BACKGROUND ART Safety standards in some areas now require the erection of anti-fall barriers about the perimeter of roofs of houses, sheds and low level commercial buildings during construction to prevent workers on the roof from falling off. Whilst safety barriers for workers on high rise buildings and the like have been in use for a considerable period, they are typically attached to scaffolding which is necessary to support workers at a suitable height on such projects or are otherwise secured to the building in a semi-permanent manner such as by bolts so that removal is undesirably time consuming and difficult. Thus such barriers are generally not suitable for use on smaller construction projects such as dwelling houses, sheds and small commercial buildings.

In some building construction projects, it is possible for roof perimeter safety barriers to be supported from the roof rafters, trusses or purlins, while in others it is necessary to support the barriers from scaffolding erected adjacent the building. The components required for supporting a barrier from the roof purlins or rafters of some types of roofs is different from that required for others, and some projects even incorporate several different types of roofs thereby requiring several different types of components. Scaffolding is generally erected adjacent a dwelling house or other building under construction for the purpose of supporting a worker thereon at a suitable height for fixing fascias, gutters, soffits and other building elements. One particularly popular form of scaffolding for this purpose is"hanging scaffolding"which includes spaced apart scaffolding units adapted to hang from the wall or wall frame of the building under construction. Several types of hanging scaffolding are available, but ali suffer from drawbacks one of which is that they are not as easily height adjustable as desirable so are not particularly suitable for the dual functions of supporting a worker as normally required and also for supporting a roof perimeter barrier. One example of a scaffolding unit intended for use in hanging scaffolding is shown in Australian patent application No. 65961/94 by De Battista. The scaffolding unit of De Battista includes a plank support frame having a plank support member which is pivotally connected to a vertical support member for easy stowage and portability of the unit and a bracing member which can be selectively connected to the vertical support member to brace the plank support member. The unit is limited in use to a predetermined height and accordingly cannot be used efficiently to provide a work platform for all tradesman, the platform being too low for some tradesman and too high for others. De Battista also describes a frame assembly intended for the erection of anti-fall barriers about the perimeter of a roof under construction with the height of the frame assembly being adjustable but the second unit is not suitable for both functions as previously described. Another example of a scaffolding unit intended for use in hanging scaffolding is shown in Australian patent application No. 74337/94 by McKay. The scaffolding unit of Mckay is similar to that of De Battista but the plank support frame has a support member and a bracing member which have aligned sleeve portions at one end which are slidably mounted to the vertical support member for securement thereto at any one of a selected number of predetermined positions. Whilst this mounting arrangement allows height adjustment of the plank support frame relative to the vertical support member to suit tradesman of different heights, adjustment cannot be easily carried out and furthermore the structure of the plank support frame does not allow easy stowage of the scaffolding unit. Australian patent No. 667061 to Kagar Developments Limited

discloses another scaffolding unit which has a hollow elongate vertical support member having a plurality of aligned slots therein and a plank support frame with spaced apart hooks adapted to be received in the slots for engagement with the vertical support member. Whilst the Kagar Developments Limited unit is height adjustable, the plank support frame must be completely disconnected and adjustment therefore appears to be more difficult and awkward than desirable.

Various types of components are also known for supporting barriers from roof rafters and purlins. French patent specification No. 2558874 describes a post and bracket assembly which clamps to the end portion of a rafter with a pair of opposed spikes being arranged to bight into the side faces of the rafter and thus relies on the shear strength of only part of the rafter. Australian patent specification No. 80156/91 by George describes a post and bracket assembly which engages the top and bottom faces of a rafter. While this assembly appears to be mounted very securely, it must be removed before the roof can be fully clad and therefore is not suitable for many applications.

International patent application No. PCT/CH84/00192 describes a bracket assembly which operates in a manner similar to that of George although it is adjustable in length but suffers from the same problem that it must be removed before the roof can be fully clad.

Another component which is generally required for the safe erection of a roof perimeter safety barrier to connect rails, braces, extension bars and the like to each other and also to posts and scaffolding units (referred to as"scaffolding components"or"barrier components") is a connector assembly. In many cases one rail is misaligned with the next rail thus requiring connector assemblies which can accommodate the misalignment and adjacent rails or rails and posts may also overlap but still require interconnection. Furthermore extension bars may be inclined to the posts or the rails to which they are to be connected at different angles and therefore connector assemblies which can accommodate the different angles are required. Typically the rails, posts, braces and extension bars are constructed of Square Hollow Section steel (SHS) pieces or other steel or aluminium tubes.

Known connector assemblies typically include two sleeve-like members constructed of SHS and adapted to be slidingly fitted to scaffolding components constructed of smaller SHS steel pieces and to be secured thereto by respective set bolts, the sleeve-like members being interconnected by two or more chain links. The chain links are able to accommodate some lateral movement of the sleeve-like members in different planes and some limited pivoting movement of one sleeve member relative to the other. However such connector assemblies do not allow as much lateral movement as desired or provide as much pivoting movement as is desirable in many cases and furthermore they do not provide as much rigidity in some directions as is desired. Additionally the chain links are generally welded to the sleeve members and difficulties can be encountered in ensuring that sufficient weld material is applied. Other known connector assemblies include two sleeve members as previously described which are interconnected by a bolt to allow pivoting movement of one sleeve-like member relative to the other. While such connector assemblies do accommodate a large amount of misalignment in one plane, they do not accommodate misalignment in other planes.

