GB2179974A

GB2179974A - Curtain walling system

Info

Publication number: GB2179974A
Application number: GB08611634A
Authority: GB
Inventors: John Arnold; Maureen June Butler
Original assignee: Pearce & Cutler Ltd
Current assignee: Pearce & Cutler Ltd
Priority date: 1983-06-28
Filing date: 1986-05-13
Publication date: 1987-03-18
Also published as: GB2179974B; GB8611634D0

Abstract

In a curtain walling system in which supplementary members (14) together with clamping member 18 secure panels 20, the supplementary members provide a continuous pressure equalisation chamber 64 within which a drainage member (110) extends to duct water outwardly. <IMAGE>

Description

SPECIFICATION improvements relating to building constructions to is inventiorT, is concerned with improvements relating to buil:dirr;g U il#in:g constructions, and particu arfy of the kind used in the cladding of the outsides of buildings and commonly known as "curtain walling".

Curtain walling is a system of cladding the outside of a building which has spaced, vertical load-bearing members and floors extending across the loadbearing members. Conventionally elongate vertical building members (commonlytermed mullions) are secured to the exterior ofthe load-bearing members, and horizontal building members (commonly termed transomes) are secured to and between adjacent mullions spaced at vertical intervals. Facing panels (which may be glazing panels for the provision of windows, or spandrel panels to extend overthe edges ofthefloors) are clamped against the mullions and transomes by external elongate securing members secured to the transomes and mullions.

Such a cladding system is highly advantageous, and is being used increasingly widely on high rise buildings.

Difficulties are however encountered in sealing the building against ingress of water. Particularly on buildings which have a large vertical face area, wind pressures exerted against the face can be high, and in conjunction with heavy rain producing high water flow over the exterior surface, the pressure differentials can cause water to be forced behind the facing panels.

Difficulty is also encountered inducting water, which may be produced through condensation or which may be trapped within the interior of the curtain walling, from the interior to the exterior face.

Further, difficulty is encountered in: (a) coveringthesecuring members, (b) sealing between abutting external members, particularly in the vicinity of the junction between mullions and transomes, and (c) allowing for expansion ofthevariousmem- bers, in a manner in which ingress of water minimize.

According to this invention there is provided a curtain walling system comprising supplementary members secured or adapted to be secured to the mullions and transomes of the building, and clamping members secured or adapted to be secured to the supplementary members, and by which facing panels ofthe building may be secured in position, between the supplementary members and the clamping members.

Preferablythe supplementary members comprise first supplementary members secured or adapted to be secured to the building mullions and second supplementary members secured or adapted to be secured to the building transomes, the construction and arrangement being such thatthefirst supplementary members extend along continuous, or substantially continuous lines with the second supplementary members extending between the first supplementary members, and clamping members secured or adapted to be securedto the supplementarymembersand by which facing panels may be secured to the building.

In this manner, a continuous orsubstantially continuous and horizontally extending pressure equalisation chamber may be provided which extends across thejunction areas of mullion and transome.

Preferably the first supplementary members are provided with means by which an apron orthe like drainage member may be secured thereto, which extends outwardly between adjacent, vertically spaced facing panels and by which water within the system may be ducted outwardly, preferably into a channel in the clamping members, from which the water may flow from the system.

Preferably sealing means is provided which is adapted to provide for sealing between the parts of the building construction as follows: (a) between the first supplementary members and the transomes; (b) between the second supplementary members and the mullions; (c) between abutting faces ofthe supplementary members; (d) between the facing panels and the sup- plementary members; (e) between the clamping members and the facing panels; (f) between the abutting faces ofthe clamping members.

Preferably the sealing means for (a), (b), (c) and (d) is provided by sealing members on the supplementary members, and for (e) and (f) bysealing members on the clamping members.

Preferably the clamping members are adapted to be secured by screws or the like fastening elements to the supplementary members, relative movement of approach between the clamping members and the supplementary members being limited either by spacer means, or by the application of a predeter minedtorquetothefastening elements on tightening thereof. Preferably the clamping members comprise or are adapted to receive additional members (such as capping strips) by which such securement may be concealed.

Whilst the system above described is particularly suited for use in building constructions in which the mullions extend vertically, it will be appreciated that the system may be used to advantage in building constructions in which the mullions are inclined to the vertical, but desirably lying in a vertical plane. In addition, the system may be utilised at the interface between mullions extending vertically and mullions inclined to the vertical.

