FIELD OF THE INVENTION

THIS INVENTION relates to a clip-on securing system and a related fastening component, and in particular to a spring-clip fastening component for metal“clip-on” roofing solutions for industrial, commercial and residential steel roofing market applications. Other envisaged applications include metal cladding, thermal insulation applications, metal-decking/flooring, ceilings, fire-walls, partitioning, light steel frame construction and metal roof-trusses.

BACKGROUND OF THE INVENTION

Fastening components, such as spacing or fastening brackets, are well known in the art, and are typically required to be assembled with the use of mechanical or electrical fastening tools. Generally, the components require pilot drilling, drilling, punching or tapping to be assembled, and may be fastened to a length of C-profile building material commonly used in construction. These typical methods of assembly are time consuming and require a high level of accuracy, for example when lining up brackets and the C-profile building materials or other members which are to be fastened to the bracket.

So-called“clip-on” metal roofing systems comprises metal roof sheeting and related roofing clipping brackets. This type of roofing is commonly known as“concealed- fixed” or“secret-fixed”, which may in turn be divided into an interlocking type and a continuous type.

In the interlocking type concealed-fixed roofing system, the installation typically comprising the following two steps: • Fastening clip-on brackets to a roof truss of a building, typically using building compliant specified type fasteners.

• Clipping a span of metal roof sheeting onto the brackets, with typically one span of roof sheeting being installed at a time.

Therefore, the installation of typical concealed-fixed roofing solutions comprises two separate and distinct steps. This can be time consuming and labour intensive, and therefore relatively costly.

The continuous type concealed-fixed roofing system, on the other hand, comprises a continuous row of aligned clips, with the roof sheeting then simply being placed on top of the clips and clipped into place.

It is an aim of the invention disclosed below to provide an improved version of the concealed-fixed roofing solution, by improving the efficiency and rigidity with which the brackets are assembled, for both the interlocking type concealed-fixed roofing system and the continuous type concealed-fixed roofing system.

SUMMARY OF THE INVENTION

According to a first aspect of the invention there is provided a fastening component for a clip-on securing system for roofing and cladding solutions, the fastening component comprising at least one full anchor bracket that can be secured to an underlying structure, the full anchor bracket comprising a substantially trapezoidal bracket body comprising a pair of spaced apart bracket legs that taper from a relatively wider lower end of the bracket body to a relatively narrower upper end of the bracket body, the lower end of each bracket leg having outwardly splayed flanges for securing the bracket to the underlying structure, the full anchor bracket further comprising an overlying, tempered spring clip extending over the upper end of the bracket body, the tempered spring clip comprising resilient spring arms that extend away from the tapering bracket legs, the resilient spring arms being arranged to clippingly receive an overlying covering sheet and to resilient engage the overlying covering sheet.

In an embodiment, the fastening component comprises a plurality of full anchor brackets secured or securable to a strip or length of material, which in turn is secured to the underlying structure, with the covering sheet defining a plurality of spaced apart elongate ridges that extend along the length of the covering sheet, each ridge comprising a lower pair of spaced apart, inwardly tapering arms, an outwardly extending kink, and an upper pair of inwardly tapering arms which terminate in a substantially flat cap portion, with the ends of the resilient spring arms including inwardly directed flanges to engage against the outwardly extending kink of the covering sheet.

In an embodiment, the spring arms of the overlying spring clip of the full anchor bracket are resiliently biased towards the spaced apart, inwardly tapering bracket legs, so that in the event of the covering sheet being urged away from the underlying structure, the spring-tension engaging fit between the inwardly directed flanges of the spring arms and the outwardly extending kink of the overlying covering sheet, ensure a secure fit of the covering sheet to the anchor bracket.

Conveniently, the shape and configuration of the overlying tempered spring clip of each bracket is complementary to that of the upper pair of inwardly tapering arms of the ridge, with the outwardly extending kinks of the covering sheet being arranged to snugly and securely accommodate the inwardly directed flanges of the resilient spring arms.

In an embodiment, the fastening component comprises at least one gooseneck anchor bracket secured or securable to the strip or length of material, adjacent the plurality of full anchor brackets, the gooseneck anchor bracket comprising a flange that can be secured to the strip or length of material, an upwardly extending, angled bracket leg and an overhanging spring clip portion to snugly and resiliently accommodate an end ridge of an overlying covering sheet and to snugly and resiliently accommodate an end ridge of an underlying covering sheet, with the spring clip portion accordingly being sandwiched between the two end ridges of the adjacent covering sheets.

