GB2383804A

GB2383804A - Waterproofing method and apparatus for a railway arch

Info

Publication number: GB2383804A
Application number: GB0200158A
Authority: GB
Inventors: Leonard Edwin Harris
Original assignee: H T MARTINGALE Ltd
Current assignee: H T MARTINGALE Ltd
Priority date: 2002-01-04
Filing date: 2002-01-04
Publication date: 2003-07-09
Also published as: GB0200158D0

Abstract

A suspended ceiling 3 is provided which provides a means for waterproofing the interior of an arch 1 whilst allowing visual inspection of the interior of the arch 1. The ceiling 3 comprises an arrangement of support brackets 5 from which a plurality of horizontal rows of ceiling tiles 6 are suspended. In order to provide a waterproof barrier each of the ceiling tiles 6 includes a waterproof backplate 8 and an overlapping backplate extension 9. Each of the support brackets 5 incorporates a deflection plate 20 which causes water to be directed on to the central portions of waterproof backplates 8 provided on the ceiling tiles 6 attached to the support brackets 5. The backplates 8 and backplate extensions 9 then direct water entering the arch 1 away from the interior of the arch 1.

Description

WATERPROOFING METHOD AND APPARATUS The present application concerns a waterproofing method and apparatus. In particular, embodiments of the present invention concern method and apparatus for waterproofing the interior of arches such as railway arches.

Arches under elevated roads or railways are frequently to be found in the commercial districts of towns and cities. Many such arches are of a size which would enable small offices or other business premises to be accommodated within the arches. However, in order for arches to be converted for such a use, it is necessary to ensure that the interior of the arches are waterproof.

One method of waterproofing the interior of an arch is to fix waterproof sheeting on the interior of the arch. The waterproof sheeting inside the arch can then be covered with cladding to form a ceiling. Although such a system is effective at preventing water passing through into the interior of the arch, the presence of the waterproof sheeting and the cladding prevents visual inspection of the brickwork forming the arch without damaging the sheeting. Structural problems can therefore develop behind the waterproof sheeting and cladding which

when a problem does become apparent require expensive repairs.

A waterproofing system is therefore required which can prevent water entering to the interior of an arch whilst permitting visual inspection of brickwork forming the arch.

In accordance with one aspect of the present invention there is provided a suspended ceiling system for a roof having an apex comprising: a plurality of support members extending down from the apex; a plurality of ceiling tiles arranged in rows parallel to said apex; and fixing means releasably fixing said ceiling tiles to said supports at the periphery of said ceiling tiles; wherein said support members each comprise a first shielding member for directing water away from the vicinity of the edge of said ceiling tiles fixed to said supports; and wherein said ceiling tiles each comprise second shielding means for preventing water from passing between said ceiling tiles.

Further aspects and embodiments of the present invention will become apparent with reference to the following description and drawings, in which:

Figure 1 is a perspective view of a brick arch and suspended ceiling in accordance with a first embodiment of the present invention ; Figures 2A and 2B are perspective views of a ceiling tile of the suspended ceiling of Figure 1; Figure 3 is a perspective view of a portion of a support bracket for attaching the ceiling of Figure 1 to the inside of an arch; Figure 4 is a perspective view of the outer surface of four ceiling tiles forming a portion of the suspended ceiling of Figure 1; Figure 5 is a cross-section through a portion of the brick arch and suspended ceiling of Figure 1 looking along the arch; Figure 6 is a partial perspective view of a pair of ceiling tiles beneath a support bracket forming part of the suspended ceiling of Figure 1; Figure 7 is a cross section through a support bracket and a pair of ceiling tiles forming part of the suspended

ceiling of Figure 1; Figure 8 is a perspective view of the outer surface of the suspended ceiling of Figure 1 in the absence of the brickwork arch; and Figure 9 is perspective view of a portion of the outer surface of a suspended ceiling in accordance with a second embodiment of the present invention.