According to this invention, there is also provided a building system in which mullions are secured to the upright members ofthe building, such as the loadbearing mom bers thereof, and in which transomes are securedtoand between adjacent mullions in a manner such that the outwardly facing surfaces provided by the mullions and transomes lie substan tiallyin a plane.

Advantageouslythe transomes are secured to the mullions by the use of mounting brackets secured to the mullions, and to which end portion ofthe transomes are secured, advantageously a sealing member being interposed between the mounting bracketandthe mullion withwhich the end face ofthe transome engages.

Advantageouslythe system comprises sup plementary members secured to thetransomes in continuous horizontal lines, adjacent supplementary members advantageously abutting at positions between adjacent mullions. Advantageously the sup plementary members are provided with sealing mem bers attheir end faces, to provide a seal between abutting supplementary members when secured to the transomes.

Advantageously each supplementary member is provided with a continuous horizontal, outwardlyfacing channel.

Advantageously the system comprises horizontal clamping members secured or adapted to be secured to the supplementary members and to clamp horizontal edge portions of panel members between outwardly-facing surfaces ofthe supplementary members and inwardly-facing members ofthe clamping members.

Advantageously a drainage member is provided which is secured in the channel and which extends horizontally across the mullions, the drainage memberextending beneath a panel memberandproviding means to ductwaterfrom the channel outwardly of the system.

Convenientlythe drainage member is secured at one side to the supplementary member and extends at its other side adjacent to a drainage channel provided by the clamping member, into which drainage channel water is ducted by the drainage member.

Advantageously a sealing member is interposed between the drainage member and a panel member beneath the drainage member.

Advantageously the system comprises second supplementary members secured or adapted to be secured to the mullions, and extending between the first said supplementary members.

Advantageouslythe second supplementary mem bers are provided with sealing members attheir end faces, by which a seal is provided between first supplementary members and the second sup plementary members.

Preferably the system comprises vertical clamping members secured or adapted to be secured to the second supplementary members and to clamp vertic al edge portions of panel members between outward ly-facing surfaces ofthe second supplementary mem bers and inwardly-facing surfaces of said clamping members.

Similarly,the building system setout in the last preceding paragraph may be utilised to advantage in building constructions in which the upright members extend vertically, and in which the upright members are inclined to the vertical, lying in a vertical plane.

There will now be given a detailed description, to be read with reference to the accompanying drawings, of a curtain walling system which is a preferred embodi ment ofthis invention, and which has been selected for the purposes of illustrating the invention bywayof example.

In the accompanying drawings: FIGURE 1 is a front elevation of part of a building cladded by the use ofthe preferred embodiment; FIGURE 2 is a vertical sectional view, viewed in the direction of of Figure 1; FIGURE3 is an enlarged view of a partofthesystem shown in Figure 1 illustrating in greater detail a junction area ofthe curtain walling; FIGURE 4 is a vertical sectional view of the junction area illustrated in Figure 3; FIGURES is a horizontal sectional view of the junction area illustrated in Figure 3; FIGURES is an exploded perpective view illustrating the components of the curtain walling in relationtothe junction area; FIGURE 7 is a part-assembled perspective view of the junction section;; FIGURE 8 is a front elevation of part ofthe junction section illustrating the securement of the transome to the mullion; FIGURE 9 is a perspective view illustrating the assembly of the vertical and horizontal clamping members of the system at the junction area; FIGURE 10 is a view corresponding to Figure 5, illustrating an alternative construction of clamping member; FIGURE 1 Oa is a front elevation of the modified construction viewed in the direction of the arrow B of Figure 10; FIGURE 11 ia a view corresponding to Figure 4, showing an alternative method of securing the horizontal supplementary memberto the transome; FIGURE 12 is a view corresponding to Figure 10, showing an alternative form of sealing member; and FIGURE 13 is a view illustrating the application of the present invention to a junction area between a sloping face and an inclined face; The curtain walling system which is the preferred embodimentofthis invention is intended to provide a surface cladding to a building, vertical load-bearing members (such asthe member 6, Figure 2) of which are accessible from the exterior.