In an embodiment, the strip or length of material comprises or defines spaced apart locators, which correspond to the spaced apart elongate ridges of the covering sheet of material, to assist in guiding and locating the brackets on the strip or length of material.

In an embodiment, the covering sheet of material takes the form of metal roof sheeting, with the underlying structure corresponding to a roof truss of a building. In alternate embodiment, the covering sheet of material takes the form of cladding, with the underlying structure corresponding to a wall or vertical support of a building.

According to a second aspect of the invention there is provided a clip-on securing system, for roofing and cladding solutions, the system comprising: a plurality of fastening components, at least one of which is a full anchor bracket that can be secured to an underlying structure, the full anchor bracket comprising a substantially trapezoidal bracket body comprising a pair of spaced apart bracket legs that taper from a relatively wider lower end of the bracket body to a relatively narrower upper end of the bracket body, the lower end of each bracket leg having outwardly splayed flanges for securing the bracket to the underlying structure, the full anchor bracket further comprising an overlying, tempered spring clip extending over the upper end of the bracket body, the tempered spring clip comprising resilient spring arms that extend away from the tapering bracket legs; and an overlying covering sheet clipped to the resilient spring arms of the full anchor bracket, the arms being arranged to resilient engage the overlying covering sheet.

In an embodiment, the system comprises a strip or length of material that can be secured to the underlying structure, with a plurality of full anchor brackets being secured or securable to the strip or length of material, with the covering sheet defining a plurality of spaced apart elongate ridges that extend along the length of the covering sheet, each ridge comprising a lower pair of spaced apart, inwardly tapering arms, an outwardly extending kink, and an upper pair of inwardly tapering arms which terminate in a substantially flat cap portion, with the ends of the resilient spring arms including inwardly directed flanges to engage against the outwardly extending kink of the covering sheet.

In an embodiment, a pan portion extends between each pair of spaced apart elongate ridges, the pan portion defining a plurality of indents that are raised and lowered relative to each other, so that under load, as the pan portions flex upwardly the tapering arms of the adjacent ridges push downwardly and inwardly, resulting in spring clipping action to ensure that the covering sheet remains securely locked to the underlying structure.

In an embodiment, the spring arms of the overlying spring clip of the full anchor bracket are resiliently biased towards the spaced apart, inwardly tapering bracket legs, so that in the event of the covering sheet being urged away from the underlying structure, the spring-tension engaging fit between the inwardly directed flanges of the spring arms and the outwardly extending kink of the overlying covering sheet, ensure a secure fit of the covering sheet to the anchor bracket.

In an embodiment, one of the fastening components is a gooseneck anchor bracket secured or securable to the strip or length of material, adjacent the plurality of full anchor brackets, the gooseneck anchor bracket comprising a flange that can be secured to the strip or length of material, an upwardly extending, angled bracket leg and an overhanging spring clip portion to snugly and resiliently accommodate an end ridge of an overlying covering sheet and to snugly and resiliently accommodate an end ridge of an underlying covering sheet, with the spring clip portion accordingly being sandwiched between the two end ridges of the adjacent covering sheets.

In an embodiment, the strip or length of material comprises or defines spaced apart locators, which correspond to the spaced apart elongate ridges of the covering sheet of material, to assist in guiding and locating the brackets on the strip or length of material. In an embodiment, the strip or length of material can be planar, relatively rigid elongate strips.

Alternatively, the strip or length of material can take the form of a continuous coiled reel that may be rolled out onto the underlying structure.

In an embodiment, the strip or length of material may be aligned on the underlying support structure, across the entire required span of the structure, by fasteners, such as self-tapping-screws, or adhesive tape (for example).

In an embodiment, the covering sheet of material takes the form of metal roof sheeting, with the underlying structure corresponding to a roof truss of a building. In alternate embodiment, the covering sheet of material takes the form of cladding, with the underlying structure corresponding to a wall or vertical support of a building.

In an embodiment, the pitch between the plurality of brackets on the strip or length of material is slightly less than the pitch between the spaced apart ridges of the covering sheet of material, so as to define a roof fixing positive compression fit.