First Embodiment Referring to Figure 1, in accordance with a first embodiment of the present invention the interior of an arch 1 is made waterproof by a suspended ceiling 3. The ceiling 3 comprises an arrangement of support brackets 5 from which a plurality of horizontal rows of ceiling tiles 6 running along the width of the arch 1 are suspended with the individual ceiling tiles 6 being removable from within and below without disturbing neighbouring tiles 6 so as to permit visual inspection of the brickwork of the arch 1. The support brackets 5 each extend across the entire span of the arch 1 following the curve of the arch 3 and are spaced periodically throughout the width of the arch 1 at distances corresponding to the horizontal extent of

individual ceiling tiles 6 forming the ceiling 3. Cover strips 7 run horizontally between the rows of ceiling tiles 6 obscuring the fixings attaching the ceiling tiles 6 to the support brackets 5 from view. If a ceiling tile 6 is to be removed so that the brickwork underneath can be inspected, the cover strips 7 adjacent to the tile 6 are removed so that the fasteners holding the tile in place (not shown in Figure 1) can be accessed and a tile 6 removed.

Together the ceiling tiles 6 act to form a waterproof barrier preventing any water seeping out of the arch 1 from passing through the ceiling 3. This is achieved by each of the tiles 6 including a waterproof backplate 8 and an overlapping backplate extension 9 and the support brackets 5 including deflection plates each of which will be described in detail later.

The applicants have appreciated that a suspended ceiling system can achieve the contradictory aims of providing a means for waterproofing the interior of an arch 1 whilst being such as to allow visual inspection of the interior of the arch 1 to ensure that the brickwork forming the arch has not deteriorated. In order to provide a waterproof barrier, each of the support

brackets 5 from which the ceiling tiles 6 are suspended incorporates a deflection plate which causes water entering the arch 1 adjacent to the support brackets 5 to be directed away from the edges of the ceiling tiles 6 on to the central portions of the backplates 8 of the ceiling tiles 6 attached to the support brackets 5.

These backplates 8 and the backplate extensions 9 then form a waterproof barrier which causes any water entering the arch 1, through the brickwork to be directed away from the interior of the arch 1.

The structure of the ceiling tiles 6 forming the suspended ceiling 3 will now be described in greater detail with reference to Figures 2A and 2B which are perspective views of a ceiling tile 6 shown with its backplate 8 uppermost and resting upon its backplate 8 respectively.

As is shown in Figures 2A and 2B, the ceiling tile 6 comprises a substantially rectangular front panel 10 having a top edge lOa, a bottom edge lOb and two short side edges 10c and 10d. Attached on one face of the front panel 10 covering the entire face of the front panel 10 is the curved backplate 8 of the ceiling tile 6. In this embodiment the curved backplate 8 is made

from galvanised steel. Integrally formed as part of the curved backplate 8 is a backplate extension 9 extending from the central portion of the curved backplate 8 beyond the bottom edge lOb of the front panel 10 of the tile 6.

Running lengthways along the entire top edge lOa of the front panel 10 and extending beyond the top edge lOa of the front panel 10 a distance of approximately 5 cm is a first flange 12 integrally formed as part of the curved backplate 8.

The backplate extension 9 is connected to the rest of the backplate 8 via a joggle 13. At the centre portion of the bottom edge lOb of the front panel 10 of the ceiling tile 6. The joggle 13 is such as to cause the backplate extension 9 to lie parallel with and spaced apart from the curve of rest of the backplate 8. A pair of flanges 14 integrally formed with the curved backplate 8 are provided either side of the backplate extension 9. The flanges 14 extend beyond the bottom edge lOb of the front panel 10 a distance of approximately 5 cm. The flanges 14 either side of the backplate extension 9 each extend between the side edges of the backplate extension 9 to the side edges of the backplate 8 flush with the side edges 10c, 10d of the front panel 10 of the ceiling tile 6.

Screw holes 15 are provided in the centres of these flanges 14 and also at either end of the first flange 12 extending beyond the top edge lOa of the front panel 10 of the ceiling tile 6. These screw holes 15 are provided to enable screw fasteners to be used to attach the ceiling tiles 6 releasably to the support brackets 5.

