TECHNICAL FIELD

This invention relates generally to sheet roofing.

BACKGROUND ART

The inventor has researched and found that sheet materials are used worldwide in more than USD 1 trillion worth of roofing each year.

However, the use of sheet materials for roofing, whilst is more than 2 centuries old, in use it is still fundamentally the same as it was in the late 1820s when corrugated iron was invented in London. Indeed, sheet forms as widely used still require the use of numerous fasteners to connect adjacent sheets to each other and to beams, posts or purlins, which provide the structural strength.

Whilst the sheet is completely modular the exact positioning and placing of fasteners is not so. Variations can and do occur.

Current roofing design has significant problems:

1. Many fasteners are needed, often 1000s, and this adds significant part and labour cost to roofing, and these fasteners perforate the sheets leading to the possibility of water passing through the roof later.

2. Fasteners perforating the sheets also lead to the likelihood of corrosion around the holes where the anti-corrosion coating is perforated.

3. The perforating fasteners do not allow easy repositioning of sheets, or removal of sheets for readjustment or repair unless the fasteners are removed entirely. This is a problem with roof assembly, particularly when providing kitsets for non-professionals to use: a. Roofing sheets can be laid out on a roof incorrectly leading to a progressive racking - a creeping error increasing with each successive sheet, which can progress to the point that the assembly is inadvertently a parallelogram rather than a rectangle as desired. b. Roofing sheets can not be slid in position to alter their overhang to line up nicely to each other 4. The connection to the underlying structure is intermittent and may be thought of as "focal" rather than "distributed". This is a problem as in cyclones the sheets can be pulled off the roof causing injury and damage.

5. No matter the care in production and inventory there are inevitable variations in the

positioning of any holes in parts. In a kitset scenario with many parts to fit together this can mean parts can be very hard to assemble.

6. When constructing a roof at height it would be better (safer and more convenient) if fasteners were preassembled to either the beams or purlins before these parts are put up or at the very least before the sheets are put up a. This preassembly would aid kitset layout on site

7. Oftentimes the sheet adds some weight to the structure but does not augment the actual strength of the roof

8. Roofing assemblies must deal with thermal expansion and contraction. Whilst expansion spaces or rubber gaskets can be used it would be better if a secure connection could be configured so that thermal expansion is allowed for without added parts.

9. When roofing sheet is arched it can flatten in the mid span area, where it is unsupported.

It can also ripple irregularly in the case of lighter plastic sheeting.

Sheet connection with fasteners is certainly very widely used but there are problems as identified above. What would be better is a way of using sheet materials substantially with fewer fasteners, but also in a kitset or modular way, which simplifies and speeds up the roof assembly significantly.

The inventor has deduced that what is needed is an invention that allows sheets to be placed on a beam structure and then repositioned, and for the sheets to be able to augment of assist in the structural integrity/performance of the roof assembly.

DISCLOSURE OF THE INVENTION

Notes:

1. For clarity, the roof described in this invention will be described as flat, and horizontal to the ground, but it shall be seen it may be arched, and it is certainly unlikely to be without a pitch, and there would normally a slope of 2 to 45 degrees so that water could drain to a gutter. Indeed, if the slope is 90 degrees then this invention may be thought as not describing a roof invention but rather a wall invention. 2. The sheets described herein are generally flat sheets with simple up turned edge details, but these are by way of example only. This invention equally applies to sheets with other edge details or profiles, or indeed simple flat sheets. Alternatively, sheets can be twin or multiwall sheets. Sheets may be formed flat or be simple arches by production, or be profile sheets which are other than flat. Sheets may be any material that can flex such as metal plastic and composites.

This invention describes a shallow mechanism or a shallow arch mechanism consisting of spaced beams (which are generally in pairs, so that one of the pair is above the edge of a roofing sheet, and the other is below the edge of a roofing sheet) where the geometry of the sheet and or the beam or beam pair is such that the sheet is configured to, or able to arrive at (via the influence of geometry and gravity for example), a slight arch between subsequent beam locations.

So, the general form is a sheet held at each long side by a beam and configured to be upward or downward in a simple or complex shallow curve. There are three possible general arrangements:

1. A beam on a first long side of a sheet forces the sheet up and a beam on a second-long side also forces the sheet up, so that the sheet is configured to an arch with it's axis generally parallel to the length of the sheet.

