Background of the invention The construction and more particularly the maintenance, repair or replacement of roof structures in large industrial buildings such as factory roofs presents numerous problems, particularly with ensuring the safety of workers. For example, factory roof structures sometimes need major work including replacement as a result of deterioration after years of use. Some factories produce or use corrosive substances which are present in the atmosphere in the factory and which, over periods of time, can cause severe corrosion of roof structures including the roofing materials and the support structure for the roofing materials including particularly roof purlins. Such corrosion and deterioration of roofing materials and the roof support structure can make it particularly dangerous to attempt to repair or replace the roof structure by walking on the roof. To solve this problem it has been usual in the past to erect scaffolding within the factory to enable the maintenance or replacement of the roof structure by workmen supported by the temporary scaffolding erected for the purpose. However, the erection and disassembly of such scaffolding can be time consuming and expensive and can substantially interfere with normal operations in the factory.

Although not widely and commonly known, the work platform for roof construction work disclosed in Australian patent specification AU-707069 includes an upper work surface mounted by a structural frame, the work surface having removable sections provided in a walkway extending around the perimeter of the frame enabling a worker to carry out work on the area of the roof structure below a removed section. This work platform has mounting feet and fastening means associated with the mounting feet so that the platform can be secured to the roof structure and, at the end of the required work being performed, the fastening means can be released to enable the platform to be moved to another work position on the roof structure or returned to the ground level.

The work platform in AU-707069 is manufactured, or at least is modified, for each particular work site. The work platform is of substantial size and mass. Therefore the construction and use of this work platform can be relatively costly. For roof construction

work on smaller buildings (including industrial, commercial, and domestic buildings) or even for smaller maintenance jobs to be carried out on small or larger buildings, there is no need for such a relatively large product as disclosed in AU-707069, nor for the need to achieve the desired function to specially manufacture and/or modify apparatus for the purpose. Similarly the expense associated with manufacturing and/or modifying apparatus such as disclosed in AU-707069 would not be needed or indeed desirable for smaller buildings and/or smaller jobs. Furthermore, a particular roof construction task may involve working with a building (including relatively large as well as smaller buildings) where the roof support structure on which the work platform of AU-707069 would be mounted may not be suitable for receiving and/or supporting such a work platform.

Brief summary of the invention It is an object of the present invention to provide a work platform for roof construction work which can enable erection, maintenance, repair, or replacement work to be carried out on a roof structure in an effective manner.

It is a further object of the present invention to provide a work platform for roof construction work which can be versatile in use by being useable with different types or sizes of buildings and/or different roof construction work situations.

It is a further object of the present invention to provide a method of performing roof construction work which can enable erection, maintenance, repair or replacement work to be carried out on a roof structure in an effective manner.

It is a further object of the present invention to provide a method of performing roof construction work suitable for use with different types or sizes of buildings and/or different roof construction work situations.

According to a first aspect of the present invention there is provided a work platform for roof construction work useable on a roof structure, the work platform including an upper work surface on which a worker can move about on the platform, and a safety barrier around at least part of the periphery of the upper work surface, the work platform further including support means for supporting the work platform in an operative position a short distance above the roof structure so that the worker can perform work on the roof structure below the platform, the upper work surface including at least one access section which enables access to an area of the roof structure below the work surface where the access section is located, the upper work surface further including at least one support section

adjacent the access section so that the worker can remain on the support section of the work surface and can gain access to and can perform work on the area of the roof structure below the adjacent access section, the work platform further including a transfer space through or adjacent the work surface and arranged to enable roofing materials such as roofing sheets and/or roofing structure supports, to be transferred from the work platform through the transfer space into position beneath the work platform for mounting to the roof structure and to enable such roofing materials removed by the worker from the roof structure beneath the work platform to be transferred through the transfer space and onto the work platform for storage and/or removal.

By providing the transfer space, new roofing materials such as roof sheets and/or roofing structure supports such as purlins can be loaded and stored on the work platform as the work platform is raised and moved into its operative position and can enable such roofing materials removed from the roof structure, particularly during maintenance or repair operations, to be placed and supported on the work platform during the work operations and either be replaced or returned to the ground while carried by the work platform as the work platform is removed from its operative position and returned to ground level. The work platform with the transfer space can therefore be used in a variety of different situations including working with different sizes and types of building structures and in different erection, maintenance, or repair situations.

Preferably, the transfer space comprises an elongated slot through which roofing materials including elongated members such as roof purlins and sheet materials such as roofing sheets or decking sheets can be passed. Also preferably, the transfer space is dimensioned so that the worker cannot pass through the transfer space from a position atop the work surface to a position beneath the work platform from where the worker may fall from the platform or roof structure.