In this embodiment, the flanges 12, 14 extending beyond the top edge lOa and bottom edge lOb of the front panel 10 are made to extend out beyond the top and bottom edges lOa, lOb respectively of the front panel 10 of ceiling tile Q to a length of approximately 5 cm. The backplate extension 9 is made to extend from the bottom edge lOb of the front panel 10 beyond the ends of the pair of flanges 14 adjacent to the bottom edge lOb of the front panel 10 about 10 cm beyond the bottom edge lOb of the front panel 10 so that the tiles 6 can be arranged with the backplate extension 9 of one tile 6 overlapping the flange 12 of an adjacent tile 6 with the ends of the flanges 14 at the bottom edge lOb of one tile abutting the flange 12 running along the top edge lOa of the other tile & .

In order to prevent water on the central portion of the curved backplates 8 from flowing out towards the side

edges of the backplate 8, an outer pair 16 and an inner pair 17 of neoprene gaskets are arranged to extend along the curved backplate 8 and backplate extension 9 parallel with to the side edges of the backplate 8. In this embodiment, the inner gaskets 17 are located within 10 cm from the sides of the backplate 8 with the outer gaskets 16 located closer to the sides of the tile 6.

These gaskets 16,17 are compressible and when uncompressed have a thickness greater than the height of the joggle 13. As will be described in detail later these neoprene gaskets 16,17 are such to channel any water running along the central portion of the curved backplates 4 away from the sides of the ceiling tile 6.

Referring to Figure 3 the support brackets 5 from which the ceiling is suspended will now be described. Each of the support brackets 5 comprises an upper deflection plate 20 that is connected via a plurality of U shaped brackets 22 to an extruded aluminium strip 24 from which the ceiling tiles 3 are subsequently suspended. Both the upper deflection plate 20 and the extruded aluminium strip 24 are such as to extend across the span of the arch 1 following the curve of the arch 1 defined by the brickwork. The upper deflection plate 20 of the support bracket 5 is in this embodiment, a galvanised steel strip

approximately 20 cm wide, the edges of which are turned down to form lips 21 approximately 1 cm deep. As will be described in detail later, when fixed to the arch 1 the upper deflection plate 20 rests against the brickwork of the arch 1 and acts as a waterproof barrier preventing water from passing directly from the brickwork forming the arch 1 through to the areas adjacent to the extruded aluminium strips 24 from which the ceiling tiles 6 are suspended.

In this embodiment, each of the extruded aluminium strips 24 of the support brackets 5 is formed so that a central portion of the extruded aluminium strip 24 extends below the rest of the strip 24 so as to form a central channel 25. The width of this central channel 25 is arranged to be twice the length of the flanges 14 from the side edges 10c, 10d of front panel 10 of the ceiling tiles 6 to the edge of the backplate extension 9. The depth of the channel 25 is made to be slightly greater than the height of the joggle 13 of the ceiling tiles 6. This ensures that when a pair of ceiling tiles 6 are abutted against one another along their side edges 10c, 10d, the lower face of the portion of the aluminium strip 24 forming the central channel 25 can overlie the flanges 14 and the portion of the curved backplate 8 running adjacent the

short edges 10c, 10d of the ceiling tiles 6, with the edges of the backplate extensions 8 of the ceiling tiles 6 lying beneath the outer section of the aluminium strip 24 beyond the central channel 25. Thus in this way the extruded aluminium strip 24 is able to lie directly upon the edge of the curved backplates 8 whilst permitting the joggles 13 to cause the backplate extensions 9 to stand proud from the rest of the curved backplates 8.

The arrangement of the ceiling tiles 6 within a suspended ceiling 3 will now be described in detail with reference to Figures 4 and 5 which are a partial perspective view of four ceiling tiles 6 forming part of the ceiling 3 and a cross-section through the ceiling 3 and arch 1 of Figure 1.

As the side edges of curved backplates 8 of the ceiling tiles 6 are flush to the side edges 10c, 10d of the front panels 10 of the ceiling tiles 6, this enables, as is illustrated in Figure 4, pairs of ceiling tiles 6 to be abutted against one another along their side edges lOc, 10d. Thus in this arrangement the ceiling tiles 6 can extend across the entirety of the width of an arch 1.

Further, when incorporated within the ceiling 1, the

first flange 12 on the top edge of a lower ceiling tile 6 is abutted against the pair of flanges 14 of an adjacent ceiling tile 6. The joggle 13 on the backplate 8 of the upper tile then causes the backplate extension 9 of the upper ceiling tile 6 to overlie the central portion of the flange 12 of the lower ceiling tile 6.