2. A beam on a first long side of a sheet forces the sheet up and a beam on a second-long side also forces, or allows (under the influence of gravity) the sheet to be down, so that the sheet is configured to a sinusoidal shape.

3. A beam on a first long side of a sheet forces or allows (under the influence of gravity), for the sheet to curve down and a beam on a second-long side also forces or allows for the sheet to curve down, so that the sheet is configured to a downward arch, or a shallow trough, with it's axis generally parallel to the length of the sheet.

The rise of the arch, sinusoidal shape, or depth of the trough is shallow. For the purposes of this invention shallow is defined as less than 10% of the width of the sheets. For example, if the width of the sheet is 1000mm, the height of the arch, or depth of the trough, will 100mm or less.

It is important to note the form of the roofing sheet may not be a pure geometrical form - a simple arc or sinusoidal form, but and it may be a modified form. For example, if there is lateral tension applied pulling on the sheet then the arch would be flattened in the middle part of the sheet. The inventor has found that an assembly of shallow arch sheets, and beams, can be stretched sideways after assembly and then secured, thereby causing the shallow mechanism to be even shallower in final use. This means that thinner sheets can be used, lowering both weight and cost. A convenient way of visualising this invention is that flat or substantially flat sheet is configured to a single corrugation by geometrical interaction with the adjacent beam or beams on each long side. The slope of the beams where the sheet exits, and or the shape of the sheet edges, taken together cause, as the parts are locked together, by fasteners for example, the sheet to arch. If the arch were up then it would be a shallow arch, whereas if the arch were down it would be in the form of a shallow trough.

The creation of the arch is by geometry substantially reduces assembly force, but alternatively flat sheet can be configured to deform in a way that it arches. For example, flat sheet can be inserted into a slot in a single beam on either side of the sheet, and the two beams brought closer, forming an arch in the sheet between them.

A shallow trough natural forms the sheet itself into a wide but shallow "longitudinal" gutter, and moves water away from the sheet joins, therefore improving waterproofing there.

The invention herein has several significant advantages:

1. The deformation of the sheet up or down means that the sheet is automatically

tensioned in an arched form and this supports the span of the sheet in the unsupported area between the beams. a. Flat sheet, or substantially flat sheet with a longitudinal lip, can be used and yet be much stronger for being in an arch, trough, or sinusoidal form.

2. When the air temperature changes the shallow arch of the sheet can increase in

curvature as the temperature rises, but conversely decrease in curvature as the temperature drops. Therefore, the roof can be considered self-adjusting in arch/trough height/depth in direct and automatic response to the air temperature.

3. In the specific case of an upward shallow arch the sheet is in both compression and tension, where the inner concave sheet surface is in relative compression and the outer convex sheet surface of the arch is in relative tension. Compression-tension arches are stronger and more stable.

4. In the specific case of an a shallow arch in its trough variation, the shallow valley formed may serve as a "longitudinal gutter" detail for the roof, whereas a traditional gutter may be called a "transverse gutter". In practice rain, can fall to the roof, and down the longitudinal gutter, falling into the standard transverse gutter, (and then along that standard gutter to a downpipe).

A preferred embodiment of this invention has several straight spaced beams, or beam pairs, interspersed with roofing sheet somewhat between, so that the roof has several shallow arches. The general plane of the roof is flat, as the beams are not arched along their length. This invention could be called a flat arch. However, an alternative embodiment of this invention has several arched spaced beams, or beam pairs, interspersed with roofing sheet between, so that the roof has several shallow arches. The plane of the roof is flat, as the beams are arched along their length.

• This arched variation solves a problem the inventor has noted in arching flat sheet where the sheet, which is unsupported mid-span, is flatter there, and there is a persistent problem with a visual ripple in the sheet.

• A shallow arch however forces the sheet mid-span to be arched and provided the arch of the beams is small enough the sheet may flatten still in the mid-span area but will not ripple. · This alternative variation may be described as arched in two directions, having multiple arches transversely, the shallow arches of the sheets, and a general longitudinal arch (that of the beams).

• As such the arches of the beams may be two-dimensional beam arches, but in this case the arches of the sheets seen as three-dimensional shallow arches. A preferred embodiment of this invention consists of at least two spaced beams, which support at least one sheet between them, where the spacing and geometry of the parts configures the sheet to form a shallow arch, between the beams.

