GB2217764A

GB2217764A - Glazing bar section

Info

Publication number: GB2217764A
Application number: GB8907359A
Authority: GB
Inventors: G J Mellin
Original assignee: SOLARCHECK
Current assignee: SOLARCHECK
Priority date: 1988-03-31
Filing date: 1989-03-31
Publication date: 1989-11-01
Anticipated expiration: 2009-03-31
Also published as: GB2217764B; GB8907359D0

Abstract

An extruded glazing bar section (80) provides a means of connecting secondary insulation (36a, 36b) to primary glazing (18, 20) which is supported by glazing bars (12) of substantially T-shaped section. The bars of the T usually support adjacent sheets of glazing, while the stem (15') of the T is upstanding between said sheets (18, 20). The section (80) comprises one or more parts and has opposing slots (60, 62) adapted to receive and retain adjacent sheets of said secondary insulation. Connection of the section to the upstanding stem is by way of a channel having internal catches adapted to engage with a corresponding flange. The flange is either part of the stem or is provided on a part separately connectible to the stem. <IMAGE>

Description

Glazing Bar Sections This invention relates to glazing bar sections for use in the secondary insulation of glazed surfaces of buildings, particularly roofs thereof.

Many buildings have glass roofs or roofs which incorporate large areas of glass and many owners or tenants of such buildings are beginning to appreciate the savings which can be made in their energy requirements by insulating their buildings against heat loss.

A particular source of heat loss through buildings occurs through glazed surfaces and it is now well recognized to double glaze windows. However, in an industrial setting, the cost of double glazing is prohibitive, and besides which, aesthetic considerations are not particularly important.

Consequently, particularly for the glazed parts of roofs of buildings, it is now common to apply sheets of twin walled polycarbonate, which is a clear plastics material. By virtue of the air gap between the layers, such polycarbonate sheets offer extremely effective heat insulation. A major consideration in its use on roofs, however, is its lightness to strength ratio, which far exceeds that of even reinforced glass. Consequently, its use on existing buildings does not entail the cost of reinforcing roof supports, which is frequently required when double glazing is employed.

Existing glazed roofs almost invariably employ some form of glazing bar which supports and fixes the glass sheet in position. It has presently been the practice to lie sheets of twin walled polycarbonate over these glazing bars and fix the sheets to the bars simply by drilling into the bar through the appropriately positioned sheet and securing the sheet to the bar by a self tapping screw. Apart from the fact that very accurate drilling is required to remain central in the glazing bar (if it is edge on as it usually is), the very localised securing of the sheet (even with large washers supporting the screws) is generally insufficient to give contractors the confidence to guarantee their work for the length of time required by the customer in order for him to realise an overall saving. A time period in excess of five years might normally be required for this.

Thus it is an object of the present invention to provide a method of fixing of secondary insulation sheets to existing building glazing bars which does not suffer this disadvantage.

In accordance with the present invention there is provided a means of connection of secondary insulation to primary glazing which is supported by glazing bars of substantially T-shaped section with the bars of the T supporting adjacent sheets of glazing and the stem of the T upstanding between said sheets, said means comprising an extruded glazing bar section in one or more parts and defining opposing slots adapted to receive and retain adjacent sheets of said secondary insulation and connection means for connection of said section to said upstanding stem, said means for connection at least including a channel having internal catches adapted to engage with a corresponding flange.

In a first embodiment of the present invention, an existing roof glazing system incorporates such a glazing bar disposed between adjacent sheets of glazing wherein the stem of the T is flanged and is adapted to receive an extruded plastics channel section having legs which bear against the glazing sheets and hold them in place, this aspect of the present invention providing an extruded plastics glazing bar section comprising said channel having internal catches and which is adapted to locate, once said existing channel section has been removed, on said existing glazing bar stem, which thereby constitutes said corresponding flange, legs being provided on the section to secure the existing glazing in place, and opposing slots spaced from said legs and adapted to receive and locate sheets of insulating material such as the aforementioned twin walled polycarbonate sheets.

Said internal catches snap over the flanged stem of the glazing bar to secure the glazing bar section in place.

