GB2063961A - Cladding building structures - Google Patents

Abstract

Buildings or roofs, constructed as skeletal frameworks clad with sheet panels are refurbished by adding a cladding (18) over the existing cladding (10). Brackets (21), of bent strip metal, have end parts secured through existing cladding to supporting frame members (14) and supports (32) for the cladding (18) are secured to the brackets. The supports (32) span several brackets (21) and can have insulation (30) secured thereto. <IMAGE>

Description

SPECIFICATION Cladding building structures The invention relates to the cladding of building structures.

Many buildings, especially large industrial buildings such as factories and warehouses, are constructed as a skeletal load-bearing framework that is then clad with weatherproof sheet panels, usually corrugated for strength and visual attraction, and, at least nowadays, associated with suitable underlying insulation.

Present-day exterior sheeting panels, such as our own available under the Registered Trade Mark TRIMAT, are often of plastics-coated metal and have a very good life expectation. However, even such sheet panels must, with time, become suspect and require refurbishing of buildings on which they are used.

Other types of sheeting panels, say of metal or cement/asbestos, such as were commonly used in the past, are also subject to deterioration with time and atmospheric pollution, often with a much shorter satisfactory life. For example, metal sheeting may become less resistant to corrosion, and cement/asbestos sheeting can become water absorbent which causes significant condensation problems within a building so clad.

There are very strong disincentives to prompt refurbishing of industrial buildings as both stripping and replacing their claddings are expensive, and use of the building will normally be adversely affected if not prevented while those operations are in progress for walls and/or roofs. It is very often the case that the basic load-bearing framework of such buildings is strong enough to support much more than the actual cladding applied, and this has lead us to investigate the possibilities for simply applying a further cladding over existing cladding.

It is in the results of developing such a system that this invention arises, especially in relation to solving the problems that inevitably occur in affixing to an existing cladding that may be unsound, or at least may later become unsound despite the protection afforded by an overcladding. Also, we have directed our attention to the economic expioitation of attaining improved insulation and reducing heat loss from such buildings.

To this end, we now propose that an existing cladded building structure have a second or further exterior cladding applied thereto by the use of standoff brackets each of which is secured at spaced positions through the existing cladding where the latter engages directly or indirectly with a supporting frame member therefor, such bracket securement being to such supporting frame members with each said bracket extending from its said positions of securement to a bracket part spaced from the existing cladding, and supports for said second or further cladding that are themselves each secured to a plurality of said bracket parts.

It is preferred that a bracket comprise strip metal bent to form flange-like feet and extend away therefrom to a medial portion that is substantially parallel with said feet and serves as said bracket part. It is further preferred that the supports for the second or further cladding comprise elongate channel-section members each spanning a plurality of the brackets and straddling each of those brackets. Such preferred embodiment of the invention results in a compact, light-weight, secure and reliable affixing for overcladding an existing building, conveniently with our added supports in register with existing frame members.

In addition, our preferred elongate supports and further cladding form with the existing framework and cladding a multi-layer structure that will usually have a desired increased overall strength, perhaps especially for roofs where, for example, regulations may change so that greater loadings, say for snow, are in force at the time of refurbishing than at the time of original building.

The preferred bracket readily permits straddling of currugation protrusions or "peaks" of the existing cladding to space the second or further cladding and even allow it to he of a different corrugation or profile pattern. We prefer to follow our normal cladding procedure of applying the second or further cladding over a layer of insulating material. We find that any resulting air gap between the two claddings can be exploited to advantage by ensuring that it is of a width consistent with good heat insulation (or sound insulation if that is the prime consideration).Also, air can be effectively trapped therein by providing, at least at tops and bottoms of walls and roof pitches, closures of the air gap, conveniently by way of strips of highly expanded foamed insulation material that will be compressed at least slightly at the maximum air gap width and yet readily accept further compression at securements of the second or further cladding to its support members.

Specific implementation of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a perspective view partly broken away, of part of a roof pitch; and Figure 2 is a sectional detail on lines A-A of Figure 1.

Whilst we do not show in the drawings a complete building structure, it is believed that our description of the roof pitch part actually shown and explanations relative thereto will permit ready appreciation of a preferred application of the invention to an entire building, or to any part thereof, as desired.

In the drawings, an existing corrugated cladding 10 is shown secured over a layer of insulation 1 2 on purlins 14 to which securement is made in any conventional manner usually bolting through "valleys" 1 6 of the cladding 10, though such details, save for the purlins 14, are of no significance to the practice of this invention in applying further cladding sheeting 1 8 without disturbing the original cladding 10.

The means of securement for the further cladding 18 comprises brackets 21 which are shown in a preferred bent strip metal form with a central portion 22 from which the bracket has splayed portions 23, 24 to outwardly bent feet 25, 26. The feet 25, 26 are shown pierced to provide holes 27, 28 by which they can be bolted or screwed to the purlins 14 through valleys 1 6 in the original cladding 10. The central bracket portion 22 is also pierced to afford a hole or holes 29 via which at least elongate channel section support members 32 are secured thereto, if not also the further cladding 1 8 and any intervening insulating 30.