The system comprises principally the following elements: (a) elongate vertical members8, hereinafter termed mullions, which are secured to the members 6; (b) elongate horizontal members 10, hereinafter termed transomes, which are secured to and between adjacent mullions 8 at spaced vertical intervals; (c) supplementary vertical members 12 which are secured to the mullions; (d) supplementary horizontal members 14which are secured to the transomes; (e) vertical clamping members 16 adapted to be secured to the vertical members 12; (f) horizontal clamping members 18 adapted to be secured to the horizontal members 14; (g) facing panels20,which may be clamped between the supplementary and horizontal members 12 and 14 by the clamping members 16 and 18, and which may be glazing panelsorspandrel panels.

Each transome 10 is provided with a recess 22 at its ends (see Figure 6) defining parallel horizontal flanges 24. Thetransomes are secured to the mullions by the use of a transome mounting bracket 26 having screw holes 28 provided in alignmentwith screw holes 30 in the mullions. The bracket 26 is secured to the mullion by the use of screws, a neoprene sealing member32 being interposed between the bracket and the mullion. The transome is moved overthe bracket, the flanges 24 entering into channels 34 of the sealing member 32.The transome is secured to the bracket 26 by a vertical screw, passing through a hole 36 in the transome and into a channel 38 of the bracket, and by horizontal screws passing through aligned holes 40 and 42 in a flange 44 ofthe bracket and the transome respectively.

Thetransomes are so secured to the mullionsthat theirfrontfaces are approximately co-planar. However, whilst, as is shown in Figure 2, the transomes have depth (left-to-right) approximately equal to the depth of the mullions, this is not necessarily the case.

Thetransomestogetherwith parts ofthe mullions thus present a generally continuous horizontal line to which the supplementary horizontal members 14 are secured. The members 14 a re of slotted box-section, having a central rib 46 into which screws may be passed and by which the members are secured to the transome, and a longitudinal slot 48 which provides access to the rib 46. On the exteriorfaces 50 on either side ofthe slot 48 there are elongate neoprene sealing gaskets 52, (see Figure 4). Alternatively, the horizontal membersi4maybesecuredtothetransomesi0by the use of interfitting formations, such as tongue-andchannel formations, as is shown in Figure 11.

The supplementary horizontal members 14 are of a length equal, or approximately so, to the centre line spacing between the mullions 8, and are secured to the transomes in abutment on the vertical centre line thereof (see Figures 7 and 9). The members 14 may be provided with neoprene sealing gaskets on their end faces, to provide a seal between abutting supplementary members, when they are secu red to the transomes.

Thus,whilstdueto the nature ofthe building construction the mullions extend vertically along a continuous line, and the transome in a broken line between the mullions, in the preferred embodiment the supplementary horizontal members extend along a continuous line.

Howeverwhilstinthe preferred embodimentthe supplementary horizontal members 14 are of a length equal to the centre line spacing between the mullions, this is not necessarily the case, and supplementary horizontal members of a greater length may if desired be used. In addition if desired,the construction and arrangement may be such thatthe horizontal members 14 do not abut on the centre line ofthe mullions, but abut elsewhere.

Additionally, if desired the neoprene sealing gaskets 52 may be continuous, extending from the exteriorfaceofone horizontal memberto that of another.

The supplementary vertical members l2arese- cured to thefront faces of the mullions, and extend between spaced parallel members 14. Each member 12 is similarly of slotted box-section, having a central rib 54 into which screws may be passed, and by which the members are secured to the mullions, and a longitudinal slot 56 which provides access to the rib 54. On the extenorfaces 58 on either side ofthe slot 56 there are elongate neoprene sealing gaskets 60, (see Figure 5).

However each member 12 is provided, inserted into each end thereof, with a sealing member 62, the sealing member being so shaped as to be capable of being press-fitted into the end ofthe member, and presenting externally of the member a generally planarfacewhich may be abutted against an adjacent horizontal member 14 (see Figures 6 and 7).

The horizontal clamping members 18 are also of box-shaped cross-section having divergent interior channels 64 on either side of a central, elongate rib 66.

The side walls 68 of the vertical members are provided, on their inner end portions, with claws 70, into which elongate sealing members 72 of neoprene are secured. Thefrontface74 of each member 16 is provided with an elongate, rebated slot 76, into which a capping member80 may bepress-fitted. Holes 82 a provided at intervals in the rib 66, through which screws (such as the screw 84, Figure 5) may be inserted to screw the clamping member 18to the supplementary member 10. If desired a collar85 may be utilised to prevent undue compression, or alternatively the screw may be inserted to a pre-set torque.

