GB2279379A - Clip for fixing roofing sheets - Google Patents

Abstract

A clip 20 for concealed fixing of cladding sheets of the type having re-entrant longitudinal ribs has a retaining formation 25 for engaging inside a rib of the sheet. The retaining formation includes an upright tab 30 disposed in a plane transverse to the rib and shaped for snap-fit engagement with a re-entrant portion of the rib. The retaining formations may be disposed along a strap 21 in opposed pairs, with fastening apertures 36 in the strap centrally disposed below each rib. <IMAGE>

Description

PANEL AND CLIP ARRANGEMENT BACKGROUND OF INVENTION The present invention relates to a retaining clip construction for the concealed fixing of roofing or other cladding sheets.

Cladding sheets for concealed fixing have a plurality of longitudinal, re-entrant ribs, with pan sections between the ribs. The edges of the sheets are adapted for interengagement with the adjacent sheets, so that an end rib of one sheet fits over the end portion of the adjacent sheet.

The sheets are typically secured to the roof structure by elongated clips which secure the trailing edge end portion of the previously laid sheet and the end rib and intermediate ribs of the sheet to be laid. The clip has retaining formations spaced along the length thereof to coincide with the rib spacing. An endmost retaining formation of the clip is engaged with the trailing edge portion of the previously laid sheet, with the remainder of the clip extending in the direction of progress, and is fixed to the roof structure. The next sheet is then pressed onto the clip so that the leading edge rib and intermediate ribs are engaged with the retaining formations and the leading edge rib also locks over the trailing edge portion of the previous sheet.

The prior art clips are formed as a strap, which is folded to form a series of humps. The humps have detents for engagement with re-entrant portions of the ribs of the sheet.

SUMMARY OF INVENTION The present invention seeks to provide an alternative clip arrangement.

The present invention thus provides a clip for concealed fixing of cladding sheets of the type having a plurality of re-entrant longitudinal ribs, the clip including means for fastening to an underlying structure and a retaining formation for engaging inside a rib of the sheet, wherein said formation includes a upright tab disposed in a plane transverse to the rib, the tab being shaped for snap-fit engagement with a re-entrant portion of the rib.

BRIEF DESCRIPTION OF THE DRAWINGS Further preferred embodiments of the invention will now be described with reference to the accompanying drawings, in which: Fig. 1 is a schematic perspective showing installation of a roofing sheet using a prior art clip; Fig. 2 is a plan view of a preferred clip in accordance with the present invention; Fig. 3 is a side view of the clip of Fig. 2; Fig. 4 is a perspective view of the clip of Fig. 2; Fig. 5A is a left hand end view of the clip of Fig. 2; Fig. SB is a right hand end view of the clip of Fig. 2; Fig. 6 illustrates the cladding sheet profile for use with the clips of Fig. 2; Figs. 7A to 7D are schematic side views illustrating the installation procedure; and Fig. 8 is a detail side view of a retaining formation of the clip engaged with the leading edge rib of a sheet and the trailing edge portion of the previous sheet.

DETAILED DESCRIPTION OF THE DRAWINGS With reference to Fig. 1, the prior art fixing system includes a clip 10 consisting of a flat strap which has been folded along lines 900 to its length to form hump-shaped retaining formations 11a,llb at its ends.

These formations have detents 12 therein to engage inside the female 13b and intermediate 14 ribs of the roofing sheets 15a,15b. In use, the first hump lia of the clip is positioned over the male rib 16a on the trailing edge of the previously laid sheet 15a, and the clip is fixed to purl in 17 by screws at positions 18a and 18b. The second sheet 15b is then positioned with its female 13b and intermediate 14b ribs over the respective formations lla, llb and is pressed downwards to snap home over the detents 12 and to engage the female rib over the full length of of the male rib 16a. The procedure is repeated for subsequent sheets, with the male rib of the final sheet being held by a finishing clip.

