TITLE

Suspended Ceilings

DESCRIPTION Field of the Invention

The invention relates to a method for fitting suspended ceilings using plasterboard, and provides a novel bracket for use in such a method.

Background Art Modern building methods often involve the use of solid concrete floors, either cast as a single slab across an entire room, for example supported on a corrugated or profiled metal support or laid in place as a pre-cast unit or array of pre-cast subunits. The pre-cast subunits may be prβrcast concrete beams laid side by side to create the entire concrete floor and then covered with a skim layer of mortar or levelling compound, or a thin bituminous layer. Above ground-floor level, however, every concrete floor also presents a rough and unfinished ceiling to the room below. To cover that rough underside of the floor above, it is usual to provide a suspended ceiling spaced slightly below the underside of that floor. Such ceilings may be tiled ceilings, in which rectangular ceiling tiles rest on a lattice of metal angle mouldings which provide edge support for individual tiles, in such tiled ceilings the metal angle mouldings are visible, around the edge of each ceiling tile, from the room below. Alternatively the ceilings may use plasterboard screwed to an array of parallel ceiling channels suspended from the floor above, and the plasterboard coated with a skim of gypsum-based plaster to give the smooth appearance of a traditional plaster ceiling. Such ceilings are referred to herein as suspended plasterboard ceilings.

To fit a suspended plasterboard ceiling, first a laser level is used to draw or display a continuous horizontal line around the entire periphery of a room, about 80 to 100 mm below the solid concrete floor above. This results in a space between the solid concrete and what will eventually be the suspended

plasterboard ceiling for services such as cabling, pipework and insulation etc. Edge channel members are then screwed to the wails along that horizontal line, around the complete periphery of the room. Soffit cleats are then secured to the rough underside of the floor above, in a regular array that is typically at 1200 mm spacings in mutually perpendicular directions. The fixings for the soffit cleats are typically drive-in expanding fasteners inserted into holes drilled into the underside of the floor above. If such a fastener is inserted into a drilled hole and then an expansion pin portion of the fastener hammered into a tapering bore in the fastener, the fastener expands within the drilled hole and creates a secure anchorage for the soffit cleat.

When the entire array of soffit cleats at regular 1200 mm intervals has been secured in position, either a flexible strap hanger or a rigid metal angle suspension member is cut to size and then bolted to the soffit cleat. All the flexible strap hangers or rigid metal angle suspension members are the same length so that when bolted to their soffit cleats they hang down to the same height, which is marginally above the height of the edge channel members.

An array of parallel primary channel members, of generally C-section, is then secured to the bottom ends of the array of depending strap hangers or metal angle suspension members, at precisely the height of the edge channels around the periphery of the room. Generally the primary channel members are secured to the flexible strap hangers or metal angle suspension members by large pan head self-tapping or self-drilling screws.

Finally at mutual spacings of typically 400 or 450 mm, ceiling channel members of top hat section are clipped perpendicularly across the primary channel members, and full sized sheets of ceiling plasterboard are screwed to the ceiling channel members using large headed self-tapping plasterboard screws. That creates a continuous plasterboard suspended ceiling which can be finished with a smooth or textured skim of ceiling plaster.

A major time-consuming element of the above method of creating a suspended plasterboard ceiling is involved in the securing of the soffit cleats to the underside of the floor above, followed by bolting the flexible strap hangers or metal angle suspension members to vertical depending flange portions of the soffit cleats. This is however a necessary part of the installation process, as the strap hangers or the metal angle suspension members are cut to length on site and cannot be secured to the underside of the floor above except by using pre-installed soffit cleats. There is therefore a need for a quick and reliable method of providing support for the primary channels across the length and width of the room, without the need to fasten in place the array of soffit cleats as a first step. To date, however, no commercial product exists to provide that support in the absence of the array of soffit cleats.

The Invention

The invention provides a bracket for use in suspended ceiling construction using plasterboard, substantially as described in claim 1 herein.

