GB2120706A

GB2120706A - Overroofing of buildings

Info

Publication number: GB2120706A
Application number: GB08314416A
Authority: GB
Inventors: Albert James Hodder
Original assignee: ITW Ltd
Current assignee: ITW Ltd
Priority date: 1982-05-26
Filing date: 1983-05-25
Publication date: 1983-12-07
Also published as: GB8314416D0; GB2120706B

Abstract

A bracket 10, for use in mounting a secondary roof 32 over a non-planar surface of an existing roof 30, is formed from a linearly-extending ribbon-like metal strip. The strip includes a lower section 12 to be secured through the existing roof 30 to an underlying support therefor 38, an upstanding section 14 to extend past a rib presented by the existing roof 30, and an upper section 16 in which the secondary roof 32 is to be secured, with longitudinally spaced- apart portions of the upper section 16 presenting mutually co-operable male and female locking means. The male locking means 20 is shown as a central downwardly struck lip 26 between two side tabs 28, and the female locking means 18 is shown as a central slot 24 extending transversely of a rebate 22, to permit adjacent brackets 10 to be secured to one another in a straight line to form a continuous purlin. <IMAGE>

Description

SPECIFICATION Overroofing of buildings There is often a need for a roof of a building to be waterproofed and/or thermaliy insulated.

As adding a false or suspended ceiling below an existing roof causes considerable disturbance within the building, necessitating the evacuation of any personnel and the shut-down of any machinery, systems have been devised for adding a secondary roof over an existing roof, any disturbance then being entirely outside the building.

A particular difficulty arises, with both flat and pitched roofs, when the existing roof is formed from aluminium, steel, asbestos cement or other sheets having parallel ribs, for example of undulatory or angular profile, so that the sheets present non-planar surfaces.

This difficulty is that, for structural soundness, an upper series of supports for the secondary roof must be firmly secured to a lower series of supports for the existing roof.

Conventionally, both of the series of supports are formed as purlins, but because of the nonplanar surface of the existing roof, it is necessary to span the gap between the upper purlins and the lower purlins either by long fastening members, leading to problems in alignment and driving, or by separate bridging members, whose use is neither economic nor efficient.

An entirely fresh approach to solving the above-described difficulty is the subject of our copending British patent application 820241 5 (GB 2 092 202A) wherein a bracket, for use in mounting a secondary roof over a non-pianar surface of an existing roof, is disclosed comprising a linearly-extending ribbon-like metal strip which includes a central flat section to which a secondary roof is to be secured, a pair of intermediate angled sections to be located on either side of at least one intervening rib presented by a non-planar surface of an existing roof, and a pair of end tab sections to be secured through the existing roof to an underlying support therefor, the end sections being of mutually cooperable shapes which permit the central sections of adjacent brackets to lie in a straight line even when the adjacent end sections of those brackets overlap one another.

The aim of the present invention is to provide an alternative approach which maintains many of the advantages of the invention of our co-pending British patent application 820241 5 (GB 2 092 202A) but which provides the further advantages of permitting construction of continuous purlins and greatly reducing the number of fastening operations required in said construction.

In accordance with one aspect of the present invention, a bracket is provided for use in mounting a secondary roof over a non-planar surface of an existing roof, the bracket comprising a linearly-extending ribbon-like metal strip which includes, defined in one spatial attitude, a lower section to be secured through an existing roof to an underlying support therefor, an upstanding section to extend past a rib presented by the existing roof, and an upper section to which a secondary roof is to be secured, with longitudinally spaced-apart portions of the upper section presenting mutually cooperable locking means to permit adjacent brackets to be secured to one another in a straight line.

In accordance with a further aspect of the present invention, a method of mounting a secondary roof over a non-planar surface of an existing roof comprises the use of a plurality of the brackets defined immediately herein-above, the brackets being arranged in straight lines with each of the straight lines effectively constituting a continuous purlin.

Preferably, female locking means is located at that end of the upper section closer to the upstanding section and male locking means is located at the other end of the upper section, but other locations for the mutually cooperable locking means are possible. Moreover, preferably the female locking means is formed by one or more openings and the male locking means is formed by one or more downwardly struck projections, but other formations for the mutually co-operable locking means are possible.

In particular examples, the female locking means could be a central slot or two side slots extending transversely of a rebate, and the male locking means could be a central lip between two side tabs or two side lips separated by a central tab, respectively.

Both the existing roof and the secondary roof can be formed of conventional roofing materials, and insluating material can be either inserted in the gap between the existing roof and the secondary roof, or incorporated in a composite construction for the secondary roof.

Where the existing roof is constructed from over-lapping sheets, brackets having upstanding sections of different height may be used, to allow the upper surfaces of adjacent secured brackets to be co-planar. Moreover, where the existing roof is of undulatory form, the lower sections of the brackets may themseives be curved rather than being straight.