Thus when ceiling tiles 6 are arranged in this manner as is shown in Figure 4 the curved backplates 8 and backplate extensions 9 of the ceiling tiles 6 form a substantially continuous surface so that water falling on to the curved backplate 8 between the inner pair of neoprene gaskets 17 runs from the ceiling tile 6 closest to the apex of an arch 1 to the backplate 8 of the next ceiling tile further away from the arch via the backplate extension 9.

Turning to Figure 5, which is a cross section through a portion of the suspended ceiling 3 looking along the arch 1, ceiling tiles 6 are attached to the aluminium strip 24 of the support brackets 5 so as to extend across the span of the arch 1. At the apex of the arch ceiling tiles 6 are arranged with the flanges 12 running along the top edges lOa of front panels 10 of the tiles 6 abutted against one another. When in position as a suspended ceiling 3 beneath the arch 1 the remaining

ceiling tiles 7 forming the ceiling 3 are attached to the aluminium strip 24 of support brackets 5 so that each of the backplate extensions 9 overlaps the flange 12 at the top edge 10c of the adjacent backplate 8 of the next ceiling tile 6 further from the apex of the arch 1.

Thus, water passing into the arch onto any of the central portions of the backplates 8 of the ceiling tiles 3 is thereby provided with a waterproof channel over a series of backplates 8 and backplate extensions 9 to flow from the centre of the arch 1 out to the edge of the ceiling 3.

In this embodiment, provided at the apex of the arch 1 is a central deflection plate 27. The central deflection plate 27 comprises a strip of galvanised steel similar to the upper deflection plates 20 of the support brackets 5 being a strip of galvanised steel with edges turned down to form lips 28. The central deflection plate 20 is arranged so as to run the width of the arch 1, along the apex of the arch 1 and is attached to arch 1 via a series of expanding anchors 29 (one of which is shown in Figure 5). Each of the holes in the central deflection plate 27 through which the expanding anchors 29 pass is itself waterproofed by the presence of a waterproof gasket 30 on the inside of the deflection plate 27 away

from the brickwork compressed by the ends of the anchors so as to form a watertight seal.

The waterproof gaskets 30 and the central deflection plate 27 are such as to prevent water from passing directly from the apex of the arch 1 through the centre of the suspended ceiling 3. Specifically, if water arrives at the apex of the arch 1 it is made to follow the outer surface of the central deflection plate 27 resting against the brickwork and is deflected away from the centre of the suspended ceiling 3 to run down the lips 28 of the deflection plate 27. From the lips 28 of the deflection plate 27 any water falls on to the curved backplates 8 of the ceiling tile 6 below the lips 28 and then runs down the surface of the curved backplate 8 along the backplate extension 9 on to the surface of the curved backplate 8 of the ceiling tile 6 next furthest away from the apex of the arch 1. The curved backplate 8 and backplate extension portion 9 of this ceiling tile 6 performs a similar function causing any water to be directed further away from the apex of the arch 1 until the edge of the suspended ceiling 3 remote from the apex of the arch 1 is reached.

The connection of the ceiling tiles 6 to support brackets

5 from which the ceiling 3 is suspended and the connections of support brackets 5 to the interior of an arch 1 will now be described in detail with reference to Figures 6 and 7 in which Figure 6 is a perspective view of a pair of ceiling tiles 6 abutted next to one another beneath a portion of a support bracket 5 and Figure 7 is a cross section through a support bracket 5 and pair of ceiling tiles 6 of Figure 6 when the ceiling tiles 6 are fixed to the support bracket 5.

The ceiling tiles 6 are attached to the extruded aluminium strip 24 of the support brackets 19 by screw fasteners 36 that pass through the screw holes 15 in the flanges 12, 14 of the ceiling tiles 6 and corresponding screw holes 37 provided the central channel 25 of the extruded aluminium strip 24. The screw fasteners 36 are then obscured from view by a cover strip 7 running between the top edge of one row of ceiling tiles 6 and the bottom edge of the next row of ceiling tiles 6.

