbeen poured into the top row of blocks, and while the concrete is still wet, each bracket can be adjusted for the correct pitch of the truss. As an example, if it is known that the roof will have 17 .50 roof trusses, it is necessary to pull or push each bracket in the wet concrete such that an imaginary line between 11 reference point 100 (see figure 4) and marking 53b is substantially vertical.

oO C This can be done using a spirit level, plumb line, or by eye (particularly for O experienced tradespersons). For the purposes of better understanding the invention, figures 3 and figure 4 illustrate particular "imaginary" lines

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O although this could foreseeably also be actual lines.

It is envisaged that if there is a special job having a large number of trusses all with the same pitch, it may be possible to manufacture the brackets where, rather than an imaginary line being present, an actual line e.g. 50 in figure 3 and 4) is applied to each bracket between the reference point 100 and the required marking 53b if the truss is 17.50 pitch), as this can make it easier again to correctly position all the brackets.

Once the brackets are all correctly angled, the concrete will harden and lock the brackets in place. Trusses can then be placed against each bracket and the side wall of each bracket (17, 18) can be bent over the top chord of the truss to fit snugly because the brackets have been correctly angled.

On the other hand, if the bracket is not correctly positioned (see bracket 10 in figure the sidewalls will not extend snugly over the top wall 51 of chord 11 and this can severely compromise the hold down strength of the bracket.

The particular bracket arrangement has many advantages.

Firstly, the bracket is lightweight. The trusses can be attached to a masonry wall more quickly than by previous methods. The hold down can be completed

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o while the crane (which lifts the trusses onto the roof) is on-site. The bracket can be attached to the truss using a hammer and nails or can be attached tusing a nail gun. A complete loop strap strapping is provided over the top of the truss. The truss is not weakened by having a large hole drilled through it

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N 5 (which is required with the prior art cleat attachment method). The hold down value can be increased by using a greater number of nails. The bracket can be 11 provided with various different thicknesses with the thicker the bracket the

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higher the hold down value will be. For small lightweight trusses only a few O nails are required. The bracket arms can be opened up to cater for all (Ni thicknesses of trusses.

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The brackets can all be quickly and easily correctly angled before the concrete hardens using the alignment means.

It is also envisaged that there may be circumstances where the brackets are attached to the trusses at the correct angle (using the above system) and then subsequently locked in place with concrete. Again, the brackets will be at the correct angle due to the alignment system.

Throughout the specification and the claims (if present), unless the context requires otherwise, the term "comprise", or variations such as "comprises" or "comprising", will be understood to apply the inclusion of the stated integer or group of integers but not the exclusion of any other integer or group of integers.

It should be appreciated that various other changes and modifications can be made to any embodiment described without departing from the spirit and scope of the invention.

Claims (17)

1. A roof truss bracket, comprising a first upstanding sidewall and a second upstanding sidewall, each said sidewall being provided with an opening to allow a reinforcing rod to extend through each said sidewall, one sidewall in use OO extending along one side of the truss and the other sidewall in use extending along the other side of the truss, each sidewall being long enough to allow it to be bent i over the top chord of the truss and down the other sidewall of the truss, each sidewall adapted to be nailed to the truss, the sidewalls being attached relative to N .0 each other, and a visual alignment means being provided on at least one sidewall to enable the bracket to be positioned against the truss in such a manner that the sidewalls are substantially at right angles to the top chord of the truss prior to being bent over the top chord of the truss.

2. The bracket of claim 1, wherein the visual alignment system comprises an imaginary line or an actual visible line between a first reference point and a marking on the bracket.

3. The bracket as claimed in claim 2, wherein the first reference point is 0 adjacent an upper edge of the sidewall.

4. The bracket as claimed in claim 3, wherein the first reference point is the part of the bracket identified by reference numeral 100 in figure 4.

5. The bracket as claimed in any one of the preceding claims wherein the line is substantially vertical when the bracket is positioned correctly.

6. The bracket as claimed in any one of the preceding claims wherein the visual alignment means is provided on each side wall.

7. The bracket of claim 6, wherein the indication means comprises numbers, letters, lines, and combinations thereof.

8. The bracket as claimed in any one of the preceding claims, wherein the S bracket comprises a metal strap. d)

9. The bracket as claimed in any one of the preceding claims, wherein each sidewall has a length of between 200-800 millimetres. IND oo 00 c

10. The bracket as claimed in any one of the preceding claims, wherein c each sidewall has a width of between 10-200 millimetres. c 0

11. The bracket as claimed in any one of the preceding claims, wherein the member has a thickness of between 0.5-10 millimetres.

12. The bracket as claimed in any one of the preceding claims, wherein the spacing between each sidewall is between 20-200 millimetres.

13. The bracket as claimed in any one of the preceding claims, wherein each sidewall is provided with a single circular opening to enable a reinforcement rod to pass through each sidewall. .0

14. The bracket as claimed in any one of the preceding claims, wherein the opening in each sidewall is between 10-50 millimetres above a lower edge of the sidewall.

The bracket as claimed in any one of the preceding claims, wherein each sidewall is provided with a plurality of nail openings.

16. The bracket as claimed in any one of the preceding claims, wherein each sidewall is provided with a cutout portion adjacent an upper portion of each sidewall, the cut out portion having an inclined edge.

17. The bracket as claimed in claim 16, wherein the cutout portion has a length of between 50-300 millimetres. The bracket as claimed in claim 16 or claim 17, wherein the cutout 17 portion reduces the width of the sidewall by about one half. A bracket substantially as hereinbefore described with reference to figures 3-4. DATED: 19 September 2007