One object of the present invention is to provide barriers and barrier systems which can be readily utilised for the protection of workers on construction projects. It is another object to provide components for barriers which enable relatively quick and easy erection on construction projects for the protection of workers, particularly projects relating to the construction of dwelling houses, sheds and/or small commercial buildings. In this respect it is an object of the present invention to provide a scaffolding unit for use in scaffolding for assisting workers in fixing facias, gutters etc which is height adjustable and ameliorates one or more of the problems of the presently known scaffolding units. It is another object to provide a scaffolding unit which is relatively rigid and stable and can be adjusted quickly thus being suitable for use in the erection of roof perimeter safety barriers. Another object is to

provide complementary components which can be used as a set on a construction project and can be quickly and easily interconnected where necessary. In this respect it is an object of the invention to provide a connector assembly which ameliorates some of the problems of the prior art connector assemblies and particularly to provide a connector assembly which is reliable and efficient in use and which can be efficiently and reliably constructed.

Other objects and advantages will become apparent from the following description.

DISCLOSURE OF THE INVENTION With the foregoing in view the present invention in one aspect resides broadly in a scaffolding unit including; elongate support means adapted to be disposed in a generally vertical attitude and to be secured to the top plate of a wall frame or the upper end portion of a wall panel, said elongate support means being substantially rectangular in cross-section and having a front face, a rear face spaced from said front face and two opposed spaced apart side faces; a frame assembly including elongate plank support means and connecting means operatively connected to said plank support means at one end for connecting said frame assembly to said elongate support means for pivoting movement of said frame assembly relative to said elongate support means from an operative in-use position in which said elongate plank support means is perpendicular to said vertical support means and an adjustment position in which said elongate plank support means is inclined upwardly towards said elongate support means, said connecting means including first engagement means adapted to engage the front face of said elongate support means and second engagement means spaced from said first engagement means and adapted to engage the rear face of said elongate support means above the position of engagement of said first engagement means with said first face when said frame assembly is in the operative in-use position and said first engagement means being spaced from said front face and/or said second engagement means being spaced from said rear face when said frame assembly is in the adjustment position and said frame assembly may be moved slidingly up or down along said elongate support means; and securing means for selectively securing said frame assembly in the operative in-use position.

Preferably the elongate plank support means includes two spaced apart support members, an upper member and a lower member, which are adapted to receive builders planks therebetween. It is also preferred that the upper member be adapted to removably receive a post or means for the attachment of a post to which a safety rail may be attached in turn.

Preferably the elongate plank support means is height adjustable for use with wall frames or wall panels of different heights. For this purpose the elongate support means may include upper and lower telescoping members adapted to be secured in any selected one of a number of predetermined positions by a pin or the like.

Preferably, the elongate support means includes mounting means at or near its upper end for mounting a post support or a post assembly thereto for the erection of a roof perimeter safety barrier.

In a second aspect, this invention resides broadly in a barrier system for the erection of a safety barrier adjacent the perimeter of a roof to prevent or at least inhibit a person from falling from the roof. said barrier system including : a plurality of mounting devices adapted to be releasably secured to selected rafters of the roof, said mounting devices each having a mounting portion adapted to depend from the respective rafters; a plurality of elongate post support means each being adapted to be pivotally mounted intermediate its ends to respective ones of said mounting portions for pivotal movement about a substantially horizontal axis

between a load bearing disposition in which one end of each said post support means abuts the underside face of the respective rafter inwardly of the position of securement of the respective mounting device and the other end extends beyond the end of the rafter, and a non-load bearing disposition in which said one end is spaced from the underside of the rafter and ; a plurality of posts or the like adapted to be operatively connected to said elongate post support means respectively at their other ends, and barrier means adapted to extend between adjacent posts and to be operatively connected thereto so as to prevent or at least inhibit a person from falling from the roof.

In a third aspect the invention resides broadly in a barrier system for the erection of a safety barrier adjacent the perimeter of a roof to prevent or at least inhibit a person from falling from the roof, said barrier system including: a plurality of mounting devices adapted to be releasably secured to selected rafters of the roof, said mounting devices each having a mounting portion adapted to depend from the respective rafters ; a plurality of elongate post support means each being adapted to be pivotally mounted intermediate its ends to respective ones of said mounting portions for pivotal movement about a substantially horizontal axis between a load bearing disposition in which one end of each said post support means abuts an inner face of a respective mounting device and the other end extends beyond the end of the rafter, and a non-load bearing disposition in which said one end is spaced from the respective mounting device; a plurality of posts or the like adapted to be operatively connected to said elongate post support means respectively at their other ends, and barrier means adapted to extend between adjacent posts and to be operatively connected thereto so as to prevent or at least inhibit a person from falling from the roof.

In a fourth aspect the invention resides broadly in a barrier erected adjacent the perimeter of a roof, said barrier including: a plurality of mounting devices releasably secured to selected rafters of the roof, said mounting devices each having a mounting portion depending from the respective rafters; an elongate post support means pivotally mounted intermediate its ends to each of said mounting portions respectively for pivotal movement about a substantially horizontal axis between a load bearing disposition in which one end of each said elongate post support means abuts the underside face of the respective rafter inwardly of the position of securement of the respective mounting device and the other end extends beyond the end of the rafter, and a non-load bearing disposition in which said one end is spaced from the underside of the rafter; a plurality of posts or the like operatively connected to each said post support means respectively at their other ends, and barrier means extending between adjacent posts and operatively connected thereto, said barrier means being arranged to prevent or at least inhibit a person from falling from the roof.