In a second embodiment of the invention, however, and in respect of existing roof, glazing systems which incorporate such a T-shaped glazing bar disposed between adjacent sheets of glazing, this embodiment of the present invention provides an extruded plastics glazing bar section comprising first and second parts, the first part thereof comprising two opposing slots adapted to receive and locate sheets of insulating material, such as the aforementioned twin walled polycarbonate sheets, and the two parts being adapted to be connected together by providing one part with said channel having internal catches and the other part with said corresponding flange over which said channel is adapted to be snapped to fix the two parts together, and said second part comprising means for connection thereof to said glazing bar.

Said means for connection to the glazing bar may comprise a further channel adapted to fit over said bar. In this event said second part may be secured to the glazing bar by any convenient means such as by bolting through the sides of the channel and through the glazing bar.

The advantage with this aspect of the present invention is that the second part can be adapted to overcome particular connection difficulties to the existing glazing bar as might arise, but always being adapted to be connected to the first part, while the first part can be used in virtually every situation.

Nevertheless, these two arrangements are only suitable for one thickness of the sheet of insulating material and consequently different sections must be provided to accommodate different thicknesses of insulating sheet. Moreover, glazing bars, apart from the type specifically described with reference to the first aspect of the invention, come in two basic types, each having said essentially Tshaped cross section. As mentioned above, it is on the bars of the Tsection that the existing glazing is generally supported, while the stem of the T provides rigidity. However, those stems are generally either flat or flanged, the latter to increase the stem's strength along the edge of maximum strain. The glazing bar sections defined in the second embodiment above can only be used with flat stem glazing bars.

A further difficulty with the aforementioned sections is that, once located on a glazing bar it may be difficult or even impossible to slide the insulating sheet up the slots provided for this purpose, because the glazed section of the roof in question may be at an angle to the rest of the roof. Consequently, it may be necessary to fit the sheet in the slots before the two parts of the section are connected together.

Thus in accordance with a third embodiment of the present invention there is provided an extruded plastics glazing bar section comprising first and second parts, the first part comprising two arms between which is disposed connection means to the second part, which part comprises two legs and means for connection both to the first part and to a glazing bar, said arms and legs being arranged when said parts are connected together to define therebetween opposing slots to locate and retain adjacent sheets of insulating material, said connection means between the two parts comprising said channel disposed on one part and said corresponding flange disposed on the other.

Thus in the first emebodiment of the invention, said corresponding flange is provided by the stem of the T of the existing glazing bar.

Where such flange is not present, the second and third embodiments provide said glazing bar section in at least first and second parts, one of which parts is formed with said corresponding flange, and the other with said channel, and said second part including means of connection to said stem. In said third embodiment as defined above, said slots are formed by said two parts only when they are connected together.

This has the advantage that the second part can be fixed to the stem of the glazing bar, insulating sheets can be laid on the legs of said second part, and finally the first part can be connected by interengagement of the catches on said flange and channel.

The connection between the two parts comprises said channel and flange interconnection with the channel preferably formed on the first part between said arms and having internal catches adjacent the edges of said channel and the flange upwardly depending from the second part between said legs and having a plurality of catches extending between its base and edge, said channel and flange being adapted to be snapped together to form said slots between respective arms and legs, the breadth of said slot being determined by the extent of the interengagement between said flange and channel which is in turn limited by the thickness of any interposed sheet of insulating material.

Said means of connection to the glazing bar in either of said second or third embodiments may comprise a downwardly depending extension disposed on said second part and by means of which said second part is adapted to be secured to the side of said upstanding stem of said glazing bar by, for instance, self drilling and tapping bolts.

Preferably said extension is stepped whereby it conforms to the shape of glazing bars having a flange on the edge of their stems, the extension having an offset connected to said second part, a step connected to said offset and connection region connected to said step.

In the plane of said connection region there is preferably disposed a frangible lip on said second part, which lip is removed when the section is to be connected to a flanged glazing bar stem, or which is left in place when the section is to be connected to a flat glazing bar stem so as to support the section adjacent the edge of said stem.