Figs. 2 to 5 illustrate a preferred clip arrangement according to the present invention. The clip 20 includes a strap 21 shaped for most of its length as a shallow, downwardly facing channel 22 (as best shown in Fig 5A). At point 23 the channel inverts to form an upwards facing channel 24 best shown in Figs. 4 and SB.

Three retaining formations 25 are attached to the strap, at positions corresponding to the leading edge rib 26 and the two intermediate ribs 27 of the roofing sheet 28 of Fig. 6. Each retaining formation is formed as a generally channel-shaped element in end view, having a base 29 and a pair of opposed upright tabs 30 of a generally similar profile to the rib.

Each tab has a pair of downwardly facing shoulders 39 for location above the re-entrant portions 40 of the rib, an inwardly turned longitudinal top flange 31 and a pair of inwardly angled longitudinal flanges 32.

The faces of angled flanges 32 are adapted to abut the inside surface of the rib. There preferably is some clearance of the top longitudinal flange 31 and the top of the rib, to allow the rib to flex while being snap-fitted onto the tab.

As illustrated in Figs. 7A to 7D, the first clip 20a is secured to the purl in by fasteners 35 passing through the fastener holes 36 in the strap between the tabs of each retaining formation. Securing the clip also compresses the insulation blanket 41.

As shown in Fig. 7B, the roofing sheet 28a is aligned above the clip 20a and pushed downwardly to snap fit the top portions of the ribs over corresponding barbed part of the tabs. Engagement between downwardly facing shoulders 39 of the tabs and opposed re-entrant parts 40 of each rib then prevent the sheet from being lifted out of engagement. The angled flanges 32 above the shoulders 39 fit tightly inside upwardly convergent top walls 42 of the rib to prevent twisting of the tab.

The next clip 20b is installed with the angled flanges 32 of the endmost retaining formation 25a hooking under the lip 43 of the trailing edge portion 33 of the previously laid roofing sheet 28a. The clip 20b is pivoted downwards and secured to the purl in 34 by fasteners 35 passing through fastener holes 36 in the clip (Fig. 7C).

The next roofing sheet 28b is then aligned above clip 20b and snapped home as described above for roofing sheet 28a, except that the leading edge rib 26 snaps over both the endmost retaining formation 25a and the trailing end portion 33 of the previous sheet. The engagement between the two clips 20a,20b and the two sheets 28a,28b is described below with reference to Fig. 8.

Fig. 8 illustrates the overlap between two adjacent sheets. The trailing edge portion 33 is shaped as one side of a rib, including an upwardly facing shoulder 44 shaped like the re-entrant parts 40 of the ribs.

The shoulder 44 of the end portion is held down by the near shoulder 39 of the tab in the same manner as the ribs. The downwardly turned lip 43 at the outer edge of the trailing edge portion is hooked behind the endmost angled flange 32 of the tab to prevent the shoulder 44 of the edge portion and the shoulder 39 of the tab from moving laterally out of alignment.

The illustrated retaining formations and the manner of connection with the projecting edge portion of the sheet allow fasteners to be positioned centrally below the longitudinal rib of the roofing sheet for greater wind uplift resistance and allows direct engagement between the retaining tabs and the leading edge rib. Furthermore, the short trailing edge portion allows greater material efficiency in the roofing sheet compared to the prior art.

The alignment of the tabs 30 across the rib profile results in the fold line 37 between the tabs and the base 29 of the retaining member being parallel to the clip length, rather than perpendicular as in the prior art. Furthermore, the angled flanges 32 of the retaining formation are closely received in the top portion of the rib, restraining against bending of the clip in both the parallel or perpendicular directions.

Consequently, the wind uplift forces acting through the flanges 32 act substantially parallel to the plane of the tab. Extreme uplift forces attempt to twist the tab. This mechanism results in considerably greater resistance to wind uplift forces than the prior art hump-shaped retaining formations, in which the uplift forces attempt to unfold the hump by bending along the existing perpendicular fold lines.