In a fifth aspect the invention resides broadly in a barrier erected adjacent the perimeter of a roof, said barrier including: a plurality of mounting devices releasably secured to selected rafters of the roof, said mounting devices each having a mounting portion depending from the respective rafters; an elongate post support means pivotally mounted intermediate its ends to each of said mounting portions respectively for pivotal movement about a substantially horizontal axis between a load bearing disposition in which one end of each said elongate post support means abuts an inner face of the respective mounting device and the other end extends beyond the end of the rafter, and a non-load bearing disposition in which said one end is spaced

from said respective mounting device ; a plurality of posts or the like operatively connected to each said post support means respectively at their other ends, and barrier means extending between adjacent posts and operatively connected thereto, said barrier means being arranged to prevent or at least inhibit a person from falling from the roof. Preferably, each said elongate post support means is releasably mounted to its respective mounting portion so that the mounting device may be secured to the rafter first and then the elongate support means secured to the mounting device.

In a sixth aspect the invention resides broadly in a mounting device for use in a barrier or barrier system including ; a cramp assembly having a fixed member with an elongate first side plate and a first end portion secured to said elongate first side plate and having a clamping face at right angles to said elongate first side plate, and an adjustable member having a second side plate in sliding and abutting engagement with said first side plate and a second end portion secured to said second side plate in spaced apart relation to said first clamping face, said adjustable member being releasably secured to said fixed member by securement means adapted to selectively secure said second side plate to said elongate first side plate in a predetermined selected position, and adjustable clamping means threadedly engaged in a complementary threaded aperture provided in said second end portion for clamping a rafter or the like between said clamping means and said clamping face; and mounting means secured to said elongate first side plate and extending substantially at right angles thereto for pivotaliy mounting thereto an elongate post support means, the mounting device being so made and arranged that said cramp assembly may be secured to a rafter with said first slide plate depending from said rafter and said mounting means extending substantially horizontally.

In a seventh aspect the invention resides broadly in a stand assembly for use in the erection of a barrier adjacent the perimeter of a roof, said stand assembly including: a mounting device adapted to be releasably secured to a selected rafter of the roof, said mounting device having a mounting portion adapted to depend from the rafter, and elongate post support means pivotally mounted intermediate its ends to said mounting portion for pivotal movement about a substantially horizontal axis between a load bearing disposition in which one end of said elongate post support means abuts the underside face of the rafter inwardly of the position of securement of the mounting device and the other end extends beyond the end of the rafter, and a non-load bearing disposition in which said one end is spaced from the underside of the rafter.

In an eighth aspect the invention resides broadly in a stand assembly for use in the erection of a barrier adjacent the perimeter of a roof, said stand assembly including: a mounting device adapted to be releasably secured to a selected rafter of the roof, said mounting device having a mounting portion adapted to depend from the rafter, and elongate post support means pivotally mounted intermediate its ends to said mounting portion for pivotal movement about a substantially horizontal axis between a load bearing disposition in which one end of said elongate post support means abuts the an inner face of said mounting device and the other end extends beyond the end of the rafter, and a non-load bearing disposition in which said one end is spaced from said mounting device.

In a ninth aspect the invention resides broadly in a mounting device for use in a barrier or barrier system including: an elongate post support member adapted to engage intermediate its ends with the upper surface of a roof batten adjacent a rafter,

load transfer means connected to said elongate post support member at one end and extending sidewards therefrom for transferring a downwardly directed load applied to the other end of said elongate post support member to the underside face of the adjacent rafter, and retaining means for retaining said elongate post support member in close proximity to the adjacent rafter, the parts being so made and arranged that the mounting device can be mounted and removed while the roof cladding remains generally in place.

In a tenth aspect the invention resides broadly in a wall panel and a bracket in combination, said bracket being secured to the wall panel so that at least a portion of said bracket is spaced from the outer face of the wall panel by a distance which allows the first end portion of a mounting device as previously described to be slidably fitted between said portion and said outer face wherein the mounting device may be clamped to said bracket such that the mounting means of the mounting device extends upwardly. Suitably, the mounting means may provide a stump to which a post may be fitted for the fixing thereto of barrier means as previously described for the purpose of erecting a barrier along the upper perimeter of the wall panel. Of course a plurality of brackets may be secured to the wall panel in spaced apart relation for securement thereto of a corresponding plurality of mounting devices.

It will be understood that the barrier would provide a safety barrier for persons erecting a roof in a manner similar to that previously described.

In an eleventh aspect this invention resides broadly in mounting apparatus for use in a barrier or barrier system, said mounting apparatus being adapted to be secured to the top flange of a Z-section or C-section purlin or the top web of a tophat section purlin or the like (hereinafter referred to as the"top flange or web") for mounting thereto a post assembly for a safety barrier to be erected adjacent the barge or gable end of a building, the mounting apparatus being referred to hereinafter for the sake of clarity as"gable end mounting apparatus"and including: a first support member adapted to be positioned on the underside of the top flange or web adjacent one end of a first purlin, said first support member having an aperture for receiving therein or therethrough a complementary mounting portion of the post assembly substantially longitudinally of the purlin and parallel to the outer face of the top flange or web, and attachment means for the attachment of a linking member whereby the mounting apparatus may be linked to a like mounting apparatus mounted to another purlin spaced from said first purlin, and securing means connected to said first support member for securing said tubular support member to the top flange or web.

In a twelfth aspect the invention resides broadly in mounting apparatus for use in a barrier or barrier system, said mounting apparatus being adapted to be secured to the top or bottom flange of a Z-section or C- section purlin or the side flanges of a tophat section purlin or the like (hereinafter referred to as the top or bottom flanges) for mounting thereto a post assembly for a safety barrier to be erected adjacent the facia of a building, said mounting apparatus being referred to hereinafter for the sake of clarity as"fascia side mounting apparatus"and including a second support member adapted to be positioned adjacent the top or bottom flange, said second support member having an aperture for receiving therein or therethrough a complementary mounting portion of the post assembly laterally of the purlin and substantially parallel to the outer face of the top or bottom flange, and securing means connected to said second support member for securing said second support member to the top or bottom flange.