The present invention in all its embodiments is further described hereinafter, by way of example only, with reference to the accompanying drawings, in which: Fig 1 is a section through a glazing bar section in accordance with the first embodiment of the invention; Fig 2 is a section through a typical existing glazing system with secondary insulation; Fig 3 is an end view of a glazing system incorporating the section of Fig 1 and glazing and secondary insulation; Fig 4 is a section through a first part of a glazing bar section in accordance with the second embodiment of the invention; Fig 5 is a section through a second part of a glazing bar section in accordance with the second embodiment of the invention; Fig 6 is a similar view to that of Fig 3, but incorporating the parts shown in Figs 4 and 5.

Fig 7 is a section through a third embodiment of the present invention; and, Fig 8 is a section through another aspect of the third embodiment.

With reference to Fig 2, an existing glazing system 10 comprises an inverted T-section glazing bar 12 having arms 14,16 and a central extension 15. The arms 14,16 support adjacent sheets of glazing 18,20.

Seals 22,24 seal the glazing 18,20 against the arms 14,16 respectively.

The glazing 18,20 is secured in place by an extruded plastics channel section 26 which is provided with internal catches 28 adapted to engage the flanged end 30 of the extension 15, and legs 32,34 which bear against the glazing 18,20 to press them against the seals 22,24.

When it is desired to add secondary insulation to such a system, the present method is to lie sheets 36 of twin walled polycarbonate over the glazing bars 12, drill through the channel section 26 into the edge of the extension 15 of the glazing bar 12, and secure the sheet 36 in place by self tapping screws 38 supported by washers 40.

The glazing bars 12 comprise a central aluminium core 42 surrounded by an enveloping sheath 44. This makes the drilling operation very difficult. In any event, should the drilling be accurate the structure of the glazing bar is severely weakened. If the drilling is inaccurate, the self tapping screw will be held largely by the enveloping plastics sheath, which, given the passage of time, may already be weak and brittle. Consequently, sheets 36 secured in this way cannot be guaranteed to stay in place for any reasonable length of time.

Thus in Fig 1 the present invention provides a glazing bar section 50 comprising a channel section 52 incorporating internal catches 54.

Legs 56,58 extend from the sides of the channel 52. Two deep mutually opposing slots 60,62 are disposed in the region of the base of the channel 52.

With reference to Fig 3, a glazing system is illustrated which employs a glazing bar section according to the first aspect of the present invention. Here, the existing channel section 26 of Fig 2 has been removed and discarded and is instead replaced by the glazing bar section 50 of Fig 1.

The channel 52 is positioned over the glazing bar 12 and the catches 54 are engaged with the flanged extension 15. In this position, the legs 56,58 press against and retain in position the glazing 18,20. The slots 60,62 are employed to retain adjacent sheets 36a and 36b of twin walled polycarbonate.

In this way the sheets 36a and 36b are securely held in place with no further fixation being required and no interference with the integrity of the glazing bar 12.

With reference to Figs 4 to 6, similar components are referred to by the same reference numeral as used in the description of Figs 1 to 3. Where parts differ slightly, the same numeral is used but with an inverted comma.

In this respect, not all glazing systems to which it may be desired to add secondary insulation incorporate gazing bars as shown in Figs 2 and 3. In Fig 6 for instance, a glazing bar 12' is shown in which the central extension 15' is not flanged. Here the glazing 18,20 is retained in position by lead flashings 66,68.

In this situation therefore (and for other varieties of glazing bar), the present invention provides in its second aspect a substantially universal glazing bar section 70 for attachment of secondary insulation. The section 70 is in two parts. The first part 80 is shown in Fig 4 and is used in every case where this system is employed.

The second part 90 is shown in Fig 5 and is particular to the type of glazing bar 12' present in the glazing system.

Where the glazing bar 12' has an extension 15' as shown in Fig 6, then the second part 90 is provided with a deep channel 92 adapted to fit over the extension 15'. To retain the part 90 in place, self drilling bolts 96 may be employed although any other suitable means could also be used if preferred.

If however the glazing bar was in some other form than shown in the drawings, then the channel 92 in the second part 90 would be replaced by a different shape which facilitates permanent connection of the part to the glazing bar. In all events however, the second part 90 is always provided with a flanged head 94.

The first part 80 of the glazing bar section 70 is adapted to be connected to the second part 90, and for this purpose is provided with a channel 52' having catches 54'. The channel 52' is positioned over the part 90 until the catches 54' snap into engagement with the flanged head 94. The first part 80 has opposing slots 60,62 which retain the edges of secondary insulation sheets 36a and 36b.