As the tabs substantially correspond to the rib profile, separate bird proofing accessories are not required.

Unlike prior art clips, the tail 38 of the clip extends past the final retaining formation 25c, thus supporting the full sheet profile and compressing the insulation blanket in the region of connection of the laid sheet with the next clip. This arrangement also allows the head of the next clip to nest within the channel section 24 at the tail of the previous clip, and the alignment of circular fastener holes 36 ensures exact positioning of the clips for correct roof pitching.

While particular embodiments of this invention have been described, it will be evident to those skilled in the art that the present invention may be embodied in other specific forms without departing from the essential characteristics thereof. The present embodiments and examples are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

In the appended claims, the invention is defined with reference to the orientation for use in roof cladding, where the plane of the sheets is generally horizontal.

This however should not be construed as limiting the invention to that orientation. The present invention can, for example, be used for wall cladding.

Claims (16)

1. A clip for concealed fixing of cladding sheets of the type having a plurality of re-entrant longitudinal ribs, the clip including means for fastening to an underlying structure and a retaining formation for engaging inside a rib of the sheet, wherein said formation includes a upright tab disposed in a plane transverse to the rib, the tab being shaped for snap-fit engagement with a re-entrant portion of the rib.

2. A clip according to claim 1 wherein said means for fastening includes a strap adapted to extend transversely to said ribs, said strap having attached thereto a plurality of said retaining formations for engaging with respective ribs of the sheet.

3. A clip according to claim 2 wherein each retaining formation comprises a pair of said upright tabs spaced from each other along said rib.

4. A clip according to claim 3 wherein said strap has fastener apertures located between the tabs of each respective pair of tabs.

5. A clip according to claim 1 wherein the tab has a pair of downwardly facing shoulders which locate above respective re-entrant portions of the rib.

6. A clip according to claim 5 wherein said tabs further include longitudinally extending flanges located above said shoulders, said flanges having faces which abut an inside surface of the rib.

7. A clip according to claim 6 wherein said longitudinal flanges abut inside surfaces of upwardly convergent walls of the rib.

8. A clip according to claim 7 wherein a lower edge of each said flange is located at the respective shoulder.

9. A clip according to claim 1 wherein said means for fastening includes a strap adapted to extend transversely to said ribs, said strap having attached thereto a plurality of said retaining formations for engaging with respective ribs of the sheet, wherein each tab has a pair of downwardly facing shoulders which locate above respective re-entrant portions of the rib.

10. A clip according to claim 9 wherein said sheet has a trailing edge portion including an upwardly facing shoulder conforming in profile to a re-entrant portion of a rib so as to engage beneath one of said downwardly facing shoulders of an endmost tab, a downwardly turned lip on the distal edge of said trailing edge portion, wherein at least said endmost tab includes means for engaging said lip while the other downwardly turned shoulder of said endmost tab is free for engagement by a subsequent sheet.

11. A clip according to claim 10 wherein said trailing edge portion does not extend beyond an upright axis of symmetry of said tab.

12. A clip according to claim 11 wherein said means for engaging the lip is a flange which hooks under the lip.

13. A clip according to claim 10 wherein said subsequent sheet includes a leading edge rib which snap-fits over the endmost tab and the trailing edge portion so that an endmost re-entrant portion of the leading edge rib engages under said shoulder of the trailing edge portion and the other re-entrant portion of the leading edge rib locates below said free downwardly turned shoulder of said endmost tab.

14. A clip according to claim 2 wherein said strap includes a tail portion which does not have a retaining formation, said tail portion having means for locating a subsequent clip.

15. A clip according to claim 14 wherein said locating means includes said tail portion being adapted for nested engagement with said subsequent clip.

16. A clip according to claim 15 wherein said locating means further includes aligned apertures in said tail portion and said subsequent clip.