In a preferred embodiment the upper work surface of the work platform has two work sections consisting of a roof construction work section having the one or more access sections and a material storage section, the material storage section providing an area for roofing materials to be carried and stored thereon while the work platform is moved into its operative position preparatory to roof construction work and while the work platform is being removed from its operative position after the roof construction work has been performed. The roof construction work section of the work surface is preferably at an

elevated upper level above a lower level of the material storage section of the work surface.

In this construction, the transfer space preferably comprises an elongated transfer slot in the step formed between the upper level of the roof construction work section and the lower level of the material storage section, the elongated slot being arranged to enable roofing materials to be moved generally horizontally from the work surface when being transferred through the transfer slot to a position below the roof construction work section and, conversely, the roofing materials can be transferred horizontally back through the transfer slot directly onto the lower level material storage section. Preferably at least one removable barrier is provided to inhibit or prevent roofing materials inadvertently passing through the transfer space during raising and lowering of the work platform between the ground and its operative position atop the roof structure. Such barriers may comprise for example some lengths of chain which can be hooked into position obstructing passage of roofing materials through the slot, e. g. if the work platform tilts somewhat which might otherwise cause roofing materials to slide laterally through the upright slot between the elevated work section and the lower level material storage section.

Preferably the access section includes a safety barrier enabling a worker to insert his hands past or through the barrier to work on the roof structure beneath the access section but being operative to prevent a worker falling through the access section from the work platform. For example, the safety barrier may be formed by a mesh having relatively large openings. The mesh however is preferably not provided so as to impede the transfer of roofing materials through the transfer space and, in particular, is not provided so as to block passage of roofing materials through the transfer space. If there is safety mesh provided in the vicinity of the transfer space, either the mesh is located so as not to interfere with or impede transfer of roofing materials through the space or, alternatively, the mesh is selectively movable or removable in the vicinity of the transfer space to enable efficient transfer of roofing materials.

The access section may include at least one removable section which is temporarily removable by the worker to enable access to the area of the roof structure below the work surface where the removable section has been removed. The or each removable section of the work surface may be hinged to a structural frame of the work platform for upward hinging movement to thereby enable access to the area of the roof structure below the work surface. Alternatively, the or each removable section of the work surface may be selectively

slidably mounted to a structural frame of the work platform for generally horizontal sliding movement so as to create an opening enabling access to the area of the roof structure below the work surface.

In an alternative embodiment to the one providing removable sections, the or each support section of the upper work surface may comprise a foot support surface adjacent to an access section and on which the worker can place his foot or feet so as to be supported while working on the roof structure through the access section and while standing or moving about on the work platform. The or each foot support surface may be permanently mounted as part of the structure of the work platform. The or each foot support surface may comprise a foot plate or an elongated tread surface.

The present invention in a second aspect provides a method of performing roof construction work on a roof structure, the method including the steps of providing a work platform according to the first aspect as summarised above, lifting the work platform into an operative position on top of the roof structure, supporting and maintaining the work platform in the operative position so that the worker can perform work on the roof structure below the work platform, performing roof construction work on the roof structure from a position atop the work surface by accessing the roof structure through the access section, and transferring roofing materials between said work platform and the roof structure by passing the roofing materials through a transfer space through or adjacent the work surface.

In the preferred method the support means for supporting the work platform in its operative position a short distance above the roof structure includes stabilising means operative to restrain the work platform against substantial movement during the performance of work on the roof structure by the worker. The stabilising means preferably includes restraining means for co-operating with the roof structure to restrain the work platform against substantial movement, the restraining means including anchoring means which is releasably coupled to the roof structure.

In one possible method, the work platform is suspended by suspension means in its operative position so that at least part of the weight of the work platform, roofing materials carried thereby, working tools, and worker carried thereby is not totally transferred to and supported by the roof structure. In this method the anchoring means may include releasable arms, guys, or struts which extend between the work platform and the roof structure and which anchor to the roof structure so as to restrain the work platform against substantial

movement when it is held suspended in its operative position a short distance above the roof structure. In this case, the suspension means, which may comprise suspension cables, chains, or the like, may be attached at attachment points provided by the work platform so that the work platform in use is suspended by means of the suspension cables or the like a short distance above the roof structure. A crane, for example, may be used for suspending the work platform in its operative position, as well as for raising the work platform from the ground to its operative position and for returning the work platform from the roof structure back to the ground. In this case where the work platform in use is suspended by suspension means, the anchoring means may comprise releasable arms or guys or struts which extend between the work platform and the roof structure and which are anchored to the roof structure so as to restrain the work platform against substantial movement when held suspended in its operative position.