The support members 32 are shown with their channel sections inverted over the brackets 21.

Matching within practical tolerances of the interior channel width to the width of the bracket strip material affords a very useful location interaction during fitting of those support members 32 after affixing of the brackets 21.

Rivetting is preferred for securing the support members 32 to the brackets 21 with the further cladding 18 screwed (31) to the support members 32.

The illustrated brackets 21 each straddle one peak of the original corrugated cladding and are readily formed to suit particular valley-to-valley spacings and desired original cladding-to-further cladding spacings. Also, of course, on-site variations of the angles of the bracket bends could enable fitting to different corrugation pitches or profiles of original cladding within a range of acceptable consequent alteration of spacing between the two claddings.

As shown, each bracket 21 has spaced securement to the same purlin 14 and the support members 32 follow those purlins in direct superposed registration therewith. That gives a particular secure and reliable attachment means for the further cladding that meets the loadspreading and support criteria for the original cladding and depends not at all on the remaining strength of the original cladding. The proposed scheme is thus greatly superior to another proposal of which we are aware and which utilises Z-shaped brackets from peaks of the original cladding and requires compressed interposed insulation sheeting completely filling the spacing between the two claddings to make up a filled sandwich construction.

Our own illustrated overciadding system can use an insulation layer 30 that does not completely fill the cladding interspacing over the majority of the lengths of sheeting panels of the further exterior cladding 18, or even omit such insulation. However, then, we do prefer to render any air-filled spaces sealed, at least at ends of such panels, by strips of insulation material that are thicker than the maximum cladding spacing but are readily compressed, say more highly foamed than that 30. Obviously, such strips could be provided at more frequent spacings, even made in a composite manner by first insulation strips, or the insulation 30, trapped between the support members 32 and the brackets 21 and second insulation strips trapped between the support members 32 and the further cladding 1 8.

One useful advantage of using foamed insulation between the two claddings is that it can, if desired, accommodate heads of bolts or screws for securing the support members 32 to the bracket portions 22 separately from securement of the further cladding to the support members 32 whether or not at positions other than overlying the brackets 21.

It will also be appreciated that irrotational affixing of nuts to the undersides of the bracket portions 22 in registration with their holes 29 could contribute usefully to aiding on-site work, as may also the similar provision of nuts above holes 27, 1 8 in the feet where bolting through the purlins 1 4 from below is practical and desired, rather than screwing as shown at 42.

If desired, the brackets 21 and support members 32 may be fixed together or integrally formed, e.g. pre-cut for pressing out and bonding the splayed end feet portions 23 to 26 thereof onsite, as a factory produced prefabrication.

The scheme shown is particularly well adapted to overcladding roof pitches, but could, if desired, also be used in an entirely analogous way in overcladding walls, especially using stronger brackets to take vertical loads or having feet of such brackets align with vertical frame members but with the cladding supports nonetheless extending horizontally over severai brackets on different verticals.

We have referred previously to the possibility of realising a desired increased overall strength of a refurbished structure. As applied to roofing in the foregoing specific description, we have found it possible to meet a 50% increase in snow loading requirements for the overall, refurbished, roof over requirements in force at the time of building the original structure, despite inevitable deterioration between times.

Claims (12)

1. A method of refurbishing buildings comprised of a skeletal load-bearing framework clad with sheet panels, wherein a second or further cladding is applied over the existing cladding by the steps of securing to supporting frame members through the existing cladding stand-off brackets each at spaced positions and with each such bracket extending from its said positions to a bracket part spaced from the existing cladding, securing supports for the second or further cladding to piuralities of said bracket parts, and securing the second or further cladding to said supports.

2. A method according to claim 1 , wherein the brackets each comprise strip metal bent to form fiange-like feet and extend away therefrom to a medial portion that is substantially parallel with said feet, and the brackets are secured to the supporting frame member through their said feet, and the supports for the second or further cladding are secured to said medial portions as said bracket parts.

3. A method according to claim 2, wherein the brackets are secured over corrugated existing cladding with their feet straddling a corrugation protrusion then below their medial portions.

4. A method according to claim 2 or claim 3, wherein the supports for the second or further cladding comprise elongate channel-section members each secured to span a plurality of said brackets and straddling each of those brackets.

5. A method according to any preceding claim, wherein the supports for the second or further layer follow and register with said supporting frame members.

6. A method according to claim 5, wherein said supports extend across roof pitches or parts thereof.

7. A method according to any preceding claim, wherein a layer of insulation is provided between the existing cladding and the second or further cladding.

8. A method according to claim 7, wherein the layer of insulation is secured to said supports before said second or further cladding.

9. A method according to any preceding claim, wherein, at least at tops and bottoms of walls or roof pitches, strips of highly expanded foamed insulation material are secured between the existing cladding and the second or further cladding as closures to any air-spaces therebetween.

10. A method according to any preceding claim, wherein the second or further cladding is of a different corrugation pattern to that of the existing cladding.

11. A method of refurbishing a building or part thereof substantially as herein described with reference to the accompanying drawing.

12. A building of which at least a part has been refurbished by a method according to any preceding claim.