The invention also provides a method for fitting a plasterboard suspended ceiling using such a bracket, substantially as described in claim 9 herein.

It will be understood that the method corresponds closely to the prior art method described above except for the use of the brackets of the invention. The brackets are pre-formed and require no on-site preparation except on occasions to be trimmed on-site to a shorter length. Such trimming can be by hacksaw or by tin-snips. The pre-formed apertures may be punched, preferably before the bracket is cold-pressed or cold-rolled into its L-section. The end portions are preferably bent over to overlie one another in a separate cold-pressing operation.

Because the brackets are pre-formed to a fixed design they can be tested and guaranteed to meet specific loading requirements, particularly when used in

combination with an approved fixing for securing the brackets to the underside of the floor.

The bracket material is preferably steel, which may be of 0.6 to 0.9 mm thickness, preferably about 0.8 mm thickness. It may be galvanised, preferably electro-galvanised. The brackets may be formed in a range of standard lengths such as 250 mm, 450 mm and 650 mm, for example.

Preferably the brackets are designed to support service cables or conduits in use at a level above that of the plasterboard suspended ceiling. For example each of the side and rear faces may be provided with pre-formed slotted elongate vertically extending apertures for receiving and supporting, in use, one or more service support shelves for supporting service cables or conduits at a level above that of the suspended plasterboard ceiling. Or the side and rear faces may be provided with an vertical array of pre-formed bolt holes for receiving bolts which can be used to support one or more such service support shelves. The invention therefore provides a bracket assembly according to claim 9 or claim 11 , comprising the appropriate bracket according to the invention in conjunction with one or more compatible service support shelves.

DRAWINGS

Figure 1 is a perspective view of a bracket according to a first embodiment of the invention, viewed from the rear and one side;

Figure 2 is a side elevation of the bent-over end portions of the side and rear walls of the bracket of Figure 1 ;

Figure 3 is an enlarged perspective view of the end portion of the bracket of Figure 1 , but viewed from the front and one side;

Figure 4 is a vertical section through a suspended ceiling incorporating brackets as shown in Figures 1 to 3;

Figures 4A, 4B and 4C are, respectively, sections through the edge channels 9, the primary channel members 10 and the ceiling channel members 12 of Figure 4;

Figure 5 is a perspective view similar to that of Figure 1 of a bracket according to a second embodiment of the invention with a service support shelf slotted thereto;

Figure 6 is a side view of the service support shelf of Figure 5;

Figure 7 is a perspective view similar to that of Figure 1 of a bracket according to a third embodiment of the invention; and

Figure 8 is a side view of a service support shelf to be bolted to the bracket of Figure 7.

Figure 1 shows the complete bracket 1 of a first embodiment of the invention. It has a side wall 2 and a rear wall 3. At its top end an end portion of the side wall 2 is folded perpendicularly to fill the angle between the two walls, and an end portion 5 of the rear wall 3 is folded perpendicularly to overlie the end portion of the side wall 2. The end portion of the side wall 2 is obscured and therefore not visible in Figure 1 but is numbered 4 in Figures 2 and 3.

Apertures are pre-formed, by punching, in the end portions 4 and 5, and overlie one another to create a continuous through-hole 6 which is used as described below. When the bracket 1 is secured to the underside of a floor with a fastener through the hole 6 created by the aligned punched apertures, that establishes a rapid rigid connection between the bracket 1 and the floor

which provides the support for the suspended ceiling, dramatically reducing the time needed to complete the installation as compared to the prior conventional use of soffit cleats, bolts and metal angle. Not only is the installation time dramatically reduced, also the rigidity of the bracket 1 is superior to that of the conventional soffit cleats and metal angle, since the overlapping of the end portions 4 and 5 of the side and rear faces 2 and 3 of the bracket creates a rigid and accurate connection to the underside of the floor.

Figure 4 illustrates the method of fitting a plasterboard suspended ceiling according to the invention. In Figure 4, 7 illustrates two opposite walls of an internal room of a building, and 8 illustrates a solid floor the underside of which is to be covered and concealed by the suspended ceiling. .