In an embodiment, the system includes a plurality of clip-on fasteners to clip the covering sheet of material onto the brackets, and thus onto the underlying structure, each clip-on fastener comprising a fastener cap arranged to overlie the substantially flat cap portion of the ridge of the covering sheet, a pair of spaced apart downwardly extending outwardly tapering fastener arms to abut against the upper pair of inwardly tapering arms of the covering sheet, and an inwardly extending fastener kink terminating in end flanges, the inwardly extending fastener kink being arranged to securely grip the outwardly extending kink of the covering sheet.

Conveniently, the downwardly extending outwardly tapering fastener arms of the fastener are biased inwardly, towards the covering sheet, with the snug/secure spring-tension engaging fit between the kink of the overlying clip-on fastener over the kink of the underlying covering sheet, together with the resilient fastener arms, further ensure a secure fit of the covering sheet to the bracket when the covering sheet is being urged away from the underlying support.

According to a third aspect of the invention there is provided a method of installing a clip-on securing system, for roofing and cladding solutions, the method comprising: securing a strip or length of material to an underlying structure; and securing a plurality of brackets to the strip or length of material, to which a covering sheet of material can be secured.

In an embodiment, the method comprises clipping a plurality of clip-on, spring lock, fasteners to the covering sheet of material over the brackets, and thus onto the underlying structure.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows a top, exploded perspective view of a concealed-fixed securing system, according to the invention, ready to be secured to an underlying roof truss of a building;

Figure 2 shows a top perspective view of the system shown in Figure 1 , in an assembled/fitted configuration;

Figure 3 shows a top perspective view of an elongate strip of material fitted with a plurality of anchor brackets, for use in the system shown in Figures 1 and 2;

Figures 4 and 5 show a side view of the assembled/fitted concealed-fixed securing system, and a related detailed side view, respectively, under normal load conditions; Figures 6 and 7 show a side view of the assembled/fitted concealed-fixed securing system, and a related detailed side view, respectively, under stressed load conditions;

Figure 8 shows a compressed fit feature of the present invention, wherein the pitch between the brackets on the strip material is slightly less than the pitch between the spaced apart ridges of the overlying covering sheet of material, so as to define a roof fixing positive compression fit;

Figure 9 shows an exploded perspective view of a seam lock arrangement for both a continuous type roof system and an interlocking type roof system;

Figure 10 shows a detailed side view of a joining arrangement used in an interlocking type roof system;

Figure 11 shows a detailed side view of a joining arrangement used in a continuous type roof system;

Figure 12 shows various views of a further embodiment of the invention, in which a spring clip is fitted with a spacer bar;

Figure 13 shows a roof sheet for use in the present invention;

Figure 14 shows a perspective view of a clip arrangement for use in the present invention, comprising a strip or length of material that can be secured to an underlying structure, the length of material carrying a pair of full anchor brackets and an end gooseneck bracket;

Figure 15 shows a perspective view of the clip arrangement of Figure 14 in use, secured to an underlying structure;

Figure 16 shows a bottom perspective view of one of the full anchor brackets secured to the roof sheet of Figure 13; Figure 17 shows a graph of the relative movement of the full anchor bracket of the invention under load;

Figure 18 shows a graph of the relative movement of the gooseneck bracket of the invention under load; and

Figure 19 shows a gooseneck clip rotation feature of the gooseneck bracket of the invention, under load.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the attached figures, a concealed-fixed securing system 10, for roofing and cladding solutions, is shown. The system 10 comprises a strip or length 12 of material that can be secured to an underlying structure 14, typically a purlin or truss. The system 10 further comprises a plurality of concealed-fixed full anchor brackets 16 secured or securable to the strip or length 12 of material, to which a covering sheet 18 of material can be secured.

As best shown in Figure 1 , a plurality of clip-on seam cap fasteners 20 are provided to clip the covering sheet 18 of material onto the brackets 16, and thus onto the underlying structure 14.

In an embodiment, the covering sheet 18 of material defines a plurality of spaced apart elongate ridges 22 that extend along the length of the sheet 18 of material. Each ridge 22 comprises a lower pair of spaced apart, inwardly tapering arms 24 (also known as gullwings), an outwardly extending kink 26, and an upper pair of inwardly tapering arms 28 (that define a clipping ledge), which terminate in a substantially flat cap portion 30. Each full anchor bracket 16 accordingly comprises a substantially trapezoidal bracket body 32 comprising a pair of spaced apart, inwardly tapering bracket legs 34. The bottom of each bracket leg 34 has outwardly splayed flanges 36 for securing the bracket body 32 to the underlying strip or length 12 of material (or directly to the underlying structure 14). An overlying tempered spring clip 38 extends over the top of the bracket body 32, the tempered spring clip 38 including spring arms 39 that extend/protrude away from the tapering bracket legs 34, with the ends of the spring arms 39 terminating in inwardly directed flanges 40.

