GB2190117A - Pitched roof, method of ventilating roof and ventilator for use in the method - Google Patents

Abstract

A roof having a corrugated outer skin (11), an inner skin (10) and an intermediate, insulating layer (12) is ventilated by cutting a hole in the crest of a corrugation (13) of the outer skin and fitting a ventilator over the hole so that the hole is covered but vapours can escape to the ambient atmosphere from spaces defined between the outer skin and the intermediate layer. <IMAGE>

Description

SPECIFICATION Pitched roof, method of ventilating roof and ventilator for use in the method Description of invention The present invention relates to the ventilation of a pitched roof of a building, the roof comprising inner and outer skins between which there is defined a space which is substantially closed off from the interiorofthe building.

It is usual to provide in the space between the skins of a roof of the kind described a layer of a thermally insulating material. This maintains a substantial temperature differential between the inner and outer skins, at least during cold weather. It is fairly com mon for water va pou r to penetrate from the interior of the building to the space between the skins ofthe roof. Although the rate of such penetration may be slow, moisturewhich has penetrated to the space between the skins cannot readily escape from known rooves. Generally, the water vapour is cooled by contact with the outer skin and the waterthus formed penetrates the thermally insulating layer. Thus, over a period of time, the effectiveness of that layer as a thermal insulator is impaired.

The aforementioned problem arises in cases where the outer skin of the roof is corrugated and the layer of thermally insulating material bears against the valleys of the corrugations so that there is defined between this layer and the crest of each corrugation an elongated chamber which is occupied by air. Watervapourwhich penetrates from the interior of the building into the space between the skins of the roof finds its way into these chambers. One possible solution to the problem is to ventilate each of the aforesaid chambers at the eves and ridge of the building but we do not regard this as an entirely satisfactory solution.

According to a first aspect of the present invention, there is provided a method of ventilating a roof having inner and outer skins defining between them a space which is substantially closed offfrom the region beneath the roof, wherein an aperture is cut in Lie outer skin and a cover is fitted over the aperture to prevent precipitation entering said space through the aperture but to permit vapours to escape from said space to the ambient atmosphere.

According to a second aspect of the present invention, there is provided a pitched roof of a building,theroofcomprising innerandouterskins, wherein there is defined between the inner and outer skins a space which is substantially closed off from the interior of the building, the outer skin is corrugated, the outer skin defines an aperture leading to the space between the skins and a cover is provided overtheapertureto prevent precipitation entering said space through the aperture but arranged to permit vapours to escape from said space to the ambient atmosphere.

The aperture is preferably formed in a single corrugation of the outer skin. At least in a case where the roof comprises an intermediate layer which is in contact with the outer skin at the underside thereof but is spaced from the lower surface of a crest of a corrugation of the outer skin, the aperture is preferably formed in the crest of the corrugation.

According to a third aspect of the invention, there is provided aventilatorforuse in a method according to the first aspect and in a roof according to the second aspect,the ventilator comprising a base defining a passage and having an outwardly protruding flange adjacent one end of the passage and the ventilatorfurthercomprising a cover mounted or adapted for mounting on the base to cover an end of the passage remote from the flange without closing that end of the passage.

Examples of a method of ventilating a roof, of a ventilated roof and of a ventilator which embodies the first, second and third aspects of the invention, respectively, will now be described, with reference to the accompanying drawing, wherein there is illustrated diagrammatically a part of a roof and a ventilator of the roof, component parts of the ventilator being shown separated from each other.

The roof illustrated in the drawing is a pitched roof of a building and comprises an inner skin 10 an outer skin 11 and an intermediate layer 12. The outer skin is formed of sheet material, typically metallic sheet material, for example plastic-coated steel . The sheet material is corrugated and each corrugation extends down the rooffroma ridgethereofto eavesofthe building. The corrugations may be curved or defined by flat surfaces, as shown in the drawing. The inner skin 10 also may be formed of corrugated sheet material or of substantially flat sheet material. The roof incorporates a supporting framework (not shown) which may be arranged and constructed in a known manner.

The intermediate layer 12 is formed of thermally insulating material. This layer may be self-supporting boards, for example of expandable polystyrene, a web of glass fibre or otherfibrous material or a layer of loose fibres or particles trapped in the space defined between the inner and outer skins 10 and 11. An elongated chamber is defined between the crest 13 of a corrugation of the outer skin and the intermediate layer 12. The intermediate layer may abut the outer skin at the valleys of the corrugations so that the elongate chamber 14 is closed offfrom the similar adjacent chambers.

Similar chambers may be defined between the intermediate layer 12 andtheinnerskin 10.

The inner skin 10 is constructed to close offfrom the interior of the building the space defined between the skins 10 and 11 of the roof. However, an hermetic seal is unlikely to be achieved.

Furthermore, the inner skin may be penetrated by fasteners used for fixing the inner skin to the supporting structure or by fasteners used for attaching lights or other items to the inner skin.

During the service life of the roof, moist airfrom within the building is likely to penetrate into the space between the skins of the roof. Watervapour which penetrates into a chamber defined between the intermediate layer 12 and the inner skin 10 is likely to remain a vapour. Furthermore, even ifthis vapour were to condense, the resulting liquid would lie on the inner skin and not affect significantly the intermediate layer 12.However, watervapourwhich penetrates to the chamber 14 between the outer skin and the intermediate layer 12 will, during cold weather, be condensed by contact with the outer skin and the resulting liquid will drain down onto the intermediate layer 12so that this layer become saturated with water and ineffective as a thermal insulator. To avoid this condition, the chamber 14 is ventilated in the manner nowto be described.

