GB2306545A - Rooflight with thermal shield and drainage channel - Google Patents

Abstract

A rooflight comprises an openable casement (22) with a metal frame (32), and a fixed metal base (20) onto which the casement closes. A thermal shield (50) is interposed between the base and the associated opening (16) in the roof structure, and provides thermal decoupling between the structure (70, 74) surrounding the opening, and the interior of the building, on the one hand, and the rooflight frames on the other. A condensation channel (62) is defined between the rooflight frames and the thermal shield, through which condensation can be removed to the outside.

Description

METAL ROOFLIGHTS This invention relates to metal rooflights, that is to say a window or skylight fitted in a roof and comprising glazing which is carried on the roof structure through at least one metallic frame.

Such a rooflight typically consists of two parts, namely a metal base which is fixed to the roof structure around the opening in the roof, and a casement which has a metal frame carrying the glazing.

The glazing typically consists of a double glazed unit fixed in the casement frame and seated on an angled seating element of the latter. The casement frame is arranged to be opened outwards and to close on to the base of the rooflight, by which it is typically carried directly, being for example articulated through hinges on the base.

Metal rooflights share with other metal-framed windows the problem of condensation from the atmosphere under certain conditions of temperature and humidity. Water which condenses on the frames is at best a nuisance, but can also lead to corrosion of the metal. In addition, in a rooflight, which by its nature faces downwards, condensed water tends not only to run down the exposed faces of the roof opening, but also to penetrate into the structure around that opening, including parts of the roof structure of the building, and generally gives rise to the well-known problems associated with damp.

According to the invention, a rooflight comprising a base to be fixed around an opening in a roof, and an openable casement adapted to close onto the base, with at least one of the base and casement comprising a metallic frame, further includes a thermal shield interposed between the base and the opening, with an external condensation channel being defined by the shield and the base.

A thermal shield is an element which acts as a barrier to flow of heat, and is therefore of a suitably thermally insulating material. In the present invention, the thermal shield can conveniently be of an appropriate weather resistant plastics material.

The effect of the shield in the rooflight of this invention is to act as a liner which decouples the metal components of the rooflight, which are in thermal contact with the atmosphere outside the building, from the lining of the roof opening, and its support or backing structure, and from the interior of the building. In this connection, the base of the rooflight typically has a side wall which extends outwardly away from the roof, and which surrounds the roof opening. The casement frame overlaps this base wall and surrounds it but does not touch it directly, so that the base wall is always in communication with the atmosphere both inside and outside the building.

The thermal shield presents, within the building, a thermally decoupled face.

Accordingly, in a preferred feature of the invention, the thermal shield comprises a baffle projecting out of the roof opening and spaced transversely away from an outwardly extending wall of the base, and a transverse portion extending towards the said wall, to define, with the latter and the baffle, the condensation channel.

The condensation channel extends around the outside of the baffle of the thermal shield, so that unevaporated water or condensation is confined within the channel, and can easily find its way by gravity down to the bottom side of the rooflight. The horizontal bottom section of the wall of the base constitutes its cill, and in preferred embodiments the condensation channel is partly bounded by the cill. Accordingly, a condensation drain is preferably provided in the wall of the base, in or adjacent to the cill and open to the outside, so that the condensed water is harmlessly removed.

The thermal shield is preferably fixed to the base of the rooflight, for example with a suitable adhesive.

To this end, it preferably includes an anchor portion which is located behind the base and fixed to the latter.

A preferred embodiment of the invention will now be described, by way of non-limiting example only and with reference to the accompanying drawings, in which: Figure 1 is a much-simplified view of a rooflight installed in a pitched roof of a building, seen in cross section on a vertical plane; Figure 2, on a larger scale, is a cross section taken on the line II-II in Figure 1 and showing one side of the rooflight in greater detail; and Figure 3 is an enlarged scrap view of the portion within the circle III in Figure 1, in one embodiment of the invention.

The roof is of any conventional construction, being shown here as having a structure 10 with rafters 12 (Figure 2) and external tiling 14 (Figure 1), with appropriate flashings, not shown, around a rectangular opening 16 in the roof. The interior of the building has a sloping ceiling 18.

The rooflight consists of a base unit 20 and a casement unit 22. The base unit 20 consists of a fabricated frame comprising a steel base plate 24 which is extended by a continuous rectangular base wall 26 projecting outwardly and surrounding the opening 16.

The base plate 24 has fastening lugs 25 whereby the rooflight is secured to the rafters 12, and the wall 26 is turned back in a terminal flange 28.

The base plate 24 carries hinges 20 on its upper horizontal side, by which the casement unit is hinged directly to the base plate. It should be noted that in Figure 1 the casement is shown open, whereas in Figure 2 it is closed. Suitable means for supporting the casement in an open position are provided, but are not shown.