In an embodiment, the shape and configuration of the overlying tempered spring clip 38 of each bracket 16 is complementary to that of the upper pair of inwardly tapering arms 24 of the ridge 22, with the outwardly extending kinks 26 of the covering sheet 18 of material being arranged to snugly and securely accommodate the inwardly directed flanges 40 of the spring clip ends.

Similarly, each clip-on fastener 20 comprises a fastener cap 42 arranged to overlie the substantially flat cap portion 30 of the ridge 22 of the covering sheet 18. A pair of spaced apart downwardly extending outwardly tapering fastener arms 44 abut against the upper pair of inwardly tapering arms 28 of the covering sheet 18, and an inwardly extending fastener kink 46 terminating in end flanges 48. The inwardly extending fastener kink 46 is arranged to securely grip/accommodate the outwardly extending kink 26 of the covering sheet 18.

In an embodiment, the ends of the overlying tempered spring clip 38 of the bracket 16 are resiliently biased towards the spaced apart, inwardly tapering bracket legs 34. The default, rest position is best shown in Figure 5. However, in the event of the covering sheet 18 being urged away from the underlying structure, as shown in Figure 7, the snug/secure engaging fit between the inwardly directed flanges 40 of the tempered spring clip ends and the outwardly extending kink 26 of the overlying covering sheet 18, together with the resilient ends, ensure a secure fit of the covering sheet 18 to the bracket 16.

In addition, similarly, the downwardly extending outwardly tapering fastener arms 44 of the fastener 20 are biased inwardly, towards the covering sheet 18, with the snug/secure engaging fit between the kink 46 of the overlying clip-on fastener 20 over the kink 26 of the underlying covering sheet 18, together with the resilient fastener arms 44, further ensure a secure fit of the covering sheet 18 to the bracket 16 when the covering sheet 18 is being urged away from the underlying structure, in windy conditions, for example, as shown in Figure 7.

As best shown in Figure 1 , the strip or length 12 of material comprises or defines spaced apart locators 50, which correspond to the spaced apart elongate ridges 22 of the covering sheet 18 of material. These locators 50 assist in guiding and locating (and ultimately securing) the brackets 16 on the strip or length 12 of material.

In an embodiment, the strip or length 12 of material can be planar, relatively rigid elongate strips, typically made from thin gauge roofing material such as zincalume (Zn-AI, AZ100/150 zinc aluminum coating of mild steel), which may be galvanized or colour coated. An objective is for the strip or length 12 of material to act as a barrier between dissimilar metals and coatings, or between metal coatings and wood.

In this version, the strip 12 may be pre-cut to size, according to the required covering sheet 18 of material, and includes corresponding, correctly pitched location points 52 for the brackets 16. The anchor brackets 16 themselves may be pre-assembled onto the strips 12. In one version, the anchor brackets 16 are secured in place onto the strips 12 using solid rivets or studs, typically electroplated coated to standard DIN 50979 (and, in particular, condition T-2 at 12 microns).

Alternatively, the strip or length 12 of material can take the form of a continuous coiled reel, also made from a thin gauge roofing material, such as zincalume (Zn-AI, AZ100/150 zinc aluminum coating of mild steel), which may also be galvanized or colour coated, as described above. Again, the aim is for the strip or length 12 to act as a barrier to address, for example, rust as a result of dissimilar metallic coatings being in contact with treated or untreated woods.

The strip or length 12 of material may be rolled out onto the underlying structure 14. This arrangement greatly facilitates the installation of the brackets 16 onto the strip 12, prior to installing the covering material 18. The accuracy of the placement of the locators 50 on the strip 12 maintains alignment between the clip-on fasteners 20, to optimize fitment of the covering sheet 18 of material. This arrangement further facilitates ease of installation of the covering sheet 18 of material, in a single-stage operation, thereby eliminating the time-consuming progressive installation process used in the prior art installations described above.

In an embodiment, the strip or length 12 of material may be aligned on the underlying support structure 14, across the entire required span of the structure, by fasteners, such as self-tapping-screws, or adhesive tape (for example).