Turning to Figure 7, the support brackets 5 are attached to the under side of the arch 1 by means of a number of expanding anchors 38 (one of which is shown in Figure 7) which pass through the central portion of the U shaped brackets 22 and upper deflection plates 20. Similarly

to the central deflection plates 27, the holes through which the anchors 38 pass are made waterproof by means of further waterproof gaskets 39.

When an arch 1 is to be waterproofed in accordance with this embodiment of the present invention initially the central deflection plate 27 is attached to the interior of the arch running along the apex of the arch 1 by means of expanding anchors 29. A series of support brackets 5 running across the span of the arch 1, along the curve of the arch 1 are then attached to the arch 1 by means of further expanding anchors 38. The attachment of the central deflection plate 27 and support brackets 5 is such to cover the interior of the arch with a lattice of waterproofed areas defined by the galvanised steel strips of the central deflection plate 27 and upper deflection plates 20 of the support brackets 5 resting against the brickwork of the arch 1. The ceiling tiles 6 are then attached to the aluminium strips 24 hanging beneath the upper deflection plates 20 of the support brackets 5 in the arrangement previously described with reference to Figures 4 and 5. When the ceiling tiles 6 are in place, cover strips 7 are inserted between the tiles 6 to obscure the screw fasteners 36 attaching the ceiling tiles 6 to the aluminium strips 24 of the support

brackets 5.

As is shown in Figure 7, when the ceiling tiles 6 are attached to the support brackets 5, this causes the outer neoprene gaskets 16 closest to the side edges of the ceiling tiles 6 to be compressed by the underside of the outer section of the extruded aluminium strip 24 beyond the central channel 25. The compression of the gaskets 16 thereby forms a waterproof seal to prevent water running from the central portion of the backplate 8 out towards the side edges of the ceiling tiles 6, beneath the aluminium strips 24.

The width of the deflection plate 20 and location of the inner neoprene gaskets 17 are such that the deflection plate 20 directs any water from the arch 1 to a position beyond the inner gaskets 17 remote from the central channel 25 of the support bracket 5. In this embodiment, these inner gaskets 17 are not compressed by the aluminium strips 24 of support bracket 19 but rather act as a physical barrier to channel water away from the portion of the ceiling tiles 6, adjacent to the support bracket 5. Thus in this way the extent of any water which might run through the gaps between the side edges of the ceiling tiles 6 is minimised.

If an individual wishes to inspect the brickwork of the arch 1 behind the ceiling 3, individual ceiling tiles 6 can be removed. This is achieved by extracting the cover strips 7 adjacent to the ceiling tile 6 so as to reveal the screw fasteners 36 attaching the ceiling tile 6 to the aluminium strips 24 of a pair of support brackets 5.

The four screws fasteners 36 attaching the tile 6 to the support bracket 5 are then removed allowing the top edge of the tile 6 along which the flange 12 runs to be pulled inward away from the arch 1. The entire tile 6 can then be manoeuvred to enable the backplate extension 9 of the tile 6 to be lifted away from flange 12 at the top edge of the adjacent ceiling tile 6 and then the entire tile 6 is separated from the rest of the ceiling 3 so that brickwork behind the tile 6 can be inspected.

When the inspection is complete the reverse operation is performed with backplate extension 9 of the ceiling tile 6 being inserted into the hole where the ceiling tile 6 was originally located. The flange 12 running along the top edge of the ceiling tile 6 is then manoeuvred to cause the screw holes 15 in the flange 12 to line up with the corresponding holes with the aluminium strips 24 of the support brackets 5. This causes the backplate extension 9 to be manoeuvred so as to overlie the flange

12 on the ceiling tile 6 adjacent to the tile being replaced. The screw fasteners 36 are then reinserted and the tile 6 reattached to the support bracket 5. Finally the cover strips 7 are replaced to restore the ceiling 3 to its original condition.

The extent of waterproof shielding, provided by the ceiling 3 in accordance with this embodiment is shown in Figure 8 which is a partial perspective view of the outer surface of the suspended ceiling 3 in the absence of the arch 1. As can be seen in Figure 8 the central deflection plate 27 runs along the apex of the arch 1.

