ROOF ASSEMBLY

Abstract: The specification describes a method of erecting a building roof which comprises constructing the roof while on the ground and lifting it into position onto load bearing columns. A roofing assembly capable of being used in the method is also described. The assembly comprises a frame, roof cladding elements and ceiling elements. The assembly is so designed that it is capable of being assembled on the ground and lifted into position using transportable lifting means such as chain blocks or mobile cranes.

Description: ROOF ASSEMBLY The present invention relates to roof assemblies and a method of Installing a roof assembly to form the roof of a building such as a factory or commercial building. Normally a building is constructed by installing the foundations and floors, constructing a framework for the walls and roof, and then installing the elements which make up the walls, ceiling and roofing. The plumbing and wiring are usually installed once the shell of the building has been constructed. Typically, the roof of a building in particular is constructed in situ, that is, above the ground. Constructing anything above ground level adds to the cost of construction. Where buildings have been required in locations having high construction costs, they have been fabricated in modules that have been transported to the site and assembled in situ thereby considerably reducing the cost of labour required at the site. However, to be transpσrtable such modular buildings have lacked aesthetic appeal and when the high cost of transport is taken into account, have not been competitive in situations where construction labour Is readily available. Because the roof of a building is largely assembled above the ground it usually represents a disproportionately high component of the total cost of construction. There is therefore a considerable economic advantage to be obtained by assembling a roof on the ground and lifting it into position as a unitary structure. Patent application No. 22914/77 describes a prefabricated roof structure having an underlying peripheral support to provide rigidity so that the structure can be raised as a unit. The prefabricated structure described Includes roof trusses, faslca, guttering and rafters. The structure is supported at a level slightly above the ground while tiling or roof sheeting is applied to the frame. The structure is then raised so that the ceiling and soffits can be readily fitted from ground level. The roof structure may be raised by hydraulic or mechanical jacks or cranes according to circumstances. The proposal described in patent application No. 22914/77 suffers from a number of disadvantages. Firstly the roof is so designed that it is necessary to add a peripheral support to provide rigidity. The addional materials and time required to construct the support add to the cost of the structure. Secondly the multi-lift assembly of the structure, adds to the cost and increases the risk of accidents arising especially while the ceiling is being installed. An objective of the present invention is therefore to reduce the cost of constructing and installing building roofs and overcome the problems associated with previous proposals. Accordingly, the present invention provides a roofing assembly for a new building comprising a frame, roof cladding elements and ceiling elements, said roofing assembly being so designed that it is capable of being assembled on the ground and lifted into position using transportable lifting means, the assembly having no additional peripheral support structure. In another aspect of the present invention there is provided a method of constructing a building roof comprising designing a roofing assembly that is capable of being assembled on the ground and lifted into position using transportable lifting means, constructing a roof frame on the ground near a building to be roofed using elements having a high strength to weight ratio, installing ceiling and tiling elements on the frame to form a roof assembly, lifting the roof assembly into position using transportable lifting means, and securing the roof assembly to load bearing columns forming part of said building. The transportable lifting means may comprise one or more chain blocks or mobile cranes. If chain blocks are to be used to raise the assembly into position, the assembly will be constructed directly below its installed position. Power for the chain blocks may be supplied from the power lines installed within the assembly. Once the roofing assembly has been raised to its installed position, the primary beams can be bolted to neighbouring load bearing columns. The roof frame may be formed from primary beams made from universal beams, channels or cold rolled Z sections and secondary beams or purlins formed from c or z metal cold rolled sections. The primary beams may be spaced such that the distance between them lies in the range between 4 and 12 metres. The secondary beams may be spaced such that the distance between them lies in the range from 0.3 to 1 metres. The roof cladding elements may be any metal deck such as for example, Lysaght Brownbuilt "Trimdek". The ceiling elements may be "Rondo" or similar suspended ceiling grids having plaster ceiling tiles. Preferably the roof has a pitch of less than 10 degrees. Preferably also, electrical wiring, lights, gutters, skylights, vents, fascias, insulation and any ducting are installed prior to lifting the roofing assembly into position. A particularly preferred method of constructing a roof according to the present invention comprises the steps of: (1) laying out primary beams and a celling grid, (2) installing load bearing columns, (3) positioning the primary beams, (4) assembling the celling grid, (5) fixing purlins to the primary beams to form a frame, (6) connecting the ceiling grid to the purlins, (7) installing electrical wiring and lights. (8) dropping ceiling panels into position, (9) fixing roof cladding to the frame and installing insulation, (10) installing gutters, skylights, vents and fascias, (11) preparing lifting points, (12) lifting the roofing assembly into position on the load bearing columns using chain blocks or mobile cranes, (13) securing the roofing assembly to the load bearing columns, (14) bracing the load bearing columns to improve their load bearing capacity, (15) removing the chain blocks or mobile cranes and (16) finishing off around the load bearing points. Ideally the method of the present invention forms part of a method for very fast building construction. This preferably involves the off-site construction of service room modules such as kitchens, bathrooms and toilets for subsequent installation in the building in a completely assembled state. Typically such a method involves the following steps: (1) constructing foundations, (2) forming a concrete slab, (3) installing load bearing columns, (4) constructing a roof according to the method of the present invention simultaneously with the preceding steps, (5) installing service modules constructed off-site, (6) constructing external and internal walls, and (7) completing fit-out and finishing off. Preferably very fast building construction also includes utilization in the pre-construction period of an integrated site management system. Such a system involves testing and assessing a construction site, preparing the site ready for construction, certifying the site for particular types of construction and maintaining It ready for construction. This system is more particularly described in co-pending patent application No. PJ8340. A preferred embodiment of the invention will now be described with reference to the accompanying drawings in which Figures 1 to 7 are perspective views of a roofing assembly erected according to the method of the present invention. Figure 8 is a construction schedule. Figure 1 depicts a concrete slab 1 having a sheet of polyethylene 2 placed over its upper surface. Primary beams 3, 4, 5 and 6 are then laid out across the concrete of polythene 2 placed over its upper surface. Primary beams 3, 4, 5 and 6 are then laid out across the concrete slab with a clearance of about 50 mm from the upper surface of the slab 1. Figure 2 depicts a ceiling grid 7 laid out between the primary beams 3, 4, 5 and 6. The 50mm clearance enables the ceiling grid 7 to be laid out under the primary beams. Lighting points 8 and ventilation points 9 are inserted in the ceiling grid as shown in Figure 3. Ceiling tiles may be installed at this stage or after the roof has been raised. Load bearing columns 10, 11, 12, 13, 14, 15, 1§ and 17 are installed in the slab adjacent to the ends of the primary beams. Figure 5 depicts the concrete slab, the primary beams and the load bearing columns without the ceiling grid and attached lighting and ventilation points. Purlins or secondary beams 18 are laid out in a direction transverse to the primary beams. The secondary beams are connected to the primary beams and the ceiling grid is connected to the secondary beams. Ideally gutters, gutter boards and wiring are installed at this stage. All fascias 25, flashings, gutters, skylights, vents, services and other installations are completed ready for elevation of the roof. The load bearing columns 10, 11, 12, 13, 14, 15, 16 and 17 are extended by means of extensions 20 and chain blocks 19 are attached to the top of the extensions as shown in Figure 6. The electric chain blocks 19 are controlled from a central control box 21 and the roofing assembly raised to its erected position as shown in Figure 7. Figure 7 depicts the roofing assembly 22 in its erected position. The roof has a ridge line 23 and a pitch of less than 10 degrees. Bracing 24 is Installed between columns 15 and 16 and columns 11 and 12 (not shown) .