In an embodiment, as illustrated, the covering sheet 18 of material takes the form of metal roof sheeting, with the underlying structure 14 corresponding to a steel or wooden roof truss of a building. In an alternate embodiment, the covering sheet 18 of material takes the form of cladding, with the underlying structure 14 corresponding to a wall or vertical support of a building.

In an embodiment, as best explained in Figure 8, the pitch between the brackets 16 on the strip or length 12 of material, 470 mm in this case, is slightly less than the pitch between the spaced apart ridges 22 of the covering sheet 18 of material, 475 mm in this case, so as to define a compression fit. This compression fit arrangement provides mechanical lateral fixing and material resistance to negative/up-load forces, which contributes to both the covering sheet 18 of material and the concealed-fixed securing system 10 of the present invention providing a resisting force working together.

The location points 52 for the brackets 16 on the strip 12 may be relatively easily and conveniently adjusted to accommodate the compression fit arrangement described above, to meet building compliance standards in respect of positive and negative load forces (SANS1200HB-1985 of 1 5kN-positive and 1 6kN-negative).

In addition, roof truss distances, typically 1.6 metres, may be extended by around 150 mm (thus providing 1.75 metre truss spans), while still exceeding load-force installation strength standards. Thus, in this case, the positive compression fit arrangement described above typically has a higher resistance to opposing (negative) roof uplift forces; in other words, a constant state of roof profile compression, relative to a non-compression fixed roof, provides a higher resistance (even with the extended roof truss distances).

In addition, the compression fit concealed-fixed securing arrangement of the present invention, as best shown in Figure 8, may eliminate the need for a gooseneck-type seam to join adjacent spans of the covering sheet of material. Alternatively, this may complement a gooseneck type application, in terms of positioning of the gooseneck for roofing installation, offering consistency of installation and eliminating manual misalignments during the installation of the roof sheets. In particular, the compression-fit roof, at design stage, revolves around a compression ratio to facilitate the positioning of the brackets 16 on the locating strip 12. The brackets 16 occupy a designated and precise position, to provide a constant positive-fixing of the roof system to the structure.

Figures 10 and 1 1 show two examples of a 700 mm roof profile, with a Figure 10 showing a joining arrangement 60 used in an interlocking type roof system and Figure 1 1 showing a joining arrangement used 70 in a continuous type roof system.

In Figure 10, a gooseneck version of the bracket 16 is shown, numbered 16’. This gooseneck bracket 16’ comprises a flange 36’ can be secured to an underlying purlin 61 with a fastener 62. The gooseneck bracket 16’ includes an upwardly extending, tapering bracket leg 34’ and a spring clip portion 38’ that extends up and around, terminating at point 63. The end of a covering sheet 18.1 (i.e. ridge 22.1 ) may be fitted over the spring clip portion 38’, as shown, terminating just under point 63 of the gooseneck bracket 16’. On the other side, the end of another covering sheet 18.2 (i.e. ridge 22.2) is snugly secured under the end of the gooseneck bracket 16’, and in particular under spring clip portion 38’.

In Figure 1 1 , the bracket 16, of the type described, is secured to an underlying purlin 71 with a fastener 72. The end of a covering sheet 18.5 (i.e. ridge 22.5) may be fitted over the spring clip 38, as shown, terminating at point 73. On the other side, the end of another covering sheet 18.4 (i.e. ridge 22.4) is snugly secured over the ridge 22.5, and terminates at point 74.

A further roof system, with reference to Figure 9, is shown, for both an interlocking type roof system 80 and a continuous type roof system 90.

Referring first to the interlocking type roof system 80, a female gooseneck end 81 of a span of roof sheeting 82 fits over a male gooseneck end 83 of an adjacent span of roof sheeting 84. In this case, a tempered spring clip 85 fits between the female and male gooseneck ends 81 , 83. The roof sheeting 82 itself will be described in more detail below in Figure 13.

Turning now to the continuous type roof system 90, a gooseneck end 91 of a span of roof sheeting 92 fits over a gooseneck end 93 of an adjacent span of roof sheeting 94. In this case, a tempered spring clip 95 fits under the gooseneck end 93, the spring clip 95 is of the type shown in Figures 4 and 5 of South African patent application number 2016/7307. In particular, a plurality of spring clips 95 are fitted between the purlins 96, as best shown at the bottom left of Figure 9. These clips 95 improve the clip strength at the joins of adjacent roof sheets, and improve the resistance against negative, uplifting forces. Improved purlin spacing may also be achieved.

