CURTAIN WALLING

Abstract: Curtain walling comprising a framework of mullions (10) and transoms (20) supporting solid or glazed panels (12, 14). Each transom (20) has a body portion (22) and a projecting nose portion (24) on which the panel above the transom is supported. Each transom (20) is joined to each adjacent mullion (10) by means of a connecting member (80, 380) secured to the mullion and projecting laterally so as to engage the nose portion (24) of the transom (20). The connecting member may be a spigot (80) shaped to fit into a cavity (32) in the nose portion (24). Engagement of the connecting member in the nose portion rather than the body portion (22) of the transom enables the weight of the panel to be supported without any turning moment being exerted on the transom. The nose portion (24) of each transom (20) may be relatively long. A pressure plate (40) connected to each transom (20) is designed to ensure ventilation of the internal cavity of the curtain walling and to allow water to drain from within the cavity.

Description: CURTAIN WALLING This invention relates to curtain walling. The invention relates more particularly to curtain walling of the kind consisting of a framework of interconnected mullions and transoms supporting panels, which may for example be solid panels or glaεed panels or windows. The mullions and transoms usually consist of lengths, for example, of aluminium extrusion, each having a body portion and a nose portion projecting outwards from the body portion so as to support a panel positioned above the transom, the panel being held in place by a pressure plate releasably attached to the nose portion. Each transom is normally supported at each end by a spigot fixed to the adjacent mullion and projecting into the body portion of the transom. This conventional construction has the disadvantage that the weight of the panel acts through the nose portion, which is horizontally spaced from the spigots, so that the weight gives rise to a turning moment on the transom. According to one aspect of this invention there is provided curtain walling comprising a framework of mullions and transoms adapted to support panels, each transom consisting of a body portion and a nose portion extending outwards from the body portion and positioned to receive the weight of the panel supported by the transom, each transom being connected to each adjacent mullion by means of a connecting member secured to the mullion and projecting laterally so as to engage and support the transom, characterised in that the connecting member is positioned to engage the nose portion of the transom. In one form of the invention, the nose portion of the transom is shaped to define a cavity and each connecting member is a spigot shaped to fit into the cavity of the nose portion. In another form of the invention, each connecting member is a bracket having one arm secured to the adjacent mullion and another arm engaging the nose portion of the transom. Preferably, a pressure plate is attached to the nose portion of each of the transoms and mullions in such a manner that peripheral portions of panels supported by the framework are clamped between the pressure plates and the body portions of the transoms and mullions, each pressure plate being connected to the adjacent nose portion in such a manner that air can circulate between the pressure plate and the nose portion, and the pressure plate being provided with holes to allow ventilation of the cavity defined by the body portion of the mullion or transom, the pressure plate, and the edges of the panels clamped between them. Suitably, the upper surface of the nose portion of each transom slopes downwards away from the body portion, carriers being interposed between the upper surface of the nose portion and the lower edge of a panel supported thereon, the carriers being arranged so that water can drain off the upper surface, the pressure plate fixed to the transom having holes in its lower peripheral portion so that water can drain out of said cavity. Advantageously, the lower peripheral portion of the pressure plate connected to the transom is shaped to form a channel to receive water draining from the nose portion of the transom, the face of the channel nearest the body portion of the transom being formed by an upwardly projecting wall on the pressure plate, the upper edge of said wall lying nearer the body portion than the outer edge of the nose portion, the said holes in the pressure plate being formed in the said channel. In accordance with another aspect of the invention, a gasket is interposed between the body portion of each transom and the body portion of each adjacent mullion. In accordance with another aspect of the invention, each connecting member extends across a gap between the end of the nose portion of the transom and the nose portion of the adjacent mullion, and