The screw may carry a clip 86 over which resiliently deformableflangesofthecapping member80 (best seen in Figure 5) may be pressed as the capping member is press-fitted into the slot 76 ofthe clamping member 16.

Anumberofbores 92 are provided at spaced intervals extending to the lowermostwalls 68, and extending to the lowermost ofthetwo divergent channels 64 (see Figure4), and the clamping members 18 are each provided at each end, with a neoprene sealing member 90, which may be in constructions similarto the sealing members 62 ofthe sup plementaryvertical members (see Figure 3).

The vertical clamping members 16 are similar in construction to the horizontal clamping members 16 above described, with the ommision of the bores 92, and similar numerals are used to identify the individual featurethereofas are used in relation to the horizontal clamping members.

In the assembly ofthe curtain walling system which is the preferred embodiment ofthis invention,the mullions are secured tothevertical load-bearing members of the building structure in conventional manner, along continuous vertical lines. Thetrans- omes are secured to the mullions, and the supplementary horizontal members 14 are secured to the transomes, extending along a generally continuous line across the width of the building. The supplementary vertical members 12 are then secured to the mullions, extending between adjacent horizontal members 14 and the facing panels are offered to the openings, conveniently initially being secured in position by the use of the vertical clamping members.

Prior however to securing of the horizontal clamping members in position, an elongate apron 110 is inserted into the uppermost channel ofthesup- plementary horizontal members,the apron extending for a significant horizontal distance, and across a numberofmullions. The apron 1 10 is conveniently moulded from a flexible plastics material such a P.V.C., and is provided with a shoulder 112 by which the inner side of the apron may be located overthe central rib 46 ofthe supplementary horizontal mem ber.The central portion 114 of the apron extends over the top of the cladding panel, conveniently in engage ment with a butyl rubberstrip 116 provided on the top edge thereof, whilst the outer edge 118 ofthe apron is inclined downwardly and extends into the lowermost ofthe two channels 64 ofthe member When the horizontal clamping members are secured to the supplementary horizontal members, the screws by which this is effected serve also to secure the apron againstthe rib 46, tending to deflect the central portion 1140fthe apron into engagement with the sealing strip 116.

The apron 110 thus serves to ductwaterfrom the interior of the curtain walling into the channel 64 from which itmayflowthroughthe bores 92, including water entering the interiorofthe assembly by condensation on the interior of a facing panel, or water blown into the central space by wind and rain Figure 10 illustrates a modification ofthe preferred embodiment, and in which similar numeral with the suffix a have been used to indicate similar parts, and in particularto the horizontal clamping member ofthe system.Whilst in the preferred embodiment a horizontal clamping member 18 is utilised, which carries a sealing member 72 carried by claws 70 ofthe member, the seal being carried into engagement with the facing panels by retightening of the clamping screws, in the modification illustrated in Figure 10 a clamping member 18a is utilised which comprises inner and outer parts 180,182. The inner part 180 is moved towardsthefacing panels by the clamping screw being tightened by an extent such asto bring the side edges of the portion 180 into approximate, but spaced relationship from the facing panels 20a. The portion 182 is provided bya moulded neoprenesealing gasket, which may in this position by snap4itted over the portion 180, as is show in Figure 10.The clamping screw may be furthertightened to prevent accidental displacement of the sealing gasket, and the operation maybecompleted by the insertion of a capping strip 188 into access apertures provided in the sealing gasket.

Preferably, the sealing gasket is rectangular, so that when fitted in position it extends around afacing panel, advantageously being formed to rectangular shape by a vulcanisation operation (see Figure 1 Oa).

As an alternative to utilising a gasket which extends overthefrontfaceoftheclamping members rectangular gasket 182b may be used (as is shown in Figure 12)which seals between the panels 20a and the various clamping members, the front faces of the clamping members (such as the front face 181) being coated with a neoprene paint 183 to provide a smooth and substantially continuous appearance.

By the construction above described, a curtain walling system is provided which has a pressure equalisationchamberprovidedin partbythecon- tinuously extending channels 64 of the horizontal members 14, and which extendsthrough each hori zontal junction, and which extends fully across some at least, preferably most of the mullions, and in which an apron 110 is utilisedto divertwatertowardsthe outside face of the curtain walling, said apron also extending substantially continuously in the widthwise direction across the mullions. In this manner the tendencyforwater to be driven into the junction area is significantly reduced, whilst an effective thermal barrier between the interior and exterior metal construction member is maintained.