First, using a laser guide, edge channels 9 are screwed to the walls 7 at a single level all around the periphery of the room, at the intended height of the suspended ceiling. Figure 4A shows the section of a typical edge channel 9. Next, brackets 1 according to the invention secured to the underside of the floor 8 at regular spacings of 1200 mm in mutually perpendicular directions. To fix the brackets 1 to the underside of the floor 8 holes are drilled at the desired centres and then a spread sleeve pin anchor is passed through the aperture 6 in each bracket 1 and into the corresponding drilled hole, and locked in place by driving home the pin to spread the sleeve inside the drilled hole. Other concrete fixings may of course be used, but spread sleeve pin anchors are rapid and efficient.

A row of primary channel members 10 is then placed, wall to wall, across each row of depending brackets 1 and secured to the brackets 1 using self- drilling or self-tapping screws 11. The brackets 1 can be trimmed to length if necessary, either before or after the primary channel members 10. are secured. Figure 4B shows the section of a typical primary channel member 10. Next, parallel rows of ceiling channel members 12 are clipped to the

primary channel members 10 using proprietary clips (not shown), and plasterboard panels 13 are screwed to the ceiling channel members 12 using plasterboard self-tapping screws (not shown). Figure 4C shows the section of a typical ceiling channel member 12. Finally, a conventional plaster skim across the underside of the plasterboard panels 13 finishes the suspended ceiling.

Figure 5 shows a bracket 20 according to a second embodiment of the invention. The same reference numerals have been used to indicate the same parts of the bracket 20 of the second embodiment of the invention as were used for the first embodiment, so further explanation of those parts in unnecessary. The bracket 20 has pre-formed in the side and rear walls 2 and 3 slotted elongate vertically extending apertures 21 for receiving and supporting in use one or more service support shelves 22 at a level spaced above that of the suspended plasterboard ceiling which ultimately will be supported by the bracket 20. One such service support shelf 22 is shown in Figure 5, and the same shelf 22 is shown in side view in Figure 6. It consists of two hooked portions 24 which pass through the slotted elongate vertically extending apertures 21 of the bracket 20, to lie closely against the inside walls of the bracket. A laterally folded vertical flange portion 25 of the shelf 22 assists in keeping the shelf 22 at approximately 90° to the respective side or rear wall 2 or 3 of the bracket 20. A laterally folded horizontal flange portion 26 of the shelf 22 provides a support surface for services, typically cables or conduits, to be supported clear of the plasterboard at above suspended ceiling height by the shelf 22.

Figure 7 shows a bracket 30 according to a third embodiment of the invention. The same reference numerals have been used to indicate the same parts of the bracket 30 of the third embodiment of the invention as were used for the first embodiment, so further explanation of those parts in unnecessary. The bracket 30 has pre-formed in the side and rear walls 2 and 3 a vertical array of mutually spaced circular bolt holes 31 for receiving and supporting in use

bolts (not shown) which support one or more service support shelves 32 at a level spaced above that of the suspended plasterboard ceiling which ultimately will be supported by the bracket 30. One such service support shelf 32 is shown in side view in Figure 6. It has two vertically spaced bolt holes 33 at one end thereof at the same spacing as the holes 31 in the bracket 30. Using bolts passing through these bolt holes 31 and 33, the shelf 32 can be secured at any of a range of different heights flush with the side or rear walls 2 and 3 of the bracket 30, to extend outwardly in cantilever as a service support shelf. A laterally folded horizontal flange portion 34 of the shelf 32 provides a support surface for services, typically cables or conduits, to be supported clear of the plasterboard at above suspended ceiling height by the shelf 32. A similar flange portion 34 beneath the shelf 32 provides symmetry so that the shelf can be used either way up, and also assists in making the shelf more rigid. Punched apertures 35 can be used to bolt on additional support structure for specific service items of may be used as anchorages for plastic ties for holding the services in place.