Periodically at right angles to the central deflection plate 27 at distances corresponding to the lengths of the top and bottom sides of the ceiling tiles 6 run the upper deflection plates 20 of the support brackets 5 along the curve of the arch. Where the upper deflection plates 20 meet the central deflection plate 27 the lips 28 of the central deflection plate 27 are cut out to form flanges 40 so that the upper deflection plates 20 of the support brackets 5 can pass beneath the central deflection plate 28.

Arranged in this manner, the central deflection plate 28 and the upper deflection plates 20 of the support

brackets 5 form a lattice of waterproof shields which act to direct water passing through the brickwork of the arch in these areas, on to the central sections of the curved backplates 8 of the ceiling tiles 6 suspended from the support brackets 5 beneath the upper deflection plates 20. When water falls on to the curved backplates 8 it runs away from the apex of the arch over the backplate extensions 9 on to the central portion of the curved backplate 8 of the next ceiling tile 6 and outward to the edge of the ceiling 3. Water is prevented from flowing from the central portion of the curved backplate 8 towards the short edges of the ceiling tiles by the neoprene gaskets 17 and 16. Thus together the deflection plates 28 and 20 and the curved backplates 8 form a complete waterproof barrier for the entirety of the interior of the arch 1.

Second Embodiment A second embodiment of the present invention will now be described. In contrast to the first embodiment in which a suspended ceiling system is described for use with a rounded archway, in accordance with this embodiment a suspended ceiling is provided suitable for use with pointed archways.

Figure 9 is a perspective view of a portion of the outside of a suspended ceiling in accordance with this embodiment of the present invention in the absence of an arch. In this embodiment the suspended ceiling is largely identical to that of the previous embodiment and description of the portions of the ceiling 3 corresponding to the first embodiment will not be repeated. However, in this embodiment, the central deflection plate 27 of the previous embodiment is replaced with a capping member 50 comprising a V shaped strip extending the width of the arch along the apex of the pointed arch. The capping member 50 is bent along its centre so as to form two plates 51,52 lying either side of the apex of the arch 1 meeting at an angle corresponding to the angle of the arch 1. Additionally, in place of the support brackets 5 running across the span of the arch 1 following the curve of the arch 1 each of the support brackets in this embodiment comprises a first support 55 and a second support 56 running down either side of the curved portion of the arch 1, the two supports 55,56 meeting at the apex of the arch 1 beneath the capping member 50.

In a similar manner to that described in the first embodiment the capping member 50 and the upper deflection

plates of the supports 55,56 act to deflect water away from the apex of the arch 1 and the peripheries of the ceiling tiles 6 where the ceiling tiles 6 are attached to the supports 55,56. Water falling on to the backplates 8 of the ceiling tiles 6 from the deflection plates, is then directed away from the apex of the arch to the edge of the archway in the same manner as has previously been described. As in the first embodiment by removing ceiling tiles 6 from the suspended ceiling, visual inspection of portion of the brickwork behind the suspended ceiling can be made.

Further Embodiments and Modifications Although in the previous embodiments two pairs of neoprene gaskets 16,17 have been described as running along the peripheries of the ceiling tiles, it will be appreciated that the inner pair neoprene gaskets 17 merely provides an additional barrier for water running on the central portions of the backplates 8 of the ceiling tiles 6 and need not necessarily be provided.

Further, in alternative embodiments of the present invention, the curved backplates 8 of the ceiling tiles 6 could themselves be shaped so as to have concavities to channel any water towards the centre of the backplates

8 away from the side edges of the ceiling tiles 6.

Alternatively, instead of providing gaskets 16 on the backplates 8 of the ceiling tiles 6, gaskets could instead be attached to the underside of the outer section of the extruded aluminium strip 24 beyond the central channel 25. A water tight seal would then be formed when a ceiling tile 6 was attached to the aluminium strip 24 which caused the gasket 16 to be compressed between the extruded aluminium strip 24 and the backplate 8 of the ceiling tile 6. An advantage of such a design would be that gaskets 16 running along the entire length of the aluminium strip 24 could be provided. Problems with gaps between gaskets 16 provided on different ceiling tiles 6 could thereby be avoided and a better waterproof seal achieved.

