GB2140841A - Adjustable roof-soffit ventilator - Google Patents

Abstract

The ventilator 10 comprises an elongate extruded strip 11 of unplasticised PVC with ventilating openings 19 punched through it and covered with fly-screen mesh 20. Strip 11 is fixed to a fascia board 7 along one edge by a fixing strip 14. Along its opposite edge, strip 11 has a channel-shaped part 13 for receiving and supporting one edge of a soffit board 8. To facilitate the insertion of the edge of soffit board 8 into channel-shaped part 13 and to enable part 13 to grip soffit boards of varying thicknesses, strip 11 is co-extruded with a portion 24 of plasticised PVC which acts as a hinge to enable the sides 21, 23 of the channel-shaped part 13 to be moved more easily away from each other, but to remain springy. <IMAGE>

Description

SPECIFICATION Improvements relating to the ventilation of roof spaces within pitched roofs In houses with pitched roofs where the roof spaces are separated and generally insulated from the remainder of the house, it is necessary for the roof spaces to be ventilated. If there is no ventilation, moisture which seeps into the roof space from the house tends to condense and over a period of time the condensation and general dampness may cause rot or other deterioration of timber parts of the roof structure.

Ventilation is generally provided through the eaves of the roof and most commonly through the soffit boards of the eaves. For this purpose holes may be bored or cut in the soffit board, but to provide an adequate total opening area, a large number of holes must be provided and the formation of them is time consuming.

To avoid the necessity of cutting or boring holes in the eaves soffit boards of pitched roofs, ventilators have been provided and these are fixed in the soffits of the eaves along one longitudinally extending edge of the soffit board, usually along the outside edge of the soffit board between the soffit board and the fascia.

One form of ventilator for fitting in the soffit of the eaves of a pitched roof to allow ventilation of the roof space comprises an elongate extruded strip of plastics material which has spaced apart openings formed through it for the fiow of air, means along one edge of the strip for fixing the strip to a fascia and, along the opposite edge, an integral channel-shaped part, the open edge of which is directed outwardly away from the remainder of the strip, the sides of the channel-shaped part converging towards the open edge to enable the channel-shaped part to receive and grip the edge of a soffit board.

When such a ventilator is used, it is necessary to fix the one edge of the ventilator to the fascia before the soffit board is fitted in position because the screws or other fixings for this purpose must be spaced from the bottom edge of the fascia while the soffit board must lie only just above the level of the bottom edge of the fascia. This means that the screws or other fixings must lie above the ventilator strip and above the soffit board once this has been fixed in position. It is therefore only possible to obtain access to the screws or other fixings before the soffit board is fixed in position.

Once the ventilator has been fixed to the fascia, the only way of introducing the edge of the soffit board into the channel-shaped part is by sliding it in from one end of the channel-shaped part. Since both the ventilator strip and the soffit board may be of substantial length, the frictional resistance acting against this sliding in as the soffit board approaches the other end of the channelshaped part is very considerable.

The ventilator strip must be extruded from plastics material which is sufficiently stiff to support the adjacent edge of the soffit board and this means that the sides of the channelshaped part are equally stiff. Soffit boards in practice vary in thickness from 6 mm to 10 mm and the sides of the channel-shaped part must accordingly converge sufficiently closely towards each other at their free edges to ensure that they grip a soffit board having a thickness of 6 mm. When a soffit board having a thickness of 10 mm is pushed into the channel-shaped part, the sides of the channel-shaped part have to be forced further apart and this, of course, increases the frictional resistance.It has been found in some cases that the resistance becomes so great that it is either impossible to push a soffit board into position or, in pushing a soffit board into position, the ventilator strip itself or its fixings to the fascia are damaged.

The aim of the present invention is to improve the construction of a ventilator for fitting in the soffit of the eaves of a pitched roof of the construction described above in such a way that the sides of the channelshaped part will still grip soffit boards of substantially different thicknesses, but the sides can be more easily forced apart so that the thicker soffit boards can still be slid into the channel-shaped part from one end thereof without the use of excessive force.

To this end, according to this invention, the strip of a ventilator as described above is formed by co-extrusion of two different plastics materials, the major part of the strip being of a plastics material which is sufficiently rigid to enable it to support the soffit board when the strip is fixed to the fascia and a portion extending along one side or along the base of the channel-shaped part being of more flexible and resilient plastics material to act as a hinge to enable the sides of the channel-shaped part to be moved more easily away from each other and facilitate the insertion into the channel-shaped part of the edge of the soffit board.

Co-extrusion of two different plastics materials is in itself a well-known technique, but its use in the context of the manufacture of a ventilator in accordance with the present invention gives rise to a very great improvement in the ventilator in a very simple manner.

Co-extrusion involves the use of two separate extruders in which the two different plastics materials are heated and extruded and the two extruders feed a single die-head to produce the strip as a single extrusion with the two different plastics materials joined integrally to each other.

Preferably the main part of the strip is of unplasticised PVC and the flexible and resilient part, which forms the hinge in the channel-shaped part, is of plasticised PVC.