Irrespective of the exact goosenecks used, the gooseneck that fits over the underlying gooseneck would need to be slightly enlarged to accommodate the underlying gooseneck.

In another embodiment of the invention, turning now to Figure 12, a tempered spring clip 100 of the type shown in Figures 4 and 5 of South African patent application number 2016/7307 may be fitted with a spacer bar 102. The tempered spring clip- spacer bar combination 104 may be clipped into a conventional roof profile 106, as indicate by arrow 107. The spacer bar 102 typically extends through soft insulation 108 and terminates at a threaded end 1 10 to accommodate a bar cap 1 12. The bar cap 1 12 may be used for various applications, including supporting a lighting arrangement 1 14, supporting the insulation 108, supporting a cable tray 1 16.

In another application, a support bar 1 18 may extend between a pair of spaced apart spring clips 100.

According to a second aspect of the invention there is provided a related method of installing a concealed-fixed securing system, for roofing and cladding solutions. The method comprises securing a strip or length of material to an underlying roof truss/purlin structure, using conventional fasteners or adhesive tape. A plurality of concealed-fixed or anchor brackets may then be secured to the strip or length of material, to which a covering sheet of material can be secured. The formed strip may have pre-punched fastening and anchor seating locations, for accurate brackets distances and alignment. The anchor brackets may be fastened using industry standard fasteners (steel or wood), fastening through the base fastening holes, through the locating strip and ultimately securing the fastener into the roof truss/purlin.

In one version, a male roof sheet end is fixed to the clip, with a female roof sheet end then being secured over the male roof sheet end. One or more clip-on fasteners may then be secured over the female roof sheet end, to improve the kN strength per square meter, therefore increasing the roof truss distances to improve structural design efficiencies, without compromising the“ultimate load-failure” of the roofing structure.

The installation benefits of the concealed-fixed securing system of the present invention, with particular reference to roofing systems but which would apply equally to cladding arrangements as well, include at least the following:

1. The installation of concealed-fixed brackets may be independent of the roof installation.

2. The continuous locating strip may be installed prior to brackets and the metal roof sheeting being fitted.

3. The installation of the brackets may be installed prior to the roof sheeting spans being installed. 4. The installation may be consistent, under compression, having continuous and aligned brackets in place, prior to the final roof sheeting being installed.

The related market benefits include installation efficiency, labor cost, structural and roofing serviceability, increased purlin/roof span spacing, reduced roof trusses per structure, and significant reduction in structural tonnage per meter square. The negative load failure point is significantly increased, primarily due to the clip-on seam cap fasteners installed over the roof sheet joins, which provide a clamping effect on both adjacent roof sheets.

The pitch between spaced apart locators may be adjusted, in increments of between 0.5 mm and 10 mm. This addresses:

1. Inconsistency of possible roof profile deformation, which may effect the exact clipping location on the roof profile.

2. Consistency of installation, relative to positive and negative load-forces and micro positive compression of the roofing profile.

3. Adjustable relative to lateral expansion and contraction linear coefficient of the roof sheeting, induced by heat and cold.

4. Ultimately, the roofing structural integrity may be formulated by computerized software to cater for compression factors, eliminate manual errors and provide consistent installation and roof fixing integrity.

5. The manufacturing of the locating-strip may be adjusted to provide an optimum roofing solution.

6. The spring locking concealed-fix roofing clip is designed so that the more the pull-force (negative-load) there is on the roof sheeting, the more the spring- clip“stretches open”, with resistance, locking the roof profile onto the clip.

7. The spring-clip has linear opposing forces, under consistent spring tension, creating a compression factor between the anchoring points, locking the roof to the clip.

8. The locating strip determines the spacing between the roof clips, with a compression factor. Turning now to Figures 13 to 16, a roof sheet 82 for use in the present invention will be described, with reference to a related clip 200 shown in Figure 14. The clip 200, in the illustrated version, comprises a strip or length 202 of material that can be secured to an underlying beam 203, as shown in Figure 15. The clip 200 further comprises a plurality of concealed-fixed anchor brackets 204 secured or securable to the strip or length 202 of material, to which the roof sheet 82 can be secured. In particular, the clip 200 comprises two full-anchor brackets 204.1 , 204.2 and a gooseneck bracket 204.3. The full-anchor brackets 204.1 , 204.2 are substantially the same in structure as the brackets 16 described above with reference to Figures 1 and 3, and will thus not be described again.