Although in the previously described embodiments, the ceiling tiles 6 have been described as being rectangular, it will be appreciated that square ceiling tiles 6 could be provided. It will also be appreciated that although in the previous embodiments a series of ceiling tiles 6 attached to supports 5 have been described, sections of suspended ceiling 3 could comprise an individual tile 6 attached to support brackets 5.

Although in the previous embodiments backplate extensions 9 have been described as being connected to the rest of a backplate 8 by a joggle 13, the joggle 13 could be omitted and other means could be provided to enable the backplate extension 9 of one ceiling tile 6 to overlie the top edge of an adjacent tile 6. Thus for example the support bracket 5 could be shaped to provide a stepped surface so the tiles 6 could be arranged to overlap.

Alternatively the flanges 14 could be arranged to suspend a backplate beneath the top flange 12 of an adjacent tile 6 to provide a surface for channelling water away from the apex of an arch 1 out to the edge of a ceiling 3.

Although in the embodiments, suspended ceilings 3 have been described as waterproofing the interiors of curved and pointed archways, it will be appreciated that the present invention is equally applicable to any form of structure in which it is desired to provide an interior waterproofing ceiling. Thus for example embodiments could be provided for waterproofing the interior of pitched or sloped roofs.

Claims

CLAIMS: 1. A suspended ceiling for a roof having an apex, comprising: a plurality of support members extending down from the apex ; a plurality of ceiling tiles arranged in rows parallel to the apex; and fixing means for releasably fixing said ceiling tiles to said support members, wherein said support members comprise first shielding means for directing water from said support members on to central portions of ceiling tiles attached to said support members; and said ceiling tiles each comprise second shielding means for channelling water from the central portions of said ceiling tiles on to the central portions of adjacent ceiling tiles further from the apex of said roof.
2. A ceiling in accordance with claim 1, wherein said first shielding means comprises a plurality of impervious strips extending above areas between said central portions of said ceiling tiles in said ceiling.
3. A ceiling in accordance with claim 2, wherein said

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ceiling tiles are releasably attached to a portion of said support members extending below said first shielding means of said support members.
4. A ceiling in accordance with any of claims 1 to 3, wherein said ceiling tiles each comprise a front panel; and wherein said second shielding means of said ceiling tiles, each comprises a waterproof sheet a portion of which extends beyond the edge of said front panel of said ceiling tile, wherein when attached to said support members to form a ceiling, said portions of said sheets of ceiling tiles overlie part of the central portion of adjacent ceiling tiles further from the apex of the roof.
5. A ceiling in accordance with claim 4, wherein said waterproof sheet comprises a sheet of galvanised steel.
6. A ceiling in accordance with any of claims 4 or 5, wherein said portion of said waterproof sheet extending beyond the edge of said front panel of said ceiling tile is connected to the remainder of said impervious sheet by a joggle.
7. A ceiling in accordance with claim 4,5 or 6, wherein said waterproof sheet of said ceiling tile is

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shaped to define a concavity in the central portion of said ceiling tile for channelling water on to the central portion of an adjacent ceiling tile.
8. A ceiling in accordance with claim 4,5 or 6, wherein said second shielding means further comprises a pair of barriers provided either side of said central portion of said ceiling tile, wherein when attached to said support members to form a ceiling said barriers and said waterproof sheet of said tiles act to define channels for channelling water from said central portions of said ceiling tiles on to the central portions of adjacent ceiling tiles further from the apex of the ceiling.
9. A ceiling in accordance with claim 4, 5 or 6, wherein said support members further comprise a pair of barriers provided either side of an attachment surface of said support members, wherein when ceiling tiles are attached to said support members said barriers and said waterproof sheet of said tiles act to define channels for channelling water from said central portions of said ceiling tiles on to the central portions of adjacent ceiling tiles further from the apex of the ceiling.