In a thirteenth aspect the invention resides broadly in a barrier system for the erection of a safety barrier adjacent the gable end of a roof having Z-section, C-section or tophat section purlins or the like to prevent or at least inhibit a person from falling from the roof, said barrier system including:

a plurality of gable end mounting apparatuses as described herein; a plurality of post assemblies each having a complementary mounting portion adapted to extend through said aperture in a respective said first support member and a post portion upstanding from said mounting portion; a plurality of linking members for linking adjacent gable end mounting apparatuses together said linking members being adapted for attachment to said first support members via said attachment means, and one or more safety rails adapted for attachment to said post portions.

In a fourteenth aspect the invention resides broadly in a barrier system for the erection of a safety barrier adjacent the fascia side of a roof having Z-section, C-section or tophat section purlins or the like to prevent or at least inhibit a person from falling from the roof, said barrier system including: a plurality of fascia side mounting apparatuses as described herein; a plurality of post assemblies each having a complementary mounting portion adapted to extend through said aperture in a respective said third support member and a post portion upstanding from said mounting portion, and one or more safety rails adapted for attachment to said post portions.

In a fifteenth aspect the invention resides broadly in a barrier erected adjacent the gable end of a roof having Z-section, C-section or tophat section purlins or the like to prevent or at least inhibit a person from falling from the roof, said barrier including: a plurality of gable end mounting apparatuses as described herein and a plurality of post assemblies, each post assembly being associated with a respective gable end mounting apparatus and having a mounting portion and a post portion upstanding from said mounting portion, one of said plurality of gable end mounting apparatuses being mounted to one end respectively of each purlin and being secured thereto by said securing means with the first support member of each respective apparatus being positioned on the underside of the top flange or web adjacent one end and the mounting portion of its associated post assembly extending through the aperture in said first support member and engaging with the underside face of the top flange or web; a linking member extending between adjacent ones of said mounting apparatuses and being attached to the respective first support means by said attachment means whereby adjacent mounting apparatus may be linked for stability, and a rail or strap extending between adjacent ones of said post portions and being attached thereto to form a barrier.

In a sixteenth aspect the invention resides broadly in a barrier erected adjacent the fascia side of a roof having Z-section, C-section or tophat section purlins or the like to prevent or at least inhibit a person from falling from the roof, said barrier including: a plurality of fascia side mounting apparatuses as described herein and a plurality of post assemblies, each post assembly being associated with a pair of fascia side mounting apparatus and having a mounting portion and a post portion upstanding from said mounting portion, each pair of fascia side mounting apparatuses including a first fascia side mounting apparatus which is secured to a top (or bottom) flange of a first purlin by its respective securing means and a second fascia side mounting apparatus which is secured by its respective securing means to the top (or bottom) flange of an adjacent second purlin laterally of the first mounting apparatus such that the apertures of said second support member of each of said first and second fascia mounting apparatuses are substantially in alignment and the mounting portion of the post assembly laterally of the purlin and substantially parallel to the outer face of the top or bottom flange, each pair of fascia side mounting apparatuses being mounted to the purlins in spaced apart relation, and a safety rail or strap extending between adjacent post portions and being attached thereto to form a barrier.

In a seventeenth aspect this invention resides broadly in a connector assembly for connecting adjacent barrier components particularly rails, posts, braces and the like, including: a first connector part adapted to be secured to a first scaffolding component; a second connector part adapted to be secured to a second scaffolding component; linking means linking said first and second connector parts, said linking means including an elongate link member having a shaft portion operatively connected at one end to said first connector part and a ball-like portion at its other end, and retaining means secured to said second connector part for retaining said link member operatively linked thereto, said retaining means having a wall portion at least partially defining a cavity and being adapted to retain said ball portion in said cavity, and an opening in said wall portion through which said shaft portion extends, the parts being so made and arranged as to allow pivoting movement of said link member relative to said first retaining means about the longitudinal axis of said link member whereby said second connector part may be moved relative to said first connector part.

In an eighteenth aspect this invention resides broadly in a connector assembly for connecting adjacent barrier components particularly rails, posts, braces and the like, including: a first connector part adapted to be secured to a first scaffolding component; a second connector part adapted to be secured to a second scaffolding component : linking means linking said first and second connector parts, said linking means including an elongate link member having a shaft portion and a ball-like portion at each end, first retaining means secured to said first connector part and second retaining means secured to said second connector part, said first and second retaining means each having a wall portion at least partially defining a cavity which houses said respective ball portions and said wall portions being adapted to retain said ball portions in said respective cavities for retaining said link member linked to said first and second connector parts, and an opening in each said wall portion through which said shaft portion extends, the parts being so made and arranged as to allow pivoting movement of said link member about its longitudinal axis relative to said first and second retaining means whereby said second connector part may be moved relative to said first connector part about the longitudinal axis of said link member.

Preferably, said opening in said wall portion is shaped to allow movement of said link member relative to said retaining means in a first plane and a second plane orthogonal to said first plane.