a dam block is positioned to cover the upper surface of the exposed portion of the connecting member to prevent the passage of moisture through the gap. In accordance with a further aspect of the invention, each connecting member slidably engages the nose portion of the adjacent transom to allow slight movement between the transom and the mullion to which it is connected, the connecting member being provided with a friction-reducing plastics coating. In accordance with yet another apsect of the invention, a gasket is interposed between the peripheral edges of each panel and the body portions of the adjacent transoms and mullions, each gasket comprising lengths of gasket material, each length extending along an edge of a panel, the lengths being welded or bonded to one another at each corner of the panel. In conventional constructions the structural strength of the transoms and mullions lies largely in the body portion which has therefore needed to have substantial dimensions. By increasing the front-to-rear dimension of the nose portion, the contribution of the nose portion to the structural rigidity increases, so that the front-to-rear dimension of the body portion can be reduced. This enables the curtain walling to be made very attractive in appearance. At the same time, it enables relatively thick panels to be supported on the nose portion without the need to form a step in the panel to enable it to fit into the nose portion, as is the case with the conventional construction. In accordance with another aspect of the invention there is provided curtain walling comprising a framework of transoms and mullions, each transom consisting of the body portion and a nose portion extending outwards from the body portion and positioned to receive the edge of a panel supported by the transom, in which the overall front-to-rear dimension of the nose portion is relatively large. Preferably, the front-to-rear dimension of the nose portion is greater than 20mm. The nose portion may for example have a front-to-rear dimension of about 6θmm. The invention will now be described, by way of example, with reference to the accompanying drawings, in which:- FIGURE 1 is a fragmentary perspective view of curtain walling in accordance with the invention; FIGURE 2 is a cross-section through a transom of the curtain walling; FIGURE 3 is a cross-section through a mullion of the curtain walling; FIGURE 4 is an exploded view showing the connection of the transoms to a mullion; FIGURE 5 is an end view of an alternative form of spigot for use in the curtain walling of Figures 1 to 4; FIGURE 6 is a cross-section through a transom of another embodiment of curtain walling in accordance with the invention; FIGURE 7 is a cross-section through a mullion of the embodiment of Figure 6; FIGURE 8 is a side elevation of a cleat used to join the transoms and mullions of Figures 6 and 7; FIGURE 9 is a plan view of a gasket used in the curtain wall; and FIGURE 10 is a cross-section on line VI-VI of Figure 9- Referring to Figures 1 to 4, curtain walling comprises a network of mullions 10 and transoms 20, supporting panels which may be solid panels 12 or glazed panels 14. The mullions 10 are adapted to be secured to the structural frame of the building in conventional manner. In the illustrated embodiment the mullions and transoms are formed from identical extrusions, though they could alternatively be of different sections. Each of the transoms 20 has a body portion 22 generally in the shape of a rectangular box-section, and a nose portion 24 projecting forwards from the body portion. The nose portion 24 tapers in its vertical dimension from the rear to the front, having inclined upper and lower walls 26 and 28. The upper wall 26 defines a sloping platform from which water can drain as described below. The upper and lower walls are joined by a solid outer portion 30. The internal cavity 3 can receive a spigot joining the transom to an adjacent mullion, as described below. A pressure plate 40 is secured to the nose portion 24 of the transom 20 by means of screws 42 which pass through holes in the pressure plate and screw into the threaded grooves in the outer portion 30 of the nose. The pressure plate 4θ is spaced from the nose 24 by insulating bushes 44, to allow air to circulate between the pressure plate and the nose, and to act as a thermal break between the pressure plate and the transom. The panels 12 and 14 adjacent the transom 20 are clamped between the pressure plate 40 and the body portion 22 of the transom. Each panel is supported along its lower edge by a number of carriers 46, each consisting of a length of aluminium extrusion, spaced along the transom. Each carrier 46 is shaped to lie against the sloping upper wall 26 of the nose portion 24 and to provide a horizontal surface on which the panel can rest. When the panel is a glazed unit 14 