A CLIP
The present invention relates to a. clip for
fixing a roof or other cladding sheet to an underlying
support structure.
The present invention relates particularly,
although by no means exclusively, to a clip for fixing a
roof cladding sheet to an underlying roof support
structure.
Typically, roof cladding sheets are roll-formed
from painted or unpainted steel strip and include one or
more parallel ribs with opposed sides, pan sections, and
side edge formations that enable the sheets to be
positioned side by side in overlapping relationship.
It is known to secure cladding sheets to an
underlying roof support structure, such as roof purlins,
by fastening the sheets directly to the underlying
structure using fasteners, such as roofing nails and
screws, that pierce the sheets and penetrate the
underlying structure.
It is also known to secure cladding sheets to an
underlying structure by using clips that are secured to
the structure by fasteners and are formed to extend into
the ribs and include retaining members or tabs that can
engage re-entrant portions of the ribu and thereby retain
the sheets to the clips. These clip assemblies are often
preferred over nails because they enable concealed fixing
of cladding sheets to an underlying structure.
In use, the concealed fixing retaining clips are
secured to an underlying structure at spaced intervals
related to the spacing between the ribs of the cladding
sheets. Thereafter, cladding sheets are positioned on the
clips in overlapping relationship by successively pressing
the sheets down onto the clips so that the sides of the
ribs are initially forced outwardly to allow the reentrant
portions of the ribs to pass over the retaining
members and then snap inwardly into engagement with the
retaining members.
There are a number of known concealed fixing
retaining clips. The clips include a series of clips
disclosed in International application PCT/GB91/00450 (WO
91/12392) in the name of Stramit Industries Limited, a
clip disclosed in Australian patent 685102 and other
Australian patents' and patent applications in the name of
Stramit Corporation, and a clip disclosed in International
application PCT/AU01/00818 (WO 01/02666) in the name of
the applicant. The clip disclosed in International
application PCT/AU01/00818 is marketed in Australia under
the trade mark KLIPLOK.
An object of the present invention is to provide
an alternative concealed fixing retaining clip to the
above-mentioned clips that has advantages over one or more
of these clips.
The applicant baa developed a new form of
concealed fixing retaining clip that is a relatively
straightforward construction compared to the abovementioned
clips and has at least comparable performance to
one or more of these known clips.
The present invention provides a concealed fixing
retaining clip for fixing a roof or other cladding sheet
to an underlying support structure of the general type
that includes:
(a) a base;
(b) a pair of side walls that extend from the base
and converge towards each other; and
(c) a pair of flanges that define retaining members
for engaging re-entrant portions in the sides of
ribs of cladding sheets, with one flange
extending from an upper end of one side wall and
the other flange extending from an upper end of
the other side wall.
The clip of the present invention has a number of
features that are described below that contribute to the
performance of the clip in a number of important areas.
One area is resistance to uplift forces acting on
a cladding sheet.
Uplift forces acting on an installed cladding
sheet can cause the sheet to be released from concealed
fixing retaining clips. Depending on the circumstances,
the uplift forces may cause:
(a) the sides of the ribs of the sheet to rotate
outwardly and thereby disengage from the flanges
of the clips; and/or
(b) the flanges of the clips to fold upwardly and
thereby release the sheet from the clips.
Another area is damage to a cladding sheet that
can occur when cladding sheets are positioned on concealed
fixing retaining clips.
Specifically, it has been found that cladding
sheets that are used with known clips, particularly clips
that have relatively short and stiff retaining members,
are susceptible to a problem of denting when cladding
sheets are forced onto the sheets. The dents form in the
sections of the sheets that contact and slide over the
clips as the sheets are forced onto the clips. The dents
do not affect the mechanical performance of the sheets.
However, the dents affect the aesthetic appeal of the
cladding sheets and this has been found to be a
significant issue.
Another area is damage to cladding sheets that
can occur when it is necessary to remove cladding sheets
from concealed fixing retaining clips.