BRIEF DESCRIPTION OF THE DRAWINGS In order that this invention may be more readily understood and put into practical effect, reference will now be made to the accompanying drawings which illustrate a preferred embodiment of the invention and wherein: Fig. 1 is a partial end elevation in schematic form of a barrier according to the invention erected along the perimeter of the roof of a dwelling house; Fig. 2 is a pictorial representation of a mounting device according to the invention which is utilised in the barrier of Fig. 1; Fig. 3 is a side view of the mounting device of Fig. 2; Fig. 4 is an end view of the mounting device of Fig. 2; Fig. 5 is an underside view of the support arm assembly which is pivotally mounted to the mounting device shown in Fig. 1; Fig. 6 is a schematic end view of a barrier erected about the upper perimeter of a wall constructed of concrete tilt slabs according to the invention; Fig. 7 is a partial end elevation in schematic form of part of an alternative barrier according to the invention

erected along the perimeter of the roof of a dwelling house ; Fig. 8 is a partial end elevation in schematic form of a stand assembly for another barrier according to the invention; Fig. 9 is a side view of a component of the stand assembly of Fig. 8; Fig. 10 is a plan view of the stand assembly of Fig. 8, and Fig. 11 is a partial end elevation in schematic form of part of an alternative barrier according to the invention erected along the perimeter of the roof of a dwelling house; Fig. 12 is a pictorial representation of another mounting device according to the invention which could be utilised in a barrier similar to that shown in Fig. 1; Fig. 13 is a pictorial representation of a mounting device according to the invention which is utilised in the barrier of Fig. 1; Fig. 14 is a side elevation of gable end mounting apparatus according to the invention attached to the top web of a top hat section purlin; Fig. 15 is a plan view of the gable end mounting apparatus of Fig. 14 attached to the top web; Fig. 16 is an end elevation of the gable end mounting apparatus of Fig. 14 attached to the top web; Fig. 17 is an end elevation of the gable end mounting apparatus of Fig. 14 attached to the top flange of a Z-section purlin; Fig. 18 is a pictorial representation of facia side mounting apparatus according to the invention; Fig. 19 is a pictorial representation of an assembly of two apparatuses of Fig. 18 connected by a post assembly; Fig. 20 is a plan view of the assembly of Fig. 19; Fig. 21 is a pictorial representation of a previously known connector assembly; Fig. 22 is a pictorial representation of another previously known connector assembly; Fig. 23 is a pictorial representation of yet another previously known connector assembly; Fig. 24 is a pictorial representation of a connector assembly according to the present invention; Fig. 25 is a side elevation of a connector assembly according to the present invention ; Fig. 26 is a plan view of the connector assembly of Fig. 4; Fig. 27 is a side elevation of the linkage assembly of the connector assembly of Fig. 24 prior to being welded to the connector parts; Fig. 28 is a plan view of the linkage assembly of Fig. 27; Fig. 29 is an underside plan view of one of the retaining blocks of the linkage assembly of Fig. 27; Fig. 30 is an end elevation of one of the retaining blocks of the linkage assembly of Fig. 27 ; Fig. 31 is a pictorial representation of a scaffolding unit according to the invention separated into its various components; Fig. 32 is a side elevation of the scaffolding unit of Fig. 31 partially assembled; Fig. 32a is a partial end elevation showing the upper and lower plank support members of the frame assembly shown in the scaffolding unit of Fig. 31; Fig. 32b is a partial end elevation of the sleeve member part of the frame assembly shown in the scaffolding unit of Fig. 31; Fig. 33 is a side elevation of a frame assembly which may be used as an alternative to the frame assembly shown in the scaffolding unit of Fig. 31; Fig. 34 is a side elevation of a top plate engaging member which may be used as an alternative to the top plate engaging member shown in the scaffolding unit of Fig. 31;

Fig. 35 is a bracket which may be attached to a wall panel for the attachment of the apparatus of Fig. 31 instead of using the top plate engagement member; Fig. 36 is a side elevation of a modified form of frame assembly which may be used instead of the frame assembly shown in the scaffolding unit of Fig. 31; and Fig. 37 is a plan view of the modified form of frame assembly shown in Fig. 36.

DETAILED DESCRIPTION OF THE DRAWINGS The barrier 10 illustrated in part in Fig. 1 is erected adjacent the lower edge of the roof of a dwelling house 11, the barrier being mounted to the top chord 12 of the roof truss 13 which overhangs the house wall 14 by about 750 mm in the normal manner.

The barrier includes a plurality of stands or stand assemblies 16 which are secured to the top chords 12 respectively in spaced apart relation for supporting horizontal rails 17 therebetween to provide a safety barrier. Each stand assembly 16 comprises a mounting device 18 which is releasably secured to the top chord 12, an arm assembly 19 which is pivotally mounted to the mounting device and a post 21 which is secured to the support arm assembly.

It will be seen in Figs. 2,3 and 4 that the mounting device 18 comprises a clamp assembly 26 having a side plate 27 and an end plate 28 at right angles to the side plate and an adjustable or moveable member 29 having a first plate 31 in sliding and abutting engagement with the side plate 27 and an end plate 32 substantially at right angles to the side plate 31 in parallel and spaced apart relation with the end plate 28. A cramping bolt 33 is threadedly mounted to the end plate 32 and passes therethrough having a clamping washer 34 mounted to its end for coacting with the end plate 28 to clamp a rafter therebewteen. The adjustable member is secured to the fixed member by a pin 36 which passes through any selected one of five apertures 37 which align with an aperture 38 provided in the side plate 31. The side plate 31 is retained in sliding engagement with the side plate 27 by pieces of angle iron 39 which are welded to the edges of the side plate so as to form grooves for slidingly supporting the side plate. It will be seen that the end plate 28 is relatively thin in form being constructed of 9 mm steel plate, the purpose of which will become apparent later when described in relation to Fig. 6. A mounting shaft 41 constructed of square steel tube is welded to the side plate 27 and extends outwardly therefrom at right angles on the side opposite to the cramping bolt 33 for mounting thereon the arm assembly 19 as shown in Fig. 1.