Claims: CLAIMS : 1. A roofing assembly for a new building comprising a frame, roof cladding elements and ceiling elements, the roofing assembly being so designed that it is capable of being assembled on the ground and lifted into position using transportable lifting means, the assembly having no additional peripheral support structure. 2. A roofing assembly according to claim 1 wherein the frame is formed from primary beams selected from the group consisting of universal beams, channels or Z cold rolled metal sections. 3. A roofing assembly according to claim 2 wherein the frame contains secondary beams or purlins formed from C of Z cold rolled metal sections. 4. A roofing assembly according to either claim 2 or claim 3 wherein the primary beams are spaced apart by a distance in the range from 4 to 12 metres. 5. A roofing assembly according to claim 3 or claim 4 when appended to claim 3 wherein the secondary beams are spaced apart by a distance in the range from 0.3 to 2 metres. 6. A roofing assembly according to any one of the preceding claims wherein the roof cladding elements are metal decking. 7. A roofing assembly according to any one of the preceding claims wherein the ceiling elements comprise suspended ceiling grids consisting of plaster ceiling tiles. 8. A roofing assembly according to any one of the preceding claims wherein the assembly when assembled has a pitch of less than 10 degrees. preceding claims wherein the assembly comprises electrical wiring, lights, gutters, skylights, vents, fascias, insulating and any ducting. 10. A roofing assembly according to any one of claims 1 to 9 wherein the transportable lifting means is one or more chain blocks or mobile cranes. 11. A method of erecting a building roof comprising; designing a roofing assembly that is capable of being assembled on the ground and lifted into position using transportable lifting means; constructing a roof frame on the ground near a building to be roofed using elements having a high strength to weight ratio; installing ceiling and tiling elements on the frame to form a roof assembly; lifting the roof assembly into position using transportable lifting means; and securing the roof assembly to load bearing columns forming part of said building. 12. A method according to claim 11 wherein the transportable lifting means comprises one or more chain blocks or mobile cranes. 13. A method or erecting a building roof comprising; laying out primary beams and a ceiling grid, installing load bearing columns, positioning the primary base, assembling the ceiling grid, fixing purlins to the primary beams to form a frame. connecting the ceiling grid to the purlins, installing electrical wiring and lights, dropping ceiling panels into position; fixing roof cladding to the frame, installing insulation, installing gutters, skylights, vents and fascias, preparing lifting points, lifting the roofing assembly into position on the load bearing columns using chain blocks or mobile cranes, securing the roofing assembly to the load bearing columns, bracing the load bearing columns to improve their load bearing capacity removing the chain blocks or mobile cranes and finishing off around the load bearing points. 14. A method of constructing a building comprising; constructing foundations, forming a concrete slab, installing load bearing columns, erecting a roof on the building using the method according to claim 11 or claim 12, installing service modules constructed off-site, constructing external and internal walls, and completing fit-out and finishing off. 15. A method of constructing a building according to claim 14 wherein the method includes the following steps prior to constructing the foundations; testing and assessing a site for the construction, preparing the site ready for construction, certifying the site for particular types of constructions and maintaining the site ready for construction. 16. A method substantially as hereinbefore described with reference to the accompanying drawings.

Inventors: MLADICHEK BRANKO, MLADICHEK, BRANKO
Applicants: POWER DEVELOPMENTS PTY LTD, POWER DEVELOPMENTS PTY. LTD.
Application year: 1990
Main classification: E04B1
IPC codes: E04B1, E04B7