GB2051910A - Roofing - Google Patents

Abstract

A method of insulating the roof 1 of an existing building by fixing a plurality of spacers 3, at spaced intervals, to the roof of a building covering the roof with insulating foam 7 to a depth not greater than the height of the spacers, and covering the foam with cladding material 6 which is attached to the spacers. The foam is preferably foamed in situ and suitably is a closed-cell polyurethane foam. <IMAGE>

Description

SPECIFICATION Roofing This invention relates to the cladding of buildings, and is especially concerned with the cladding of roofs for the purpose, for example, of repairing, insulating or upgrading them. The invention is especially concerned with the cladding of roofs of schools, hospitals, factories and other industrial or agricultural buildings.

Such buildings have roofs which are usually made up of sheets of roofing material, e.g.

asbestos-cement sheets, fibre reinforced sheets and the like, either flat or pitched, with a corrugated or otherwise profiled shape, which are attached to the roof supports. These may be for example steel, timber or concrete purlins. It is particularly important nowadays to thermally insulate buildings, and this applies just as much to agricultural and industrial buildings as it does to domestic buildings. Insulation of these buildings may be carried out by placing insulation material either inside the building, i.e. beneath the roofing sheets, or outside the building, i.e. on top of the roofing sheets.

When a building is being constructed, it matters little whether the insulation is being applied from the inside or from the outside.

However, when an existing building is being insulated, or indeed the roof is being repaired, it is highly desirable that this should be accomplished from the outside, since working from the inside of the building will inevitably disrupt whatever operations are being conducted inside the building.

One known method of repairing roofs, or insulating roofs of existing buildings, is to spray the roof with polyurethane insulating foam and then to coat the surface of the hardened foam with a waterproof layer. It is of course most important that the waterproof coating is a continuous one, since otherwise the insulating layer beneath will be exposed to the elements and become liable to damage by UV light, water, frost etc. The application requirements are critical in terms of wind speed, and of the temperature and moisture content of the existing surface to ensure adequate bonding to it by the foam. Further, various known and available coatings are unreliable and are easily damaged, e.g. by birds.

Another disadvantage of this method is that to meet the surface spread of flame British Standard the insulating materials must be of a flame retardent grade and have an appropriate fire resistant protective coating. However, such coatings have a high resistance to water vapour transmission and in certain circumstances this could result in interstitial condensation of water vapour in the insulating material, thus reducing its performance.

It is an object of the present invention to provide a method of up-grading an existing roof, which can be performed from outside a building and which does not suffer from the disadvantages of the system described above.

According to the present invention a plurality of spacers is fixed, at spaced intervals, to the roof of a building, the roof is covered with insulating foam to a depth not greater than the height of the spacers, and the foam is covered with cladding material which is attached to the roof supports or to the spacers.

The materials required for putting the invention into effect include a supply of spacers and fasteners therefor (to attach the spacers to the existing roof or roof supports), a source of insulating foam, a supply of external cladding materials and fasteners for attaching the latter to the spacers or the roof supports.

The accompanying drawings shows one embodiment of the invention. In the drawing Figure 1 is a perspective view, partly in section and partly broken away, of a portion of a roof upgrading in accordance with the invention; and Figure 2 is a side view of the structure shown in Figure 1.

Referring to the drawing, a portion of an existing corrugated roof of a building is shown at 1. This is shown as a sine-wave corrugation, aithough it will be appreciated that the invention is applicable to roofs of any shape or slope'.

Attached to the roof 1 are longitudinally extending spaced spacer rails 2, each comprising a central web 3 and lower and upper flanges 4, 5 respectively. The spacer rails 2 may be spaced between 2' and 5' apart, depending on the nature of the roof which is being covered and the size and nature of the external cladding materials.

Attached to the upper flanges 5 of the spacer rails 2 are external cladding sheets 6. These sheets 6 may also take any suitable form, but as shown they have a box-shaped corrugated profile.

Between the roof 1 and the outer sheets 6, and completely covering the roof 1, is insulating foam 7. This is suitably foamed in situ, but it may take for form of pre-foamed granules or spheres which are held in place by a suitable adhesive material.