As shown in Fig. 1, the mounting device 18 is clamped to the rafter 12 with the end 28 in abutting engagement with the top side of the rafter and the clamping washer 34 in abutting engagement with the underside of the rafter so that the cramping bolt 33 holds the mounting device rigidly mounted to the rafter. In this position the mounting shaft 41 extends horizontally from the side plate 27 to provide a mounting for the support arm assembly 19 as will now be described.

The support arm assembly 19 includes a bracing arm 46 and a support arm 47 which are each connected at one end to a mounting tube 48 and extend outwardly therefrom in generally opposite directions to enclose an angle of about 120 degrees. The mounting tube extends sidewardly of the arms and is adapted to slidably engage about the mounting shaft 41 to allow up and down pivoting movement of the arms 46 and 47 about the longitudinal axis of the shaft 41 under the chord 12. It will be seen that the arm 46 has a lug 49 extending sidewardly therefrom and parallel to the mounting tube 48 for engaging with the underside of the chord 12, the bracing arm and the support arm being offset from the chord. The arm 47 has an upstanding stub post 51 secured thereto at its end remote from the mounting tube to which themain post 21 can be slidably fitted thereabout.

The arm assembly is secured to the mounting shaft 41 by a pin not shown which can be fitted to either one

of apertures 45 provided in the ends thereof to prevent the arm assembly 48 being removed from the mounting device.

It will be appreciated that in use any load applied to the barrier rail 17 or the post 21 will be transmitted to support arm 47 and in turn to the underside of the rafter by the bracing arm 46 and lug 49. Advantageously the support arm and bracing arm are arranged so that the load applied to the mounting device 18 is applied substantially at right angles to the chord 12 so that twisting of the mounting device is avoided or at least reduced.

Fig. 6 illustrates the use of the mounting device 18 with a tilt slab 61. In this embodiment the tilt slab 61 has a bracket 62 secured thereto by a bolt 63 threadedly engaged with a ferrule 64 pre-cast in the concrete tilt slab.

The bracket 62 has a lower portion 66 which abuts the outer face 67 of the wall and through which the bolt 63 passes to secure the bracket thereto and an upper portion 68 which is spaced from the wall by a distance approximately equal to the thickness of the end plate 28, which in this case is approximately 6 millimeters. This spacing allows the end plate 28 to be fitted between the face 67 and the bracket portion 68 whereupon the mounting device can be clamped thereto by the cramping bolt 33. It will be seen that the mounting tube 41 extends upwardly to provide a spigot with which the post 21 can slidably engage to provide a mounting for the rail 17 adjacent the upper perimeter of the tilt wall.

The barrier illustrated in part in Fig. 7, is similar to the barrier of Fig. 1 but the bracing arm portion 146 and support arm portion 147 of the arm assembly 119 are adjustable in length to accommodate different roof pitches and different widths of roof overhang. It will be seen that corresponding reference numerals are used in relation to corresponding components of the embodiment of Fig. 1 but prefixed by the number"1"and for the embodiments of Figs. 8 and 11, the reference numerals are prefixed by a"2"and a"3"respectively. The bracing arm 146 is slidably mounted in a sleeve portion 147a which is welded to the inner end of the support arm 147 and is secured thereto by a set bolt 147b. The effective length of the bracing arm may be adjusted to maintain the support arm horizontal when in the operative position or if desired to achieve a predetermined inclination. In this respect it will be appreciated that in some circumstances it is preferable to incline the posts 121 (not shown). Typically such inclination would be up to 20 degrees. The embodiment illustrated in Fig. 8 is similar to that of Fig. 7 but in this form of the invention, the bracing arm abuts an inner face of the mounting device indicated at"A"in Fig. 10 rather than the underside of the rafter. Fig. 11 shows an embodiment including an additional sleeve portion 346c which is welded to the support arm 347 via the mounting tube 348 thereby providing the option of mounting the posts at an inclination of up to 20 degrees while maintaining the support arm horizontal.

The mounting device 410 illustrated in Figs. 12 and 13 is particularly suitable for the erection of barriers around roof perimeters for re-roofing existing houses and other buildings but can be used with new construction projects also. The device includes an elongate post support member 461 constructed of 75mmx12mm steel plate having a bend 462 intermediate its ends 463 and 464, the bend being such as to apportion the member into an inner portion 466 and an outer portion 477 which enclose an angle of approximately 160 degrees. A internally threaded mounting tube 468 is welded to the inner end extending laterally of the support member and an L-shaped retaining pin 469 has one leg screw-threadedly engaged therein. The L-shaped retaining pin can be pivoted to any desired position within 360 degrees and locked in that position by a lock nut 470. A stub post assembly 472 is releasably secured to the outer portion 467 by a set bolt 473 and is adapted to slidably receive thereabout a post 421 in a manner similar to that described in relation to Fig. 1. In use, the L-shaped retaining pin is pivoted to a position in which the leg 471 lies in the same plane as the inner portion 466 and is locked in this position by the lock nut 470. The support member can then be slid under the roof cladding above the baton 412a whereupon the lock nut can be released and the retaining member be pivoted so that the leg 471 engages with one side of the rafter 412 while the adjacent edge of the support member engages with the other side of the rafter thereby securing

it in the position shown in Fig. 13. It will be appreciated that downwardly directed loads applied to the outer portion 467 will be transmitted to the underside of the rafter by the retaining pin in a manner similar to that described in relation to the barrier of Fig. 1.

