GB2089864A

GB2089864A - Overcladding Structure for a Roof

Info

Publication number: GB2089864A
Application number: GB8137719A
Authority: GB
Original assignee: NORPEE CONSTRUCTION ENGINEERS
Current assignee: NORPEE CONSTRUCTION ENGINEERS
Priority date: 1980-12-15
Filing date: 1981-12-15
Publication date: 1982-06-30

Abstract

Fresh sheeting 3 is supported by elements 4 which pass through the existing roof-sheeting 1 and transmit the full load of the fresh sheeting to purlins or rafters 2 of the existing roof. Elements 4 may be drill-ended self- tapping bolts, securing short channel- sections 6. Top-hat section 8, fitting over and secured to section 6, fits against and is secured to original roof- sheeting 1, thus providing support for the original roof. Alternatively new cleats 23 are inserted through existing cladding 24 from the outside, and bolted to existing cleats 21 through existing purlins 22 the original bolts securing cleats 21 to purlins 22 having been removed. Fresh purlins 25 are secured to cleats 23 by further cleats 26 and fresh cladding 27 is secured to purlins 25. Various profiles of cleats 23 and 26 and purlins 25 are depicted in Figures 4-8 (not shown). Existing gulley gutter 10 may be overlaid by new gutter 12 having side sections extending over and locating a top-hat section 8. New gutter 12 is laid on leaver- members 12 of top-hat section. Thermal insulation material is disposed between old and new gutters 10 and 12. <IMAGE>

Description

SPECIFICATION Overcladding Structure for a Roof This invention relates to an overcladding structure for the roof of a building, to form a fresh roof overcladdiny the existing roof.

Our patent application 79.38907 describes and claims an overcladding structure for the roof of a building, in which the existing roof is overclad with fresh sheeting to form a fresh roof overcladding the existing roof, the fresh sheeting being secured in position by anchoring to purlins of the existing roof with or without thermal insulation material being disposed between the existing roof and the fresh sheeting: elongate bearer members are first laid on the existing roof in alignment with the existing purlins and are anchored to the existing purl ins by fixing elements additional to and independent of the fixing elements already securing the existing roof sheeting to the purlins, then the fresh sheeting is applied and secured to the bearer members.

In accordance with the present invention, there is provided an overcladding structure for the roof of a building, in which the existing roof is overclad with fresh sheeting to form a fresh roof overcladding the existing roof, in which the fresh sheeting is supported by elements which pass through the existing roof and transmit substantially the full load of the fresh sheeting to purlins or rafters of the existing roof.

Also, in accordance with the present invention, there is provided an overcladding gutter for the overclad roof of a building, comprising a fresh gutter laid over an existing gutter with thermal insulation material disposed between the existing and fresh gutters.

Embodiments of the present invention will now be described, by way of examples only, with reference to the accompanying drawings, in which: Figure 1 is a section through part of a roof, showing fresh sheeting overcladding the existing roof and elements transmitting the load of the fresh sheeting to rafters of the existing roof; Figure 2 is a section through a gulley gutter of a roof, showing fresh sheeting overcladding the roof and a fresh gutter laid over the existing gutter; and Figures 3 to 8 show modifications relative to Figure 1.

Referring to Figure 1, an existing roof comprises sheeting 1 of single or double skin construction laid over and fixed to purlins (not shown) of the existing roof. One of the rafters of the existing roof is shown at 2, there being a plurality of rafters extending parallel to each other up the slope of the roof and a plurality of purlins laid over the rafters and extending parallel to each other and spaced apart up the slope of the roof.

The existing roof is overclad with fresh sheeting 3, anchored to the rafters by elements 4 which serve to transmit substantially all the load of the fresh sheeting directly to the rafters. Instead, the anchoring and load transmitting may be made to the purlins, depending on the design of the roof and the accessibility of the purlins and rafters.

The elements 4 are Tek bolts which are passed through holes bored in the existing roof and engaged with the existing rafters (which are metal angle members in the example shown). The Tek bolt is provided with a formation 4a at its end for drilling its own bore through the rafter, followed by a threaded section 4b for self tapping into the bore which the bolt drills into the rafter. A locking nut 5 is carried on this threaded section 4b and lies against the upper surface of the rafter when the Tek bolt is driven fully into position, as shown.