The spaced beams may be of a sandwich design consisting of at least one generally lower part, and one generally upper part, so that a sheet edge sheet lip may be retained in a void between the parts.

The sheet may have a lip along its two long edges where the lip is generally downward, when fitted to the beams, or where the lip is generally upward, when fitted to the beams.

There are number of details that can be varied to optimise a shallow arch mechanism:

1. The geometry of parts relative to other parts, 2. The spacing of parts relative to other parts,

3. Translational movement of parts relative to other parts, which may stretch the sheets,

4. Rotational movement of parts relative to other parts,

5. Compression of parts to other parts,

Noting that [1] the spacing of parts is critical to repeatable delivery of shallow arches, and also [2] that all parts have to be manufactured within tolerances, the inventor has devised a way to optimize the implementation of this invention (or other roof forms) where it is beneficial to use a pin mechanism where at least one structural beam (shown as an angle form in the attached figures) has at least two vertical fasteners (pins) formed in, or assembled to, along the beam length so that horizontal purlins may be placed at right angles (usually) on the horizontal beam in positions defined by the spacing of the pins.

In a preferred embodiment of this the vertical fasteners will be threaded bolts or threaded setscrews, which perforate part of the beams. These pins can be temporarily or permanently attached to the beams, and can be seen to be regularly spaced pins to aid and define the layout of the parts.

• Threaded washers may also be used to retain pins in support beams, as an alternative to the support beams being threaded to accommodate the pins. In a preferred embodiment of this invention there would be two (generally parallel) spaced horizontal support beams each with at least two vertical fasteners (pins) assembled along the beam lengths so that horizontal purlins may be placed at right angles (usually) on the horizontal beams in positions defined by the spacing of the pins.

The pins will serve to define the purlin positions and therefore subsequently the sheet positions. In a preferred embodiment of this invention the purlins will have pre-drilled holes in them which are oversized to the pins. So, for example if the pins are 8mm setscrews then the holes in the purlins could be 10 or 13mm. This would significantly aid assembly on site. It would allow the following sequence to occur:

1. Pins are attached to, or through, beams, 2. Beams are supported (on posts, or attached to a building wall or eave),

3. Purlins are positioned on the beams via placing the oversized holes in the purlins over the pins,

4. Roofing sheet is placed on the purlins, and secured there via (for example) a washer and nut. An alternative sequence could use a sandwich design where there is a lower structural purlin and an upper cap beam which trap in the middle the roofing sheet, and in this scenario, the following would be the assembly sequence:

1. Pins are attached to beams,

2. Beams are supported (on posts, or attached to a building wall or eave), 3. Purlins are positioned on the beams via placing the oversized holes in the purlins over the pins,

4. Roofing sheet is placed on the purlins, 5. Cap beams are placed on the roofing sheet, overlying purlins, and secured there via (for example) a washer and nut.

Roofing sheet could have pre-drilled holes, or be slightly narrower that the spacing of the pins so that it does not need holes for the pins to pass through. In this scenario, the pins would be adjacent to the sheet edges.

This invention describes key character of the parts and the method of using the parts.

Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope therein.

BRIEF DESCRIPTION OF DRAWINGS

Note: For visual clarity, the spaces, relative dimensions, and curves in the drawings are somewhat exaggerated, and all fasteners, and any scaffold/supports/posts, are not shown.

Fig 1 shows a progressive shallow arch mechanism in three stages where in A the parts are loose, and in C the parts are locked together.

(For clarity any fasteners or clamping means to cause or retain the locking together is omitted from the figures) There is a lower beam 10 and an upper beam 11 with a sheet 12 in between. Fig 2 shows an isometric view of Figure 1.

Fig 3 shows a close-up of the parts in Figure 1 , where the sheet 12 can be seen to have a bend 30 and a flange area 33. When a force F is applied in the direction of the arrow of F the cap beam 11 moves towards the box beam 10 pushing down the sheet 12 which slides a little on the ramp area 36 and the sheet bend area 30 is pushed down so that in settles into the angle 35. This creates a leverage force and a fulcrum area 34 and the sheet progressively arches as shown from A to B to C

Notes:

The areas 30 31 32 33 34 35 36 and all other details such as the forms, relationships, and number of beams 10 11 that are shown in the drawings of this invention are merely representative of possible forms. For example, a large number sharp angle or curved details are possible for all areas labelled and discussed.