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10. A ceiling in accordance with claim 8 or 9, wherein said barriers comprises elastic gaskets wherein when said ceiling tiles are attached to said support members to form said ceiling, said gaskets are compressed between said ceiling tiles and said support members to form a waterproof seal to prevent water from said central portions of said tiles flowing across said gaskets.
11. A ceiling in accordance with any preceding claim, further comprising third shielding means provided along the apex of said roof for directing water from the apex of said roof on to said second shielding means of ceiling tiles adjacent to said apex of said roof.
12. A method of waterproofing the roof of a structure, the roof having an apex, the method comprising the steps of: attaching a plurality of support members to the interior of the roof of a structure extending down from the apex; and releasably attaching a plurality of ceiling tiles to said support members said tiles being arranged in rows parallel to said apex, wherein said support members comprise first shielding means for directing water from said support members on to the central portions of

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ceiling tiles attached to said support members ; and said ceiling tiles each comprise second shielding means for channelling water from the central portions of said ceiling tiles on to the central portions of adjacent ceiling tiles further from the apex of said roof.
13. A method in accordance with claim 12, further comprising the step of attaching a third shielding means along said apex of said roof, said third shielding means being adapted to direct water from said apex of said roof on to said second shielding means of ceiling tiles

attached to said said support members. j
14. A support member for suspending a suspended ceiling from the interior of a roof, said support member comprising means providing an attachment surface for releasably attaching ceiling tiles to said support member; and shielding means for directing water away from the vicinity of the edges of ceiling tiles attached to said attachment surface of said support member.
15. A support member in accordance with claim 14, wherein said shielding means comprises a strip of galvanised steel.

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16. A support member in accordance with claims 14 or 15, wherein said portion of said support member providing an attachment surface comprises an aluminium strip attached to said shielding means by a plurality of brackets.
17. A support member in accordance with claim 16, wherein said aluminium strip comprises a shaped aluminium strip having a central portion which forms a channel which extends beneath the edges of said strip, wherein said attachment surface is formed by said portion of aluminium strip forming said central channel.

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18. A support member in accordance with any of claims 14 to 17, further comprising: a first and a second barrier each having one edge extending along the edge of said attachment surface wherein said shielding means is arranged to direct water to areas beyond the opposite edges of said barriers.
19. A support member in accordance with claim 18, wherein said barriers comprise elastic gaskets operable when ceiling tiles are attached to said attachment surface to be compressed by said ceiling tiles to form a waterproof seal to prevent water from flowing to the edges of said ceiling tiles attached to the attachment

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surface of said support member.
20. A ceiling tile, said ceiling tile including a front panel 10, on one surface of which is provided a waterproof sheet, a portion of which extends beyond the edge of said front panel, said ceiling tile further being provided with means for channelling water on the surface of said sheet from central portion of said tile on to said portion of said sheet.
21. A ceiling tile in accordance with claim 20, wherein

said waterproof sheet comprises a sheet of galvanised I steel.
22. A ceiling tile in accordance with claim 20 or 21, wherein said portion of said waterproof sheet extending beyond the rest of said ceiling tile is connected to the remainder of said waterproof sheet by a joggle.
23. A ceiling tile in accordance with claim 20,21 or 22, wherein said waterproof sheet of said ceiling tile is shaped to define a concavity in the central portion of said ceiling tile for channelling water on to said portion of said waterproof sheet extending beyond the rest of said ceiling tile.

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24. A ceiling tile in accordance with claim 20,21 or 22, wherein said ceiling tile further comprises a pair of barriers provided either side of said central portion of said ceiling tile, wherein said barriers and said waterproof sheet act to define a channel from said central portion of said ceiling tile on to said portion of said waterproof sheet extending beyond the rest of said ceiling tile.
25. A ceiling tile in accordance with claim 21, wherein said barriers comprise elastic gaskets.

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26. A kit of parts for forming a suspended ceiling comprising: at least one ceiling tile; and a plurality of support members; wherein said at least one ceiling tile comprises a front panel and a backplate covering one surface of said front panel; said backplate comprising a waterproof sheet a portion of which extends beyond the edge of said front panel, said ceiling tile being provided with means for channelling water on to the surface of said sheet from a central portion of said tile on to said portion of said sheet; and said support members each comprise means providing an attachment surface for releasably attaching

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said at least one ceiling tile to said support members; and shielding means for directing water away from the vicinity of the edges of ceiling tiles attached to said surface of said support members.
27. A kit in accordance with 26, further comprising a capping member comprising further shielding means for directing water away from the apex of a roof.
28. A method of waterproofing the interior of a structure substantially as described with reference to

the accompanying drawings.

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29. A suspended ceiling system substantially as described with reference to the accompanying drawings.