The structure shown in the drawing is suitably constructed as follows. Spacer rails 2 are attached to the roof 1 by suitable fasteners. Any proprietary fastener will suffice, and the choice of fasteners will depend upon the material and condition of the roof 1 and the material of the rails 2. As mentioned, the roof 1 may be any existing roof, and for example may be a corrugated iron or aluminium roof, a zinc roof, an asbestos cement roof, or afibre-reinforced plastics root Although the rails 2 are shown in the drawing as attached to the roof 1, they could if desired be attached to the purlins of the roof, by the use of suitable fasteners.

The next stage in the operation is the application of the insulating foam 7. This foam may be pre-foamed or foamed in sits. Suitable "pre-foams" are foamed polystyrene beads which may be sprayed onto the roof together with adhesive, e.g. PVA adhesive. It is preferred, however, to spray onto the roof 1 a mixture of a foamable material together with a foaming agent.

Suitable foamable materials are those described in Patent Specifications Nos. 1,153,152 and 1,470,953. The foamable mixture will normaliy also contain a hardener and a stabiliser for the foam. The curable material is suitably a phenolformaldehyde or ureaformaldehyde resin foam, which may be open-or closed-cell. Most preferably, however, it is a polyurethane foam, and preferably also it is of the closed-cell variety.

As mentioned, the roof 1 is completely covered with foam. When the foam has cured, and with a suitable choice of foam ingredients this may take no more than a few minutes, the outer cladding sheets are placed over the foam and on the spacers 2, and are attached to the spacers through their upper flanges 5.

The foam material 7 may occupy the whole of the space between roof 1 and external cladding sheet 6. As seen in the drawing, however, there is a gap 8 between the top of the foam 7 and the external sheet 6. This serves a dual purpose. It acts as a water channel, so that any water passing through or between the outer sheets 6 can escape without damaging the insulation system or entering the buildings. And further, it allows air to circulate on the outer side of the insulation to remove any water vapour which has diffused into the gap.

The thickness of the foam layer 7 is suitably between 65 and 85% of the distance between the roof 1 and external cladding sheet 6, in other words the height of the central web 3 of the spacer rail 2. For example, if the web 3 of the spacer rail is 100 mm. in height, the foam layer 7 may be applied to a depth of, say, 75 mm.

The outer cladding 6 may be of any desired material and shape. They may, for example, be sheets of a box-like corrugated form as shown, or a sine-wave corrugated form, or of any other profile. They may for example be of steel, other metals, fibre-reinforced polyester resin, asbestos cement, or timber covered by conventional roofing felts or similar.

The spacer rails 2 may be of steel, aluminium or timber. Their rigidity is enhanced by being embedded in the foam material 7, which reduces any tendency to buckling experienced by rails 2.

The gap between outer sheets 6 and roof 1 is preferably not less than 40 mm., and preferably not more than 150 mm.

It will be seen that the present invention provides a complete system for upgrading and/or repairing existing roofs without disruption of the processes taking place within the building.

Indeed, an entirely new roof is produced, and this gives maximum flexibility of design. The existing roof is completely protected by the outer cladding, and the roof space is fully insulated.

Using a system as shown in the drawing, and with a polyurethane closed-cell foam of thickness 30 mm., the "U" value of the roof can be reduced to less than 0.6W/(m2K).

Claims (10)

Claims

1. A method which comprises fixing a plurality of spacers, at spaced intervals, to the roof of a building, covering the roof with insulating foam to a depth not greater than the height of the spacers, and covering the foam with cladding material which is attached to the roof supports or to the spacers.

2. A method as claimed in claim 1 wherein the insulating foam is provided in the form of prefoamed granules or spheres.

3. A method as claimed in claim 2 wherein the insulating foam comprises foamed polystyrene beads.

4. A method as claimed in claim 1 wherein the insulating foam is provided in the form of a material which foams in situ.

5. A method as claimed in claim 4 wherein the insulating foam is a polyurethane foam.

6. A method as claimed in claim 4 or 5 wherein the insulating foam is a closed-cell foam.

7. A method as claimed in any of claims 1 to 6 wherein the insulating foam occupies the whole of the space between the roof and the cladding material.

8. A method as claimed in any of claims 1 to 6 wherein the thickness of the insulating foam is 65 to 85% of the distance between the roof and the cladding material.

9. A method as claimed in claim 1, substantially as described in the accompanying drawing.

10. A roof, insulated, up-grading or repaired in accordance with the method of any preceding claim.