(Sharp angles are generally used for these drawing as they are more easily seen particularly in isometric views) It can be seen that the slope 32 is inclined at an angle other than 0 degrees to a horizontal reference H. This slope is continuous in the figure for simplicity but need not be.

Fig 4 shows the parts of Figure 2 in an upside down isometric view, and shows that a shallow arch mechanism can be configured to be a downward arch form thereby forming a trough, which will act like a longitudinal gutter - parallel to the length of the beams.

Fig 5 shows a pair of structural angle beams 51 with pins 50 inserted. The pins shown here are fully threaded cap screws, and are threaded into the beams, but the threads are not shown in this figure for clarity. B is an isometric view of A from underneath. In C three lower box beams have already been added and are located via pre-drilled and oversized holes on the pins. In D and E other parts have been added, (including washers and nuts in E) and for completeness the sheet 12 is shown in E, with three shallow sheet arches to be seen.

Note: The geometry of the parts can define the arch nicely, but also if the pins are moved closer more arch is created, and conversely if further apart less arch is created in the sheet, or indeed a modified arch where the sheet is flattened - even near completely flat - in the mid span area.

Fig 6 shows close-up views of a single pin in A, a lower beam added in B, a further beam added in C (the sheet is not shown in C for clarity but would be present of course), and finally in D there is a complete assembly (the sheet 12 is shown here) with the added washer and nut securing things. Fig 7 shows in A an assembly (on a pair of structural L sections) with flat form in both the sheets and beams, in B an assembly with flat form in beams but the sheets have a shallow arch, and in C an assembly with arched form in both the sheets and the beams.

In C, the sheets are effectively now in a 3-dimensional arch, but the beams are a 2-dimensional arch.

Note: For clarity, all pins, washers and nuts are omitted in this figure.

Fig 8 shows a close-up of a pair of beams where A is an end pair of beams of Figure 7A, and B is an end pair of beams of Fig 7B. The flange area 80 in A is substantially without an angle, and therefore will not arch the sheet, whereas in B there is an upward angle in the flange area 81 , so a shallow arch will be automatically formed as assembly occurs. Fig 9 shows the pair of beams of Fig 8 upside down to be used to configure a downward shallow arch. In A, the sheet can drop by the influence of gravity, whereas in B the sheet can be started in a downward direction by the geometry of the parts, and the downward arch will be increased by the influence of gravity. • A distinction between arched and trough versions of this invention can be seen comparing Fig 9 with Fig 8. o Fig 8: The upward angle in the flange area 81 in Fig 8B (the arched version) is needed to force an upward arch. o Fig 9: However, when the same parts are reversed as in Fig 9 the flanges 92 and

93 are not even needed (but shown here). In Fig 9 (the trough version) the sheet can be merely trapped by the upper and lower beams, and then be allowed to fall-down under the influence of gravity.

(Note: The sheet 91 is shown flat as if tensioned sideways by a force F, but it would more commonly fall-down similarly to the sheet 90 depicted in Fig 9B.)

Fig 10 ABC show views of a preferred form of the beam pair shown in Fig 9A, with a lower U channel part 100 that has a primary structural function, and an upper cap part 101 , that has a primary sheet retention function retaining the sheet 102, via a lip 104. Fig 10A is a wider-angle view of 3 sheets supported by 4 beam pairs, and Fig 10B is a closer view of the central sheet in Fig 10A. Fig 10C is a close-up view of the beams in B and C.

• The cap beam 101 can be secured to the U channel 100 via a fastener (not shown), where the fastener's axis is generally depicted by the line 105. A threaded bush detail, captive nut or nutsert, could be used in the lower area location 107 of the cap beam 101.

• The U channel 100 and cap beam 101 parts could leave a space 108 below the cap beam suitable for the location of parts such as light fittings, and/or forming a conduit passage for electrical cable.

• In Fig 10 AB there are dashed arrows highlighting the sheets arc down, and therefore this figure depicts a shallow mechanism configured as a trough assembly of beams and sheets, with a low-point in the sheet 106. · A preferred arrangement is to have an inclined or taper fit area 108 where the upper cap part 101 can wedge lock the sheet 102, via a sheet lip 103 to a corresponding inclined or taper surface of the lower part 100 (here depicted as a U channel part).

Fig 11 AB show respectively isometric views of Fig 10 BC