Whilst the construction which is the preferred embodiment of this invention has been described above in relation to the provision of a vertical curtain walling, it is to be appreciated that the invention may be used in othersituations,forexample in planarbut sloping curtain walling, orwhere a sloping wall and a vertical wall meet.

Thus as is illustrated in Figure 13 (in which similar numerals with an apostrophe have been used to identify parts similar to those above described) ofthe two exteriorfaces50'ofthe horizontal members 14', one is inclined relative to the other at a selected angle (illustrated as being 45 ), providing a horizontallyextending but inclined sealing gasket 52' against which a facing panel maybe seated. Similarly of the horizontal clamping member 18', of the two exterior walls 68', one is inclined relative to the other and ata similarangle,andtheuppermostofthetwosealing gaskets 72' is similarly inclined, in parallel opposition to the said sealing gasket 52'.Thus, by the tightening of clamping screws 84,the clamping member 18' may be drawn towards the supplementary member 14', serving to clamp between the lowermost pairofseals the vertically-extending panel, and to clamp between the uppermost, inclined pair ofsealsthe inclined facing panel 20'.

The members 12' corresponding to the supplementaryvertical members 12, and the clamping member 16' corresponding to the vertical clamping members 16, differ from the construction of the preferred embodiment essentially in that lower end portions thereof are chamfered, so that at its lower end the supplementary member 16' abuts against the mullion 8to which it is secured, whilstthe clamping member 1 6' abuts against the top face of the horizontal clamping member 18' (see Figure 13). It will of course be appreciated that the apron 110 similarly ducts waterfrom the interior ofthe interlace into the lowermost channel 64' of the horizontal clamping member in the manner above described.

The features disclosed in the foregoing description, orthefollowing claims, orthe accompanying drawings, expressed in their specificforms or in terms of a meansfor performing the disclosedfunction, ora method or process for attaining the disclosed result, or a class or group of substances or compositions, as appropriate, may, separately or any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

1. A curtain walling system comprising sup- plementary members secured or adapted to be secured to the mullions and transomes ofthe building, and clamping members secured or adapted to be secu red to the supplementary members, by which facing panels of the building may be secured in position, between the supplementary members and the clamping members.

2. A system according to Claim 1 wherein the supplementarymemberscomprisefirstsup- plementary members secured or adapted to be secured to the mullions and second supplementary memberssecuredoradaptedto besecuredtothe transomes, the construction and arrangement being such thatthefirst supplementary members extend along continuous, or substantially continuous lines with the second supplementary members extending between the first supplementary members.

3. A system according to Claim 2 wherein the first supplementary members provide continuous or substantially continuous and horizontally extending pressure equalisation chamberwhich extends across the junction areasofmullionandtransome.

4. A structure according to any one ofthe preceding claims wherein the drainage member is clamped in position bythe means by which the clamping members are secured to the structure.

4. A system according to Claim 3 wherein the first supplementary members are provided with means by which a drainage member may be secured thereto, which extends outwardly between adjacent, vertically spaced facing panels and bywhich water within the system may be ducted outwardly.

5. Asystem according to Claim 4 comprising a channel provided by the clamping members, from which the water may flow from the system.

6. A system according to any one of the preceding claims comprising sealing means which is adapted to provide for sealing:~ (a) between thefirstsupplementary members and the transomes; (b) between the second supplementary members and the mullions; (c) between abutting faces of the supplementary members; (d) betweenthefacing panels andthe sup- plementary members; (e) between the clamping membersandthefacing panels; (f) between abutting faces of the clamping members.

7. A system according to Claim 6 wherein the sealing means for (a), (b), (c) and (d) is provided by sealing members on the supplementary members.

8. A system according to one of Claims 6 and 7 wherein the sealing means for (e) and (f) is provided by sealing members on the clamping members.

9. A system according to any one ofthe preceding claims wherein the clamping members are adapted to be secured by screws or the like fastening elements to the supplementary members.

10. A system according to Claim 9 wherein relative movement of approach between the clamping members and the supplementary members is limited by spacer means.

11. Asystem according to Claim 9 wherein relative movement of approach between the clamping members and the supplementary members is limited by tightening of the fastening elements to a predetermined torque.