The upper end of the bolt 4 comprises a threaded section 4c which projects upwards through the existing roof and a short length of metal channel section 6 is secured over this projecting end of the bolt, by passing an aperture of the channel section over the bolt end and securing it in place with a pair of locking nuts 7. A much longer metal section 8, of top hat shape, is then placed on the existing roof, so as to fit over a plurality of members 6 (and their bolt ends 4c) secured to respective rafters and spaced apart across the roof. The top hat section 8 shown fits, together with the members 6, against the upper surface of the existing roof and projects above the members 6 so as to provide a space for receiving the ends of the bolts 4.The top hat section 8 is secured to the members 6 by self-tapping bolts 9 and its flanges 8a may be secured to the existing roof by any convenient fixing elements (e.g. pop rivets, Tek bolts), in order to provide support for the existing root The arrangement is such that a plurality of top hat sections 8 will run across the roof, spaced apart up the slope of the roof. The fresh sheeting is then laid over the top hat sections 8 and secured to them by appropriate fixing elements with or without thermal insulation material disposed between the existing roof and fresh sheeting.

The bolts 4 serve to transmit substantially the whole load of the fresh sheeting directly to the existing rafters (or, as indicated above, possibly directly to the existing purlins), and thus the overclad roof does not load the existing roof sheeting and indeed the existing roof sheeting may be supported by fixing to the top hat section 8 as indicated above. Thus, any degradation of the existing roof sheeting will not affect the integrity of the cladding.

In a modification, the sections 6 may be welded to the flat heads of the bolts 4 and then the sections 8 may be designed to sit flush upon the upper surfaces of the sections 6.

Referring to Figure 2, an existing gulley gutter 10 is shown in the gulley between two sloping roofs. Fresh sheeting 11 is shown overcladding each roof and the lowest top-hat section 8 of each overcladding is shown. Prior to application of the fresh sheeting for each roof, a fresh metal gutter 1 2 is laid over the existing gutter, the fresh gutter having side sections which extend over the top hat section 8 and locate with them by means of in-turned edges of the fresh gutter. The fresh gutter is laid on bearer members 1 3 spaced along the existing gutter, each bearer member comprising a top hat section extending across the gutter and bent to shape. Thermal insulation material is disposed between the two gutters and serves to insulate the interior space of the building immediately below the existing gutter 10.Tek bolts or other fixing elements are then used to bolt the fresh gutter to the existing gutter, the bolts being passed through the top hat sections 1 3.

In each of Figures 3 to 8, the existing rafters 20 have existing L-sect-on cleats 21 welded to them, to which cleats the ends of the existing Z-section purlins 22 are bolted. In order to effect the overcladding, purpose made cleats 23 are inserted through the existing cladding from the outside and bolted to the existing cleats 21 through the purlins 22: thus, it is necessary first to remove the original bolts holding the end of purlin 22 to its cleat 21, then to apply the new cleat and bolt the assembly 23, 22, 21 together. In Figures 3-7 the purpose made cleat is an L-section with a top plate welded to its inverted foot, and in Figure 8 it is a simple L-section. The purlins of the overcladding are then applied to the top plates of the purpose made cleats 23 which are applied inline correspondence with the ends of the existing purlins (i.e. adjacent the rafters). Figures 3-8 show different standard types for the purlins 25: Figure 3 a multibeam purlin, Figure 4 a zeta purlin, Figure 5 a channel, Figure 6 a zed, Figure 7 a rectangular section timber purlin and Figure 8 an L-section purlin. The new purlins 25 are fixed to the new cleats 23 by appropriate standard cleats 26, appropriately profiled as shown in Figures 3 and 4 and L-section in Figures 5 to 8.

The new cladding sheeting 27 is then applied and fixed to the new purlins 25. In each of Figures 38, it will be noted that the full overcladding load is taken through to the rafters (by way of the cleats 21) which also carry the existing purlins, without loading the existing purlins.

Claims

1. An overcladding structure for the roof of a building, in which the existing roof is overclad with fresh sheeting to form a fresh roof overcladding the existing roof, in which the fresh sheeting is supported by elements which pass through the existing roof and transmit substantially the full load of the fresh sheeting to purlins or rafters of the existing roof.

2. An overcladding structure substantially as herein described with reference to Figure 1 of the accompanying drawings.