GB2142359A - Cavity tray - Google Patents

Abstract

A cavity tray has a base 14 on which a building module (e.g. a brick) of the outer skin of a cavity wall is to stand. A rear wall 16 extends upwardly from the base 14, and has a line of weakness 18 leading to an upper portion 20 which is resiliently biased rearwardly. Thus in use the upper portion 20 bridges the cavity and presses against the inner skin. A side wall 22 shields the side of the brick against seeping water. Guide formations 28, 30 conduct water to the opposite side for discharge. At the front, a channel 36 retains a flexible flashing 40. <IMAGE>

Description

SPECIFICATION Cavity tray This invention relates to cavity trays (or cavity gutters) for cavity walls.

In the construction of buildings with cavity walls it is necessary to make provision for preventing rain which penetrates into the cavity from running down within it onto window or door frames or from seeping to the inside of the building. It is particularly necessary to make such provision when a wing or projection from a building is of lower height than the main structure or if a new section of building is to be constructed abutting an existing structure or where an outside skin becomes an inside wall.

According to the present invention there is provided a cavity tray having a base portion and an upwardly extending rear wall portion such that the tray can be installed with the base portion extending generally horizontally in the outer skin of a cavity wall and the rear wall portion extending upwardly and rearwardly from the base portion within the cavity, and wherein at least part of the wall portion is orientable at a variable angle to the base portion so that the wall portion is disposable to bridge the cavity.

Preferably the wall portion or part thereof is resiliently biassed to a relatively large rearward angle such that the installation in a cavity wall generally leads to partial resilient closing of the angle, with the wall portion resiliently urged against the inner skin.

Preferably the cavity tray has a side wall portion connected to the base portion and the rear wall portion so as to extend in use substantially through the outer skin. It may be connected to an immovable lower portion of the rear wall portion to which an upper portion is connected so as to be capable of relative angular displacement. At the front of the base portion adjacent the side wall portion there may be a short front wall portion, connected to the side wall portion and the base portion, so as to prevent water in the tray from being discharged forwardly adjacent the side wall portion. There may be water guide means in the base portion, e.g. a drainage channel extending to an edge opposite the side wall portion, and/or upstanding ribs.

At or adjacent the front of the base portion there is preferably a flexible flashing, which in use will generally extend downwardly, or means for attachment thereof. The flashing may comprise lead sheeting. The tray may have a longitudinal channel in the front edge of the base portion in which an edge portion of the flashing is receivable, and retainable e.g. by stapling.

Alternatively or additionally there may be a downturned lip at the front of the base portion.

A plurality of cavity trays embodying the present invention are particularly useful in cavity walls linking the levels of a broken roofline, when they would suitably be arranged in an overlapping formation corresponding generally to the shape of the lower roof, with the flashings extending to the lower roof. If the roof is a ridge roof, it will be convenient to embody the invention in cavity trays having the end wall portion alternatively at opposite edges of a rectangular planar base portion. Complementary pairs of such cavity trays would thus be available. Such a tray may have a side wall portion extending substantially to the height of a building unit (such as a brick) to be received in the tray, so as substantially to prevent lateral passage of water.There may be a further portion of the side wall portion extending upwardly from its top and away from the base portion, so as to lie in use under a next higher tray of a series and collect water therefrom.

The tray preferably comprises a unitary plastics moulding (to which a separate flashing may be attachable). The rear wall portion may then have an upper portion which is connected to a fixed lower portion by means of a line of weakening, e.g. a line of reduced thickness, to provide a pivotable connection.

The skilled reader will appreciate that various of the features outlined above may be of wide applicability, and are not restricted to use in trays having all or any of the other features. In particular, the following features would seem to be widely useful: (a) the use of a spanned; (b) use of a side wall portion providing an essentially complete screen to the passage of water horizontally within the outer skin; (c) use of a base with water guide means; and (d) the unitary plastics construction (with means for attachment of a lead sheet).

Preferred embodiments of the invention will now be described in greater detail with reference to the accompanying drawings in which: Fig. 1 is a perspective view of a cavity tray embodying the invention; Fig. 2 is a plan view of the tray from beneath; Fig. 3 is a plan view from above; Fig. 4 is a sectional view along line IV-IV in Fig. 3, on a larger scale; Fig. 5 is a sectional view through a cavity wall showing the cavity tray in position; and Fig. 6 is a detail of an end view of a second embodiment.

The cavity tray 10 of Figs. 1 to 5 has a body portion 1 2 formed of a plastics material, suitably polypropylene. It has a substantially rectangular and planar base portion 14. At one long edge a rear wall 1 6 extends upwardly (and possibly rearwardly). At an intermediate region of the rear wall 1 6 there is a line of reduced thickness 1 8 to provide a hinge about which an upper portion 20 of the wall 16 can be flexed. At one of the shorter edges of the base portion 14 there is an end wall 22 which is perpendicular to the base portion 1 4. It extends to the height of the line 1 8 on the rear wall 16, except for an upstanding flap 24 which extends to a greater height and projects away from the base portion 14.

The front long side of the base portion 14 is open, except for a triangular corner gusset portion 26 which extends from the top outer edge of the end wall 22 to the base portion 14. The remaining short side of the base portion 14 is open.

The base portion 14 has an elongate depression 28 extending for most of its length from the free shorter edge, adjacent the rear wall 1 6. The depth of the depression 28 decreases away from the free edge. As can be seen in Fig. 3, the top face of the base portion 14 has a multiplicity of curved ribs 30 extending generally from the front edge towards the free short edge. As can be seen from Fig. 2, on the underside there are strengthening ribs 32.