The gable end mounting apparatus 510 illustrated in Figs. 14 to 17 includes a tubular mounting member 511 constructed of 40mm x 40mm Square Hollow Section steel (SHS) and a spacer plate 512 is welded to the upperface 511a of the mounting member. In turn a tongue member 513 is secured to the spacer plate by a plug weld 514, the spacer plate acting to space the tongue member from the upper face 511 a so as to form a recess adapted to slidably receive the top web 515 of the top hat section purlin 516 or the top flange 517 of the Z-section purlin 518. The tubular member is adapted for securement to the web or flange by a thumb screw or locking bolt 521 which is threadedly mounted in a complementary nut 522 welded to the tongue member 513.

In use, a mounting portion 525 of a post assembly 520 extends through the hollow of the tubular mounting member 511 and is secured therein by a second thumb screw or lock bolt 524 which is threadedly mounted in a complementary nut 526 also welded to the upper face 511 a. A post portion 527 stands upwardly from the mounting portion 525 for supporting a rail or strap (not shown). It will be appreciated that once a down load is applied to the post portion the inner end of the mounting portion will engage with the underside face of the web 515 or flange 517 as flexing of the purlin occurs.

A second tubular member 531 is welded to the bottom face 511 b of the tubular member 511 and extends substantially perpendicular thereto. A thumb screw or lock bolt 533 is mounted to the lower face of the second tubular member for securing therein a link member 534 adapted to link the apparatus 510 to a similar apparatus attached to an adjacent purlin spaced from the purlin 516. It will be appreciated that the purlins are subject to undesirable twisting and suitably the link member stabilises the purlins and the post portions 527 thus allowing a stable barrier to be erected.

The facia side mounting apparatus 550 illustrated in Fig. 18 includes a support member 551 constructed of 40mm x 40mm x 6mm steel angle having lock bolts 552 and 553 mounted to a first flange in a manner similar to that previously described adjacent each end. A tubular member 556 constructed of 40mm x 40mm SHS is welded to the edge of the second flange of the support member and has an upper face 556a which is parallel to the underside face of the first flange 551 a but extending perpendicularly to the second flange to form a recess 557 for receiving therein the flange of a C-section, Z-section or top hat section purlin. The lock bolts 552 and 553 are adapted to secure the apparatus to the desired flange of the purlin with the tubular member 556 extending substantially laterally of the purlin.

In use, two of the apparatuses 550 are slidably mounted on the mounting portion 563 of a post assembly 564 and the apparatuses are secured to the bottom flanges of the spaced apart Z-section purlins 568 and 569 by the thumb screws 552 and 553. The post assembly is then moved to the desired distance from the purlin 568, which is typically the lower most purlin of a roof, and the respective post mounting portions 563 are then secured in position by the thumb screws 566. Rails or straps can then be attached to the post portions 567 or extensions of the post portions in any suitable manner to form a barrier.

The prior art connector assembly 610 illustrated in Fig. 21 includes two connector parts 611 and 612 constructed of Square Hollow Section Steel tube adapted to receive rails and the like therethrough and linked by two inter-engaging chain links 613 and 614 which are welded to the connector parts respectively. The connector parts have set bolts 616 and 617 mounted thereon for securing rails, posts, braces or the like thereto. The connector assembly 620 illustrated in Fig. 22 is the same as that of Fig. 1 except that the connector parts 621 and 622 are linked by two inter-engaging half chain links 623 and 624. It will be appreciated that the half links are butted endwise to the respective connector parts and only a very small amount of chain material is available for accepting

weld material. The connector assembly illustrated in Fig. 23 includes two connector parts 631 and 632 which are similar to the connector parts of Figs. 21 and 22 but are linked by a bolt 633 which allows pivoting movement of one connector assembly relative to the other about the bolt axis 635.

The connector assembly 640 shown in Figs. 24,25 and 26 is constructed in accordance with the present invention and is particularly suitable for connecting rails of barriers as previsouly described together and also for connecting braces to posts and the like. The connector assembly includes first connector part 641 and a second connector part 642 which are linked by a linkage assembly 643 includes two retaining blocks 644 and 646 which are welded to the connector parts respectively, and a link member 647 which has a shaft portion 648 and two ball- like end portions 649 and 651 connecting the two retaining blocks.

The retaining block 644 has an inner face 644a which is in abutment with the outer face 641 a of one of the side walls of the connector part 641, an outer face 644b parallel to and spaced from the inner face, two spaced apart parallel side faces 644c and 644d and two spaced apart parallel end faces 644e and 644f. The block 646 is identical to the block 644 and corresponding faces are correspondingly referenced and thus the description in relation to block 644 is generally applicable to block 646.

A recess 644g is provided in the block 644 having a substantially hemispherical inner end of a diameter which is slightly greater than the ball-like end portions of the link member 648. The recess opens via a short cylindrical passage 644h of the same diameter to the inner face 644a. It will be appreciated that either ball-like end portion 649 or 651 can be received in the recess prior to the block being welded to the connector part and once welded to the connector part a cavity is formed which houses the ball-like end portion.

An inwardly tapered recess 644j is provided in the retaining block 644 extending from the face 644b and opening into the recess 644g, the recess being of a width slightly greater than the diameter of the shaft portion 648 and having end faces parallel to the end faces 644e and 644f. Another recess 644k extends from the end face 644f and opening into the recess 644g and the recess 644j and being generally perpendicular thereto and extending over the full height of the end face 644f. The width of the recess 644k is also slightly greater than the diameter of the shaft portion 648.