A bracket, and its manner of use, in accordance with the present invention, will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a plan view of the bracket; Figure 2 is a perspective view clearly showing the female locking means of the upper section of the bracket; Figure 3 is a perspective view of just the male locking means of the upper section of the bracket; and Figure 4 is a schematic side section of two of the brackets secured together also showing an existing roof and a secondary roof in phantom.

A bracket 10 in accordance with the present invention is formed by a linearly-extending ribbon-like metal strip.

As shown in Figures 1 to 3, the strip forming the bracket 10 includes, defined in one spatial attitude, a lower section 12 to be secured through an existing roof to an underlying support therefor, an upstanding section 14 to extend past a rib presented by the existing roof, and an upper section 16 to which a secondary roof is to be secured, with longitudinally spaced-apart portions of the upper section 16 presenting mutually co operable locking means 1 8 and 20 to permit adjacent brackets 10 to be secured to one another in a straight line.

That end of the upper section 16 closer to the upstanding section 14 is shaped to present a rebate 22 having a transversely extending slot 24 to constitute the (female) locking means 18, and the other end of the upper section 1 6 is shaped to present a downwardly turned lip 26 between a pair of tabs 28 to constitute the (male) locking means 20.

Referring now to Figure 4, two of the brackets 10 described hereinabove are shown, in situ, -secured to one another and mounted between an existing roof 30 and a secondary roof 32.

The existing roof 30 is formed from undulatory asbestos cement sheets 34 which are secured by a plurality of hook-shaped fasteners 36 to rows of flanged steel purlins 38. The secondary roof 32 is of composite construction including a layer of insulating material 40 secured below exterior ribbed sheeting 42.

In use, each of the brackets 10 is sequentially secured in position by: inserting its lip 26 through the slot 24 in the last one of a straight line of already secured brackets 10; manipulating until its lower section 12 rests on the asbestos cement sheet 34 and its tabs 28 rest on the rebate 22 of said last of the already secured brackets 10; and then fixing by driving a self-drilling self-tapping screw 44 through its lower section 12, the asbestos cement sheet 34 and the flanged steel purlin 38.

This is repeated until the brackets 10 have been arranged in straight lines with each of the straight lines effectively constituting a continuous purloin to which the secondary roof 32 is secured by the use of further self-drilling self-tapping screws 46.

Naturally, specially shaped brackets may be required at the start of each straight line of brackets 10. To allow the upper surfaces of each straight line of brackets 10 to be co-planar, those of the brackets 10 to be fixed to overlapping areas of the asbestos cement sheets 34 may have shorter upstanding sections 14. The particular shapes of the brackets 10 will largely be determined by the particular shape of the non planar surface presented by the existing roof 30.

For example, the upper section 16 could be longer to extend over more than one rib of the existing roof 30; the lower section 1 2 need not be formed with a pre-drilled aperture (as shown) and need not be notched to present a central tab (as shown); the positions of the slot 24 and the lip 26 could be interchanged, the lip 26 then being struck upwardly from the rebate 22 to extend into but preferably not through the slot 24; the slot 24 could be replaced by two side slots, and the lip 26 could be replaced by two side lips, such an arrangement providing better stability against rocking as well as assisting in the formation of a plurality of the brackets from a continuous strip; and the strip could be thinner and formed with strengthening ribs to allow an overall saving of material.

Claims

1. A bracket, for use in mounting a secondary roof over a non-planar surface of an existing roof, comprising a linearly-extending ribbon-like metal strip which includes, defined in one spatial attitude, a lower section to be secured through an existing roof to an underlying support therefor, an upstanding section to extend past a rib presented by the existing roof, and an upper section to which a secondary roof is to be secured, with longitudinally spaced-apart portions of the upper section presenting mutually co-operable locking means to permit adjacent brackets to be secured to one another in a straight line.

2. A bracket according to claim 1, in which female locking means is located at that end of the upper section closer to the upstanding section and male locking means is located at the other end of the upper section.

3. A bracket according to claim 1 or claim 2, in which the female locking means is formed by one or more openings and the male locking means is formed by one or more downwardly struck projections.

4. A bracket according to claim 2 and claim 3, in which the female locking means is formed as two side slots extending transversely of a rebate at that end of the upper section closer to the upstanding section, and the male locking means is formed as two side lips separated by a central tab at the other end of the upper section.

5. A bracket substantially as hereinbefore described with reference to the accompanying drawings.

6. A method of mounting a secondary roof over a non-planar surface of an existing roof comprising the use of a plurality of the brackets according to any preceding claim, the brackets being arranged in straight lines with each of the straight lines effectively constituting a continuous purlin.

7. A method according to claim 6, in which the upstanding sections of different brackets are of different height to allow the upper sections of adjacent brackets to be co-planar even where the existing roof is constructed from overlapping sheets.