By making the strip in accordance with the invention, it is possible to make a single strip, the channel-shaped part of which can accommodate a soffit board of any thickness between 6 and 10 mm inclusive with the thinner board still properly gripped when in position and with the thicker board being able to be pushed into the channel-shaped part from one end over a length of up to about 2.4 m, which is the usual length of soffit board fitted when building houses. Since the soffit boards are provided in lengths of 2.4 m, the ventilator is also preferably made in strips of this length.

The openings in the strip are preferably formed in a stamping operation after extrusion has taken place.

The means along one edge for fixing the strip to a fascia may consist merely of a flange extending transversely to the main part of the strip and provided with holes at intervals for fixing screws or other fastenings. In this case the main part of the strip is preferably offset relatively to the open edge of the channelshaped part so that screws can be inserted through the holes in the flange and be screwed in with a screw driver which can be held clear of the channel-shaped part of the strip.

As an alternative, the fixing means may consist of a flange formed along the one edge of the strip and a separately extruded fixing strip which has a longitudinally extending socket for receiving the flange of the ventilator strip. The fixing strip is then first fixed to the fascia with screws or other fastenings and the flange of the ventilator strip is then slid into the socket of the fixing strip from one end.

Preferably the openigs through the strip are covered by metal or fabric mesh having sufficiently small holes through it to act as a fly screen to exclude flies from the roof space of the roof to which the ventilator is fitted.

Two examples of ventilators in accordance with the invention are illustrated in the accompanying drawings in which: Figure 1 is a cross-section through a first example; Figure 2 is a perspective view from above showing the first example fitted to the eaves of a roof; Figure 3 is a cross-section through a second example showing the edge of a soffit board fixed to it; and, Figure 4 is a perspective view similar to Fig.

2, but showing the second example fitted to the eaves of a roof.

Both of the examples of the ventilators in accordance with the invention are incorporated in pitched roofs which, as shown in Figs.

2 and 4 of the drawings, include a number of rafters, part of one of which is shown at 1.

The rafters are carried on a .timber wall plate 2 which is in turn supported on the top of an inner skin 3 of a cavity wall which also includes an outer skin 4 and a cavity 5. The top of the cavity 5 is closed by closure blocks 6.

As is usual, at the eaves of the roof, there is a fascia board 7 which is fixed to the ends of the rafters 1. Between the lower edge of the fascia board 7 and the outside- face of the outer skin 4 of the wall is a soffit board 8 and a ventilator in accordance with the present invention. One edge of the soffit board 8 is fixed in position by being sandwiched between the top of the outer skin 4 and the blocks 6, and the other edge of the soffit board 8 is supported by the ventilator.

As far as all the details so far described are concerned, the two illustrated examples are the same as each other. However, in the first example illustrated in Figs. 1 and 2 of the drawings the ventilator 10 comprises an extruded strip 11 having along one edge-an integral fixing flange 1 2 and along the opposite edge a channel-shaped part 1 3 which receives and grips the edge of the soffit board 8.

The flange 1 2 is fixed to the fascia board 7 by means of an extruded fixing strip 1 4 which is itself directly fixed to the inside face of the fascia board 7 by screws 1 5 which are screwed through holes 1 6 provided through the strip 14 at intervals. The fixing strip 14 has a- portion 1 7 which together with a ledge 1 8 form a socket into which the flange 1 2 and the adjacent part of the strip 11 fits.

The strip 11 is provided along its length with a series of spaced apart ventilating openings 1 9 which are covered by a mesh sheet 20 which forms a fly screen. The mesh 20 is woven out of plastic filaments and is welded to the upper face of the strip 11.

The channel-shaped part 13 has a bottom side 21, a base 22 and a curved upper side 23.

The fixing strip 14 and all the parts of the strip 11 so far described are extruded out of a relatively rigid unplasticised PVC. The upper side 23 of the channel-shaped part 1 3 is, however, integrally connected to the top of the base 22 by a portion 24 which is coextruded with the remainder of the strip 11, but which is mde of plasticised PVC which is much more flexible and resilient than the material of which the remainder of the strip 11 is made. The portion 24 thus forms a resilient hinge and, as extruded, the side 23 adopts the position shown in chain-dotted lines at 23a.

To fit the soffit board 8 in position, the fixing strip 14 is first of all screwed to the fascia board 7 and the strip 11 is slid into position into the socket formed between the parts 1 7 and 1 8 of the strip 14. One end of the soffit board 8 is then inserted into the end of the channel-shaped part 1 3 and on being so inserted, the side 23 is moved upwards against the resilience of the portion 24 into the position shown in full lines in Fig. 1. The soffit board 8 is then pushed longitudinally into position and when its leading end abuts the end of a length of soffit board already fixed, the side of the soffit board 8 remote from the ventilator 10 rests on the skin 4 and the blocks 6 are then set in position with mortar.