The casement 22 comprises a steel frame 32 and a glazing unit 33. The frame 32 consists of a rectangular wall 34, and an angle element 36 projecting inwardly from the wall 34 and comprising a transverse seating portion 38 which is extended by a downward flange 40. The glazing unit 33, double-glazed in this example, lies on the seating portion 38, onto which it is held in any known way.

In the closed position (Figure 2), the casement 22 rests on the base 20 by the portion 38 engaging on the base wall flange 28 through an edge seal 42, with the base wall 26 being overlapped by, but spaced transversely away from, both the casement wall 34 and the flange 40, which then lie on either side of the wall 26.

Interposed between the base 20 and the roof opening 16 is a thermal shield 50 of weather-resistant plastics material. The shield 50 comprises: a rectangular baffle 52 which projects outwardly from the roof opening towards the glazing unit 33; a transverse portion 54 extending from the baffle towards the base wall 26; and a transverse anchor portion 56, joined through an upright portion 58 to the portion 54 and lying below the base plate 24. The thermal shield 50 may be made in any suitable way, e.g. as a single injection moulding or by fabrication from four plastics extrusions, mitred and welded at the corners.

The portion 56 is secured, preferably by adhesive bonding, to the base plate 24, and preferably has projections 60 to define a gap between them, which may be completely filled with adhesive.

The baffle 52 and transverse portion 54 of the shield 50, together with the base wall 26, define a condensation channel 62 into which the casement flange 40 projects when the rooflight is closed. The shield portion 58 has at least one projection 61 (Figure 3), which may be a continuous rib as shown, or may be in the form of a resilient lip. The projection 61 bears on the wall 26, sealing the channel 62 to prevent any penetration of water into the region below it.

Any water condensed from the atmosphere on the frame 20, and on the frame 32 when the latter is closed, collects in the channel 62 and falls to the bottom horizontal section or cill 27 of the base wall 26.

From there it is removed to the outside in any suitable way. Figure 3 shows one example in this connection, in which the cill 27 has one or more local press-formed dimples 64, acting as a well and having a drain hole 66.

In Figure 2, the roof opening 16 is lined with fascia boards 70, with architraves 72 on the inside. The thermal shield 50 is nested on the upper edge of the fascia board, and it will be noted that the baffle 52 extends a little way below the upper edge of the latter. Suitable packing 74 is inserted behind the fascia board, and the anchor portion 56 of the shield is in at least partial contact with this packing. The fascia boards, packing, and ceiling lining 18, with the architraves if provided, constitute an internal lining structure around the opening 16 which supports the thermal shield and is thermally decoupled by the latter.

Such a lining structure is necessary for proper functioning of the thermal shield as a thermal decoupling device in the way mentioned earlier herein.

It will however be realised that the actual form of this lining structure can be varied to enable different materials or methods of construction to be used. Thus, for example, Figure 1 shows the opening 16 lined with plasterboard 80, and with no architrave or fascia board.

The baffle 52 may be a plain flat wall; but it may optionally have a widened upper edge 53 formed with a groove which carries a resilient seal such as a lip 82 (Figure 2), of an elastomeric or similar material, for engaging against the glass of the unit 33 when the rooflight is closed, thus isolating the channel 62 from within the building.

The invention is applicable to openable rooflights of any shape, not necessarily rectangular. The mode of opening is also not relevant to the invention, in that the casement may be articulated with respect to the base elsewhere than at the top. Either the casement frame or the base may be of a non-metallic material such as uPVC, but if there are any metallic frame components so that condensation is still likely to occur, it is desirable to provide the thermal barrier of the invention. The profiles of the casement and base frames, and of the thermal shield, may be different from that shown, provided that a channel is formed to remove condensation, and provided the thermal decoupling effect discussed above is obtained from the thermal shield.

The frames may be of any suitable metal, such as steel or aluminium. They may be in the form of castings or forgings, or be made by press-forming or by fabrication from pieces made in any of these ways, or by extrusion.

Claims (6)

1. A rooflight comprising: a base to be fixed around an opening in a roof; an openable casement adapted to close onto the base, with at least one of the base and casement comprising a metallic frame; and a thermal shield interposed between the base and the opening, with an external condensation channel being defined by the shield and the base.

2. A rooflight according to Claim 1, wherein the casement has a metallic frame including an angled seating element which projects into the condensation channel when the casement is closed.

3. A rooflight according to Claim 1 or Claim 2, wherein the thermal shield comprises a baffle projecting out of the roof opening and spaced transversely away from an outwardly extending wall of the base, and a transverse portion extending towards the said wall, to define, with the latter and the baffle, the condensation channel.

4. A rooflight according to any one of Claims 1 to 3, wherein the base includes an outwardly extending wall including a cill and constituting a wall of the condensation channel, and a condensation drain in the said wall in or adjacent to the cill and open to the outside.

5. A rooflight according to any one of the preceding Claims, wherein the shield includes an anchor portion located behind the base.

6. A rooflight substantially as described in the foregoing description with reference to the accompanying drawings.