Specifically, it has been, found that it is
difficult to remove cladding sheets from known clips,
particularly clips that have relatively short and stiff
retaining members, without damaging the sheets. This is a
significant issue because there are often situations, for
example when installing an air conditioner onto a roof,
when it ie necessary to be able to remove cladding sheets
to allow access to the roof cavity and thereafter replace
the removed sheets.
With regard to the above, the clip of the present
invention includes the following features.
Preferably the side walls of the clip of the
present invention are formed so that they do not contact
each other in the as-manufactured form of the clip and are
forced inwardly towards each other or into contact with
each other when, in use, a cladding sheet is positioned on
the clip. This feature makes it easier to install the
clip to an underlying structure because there is a gap
between the clip side walls for inserting a screw-driver
to facilitate securing the clip to the underlying
structure.
Preferably the clip is formed from a resilient
material so that each side wall of the clip applies an
outwardly directed force in. response to the side walls
being forced together when/ in use, a cladding sheet is
positioned on the clip. This feature contributes to
ensuring engagement of the flanges and the re-entrant
portions of the ribs of the cladding sheet. Specifically,
the resultant outward force forces the flanges against the
cladding sheet.
Preferably the flanges are a mirror image of
each other about a centre-line plane that passes
perpendicularly through the base of the clip.
Preferably the side walls and the base are
straight sides so that the side walls and the base define
a triangular structure when viewed from a side of the
clip. This feature contributes to the overall strength
and stiffness of the clip. More particularly, the
triangular structure contributes to the capacity of the
clip to withstand downward loading of the clip, for
example when a person presses down on a rib of a cladding
sheet to force the rib over the clip. In addition, the
triangular structure can accommodate off-centre downward
loading that may be applied to the clip when a cladding
sheet is forced down onto the clip. Specifically, the
side walls of the clip can slide relative to each other in
response to off-centre downward loading and return to the
original profile. In addition, the triangular structure
contributes to the resistance of the side walls to outward
movement of the side walls beyond the as-manufactured
positions of the side walls and therefore is a factor in
the clip being able to resist uplift forces on a cladding
sheet.
Preferably each side wall includes one or more
than one reinforcing rib to improve the strength and
stiffness of the side wall.
Preferably at least one edge of each side wall
includes an inwardly turned flange to improve the strength
and stiffness of the side wall.
Preferably the flanges define at least part of an
arch when/ in use, a cladding sheet is positioned on the
clip with the side walls forced together. This feature
contributes to the capacity of the clip to resist uplift
forces acting on the cladding sheet. Specifically, this
feature takes advantage of a characteristic of an arch
that it is a structure that can translate uplift forces to
outward forces.
Preferably the side walls contact each other or
are in close proximity to each other at or in the vicinity
of the upper ends of the clip when, in use, a cladding
sheet is positioned on the clip and forces the side walls
together. This feature ensures that there is clip material
as close as possible to the apex of the arch and thereby
contributes to concentrating as much clip material as
possible in the upper section of the clip and thereby
optimising the strength of the clip in this section of the
clip.
Preferably the flanges extend outwardly and
downwardly relative to each other as viewed when the clip
is positioned with the clip baee on a horinontal surface.
The flanges may describe a relatively steep
approach angle relative to a rib of a cladding sheet so
that there is gradual rather than sudden outward
deflection of the sides of the rib of the claddluy sheet
when, in use, the cladding sheet is forced downwardly onto
the clip to position the sheet on the clip. This feature
contributes to minimising denting of the sheet.
With this arrangement, preferably the flanges are
relatively long, preferably at least 25% of the height of
the clip.
Preferably the approach angle, described by each
flange and the base of the clip, is between 40° and 75°.
Alternatively, the flanges may describe a
relatively gentle approach angle relative to a rib of a
cladding sheet so that there is sudden rather than a
gradual outward deflection of the sides of the rib of the
cladding sheet when, in use, the cladding sheet is forced
downwardly onto the clip to position the sheet on the
clip.