12. Asystem according to any one of Claims 10,11 and 12 wherein the clamping members comprise or are adapted to receive additional members by which such securement may be concealed.

13. A system according to any one of the preced- ing claims wherein the supplementary members are adapted to be secured to the building members by screws.

14. A system according to any one of Claims 1 to 12 wherein the supplementary members are adapted to be secured to the building members by interfitting formations.

15. A system according to any one of the preced- ing claims, suitable for use in a building construction in which the mullions extend vertically.

16. A system according to any one of Claims 1 to 14, suitable for use in a building construction in which the mullions are inclined to the vertical.

17. A building system in which mullions are secured to the upright members of the building, and in which transomes are secured to and between adjacent mullions in a mannersuchthattheoutwardlyfacing surfaces provided bythe mullions and transomes lie substantially in a plane.

18. A system according to Claim 17 wherein the transomes are secured to the mullions by the use of mounting brackets secured to the mullions, and to which end portions ofthe transomes are secured

19. A system according to Claim 18 in which a sealing member is interposed between the mounting bracket and the mullion, with which the end face ofthe transome engages.

20. A system according to any one of Claims 17 to 19 comprising supplementary members secured to the transomes in continuous horizontal lines.

21. Asystem accordingtoClaim20wherein adjacent supplementary members abut at positions between adjacent mullions.

22. A system according to one of Claims 20 and 21 wherein the supplementary members are provided with sealing members at their end faces, to provide a seal between abutting supplementary members when secured to the transomes.

23. A system according to any one of Claims 20 to 22 wherein the supplementary members provide a continuous horizontal, outwardly-facing channel.

24. A system according to Claim 23 comprising horizontal clamping members secured oradaptedto be securedtothe supplementary members and to clamp horizontal edge portions of panel members between outwardly-facing surfaces ofthe supplementary members and inwardly-facing members oftheclamping members.

25. A system according to Claim 24 comprising a drainage member secured in the channel and which extends horizontally across the mullions,the drainage member extending beneath a panel member and providing meanstoductwaterfromthechannel outwardly of the system.

26. A system according to Claim 25 wherein the drainage member is secured atone sideto the supplementary member and extends at its outer side adjacent to a drainage channel provided by the clamping member, into which drainage channel water is ducted by the drainage member.

27. A system according to one of Claims 25 and 26 comprising a sealing member interposed between the drainage member and a panel member beneath the drainage member.

28. Asystem according to any one of Claims 17 to 27 comprising second supplementary members se cured oradaptedto be secured to the mullions, and extending between the first said supplementary members.

29. A system according to Claim 28 wherein the second supplementary members are provided with sealing members attheirendfaces, by which a seal is provided between the first supplementary members and the second supplementary members.

30. A system according to one of Claims 28 and 29 comprising vertical clamping members secured or adapted to be secured to the second supplementary members and to clamp vertical edge portions of panel members between outwardly-facing surfaces ofthe second supplementary members and inwardly-facing surfaces of said clamping members.

31. A building system constructed and arranged substantially as hereinbefore described with refer ence to the accompanying drawings.

32. Any novel feature onnovel combination of features disclosed herein and/or shown in the accompanying drawings.

Amendments to the claims have been filed, and havethefollowing effect:~ Claims 1-32 above have been deleted or textually amended.

Newortextuallyamended claims have been filed as follows:

1. Acurtainwallingstructurecomprisingelon- gate, vertical mullions,transoms secured to and extending between adjacent mullions, and facing panels clamped in position by external elongate securing members, wherein continuous or substan tially continuous and horizontally-extending pressure equalisation chambers are provided which extend across the junction areas of mullion and transom, in each of which an elongate, horizontally-extending drainage memberissecured,thedrainagemember extending, in a direction at right angles to its length, between vertically spaced facing panels from a region ontheinnersideofthefacing panels to a region on the outer side thereof, whereby water within the structure may be ducted outwardly therefrom.

2. A structure according to Claim 1 wherein an inner edge portion of the drainage member is located in a downwardly-extending channel which is located ontheinnersideofthefacing panel.

3. A structure according to one of Claims 1 and 2 wherein the drainage member extends, in a direction at right angles to its length, adjacentto an elongate channel ontheoutersideofthefacing panel into which water ducted outwardly by the drainage member is channelled, and from which it flows from the structure.