Owing to the flexibility and resilience of the co-extruded portion 24 of the plasticised PVC, the side 23 can be deflected upwards from the position shown at 23a into the position shown at 23 to receive and grip a soffit board 8 having a thickness of 6 mm or it may be deflected further upwards into a position shown at 23b to receive a soffit board 8a, which is indicated in chain-dotted lines, having a thickness of 10 mm.

Owing to the flexibility and resilience of the portion 24, soffit boards of both these thicknesses can easily be pushed longitudinally into position within the channel-shaped part 1 3 and both boards will still be firmly gripped and supported by the strip 11. Of course, soffits of any intermediate thickness may also be used.

The second example of the ventilator in accordance with the invention illustrated in Figs. 3 and 4 of the drawings has a number of parts which correspond to similar parts in the first example and have the same reference numerals with a' added. However in the second example, the strip 11' extends at an acute angle to the base 22' of the channelshaped part 13' and the strip 11' has at its edge remote from the channel-shaped part 13', a flange 12' which lies at an obtuse angle to the strip 11'.

Instead of fixing the strip 11' to the fascia board 7 by means of the fixing strip 14, the flange 12' is screwed directly to the fascia board 7 by screws 15' which are screwed through holes 16' in the flange 12'. Owing to the off-setting of the flange 12' from the channel-shaped part 13', the screws 15' are readily accessible with a screw driver before the fascia board 8 is slid into position. The channel-shaped part 1 3' is identical to and acts in exactly the same way as the channelshaped part 1 3 of the first example.

The co-extruded part 24, 24' is shown in both of the examples extending through the whole thickness of the side 23, 23' of the channel-shaped part 13, 13'. Alternatively, however, a thin web of unplasticised PVC may connect the lower face of the side 23 or 23' to the base 22 or 22' and in this case the portion 24 or 24' does not extend through quite the whole thickness of the side 23 or 23'.

With either construction, the portion 24 or 24' acts as a hinge and allows the side 23 or 23' to bend to enable the soffit board 8 or 8a to be slid, easily into position.

The ventilating openings 1 9 and 1 9' and also the screw holes 1 6 and 16' are punched out of the respective strips in which they are provided after extrusion has taken place.

The screw holes 1 6 in the fixing strip 14 are provided at 500 mm centres, but the screw holes 16' in the flange 12' are provided at 100 mm centres because the flange 12' is not, of course, longitudinally nearly so rigid as the fixing strip 14. Accordingly, although the first example is more expensive owing to the provision of the fixing strip 14 in addition to the ventilating strip 11, the cost of fixing the ventilator is reduced because many fewer fixing screws are necessary. Owing to the flexibility of the side 23 of the channelshaped part 1 3 provided by the hinge portion 24, the soffit board 8 may be inserted by an alternative technique which in some cases is easier.

Instead of sliding the soffit board into position longitudinally through one end of the channel-shaped part 13, the board is positioned longitudinally, but is tilted upwards above the top of the skin 4 so that the lefthand edge of the board can just be entered into the mouth of the channel-shaped part.

The board is then pushed laterally home into the channel-shaped part and is then lowered on to the top of the skin 4.

Claims (8)

1. A ventilator for fitting in the soffit of the eaves of a pitched roof to allow ventilation of the roof space, the ventilator comprising an elongate extruded strip of plastics material which has spaced apart openings through it for the flow of air, means along one edge of the strip for fixing the strip to a fascia and, along the opposite edge, an integral channelshaped part, the open edge of which is directed outwardly away from the remainder of the strip, the sides of the channel-shaped part converging towards the open edge to enable the channel-shaped part to receive and grip the edge of a soffit board, wherein the strip is formed by co-extrusion of two different plastics materials, the major part of the strip being of a plastics material which is sufficiently rigid to enable it to support the soffit board when the strip is fixed to the fascia and a portion extending along one side or along the base of the channel-shaped part being of more flexible and resilient plastics material to act as a hinge to enable the sides of the channel-shaped part to be moved more easily away from each other and facilitate the insertion into the channel-shaped part of the edge of the soffit board.

2. A ventilator according to Claim 1, in which the major part of the strip is of unplasticised PVC and the portion which acts as a hinge is of plasticised PVC.

3. A ventilator according to Claim 1 or Claim 2, in which the openings in the strip are stamped out after extrusion of the strip.

4. A ventilator according to any one of Claims 1 to 3, in which the means along the one edge of the strip for fixing the strip to a fascia comprises a flange which extends transversely to the main part of the strip and is provided at intervals with holes for fixing screws or other fastenings.

5. A ventilator according to Claim 4, in which the main part of the strip is off-set relatively to the open edge of the channelshaped part.

6. A ventilator according to any one of Claims 1 to 3, in which the means along the one edge of the strip for fixing the strip to a fascia comprises a flange formed along the one edge of the strip and a separately extruded fixing strip which has a longitudinally extending socket for receiving the flange.

7. A ventilator according to any one of the preceding Claims, in which the openings through the strip are covered by metal or fabric mesh which acts as a fly screen.

8. A ventilator according to Claim 1, substantially as described with reference to Figs.

1 and 2, or Figs. 3 and 4, of the accompanying drawings.