In a further possible method, the work platform may include means for engaging with the roof structure so that at least part of the weight of the work platform, roofing materials carried thereby, working tools, and worker carried thereby is transferred to the roof structure when the work platform is in its operative position. In this further method the stabilising means for the work platform may include feet which engage with the roof structure, the restraining means including releasable fasteners or attachments for attaching the feet of the work platform to the roof structure. It will also be appreciated that if the work platform is brought into its operative position resting on the roof structure, not all of the weight thereof need be transferred to the roof structure and, in particular, the suspension means can continue to be employed to carry some of the weight so that only a portion of the weight is transferred to the roof structure.

In a method using a platform with removable sections, the roof construction work is performed on the roof structure from a position atop the upper work surface by first removing the removable section to permit the worker positioned on the upper work surface to access the roof structure through the opening created upon removal of the removable section.

The roofing materials which are carried on the platform, and on the material storage section in particular, can be new materials loaded onto the material storage section with the work platform resting on the ground, after which the work platform is lifted by crane into its operative position and the roofing materials can be transferred through the transfer space for

installing the new roofing materials in the roof structure. Likewise, the roofing materials removed from the roof structure, e. g. during maintenance or repair operations, can be passed through the transfer space and stored on the material storage section and then returned to ground level with the work platform.

The provision of the safety barrier around at least part of the periphery of the work surface, and preferably entirely around the work platform, together with the overall constructional features of the work platform, enable the worker to ride on the platform as it is lifted from the ground into its operative position and vice versa. This can be particularly advantageous for relatively small roofing maintenance, repair or other construction tasks.

Brief description of the drawings Possible and preferred features of the present invention will now be described with particular reference to the accompanying drawings. However it is to be understood that the features illustrated in and described with reference to the drawings are not to be construed as limiting on the scope of the invention. In the drawings: FIG lisa schematic perspective view of a work platform according to an embodiment of the present invention in use, FIG 2 is a side view of the work platform of FIG 1, FIG 3 is a plan view of the work surface of the work platform of FIG 1, FIG 4 is a sectional view along the line A-A of FIG 3, FIG 5 is a sectional view along the line B-B of FIG 3, FIG 6 is a sectional view along the line C-C of FIG 3, and FIG 7 is a schematic perspective view of the work surface of an alternative configuration of work platform according to a further embodiment of the present invention.

Detailed description Referring to the drawings, the work platform comprises a frame 10 made of any suitable material such as metal sections bolted or otherwise fastened together so as to provide a rigid structural mounting for other parts. The length of the platform may be generally about the length of the rafters of the roof structure 5 so that when the platform is in its operative position as shown in FIG. 1, a worker by moving around on the platform can have access to the roof structure along a long side of the platform, to the ridge 14 of the building along the upper short side, and to the outer lower edge of the roof structure along

the opposite short side of the platform. However, dimensions are not critical and indeed the platform can be useable with different sizes and types of buildings and roofs.

On the frame 10 there is an upper work surface 15 mounted by the frame 10 and on which the worker can move about on the platform. The upper work surface can be made of any suitable construction and materials and in the illustrated embodiment comprises a grid material suitable for supporting the weight of the person and weight of building materials.

The upper work surface has two sections, a roof construction work section 15a and, at a slightly stepped down lower level, a material storage section 15b. The material storage section 15b can be of continuous mesh construction having a fixed floor and is provided for carrying and supporting roofing materials. The elevated work section 15a provides at least one access section 11 enabling worker access to work on the roof structure beneath the platform. Adjacent the access section 11 is at least one support section 12 of the work surface 15 so that a worker can be supported on the support section 12 while accessing and working on the roof structure 5 through the access section 11. In Fig. 1, the access through the support section 12 is enabled by providing a surface made of multiple sections, such as panels 16 which have peripheral frames to which the grid material 18 on which the worker walks is mounted (see Fig. 4). Each panel 16 can be mounted to the frame 10 of the platform by hinges 17 so that each work surface section or panel 16 can be independently removable by hinging upwardly (as shown at 16a in FIG 1) to enable access to the area below the removed section. Below the movable sections 16 of the work surface there is provided a relatively open safety mesh 48 having relatively large openings sufficient to enable the worker to carry out operations beneath the mesh but being sufficiently small to prevent a worker falling through.

Instead of the pivoted or hinged removable panels 16a as shown in Fig. 1, removable panels 16b may be selectively slidably mounted to the structural frame 10 of the work platform, e. g. in parallel spaced tracks, for generally horizontal sliding movement as shown by arrow A above or below an immediately adjacent panel so as to create an opening 11 enabling access to the area of the roof structure below the work surface.

In the step formed between the elevated work section 15a and the lower material storage section 15b there is an upright transfer space 19 in the form of an open slot through which roofing material such as roofing sheets, structural supports, etc can be transferred from the lower level storage section 15b into position beneath the elevated work section 15a

and, vice versa. The transfer space 19 is sufficiently small in height to prevent a person fitting through the space but is elongated to enable roofing sheets, purlins, etc to pass therethrough by transverse movement. Removable barriers 22, such as chains, prevent roofing materials sliding laterally through the space 19 during raising and lowering of the platform to and from the roof structure.