It will be seen that the link member is pivotable about the hemispherical centrepoint of the cavity and the shaft portion 648 can slide neatly in the recesses 644k and 644j upon pivoting of the link member in orthogonal planes through the two recesses. Engagement of the shaft portion with the parallel side walls 644j1 and 644j2 of the recess 644j limit the pivoting movement of the link member to a predetermined range governed by the length of the recess. Similarly engagement of the shaft portion with the parallel side walls 644k1 and 644k2 of the recess 644k limit the pivoting movement of the link member when the shaft portion is positioned in the recess 644k to a similarly predetermined range. The link member is movable in a similar manner relative to the mounting block 646 which has recesses corresponding to those described in relation to mounting block 644.

The cylindrical portion of the recess 644g is sufficiently long to allow some movement of the ball-like end portion towards and away from the face 641a of the connector part 641 thereby allowing some lateral misalignment of the connector parts 641 and 642 whereby misalignment of rails 651 and 652 connected thereto respectively can be accommodated. The rails 651 and 652 are secured to the connector parts by set bolts 653 and 654 respectively which are similar to those shown in the previously known connector assemblies. It will be appreciated that the connector assembly interconnects various other components of the barrier system easily and sufficiently.

The scaffolding unit 710 illustrated in Figs. 31 to 37 is constructed in accordance with the present invention and is particularly adapted for use in the construction of a dwelling house. The unit includes an upstanding elongate support stand 711 having a main member 712 constructed of rectangular hollow section steel (RHS) having a front wall 712a, a rear wall 712b and two opposed side walls 712c and 712d, the main member being intended to stand

adjacent the external face of a wall frame with the front and rear faces parallel thereto. It will be seen that the front and rear walls form the narrow faces of the member and the side walls form the wide faces and the main member is suitably selected to support the frame assembly 713 which will be described later, without undesirable bending.

A sleeve member 714 is welded to the upper end of the support member with its axis parallel to the side faces of the main member and is adapted to receive a bracket 715 which is adapted to engage with the top plate of a wall frame. The sleeve member is also adapted to receive an L-shaped post support bracket 716 which in turn is adapted to receive a post for the attachment of safety rails. It will be appreciated that the bracket 714 allows the apparatus to be used for providing a safety rail about the perimeter of the roof of a house under construction. A Tee shaped foot bracket 717 has one leg of the Tee telescopically engaged in the main member at its lower end and can be selectively secured therein by a securement pin 718a adapted to pass through aligned apertures in the side walls 712c and 712d and aperture 719 provided in the foot bracket. Advantageously, the foot bracket can be of any preselected length so that the unit can be used with walls of different heights. The other leg of the Tee is a tubular member which is adapted to receive a connecting member (not shown) for connecting the support stand to an adjacent support stand and has a set bolt 721 for this purpose.

The frame assembly 713 includes spaced apart upper and lower plank support members 723 and 724 interconnected to form a truss-like structure by spaced apart connecting lugs 726. At one end the plank support members are welded to a sleeve member 727 adapted to be slidingly mounted on the main member 712 for movement therealong. The sleeve member 727 is comprised of a front plate 727a adapted to engage with the front wall 712a of the main member, a rear plate 727b adapted to engage with the rear wall 712b and two spaced apart side plates 727c and 727d adapted to slidingly engage with the side walls 712c and 712d respectively. The front plate extends vertically over less than half the length of the side plates and the two plank support members are welded to the front plate. The rear plate extends downwardly over much less than half the vertical length of the sleeve member and is spaced vertically from the front plate so that most of the rear face and the front face of the sleeve member are open. It will be appreciated that in use the front and rear plates engage with the front and rear walls of the main member when the plank support members are in the horizontal attitude. Furthermore the sleeve member can be secured in position by the pin 728 which is adapted to pass through aligned apertures provided in the side plates 727c and 727d and a selected one of the apertures 718 provided in the main member to prevent sliding movement of the frame assembly relative to the main member. It will be understood that the front and rear plates may bind with the front and rear walls when sufficient load is applied downwardly on the plank support members, but in the interests of safety the securing pin 728 should be inserted. Advantageously, the height of the frame assembly relative to the main member can be adjusted by simply removing the pin 728 tilting the plank support members upwardly so that the front and rear plates disengage from the main member allowing the sleeve member to slide easily therealong.

A tubular connecting bracket 731 is welded to the underside of the lower plank support member 724 and extends perpendicularly thereto for receiving therein a connecting member (not shown) for connecting adjacent scaffolding units. Suitably a set bolt is provided in a similar manner to that described in relation to the foot bracket for securing the connecting member therein.

Two post mounting brackets 733 and 734 are slidably mounted to the upper plank support member 723 for mounting posts thereto for the purpose of attaching safety rails. The brackets have set bolts 736 and 737 respectively for securing them to the upper plank support member in any desired position. Adjacent rails can be connected to each other by the connector assembly previously described.

The frame assembly illustrated in Fig. 33 is similar to that shown Fig. 32 except that it is much shorter and has only one post support bracket 734.

Fig. 36 illustrates an alternative frame assembly which is the same as that of Fig. 32 in all respects except that the sleeve member 727 has been replaced by a slightly modified sleeve assembly 827, the side plates of which have parallel inclined edges thus allowing easier manufacture.

The bracket 815 illustrated in Fig. 34 is intended to replace bracket 715 if the scaffolding unit is used with tilt-up concrete wall panels or concrete block walls and is slightly longer than the bracket 715.

It will be understood that all of the components described can be effectively utilised for the erection of barriers around the perimeter of roofs under construction. However, the various components also have other applications in the building industry not necessarily in the erection of barriers. It will also be understood that while the foregoing description has been given by way of illustrative example of the various aspects of the invention all modifications and variations thereto as would be apparent to persons skilled in the art are deemed to fall within the broad scope and ambit of the invention as defined in the appended claims.