Apart from the depression 28 and the ribs 30,32 the base portion 14 is generally of uniform thickness, except adjacent the front edge where there is a thickened portion 34 which is formed with a slot 36 which extends along the whole length of the base portion 14, and is open at the front. This receives a sheet of flexible flashing 40, here constituted by a sheet of lead. (The flashing is not shown in Figs 2 and 3.) In the illustrated embodiment this is secured in place by staples 42, one of which is shown, which extend through the thickened portion 34 and the edge of the flashing 40 sandwiched therein. The flashing 40 has an unsymmetrical shape, here pentagonal, such that it extends more towards the open end of the tray 10.

In use, the cavity tray 10 is placed in the outer skin of a cavity wall W, e.g. projecting from the roof-line of a roof R. The base portion 14 has an area slightly greater than that of the building unit, for example a brick.

The base portion 14 is bedded on mortar M, a further bed is placed on it, and a brick B is placed thereon, possibly leaving a weephole between its end and the end wall 22. The tray 10 is inserted just above the roofline of the roof R, and the flashing is turned down and applied closely over the edge tile of that roof to make a fluid-tight seal between the roof and the wall.

The tray 10 projects rearwardly of the brick B. In particular, the angled rear wall 1 6 bridges the cavity and abuts the inner skin or is closely spaced from it. The upper portion 20 may be resiliently biased so that the wall 1 6 tends to extend rearwardly sufficiently to bridge any likely cavity. Thus on installation of the tray 10 the upper portion 20 will generally be pivoted forwards about the line 18, and will be resiliently pressed against the inner skin.

If the roof R is a ridge roof, then it will be necessary to use two complementary series of cavity trays. The trays of one series may be as shown in Fig. 1, whereas the trays of the other series are the mirror image thereof.

In either series, next higher cavity trays 10 in the array overlap that end of the next lower tray which bears the end wall 22. The flap 24 of the lower tray 10 is located under the base of the next higher tray.

Water within the wall cavity is caught by a cavity tray 10 and passes onto the base portion 14 thereof. It is prevented from discharging from the outer corner adjacent the end wall 22 by the gusset portion 26. It may be discharged from the rest of the front edge of the base portion 14, whereupon it can escape via a weephole or run down a flashing 40 (as shown). This will have been bent so that it can conduct water to where it can be safely discharged. Furthermore, the flashings 40 of adjacent trays can be in overlapping arrangement, so that water cannot seep into the angle of the roof.

Most of the water falling on the base portion 14 of a tray is likely to be conducted by the curved ribs 30 and the drainage depression 28 so as to flow off the open short edge of the base portion 40. Since the tray 10 will generally be installed so as partly to overlap the next lower tray 10, the water will then fall into that next lower tray, assisted by the flap 24 thereof. It may be pointed out that the shape and size of the end wall 22 are such that it forms a substantially complete barrier across the end face of the brick on the tray.

This may be contrasted with earlier trays having smaller end walls which, in use, were bridged by mortar which tended to allow water to seep laterally.

It will be appreciated that much variation is possible in the design of cavity trays embodying the invention, e.g. to meet particular needs. Plainly different shapes of flashing 40 may be appropriate for different situations in which the trays are to be installed. Whereas it is felt to be particularly convenient to produce a tray largely from a plastics material, of course it is possible to use other materials and/or means other than a line of reduced thickness 18 to produce a rear wall whose rearward extension is variable. A flashing, when present, may be held by staples as shown, or adhered, or both.

Fig. 6 is a detail of a tray made of sheet metal, showing how the flashing 40 may be retained. While a plastics tray can be moulded with a channel or slot 36, a metal tray can have a portion 100 bent back on itself to create a rearwardly opening channel 1 36. The flashing 40 can be retained in it by indenting (102). Otherwise, the tray may be very similar to that shown in Fig. 1.

Trays can be made to suit all wall modules, not just brickwork.

Claims (10)

1. A cavity tray having a base portion and an upwardly extending rear wall portion such that the tray can be installed with the base portion extending generally horizontally in the outer skin of a cavity wall and the rear wall portion extending upwardly and rearwardly from the base portion within the cavity, and wherein at least part of the wall portion is adapted to be onentable at a variable angle to the base portion so that the wall portion is disposable to bridge the cavity.

2. A cavity tray according to claim 1 wherein said wall portion or part thereof is resiliently biassed to a relatively large rearward angle such that the installation in a cavity wall generally leads to partial resilient closing of the angle, with the wall portion resiliently urged against the inner skin.

3. A cavity tray according to claim 1 or claim 2 wherein said base and rear wall portions are provided by a unitary plastics moulding, and the rear wall portion has a line of weakening to serve as a hinge for said variable orientation.

4. A cavity tray according to any preceding claim which includes a side wall portion connected to the base portion and the rear wall portion so as to extend in use substantially through the outer skin, so as to form a substantially complete barrier across the end face of the building module of the wall which stands in use in the tray; said side wall portion being connected to an immovable lower portion of the rear wall portion to which an upper portion is connected so as to be capable of relative angular displacement.

5. A cavity tray according to claim 4 having a short front wall portion, connected to the side wall portion and the base portion, so as to prevent water in the tray from being discharged forwardly adjacent the side wall portion.

6. A cavity tray according to any preceding claim wherein the base portion has longitudinal guide formations to guide water to a side edge.

7. A cavity tray according to any preceding claim having a flexible flashing or means for attachment thereof at or adjacent the front of the base portion.

8. A cavity tray according to claim 7 having a longitudinal channel in the front edge of the base portion in which an edge portion of the flashing is receivable and retainable.

9. A cavity tray according to any preceding claim having a downturned lip at the front of the base portion.

10. A cavity tray substantially as any herein described with reference to and as illustrated in the accompanying drawings.