A safety barrier 20 is provided around the platform. The safety barrier is comprised by upright posts 45 mounted to the frame 10 and multiple safety rails or lines 49 extending between adjacent posts.

The safety barrier 20 at the upper end of the platform can be mounted at point 50 to the frame 10 for hinging movement outwardly. The purpose of enabling outward hinging movement to a limited extent is to enable more easy access to the ridge 14 of the roof structure when the platform is mounted in position on an inclined roof structure as shown in FIG 1.

A support means 30 supports the work platform in its operative position a short distance above the roof structure 5. The support means 30 includes suspension means 31 having suspension cables 32,33. The cables 33 are fixed at attachment points 34 provided on the frame 10. A crane (not shown) lifts the platform from the ground to the operative position shown in FIG 1 and carries the weight of the platform and the materials, tools, and worker (s) both during raising and lowering of the platform to and from its operative position and during maintenance of the platform in its operative position during the performance of work on the roof structure. To stabilise the platform in its operative position, restraining means such as the anchoring arms, guys or struts 35 co-operate with the building or roof structure (or possibly with points at ground level) to restrain the work platform against substantial movement. These stabilising means 35 can be installed in position by releasable anchoring means 36 and released by the worker at the start of and at the end of the work operation.

Some of the weight of the platform and its load can be transferred to the building structure by engaging feet 38 which can be releasably fastened or attached at 39 to the roof structure.

In the embodiment of Fig. 7, the access space 11 provided by the upper roof construction work section 15a is provided by one or more spaces, provided with mesh 48 to prevent a worker falling through, adjacent foot support surfaces on which a worker can

place his foot or feet so as to be supported while working on the roof structure through the access section 11 and while standing or moving about on the work platform. Each foot support surface 51 is securely and preferably permanently mounted as part of the structure of the work platform. As illustrated, each foot support surface can comprise a foot plate or, as illustrated, an elongated tread surface 52. In this embodiment of Fig. 7, there is no need for the provision of removable sections such as the hinged panels 16a or sliding panel 16b of Fig. 1.

When the work platform of either embodiment illustrated in the drawings is in its operative position on a roof structure with the support means and stabilising means maintaining the platform in its position, it is possible for worker (s) on the platform to carry out erection, maintenance, repair and replacement work on the roof structure. For example, to remove and replace corroded or otherwise structurally unsound roofing sheets or purlins, the worker can move around work section of the platform unfastening the roofing materials and passing them through the transfer space onto the storage section. When the roofing materials have be unfastened and placed on the storage section, the entire platform can be released and the platform with the roofing materials therein can be lifted and lowered to the ground by crane. After removal of the old materials, new materials can be loaded onto the storage section and the platform lifted and relocated in its operative position. The worker can pass the new materials through the transfer space and secure the new materials to the roof structure.

It will be understood from the preceding description in conjunction with the possible embodiment illustrated in the drawings, that variations and modifications of the platform and its use are feasible. For example the upper level of the work surface in the illustrated embodiment comprises the work section and the lower level comprises the material storage section, however the reverse is equally feasible. Likewise, the split level work surface is not essential and also the transfer space could be provided at other locations. For example, the transfer space could be provided along an edge of the work platform so that roofing materials can be transferred through the transfer space to a position adjacent or at least overlapping with the edge of the platform before being installed in position. The roof construction work does not need to be entirely carried out directly below the work surface, but at least some of the work operations can be carried out outside the perimeter of the work platform. The entire area of the work surface can be provided with removable sections.

Various other constructional features of a work platform according to the invention can be provided as alternatives or as additional components of the work platform particularly described and illustrated herein. In particular, the entire contents of patent specification AU-707069 are incorporated herein in full by cross-reference so as to provide examples and details of constructional and operational features of a work platform that can possibly be incorporated in the platform of the present invention. Examples of such alternative or additional features include: details of the construction and operation of the hinged platforms of the work surface, details of the mesh provided beneath the hinged panels, the construction, configuration and operation of the safety barrier around the periphery, and the construction and operation of the mounting feet and associated fastening means (if provided) are all described in AU-707069 in more detail and can be incorporated in the platform of the present invention.

It will be understood from the preceding description and accompanying drawings that the present invention provides an effective solution (both apparatus and method) to problems of safely and readily enabling work on a roof structure. Such work can include erection as well as maintenance, repair and replacement of the roof structure. The work platform is versatile and is useable with different types and sizes of buildings and does not require to be constructed or modified for different uses. It can be used with small buildings and for small roof maintenance tasks.

It is to be understood that various alterations, modifications and/or additions may be made to the features of the possible and preferred embodiment (s) of the invention as herein described without departing from the scope of the invention.