With this arrangement, preferably the flanges are
relatively short, preferably less than 25% of the height
of the clip.
Preferably the approach angle, described by each
flange and the base of the clip, is less than 40°.
Preferably each flange has a sharp outer end that
contacts and thereby engages securely the re-entrant
portion of one of the ribs of a cladding sheet when, in
use, the cladding sheet is positioned on the clip.
Preferably the outer ond of each flange is
outwardly directed. In other words, preferably the outer
end of each flange is not inwardly turned t-.owarde the side
walls of the clip.
Preferably each flange includes the two corner
sections that are folded inwardly and form surfaces that
extend transversely to the outer end of the flange and
contact and thereby engage a re-entrant .portion of one of
the ribs of a cladding sheet when, in use, the cladding
sheet is positioned on the clip. This feature increases
the surface area of contact between the flanges and the
re-entrant portions and thereby makes it possible to
minimise damage to the sheet when it is necessary to
remove the sheet from the clip.
Preferably the transitions between the side walls
and the flanges are tight radius curves in order to
concentrate as much clip material as possible in the upper
section of the clip to optimise the strength and stiffness
of this section of the clip.
Preferably the upper ends of the side walls are
shaped to define a generally circular opening in the asmanufactured
clip to facilitate insertion of a screwdriver
to secure the clip to an underlying structure.
According to the present invention there is also
provided a clip assembly which includes:
(a) an elongate strap; and
(b) a plurality of the concealed fixing
retaining clips described above mounted to
an upper surface of the strap.
The present invention is described further by way
of example with reference to the accompanying drawings, of
which:
Figure 1 is a perspective view of one preferred
embodiment of a clip in'accordance with the present
invention in an as-manufactured form;
Figure 2 is a side elevation of the clip shown in
Figure 1 in the direction of the arrow *W in Figure 1;
.(o-
Figure 3 is a side elevation of the clip shown ii
Figure 1 in the direction of the arrow WB" in Figure 1;
Figure 4 is a top view of the clip shown in
Figure 1;
Figure 5 is a bottom view of the clip shown in
Figure 1;
Figures 6a, 6b, and 6c are sketches that
illustrate engagement of a cladding sheet with the clip
shown in Figure 1;
Figure 7a and 7b are sketches that illustrate
release of a cladding sheet from the clip shown in Figure
1;
Figure 8 is a perspective view of one preferred
embodiment of a clip assembly in accordance with the
present invention which includes a strap and two clips
similar to the clip shown in Figures 1 to 7 in an asmanufactured
form mounted to the strap;
Figure 9 is a top view of the clip shown in
Figure 8;
Figure 10 is a side elevation of the clip shown
in Figure 8;
Figure 11 is a bottom view of the clip shown in
Figure 8;
Figure 12 is an end view from the right hand end
of the clip shown in Figure 8 as viewed in Figure 8; and
Figure 12 is an end view from the left hand end
of the clip shown in Figure 8 as viewed in Figure 8.
Figures 1 to 5 illustrate one preferred
embodiment of a clip 3 formed in accordance with the
present invention. Figure 6 illustrates the interaction
between the clip and a cladding sheet 29 as the cladding
sheet is being positioned onto the clip. Figure 7
illustrates the interaction between the clip and a
cladding sheet as the cladding sheet is being removed from
the clip.
The clip 3 is formed by folding a flat metal,
preferably steel (but not necessarily spring steel), blank
into the configuration shown the figures.
The clip 3 includes:
(a) a base 5;
(b) a pair of side walls 7 that extend from the base
and converge towards each other; and
(c) a pair of flanges 9 that define retaining
members for engaging re-entrant portions of ribs
of cladding sheets/ with one flange 9 extending
from an upper end of one side wall 7 and the
other flange 9 extending from an upper end of
the other side wall 7.
The base 5 includes a pair of outwardly extending
tabs 15 to facilitate locating a plurality of the clips
onto a strap (see Figure 8 embodiment ).