The shape of the head 94 and channel 52' are arranged to provide a secure connection therebetween, and are trapeziform so that the arms of the channel 52' are sprung apart and preferably retain internal resilience after snapping into position around the flanged head 94. The slots 60,62 are positioned inter alia so that the weight of the sheets 36a and 36b tend to further tighten the connection between the two parts 80,90.

With reference to Fig 7 a glazing bar 12' is shown which is essentially T-shaped in section and on bars 13 of which are carried adjacent sheets 18,20 of glazing. The glazing 18,20 is secured in place by lead flashings 66,68. The glazing bar 12' has an upstanding stem 15'.

To secure sheets 36a,b of insulating material at a distance above the existing glazing 18,20 a glazing bar section 100 according to the third embodiment of the present invention is provided. This comprises a first part 110 and second part 120. The first part 110 has arms 112,114 between which is formed a downwardly depending channel 116 having internal catches 118 formed near the edges of the channel 116.

The second part 120 has legs 122,124 between which is disposed an upstanding flange 126 having a plurality of external catches 128 disposed between its connection to the legs 122,124 and its edge.

An extension 130 depends from said legs 122,124 and comprises an offset 132, a step 134 and a connection region 136. The connection region is adapted to receive self drilling bolts 140 or any other form of connection to the side of the stem 15' of the glazing bar 12'.

In the plane of the connection region 136 there is disposed between the legs 122,124 a frangible lip 150 which is adapted to locate and support the section 100 against the stem 15'. The extension 130 is stepped for reasons explained further below with reference to Fig 8.

To fix said sheets 36a,b in place, the second part 120 is first secured to the glazing bar stem 15' by means of said bolts 140. Next the sheets 36a,b are laid on the legs 122,124 and then secured in place by fitting said first part 110 over the flange 126. How many of the catches 128 are engaged by the catches 118 on the channel 116 depends on the thickness of the sheets 36a,b. In Fig 7, relatively thick sheets are shown so that the first catch 128 is engaged by the catches 118 to securely hold the sheets in place.

Fig 8 shows a second aspect of the present embodiment which differs from Fig 7 in a number of respects. The first difference to note is that here the stem 15" of the glazing bar 12" has a flange 17 at its edge. This provides the bar 12" with extra strength and rigidity along its region of maximum strain.

When such glazing bars are encountered, the glazing bar section 100 of Fig 7 can be used if the lip 150 is first removed from the second part 120 before it is fixed in place. In Fig 8, the glazing bar section 100' has first and second parts 110',120' which differ from those of Fig 7 as described further below. However, the arrangement of the stepped extension 130 is the same and here the lip 150 has been removed to allow the second part 120' to be fixed to the glazing bar 12". The stepped extension 130 is in fact shaped to conform with the contours of the flange 17 and stem 15' of the glazin#g bar 12".

In Fig 8, the first and second parts 110',120' differ from those shown in Fig 7 only in the location and nature of the flange and channel inter-connection means 116,126 of the two parts 110,120 as shown in Fig 7. Here a channel 116' is formed on the second part 120' between its legs 1221124. Moreover, instead of merely one internal catch, the channel has a plurality of internal catches 128'.

Correspondingly, a downwardly depending flange 126' with just one external pair of catches 118' is formed between the arms 112,114 of the first part 110'.

In Fig 8, relatively thin sheets 36a',36b' of insulating material are employed so that, when they are in place, the catches 118' on the flange 126' engage the last of the catches 128' in the channel 116' when the two parts 110',120' are connected together. The embodiment of Fig 7 also has the facility to accommodate thin sheets of insulating material, just as the glazing bar section 100' of Fig 8 has the facility to accommodate the thicker sheets of Fig 8. The only constraint on the thickness of sheet capable of being accommodated by either embodiment 100,100' is the length and depth of their flanges 126,126' and channels 116,116' respectively; and of course on the number of catches 128,128' formed on the flange 126 or in the channel 116' respectively.