An aperture, conveniently a circular aperture, is cut in the outer skin 11 to communicate with the chamber 14. In a case such as that illustrated, where the crest of the corrugations 13 defines a flat, upwardly facing surface, the aperture is preferably confined to that flat surface. It will be noted thatthe aperture communicates with the space between the outer skin and the intermediate layer 12 but does not penetrate that intermediate layer and does not penetrate the inner skin 10.

A base 15 is fixed on the external surface of the outer skin 11 to surround the aperture. The base includes a generally cylindrical collar 1 6which defines a passage extending upwardly from the aperture and a flange 17 extending laterally outwardlyfromthecollaratthe lowerend ofthe passage. In the example illustrated,the flange is square and is generally flat. The width of the flange does not exceed the width of the fiat surface around the entire perimeterofthe aperture and is secured two the outer skin 11 by rivets or other fasteners. There is interposed between the flange 17 and the outer skin a seal, which may be a preformed seal or a layer of a flowable composition.The base may be modified by the provision of downward extensions at opposite sides of the flange 17, these extensions lying over those surfaces of the outer skin 11 which slope down to the valley of the adjacent corrugations.

There is mounted on the base 15 a carrier 18 including a tubuiar portion 19 which fits overthe collar 16 of the base. The portion 19 is preferably a sliding fit on the outside of the collar and retaining means are provided for retaining the carrier on the base. The retaining means may comprise dimples in the external surface of the collar and corresponding projections pressed out from the internal surface of ::-.etubular portion 19 that the carrier is a snap-fit on the base. Alternatively, fasteners which penetrate through the carrier and the collar 16 may be used.

The height ofthe tubular portion 19 is somewhat greaterthan that ofthe collar 16, so thatthe carrier defines a further part of the passage extending upwardlyfrom the aperture in the outer skin.

Laterally projecting arms 20 are provided at the upper end of the carrier to receive a cover 21 which may be a press-fit or a snap-fit on the arms. The cover is hollow, open at its lower side and so formed that, when fully engaged with the arms 20, it is clear ofthe upper end of the tubular portion 19 of the carrier. Thus, the passage defined by the carrier is open at its upper end but is covered so that precipitation falling on the ventilator cannot enter the passage. The cover extends overthe passage and the aperture in the outer skin and extends laterally outwardly beyond the passage a substantial distance and downwardly below the level ofthe upper end of the tubular portion 19 of the carrier. The cover may additionally be secured to the carrier by means offasteners.

As shown, a mesh 22 may be placed overthe upper end ofthecarrierto prevent insects our debris enteringthechamber 14through the aperture inthe outer skin.

It will be noted that the ventilator can be applied to a roof retrospectively, that is after the roof has been constructed and the building has been in use. Access is required only to the upper surface of the roof from the outside ofthe building.

The features disclosed in the foregoing description, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately or any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims (11)

1. A pitched roof of a building, the roof comprising inner and outer skins wherein there is defined between the inner and outer skins a space which is substantially closed off from the interior of the building, the outer skin is corrugated, the outer skin defines an aperture leading to the space between the skins and a cover is provided overthe aperture to prevent precipitation entering said space through the aperture but arranged to permit vapours to escape from said space to the ambient atmosphere.

2. A roof according to Claim 1 wherein the aperture is formed in a single corrugation.

3. A roof according to Claim 2 further comprising an intermediate layer which is in contact with the outer skin at the underside thereof but is spaced from the lower surface of a crest of a corrugation and wherein said aperture is formed in the crest of the corrugation.

4. A roof according to Claim 3 further comprising a base forthe cover, the base being sealed to the outer skin of the roof and defining a passage extending upwardly from said aperture and the cover being mounted on the base.

5. A method of ventilating a roof having inner and outer skins defining between them a space which is substantially closed off from the region beneath the roof, wherein an aperture is cut in the outer skin and a cover is fitted over the aperture to prevent precipitation entering the space through the aperture but to permitvapourto escape from said space to the ambient atmosphere.

6. A method according to Claim 5, as appiied to a roof having a corrugated outer skin and an intermediate layer which is in contact with the valleys of the corrugations of the outer skin, the method comprising the step of cutting the aperture in the crest of a corrugation.

7. A method according to Claim 5 or Claim 6 wherein a base which overlaps the margin ofthe outer skin adjacent to the aperture is sealed to the outer skin afterthe aperture has been cut and the cover is then mounted on the base.

8. A ventilator for use in a roof according to Claim 1 and in a method according to Claim 5, the ventilator comprising a base defining a passage and having an outwardly protruding flange adjacent to one end of the passage and further comprising a cover mounted or adapted for mounting on the base coverthe end of the passage remote from the flangewithout closing that end ofthe passage.

9. Aventilator according to Claim 8 wherein the cover is adapted to be repeatedly mounted on and dismounted from the base.

10. A roof substantially as herein described with and fitted a ventilator substantially as herein described with reference to the accompanying drawing.

11. Any novel feature or novel combination of features disclosed herein or in the accompanying drawing.