With reference to Figure 1, in addition, each
side wall 7 includes a relatively narrow strap section 7a
that extends upwardly from the base 5 and a relatively
wider upper section 7b that extends from the strap section
7a. The upper section 7b is symmetrically positioned with
respect to the strap section 7a so that the side wall 7
12 -
has 2 downwardly facing shoulders 73. These shoulders 73
further facilitate locating the clip 3 onto a strap (see
Figure 8 embodiment).
The base 5 includes an opening 63 to facilitate
securing the clip 3 to an underlying roof structure, such
as a roof purlin (not shown).
The side walls 7 and the base 5 are straight
walls and define a substantially triangular structure in
side view shown in Figure 2.
In the as-manufactured form shown in Figures 1 to
5 the side walls 7, whilst converging towards each other,
do not actually contact each other and there is a gap G
between the side walls 7 at the upper end of the side
walls. However, as is shown in Figure 6c, in use, the
side walls 7 are forced into contact with each other at
the upper ends of the side walls when a cladding sheet is
positioned on the sides walls.
Each side wall 7 includes a reinforcing rib 11 to
Improve the stiffness of the side wall 7.
The upper ends of the side walls 7 are shaped to
define a generally circular opening 13 that facilitates
insertion of a screw-driver (not shown) to install the
clip to an underlying structure.
The flanges 9 are shaped to form at least part
of an arch.
The transitions between the side walls 7 and the
flanges 9 are tight radius curves in order to concentrate
as much clip material as possible in the upper section of
the clip 3 to optimise the strength and stiffness of this
section of the clip.
Each flange 9 has a relatively steep approach
angle of the order of between 40° and 75° described by the
flange and the base 5. With reference to Figure 2, the
approach angle is described by the 2 dotted lines in the
Figure and the angle between the lines is indicated to be
40°.
Each flange 9 terminates in a sharp lower
outwardly facing (as opposed to inwardly turned) end that
forms a contact surface 25 for engaging a re-entrant
portion of one of the ribs of a cladding sheet.
Each flange 9 includes in-turned sections 17 at
the two corners at the lower ends of the flange 9. The
corner sections 17 form contact surfaces 21 that extend
transversely to the contact surface 25 of the outer end of
the flange.
With reference to Figures 6 and 7, each cladding
sheet 29 is roll-formed from sheet steel and includes a
leading edge (not shown), a trailing edge (not shown) , a
central lengthwise extending rib, generally identified by
the numeral 31, and pair of lengthwise extending pans 51
on opposite sides of the rib 31.
The cladding sheet 29 may be of any suitable
length and width and may include any suitable number of
ribs separated by pans.
The rib 31 of the cladding sheet 29 includes two
sides, generally identified by the numeral 35, that are
separated by a flat upper section 33. Each side 35
Includes a section 41 that extends outwardly and
downwardly from the upper section 33, a section 43 that
extends downwardly and inwardly from the lower edge of the
section 41, and a section 45 that extends downwardly and
outwardly from the section 43, and a downwardly and
outwardly shoulder 45 that merges with a pan 51.
The sections 43 of each upper retaining clip
section 15 define opposed re-entrant portions of the rib
13 and are hereinafter referred to as "re-entrant portions
43".
The leading and trailing edges (not shown) of the
cladding sheet 29 are formed as partially-completed ribs
in order to facilitate interlocking of successive cladding
sheets. These partially-completed ribs are hereinafter
referred to as "leading edge formations" and "trailing
edge formations'".
In use, a plurality of the clips 3 are fastened
to purlins at spaced intervals along the length of the
purlins using screws.
Thereafter, cladding sheets 29 are successively
placed over the purlins in overlapping relationship.
The cladding sheets 29 are then progressively
engaged with, the clips 3 as the sheets are successively
placed over the purlins.