While the invention has been described with reference to specific elements and combinations of elements, it is envisaged that each element may be combined with any other or any combination of other elements. It is not intended to limit the invention to the particular combinations of elements suggested. Furthermore, the foregoing description is not intended to suggest that any element mentioned is indispensable to the invention, or that alternatives may not be employed. What is defined as the invention should not be construed as limiting the extent of the disclosure of this specification.

Claims

1. An extruded glazing bar section, providing a means of connection of secondary insulation to primary glazing which is supported by glazing bars of substantially T-shaped section with the bars of the T supporting adjacent sheets of glazing and the stem of the T upstanding between said sheets, said section comprising one or more parts and defining opposing slots adapted to receive and retain adjacent sheets of said secondary insulation and connection means for connection of said section to said upstanding stem, said means for connection at least including a channel having internal catches adapted to engage with a corresponding flange.

2. A glazing bar section as claimed in claim 1 providing a means of connection of secondary insulation to primary glazing on an existing roof glazing system incorporating such a glazing bar disposed between adjacent sheets of glazing wherein the stem of the T is flanged and is adapted to receive an extruded plastics channel section having legs which bear against the glazing sheets and hold them in place, said section comprising said channel having internal catches and which is adapted to locate, once said existing channel section has been removed, on said existing glazing bar stem, which thereby constitutes said corresponding flange, legs being provided on the section to secure the existing glazing in place, and said opposing slots being spaced from said legs and adapted to receive and retain said sheets.

3. A glazing bar section as claimed in claim 1 providing a means of connection of secondary insulation to primary glazing on an existing roof glazing system incorporating such a T-shaped glazing bar disposed between adjacent sheets of glazing, said section comprising first and second parts, the first part thereof comprising two opposing slots adapted to receive and retain said sheets of insulating material, and the two parts being adapted to be connected together by one part being provided with said channel having internal catches and the other part with said corresponding flange over which said channel is adapted to be snapped to fix the two parts together, and said second part comprising means for connection thereof to said glazing bar.

4. A glazing bar section as claimed in claim 3 in which said means for connection to the glazing bar comprises a further channel adapted to fit over said bar.

5. A glazing bar section as claimed in claim 4 in which said second part may be secured to the glazing bar by bolting through the sides of the channel and through the stem of the glazing bar.

6. A glazing bar section as claimed in claim 1 comprising first and second parts, the first part comprising two arms between which is disposed connection means to the second part, which part comprises two legs and means for connection both to the first part and to the glazing bar, said arms and legs being arranged when said parts are connected together to define therebetween opposing slots to receive and retain said adjacent sheets of insulating material, said connection means between the two parts comprising said channel disposed on one part and said corresponding flange disposed on the other.

7. A glazing bar section as claimed in claim 6 in which said channel is formed on the first part between said arms and has at least one internal catch adjacent the edges of said channel and said flange depends upwardly from the second part between said legs and has at least one catch extending between its base and edge, said channel and flange being adapted to be snapped together to form said slots between respective arms and legs, the breadth of said slot being determined by the extent of the interengagement between said flange and channel which is in turn limited by the thickness of any interposed sheet of insulating material.

8. A glazing bar section as claimed in claim 3, 6 or 7 in which said means of connection of said second part to the glazing bar comprises a downwardly depending extension disposed on said second part and by means of which said second part is adapted to be secured to the side of said upstanding stem of said glazing bar.

9. A glazing bar section as claimed in claim 8 in which said second part is adapted to be secured to the side of said upstanding stem of said glazing bar by self drilling and tapping bolts.

10. A glazing bar section as claimed in claim 8 or 9 in which said extension is stepped whereby it conforms to the shape of glazing bars having a flange on the edge of their stems, the extension having an offset connected to said second part, a step connected to said offset and connection region connected to said step.

11. A glazing bar section as claimed in claim 10 in which, in the plane of said connection region, there is disposed a frangible lip on said second part, which lip is removed when the section is to be connected to a flanged glazing bar stem, and which is left in place when the section is to be connected to a flat glazing bar stem, so as to support the section adjacent the edge of said stem.

12. A glazing bar section as claimed in any of claims 7 to 11 in which said channel has one catch and said flange has a plurality of catches spaced between its base and edge.

13. A glazing bar section substantially as hereinbefore described with reference to Fig 1 or Figs 3 to 8 of the accompanying drawings.