The gooseneck bracket 204.3 over-clips onto a male end 206 of the roof sheet 82, as best shown in Figure 15 (and which largely corresponds to the interlocking arrangement shown in Figure 10).

The roof sheet 82 itself comprises a plurality of raised ribs 208 with a pan portion 210 extending between each pair of raised ribs 208. The ribs 208 are substantially the same in structure to the ridge 22 described above with reference to Figure 1 , and will thus not be described again. The pan portions 210 comprise a plurality of indents 212 along their lengths, which are raised and lowered relative to each other.

The arrangement shown in Figures 13 to 16 provides a consistent spring-memory roof fixing arrangement. In particular, under load, as the pan portions 210 flex upwardly, as indicated by arrows 214, the tapering arms 24 of the adjacent ridges 22 pushes downwardly and inwardly, as indicated by arrows 216. The resulting spring clipping action ensures that the roof sheet 82 remains securely locked to the underlying structure, in this case the underlying beam 203 shown in Figure 15.

When viewed from below, as shown in Figure 16, the full-anchor bracket 204.1 locks the roof sheet 82 in place. In particular, the spring arms 39 biasingly engage against the inwardly tapering arms 28 of the roof sheet 82, so that the greater the force applied by the arms 28 of the roof sheet 82, under load, the greater the return force applied by spring arms 39 against the clipping ledge defined by the arms 28. Figure 17 shows a graph of the relative movement of the full-anchor bracket 204.1 and related components shown in Figure 16 as a wind uplift force is applied to the pan portion 210 between a pair of raised ribs 208. From a rest position, shown by arrow 220, the spring arms 39 and the tapering arm 28 of the roof sheet 82 move to the intermediate position shown by arrow 222, under moderate load.

At full load, in this case 4.99 kPa, shown by arrow 224, the spring arms 39 are in a fully opened position, but are nonetheless arranged to grip or hold the arms 28 of the roof sheet 82. In particular, the inwardly directed flanges 40 at the end of the spring arm 39 engage against the outwardly extending kink 26 of the roof sheet 82. As described above, the greater the force applied by the arms 28 of the roof sheet 82, under load, the greater the return force applied by spring arms 39 against the clipping ledge defined by the arms 28.

Figure 18 shows a graph of the relative movement of the gooseneck bracket 204.3 that over-clips onto a male end 206 of the roof sheet 82, corresponding to Figure 15, as a wind uplift force 226 is applied to the roof sheet 82. From a rest position, shown by arrow 228, the gooseneck bracket 204.3 moves to the loaded position shown by arrow 230. The relevant reference numerals from Figure 10 are shown in Figure 18. At full load, in this case 2.24 kPa, shown by arrow 230, the gooseneck bracket 204.3 is still arranged to grip or hold the male end 206 (corresponding to 22.2) of the roof sheet 82.

Figures 17 and 18 also show the overall ability of the clip 200 to flex under negative wind-load, and the related ability to pull the roof sheet 82 back under spring-tension resistance, in milliseconds. This accommodates wind and gust pulses.

In a preferred version of the invention, as shown in Figure 14, the strip or length 202 of material comprises two full-anchor brackets 204.1 , 204.2 and a gooseneck bracket 204.3. Each full-anchor bracket 204.1 , 204.2 can hold 500 kg, with reference to Figure 17, and the gooseneck bracket 204.3 can hold 230 kg, with reference to Figure 18, thus holding a combined weight of 1230 kg. A further feature of the gooseneck 204.3 arrangement shown in Figures 10, 15 and 18, as shown in Figure 19, is that as pan portion 210.1 of covering sheet 18.2 lifts under extreme wind-load, the pan portion 210.2 of covering sheet 18.1 tends to positively compress downwardly. The gooseneck spring-flex 204.3 consistently resists the wind-load and retains its original geometry tensioned spring-state, due to the tensioned, flexible and shape memory of the spring-steel, with provides resistance to deformation. The extended curl at the end of the gooseneck clip 204.3, corresponding to point 63 in Figures 10 and 18 curls around the corresponding bulge 232 of the male end 206 of the roof sheet 82. This feature grips into the anchoring roof profile, bulge 234, of the“female” (top span of roof) ledge 22.1 of the covering sheet 18.1 , further resisting ultimate failure.