This is achieved by successively pressing the
leading edge formations, the ribs 31, and the trailing
edge formations of the sheets 29 onto the clips 3 so that
the leading edge formations, the ribs 31, and the trailing
edge formations deflect outwardly and the flanges 9 of the
clips 3 deflect inwardly.
This movement allows the leading edge formations
8, the ribs 11, and the trailing edge formations 10 to be
positioned on the clips 3 with the surfaces 25 at the
lower ends of the flanges 9 and the surfaces 21 of the
turned corner sections 17 of the flanges 9 engaging the
re-entrant portions 43 of the ribs 31 so that the cladding
sheets 29 are secured to the clips 3.
This movement is illustrated in Figure 6 in
relation to locating the rib 31 of one cladding sheet 29
onto one clip 3. It is noted that the steep approach
angle of the flanges 9 and the inward movement of the side
walls 7 illustrated in the Figures minimises the
possibility of denting of the sections of the cladding
sheet that contact and slide over the flanges 9. It is
also noted that in the installed position shown in Figure
6c the upper ends of the side walls 7 are in contact with
each other.
Figure 7 illustrates the interaction between the
clip 3 and the cladding sheet 29 as the cladding sheet is
being removed from the clip — as may be necessary in order
to gain access to the roof cavity.
With reference to Figure 7a, the first step of
removing the cladding sheet 29 from the clip 3 involves
lifting the right hand side of the cladding sheet 29, as
viewed in the figure, outwardly so that the cladding sheet
is moved clear of the flange 9 on that side of the clip 3
and the section 45 of that side of the rib 31 is brought
into contact with and rests on the outer surface of the
flange 9 on that side of the clip - as shown in Figure 7b.
With reference to Figure 7b, the second step of
removing the cladding sheet 29 from the clip 3 involves
moving the left hand side of the cladding sheet 29, as
viewed in the figure/ outwardly so that the cladding sheet
is moved clear of the flange 9 on that side of the clip 3.
It can be appreciated that the contact surfaces 21 of the
in-turned corner sections 17 of the flanges 9 on that side
of the clip prevent the contact surfaces 25 formed on the
lower end of the flange 9 digging into and damaging the
rear-entrant portion 43 of the cladding sheet on that side
of the cladding sheet.
Figure 8 is a perspective view of one preferred
embodiment of a clip assembly in accordance with the
present invention which includes a strap 81 and two clips
83 that are similar to the clip 3 shown in Figures 1 to 7
in an as-manufactured form mounted to the strap 81.
As is indicated above and is apparent from the
drawings, the clips 3 and 83 are similar and the same
reference numerals are used to describe the same
structural features.
The strap 81 is a convenient means of fastening a
plurality of the clips 81 to purlins (not shown) at
required spaced intervals along the length of the purlins.
The strap 81 includes a flat base 87 and raised
lengthwise extending sides 89. The sides 89 are in the
form of downwardly opening channels. The inwardly facing
walls (see Figure 8} of the sides 89 have spaced apart
slots (not shown) for receiving the outwardly extending
tabs 15 of the base 5 of each clip 83. In addition, the
width of the flat base 87 and the height of the sides 89
of the strap 81 are selected so that the clips 83 fit
snugly on the flat base 87 and the downwardly facing
shoulders 73 of the clips 81 (see the shoulders 73 of the
Figure 1 embodiment) rest on the top walls 93 of the sides
89 of the strap 81.
The main differences between the clips 3 and 83
are as follows.
1. The flanges 9 of the clip 83 have a relatively
steep angle of approach and the length of the flanges is
relatively short compared to the angle of approach and
length of the flanges of the clip 3.
2. The clip 83 does not have inwardly turned
corners on the flanges.
3. The clip 83 has inwardly turned flanges 97
along the edges of the side walls 7 to improve the
stiffness of the side walls.
Many modifications may be made to the preferred
embodiment of the roofing system described above without
departing from the spirit and scope of the present
invention.

We claim:
1. A concealed fixing retaining clip for fixing a roof or other cladding sheet to an underlying
support structure characterised in that it comprises:
(a) abase;
(b) a pair of side walls extending from said base and converging towards each other but not contacting each other and being forced inwardly towards each other or into contact with each other when, in use, a cladding sheet is positioned on the clip; and
(c) a pair of flanges defining retaining members for engaging re-entrant portions in the sides of ribs of cladding sheets, with one flange extending from an upper end of one side wall away from the other side wall and the other flange extending from an upper end of the other side wall away from the one side wall..

2. The clip as claimed in claim 1 wherein said clip is formed from a resilient material so that each side wall of the clip applies an outwardly directed force in response to the side walls being forced together when, in use, a cladding sheet is positioned on the clip.
3. The clip as claimed in claim 1 or claim 2 wherein the flanges are a mirror image of each other about a centre-line plane that passes perpendicularly through the base of the clip.
4. The clip as claimed in any one of the preceding claims wherein the side walls and the base are straight sides so that the side walls and the base define a triangular structure when viewed from a side of the clip.

5. The clip as claimed in any one of the preceding claims wherein each side wall has one or more than one reinforcing rib to improve the stiffness of the side wall.
6. The clip as claimed in any one of the preceding claims wherein the flanges define at least part of an arch when, in use, a cladding sheet is positioned on the clip with the side walls forced together.
7. The clip as claimed in any one of the preceding claims wherein the side walls contact each other or are in close proximity to each other at or in the vicinity of the upper ends of the clip when, in use, a cladding sheet is positioned on the clip and forces the side walls together.

8. The clip as claimed in any one of the preceding claims wherein the flanges extend outwardly and downwardly relative to each other as viewed when the clip is positioned with the clip base on a horizontal surface.
9. The clip as claimed in any one of the preceding claims wherein the flanges are at a relatively steep approach angle relative to a rib of a cladding sheet so that there is gradual outward deflection of the sides of the rib of the cladding sheet when , in use, the cladding sheet is forced downwardly onto the clip to position the sheet on the clip.
10. The clip as claimed in claim 9 wherein the flanges are relatively long, preferably at least 25% of the height of the clip.
11. The clip as claimed in claim 9 or claim 10 wherein the approach angle, described by each flange and the base of the clip, is between 40° and 75°.
12. The clip as claimed in any one of claims 1 to 8 wherein the flanges describe a relatively gentle approach angle relative to a rib of the cladding sheet so that there is sudden gradual outward deflection of the sides of the rib of the cladding sheet when, in use, the cladding sheet is forced downwardly onto the clip to position the sheet on the clip.
13. The clip as claimed in claim 12 wherein the flanges are relatively short, preferably less than 25% of the height of the clip.
14. The clip as claimed in claim 12 or claim 13 wherein the approach angel, described by each flange and the base of the clip, is less than 40°.
15. The clip as claimed in any one of the preceding claims wherein each flange has a sharp outwardly facing outer end that contacts and thereby engages securely the reentrant portion of one of the ribs of a cladding sheet when, in use, the cladding sheet is positioned on the clip.
16. The clip as claimed in any one of the preceding claims wherein each flange consists of two
inwardly folded corner sections at the outer end of the flange that form surfaces that extend
transversely to the outer end of the flange and contact and thereby engage a re-entrant portion
of one of the ribs of a cladding sheet when, in use, the cladding sheet is positioned on the clip.
17. The clip as claimed in any one of the preceding claims wherein the upper ends of the side walls are shaped to define a generally circular opening in the as -manufactured clip to facilitate insertion of the screw driver to secure the clip to an underlying structure.

18. The clip as claimed in any one of the receding claims wherein the transitions between the side
walls and the flanges are tight radius curves in order to concentrate as much clip material as
possible in the upper section of the clip to optimize the strength and stiffness of this section of
the clip.
19. A clip assembly comprising an elongate strap; and a plurality of the concealed fixing retaining clips defined in any one of the preceding claims mounted to an upper surface of the strap.