as shown in Figure 2, a setting block 48 of suitable material can be interposed between the panel and the carrier 46. Where the panel is of.a thickness less than the maximum which can be accommodated by the transom, as with the glazed panel 14 in Figure 2, a spacer 50. consisting of a length of extruded aluminium, is positioned between the panel 14 and the body 22 of the transom. The spacer 50 is secured to the body 22 of the transom by any suitable means, such as interengaging elements on the spacer and transom which allow the spacer to be snap-fitted to the transom. Sealing gaskets 52 and 1 6 are interposed between the panels and the body 22 of the transom and between the panels and the pressure plate 40, the gaskets being held in channels ^ formed in the pressure plate and in channels 56 in the body 22 of the transom or in the spacer 50. The gaskets are described in more detail below. In accordance with another aspect of the invention, the lower peripheral portion of the pressure plate 40 is shaped to form a channel 60 which can receive water draining from the nose portion 24. The channel is defined by a wall 62 extending upwards from the lower wall 64 of the pressure plate. The wall 62 extends upwards to an edge 66 which is close to, but spaced from, the lower edge 70 of the nose portion 24. The edge 70 is formed with a downwardly directed beak to prevent water draining down the vertical face 72 of the nose portion from running onto the lower face of the nose portion. The upper edge 66 of the wall 62 is spaced rearwards below the edge 70 of the nose and is bevelled to encourage water to drain into the channel 60. The lower wall 64 of the pressure plate 40 is formed with drainage slots 74 to allow water to escape. A decorative capping 76 fits snapwise over the pressure plate 40. The part of the capping 76 lying against the lower wall 64 of the pressure plate is formed with drainage slots 7δ. The design of the transom and pressure plate of the described embodiment ensures that any moisture which leaks between the glazed panel 14 and the pressure plate 40 or the body 22 of the transom, runs down the sloping platform provided by the upper wall 26 of the nose portion 24 and is directed into the channel 6θ, from which it can drain out through the slots 74 and 78. At the same time, the area above the top of the panel 12 is open to the atmosphere through the slots 74 and 78, so that entire cavity between the panels 12 and 14 and the transom and pressure plate is vented, allowing a free circulation of air to inhibit the build-up of moisture in the cavity. As mentioned previously, the mullions 10 may be made from the same extruded section as the transoms 20. As shown in Figure 3. each mullion 10 has a body portion 122 and a nose portion 124. A pressure plate l4θ, similarly formed of the same extruded section as the pressure plate 40 for each transom, is secured to the nose 124 by means of screws 146, with the interposition of spacers 144. The vertical edges of the panels 12 and l4 are gripped between the pressure plate 140 and the body 122 of the mullion, with gaskets 1 6 interposed to inhibit leakage of water. A decorative capping 176 snaps over the pressure plate 140. Each transom 20 is joined at each end to the adjacent mullions 10 by means of spigots 80. Each spigot is a length of aluminium extrusion having a cross-section shaped so that the spigot fits closely into the internal cavity 32 of the nose portion 24 of the transom. The spigot 80 is formed with two slots 82 which can receive the shanks of self-tapping screws 84 by means of which the spigot is fixed to the nose portion 124 of the mullion 10. The face 86 of the spigot engaging the mullion is inclined so that the spigot extends in the same direction as the transom 20. The transom can slide on the spigot, so that some movement can occur between the transoms and mullions to allow for thermal movement. The spigots may have a coating of plastics to decrease friction between the spigot and transom. Since, in the described embodiment, each spigot 80 is positioned within the nose portion 24 of the transom, it is positioned directly beneath the panel which is supported by the transom. The weight of the panel is therefore transmitted through the transom to the adjacent mullions without any turning moment being exerted on the transom as is the case with conventional systems, in which the spigots are received in the body of the transom. In cases where extra strength or rigidity is required, an additional spigot 88 may be positioned at each end of the transom 20, each spigot 88 being shaped to fit into the body 22 of the transom. Similar spigots such as spigot 180 (Figure 3) are used to connect the mullions at their lower ends to a cill bar and at their upper ends to brackets secured to the frame of the bulding and to join members of the system to one another. In the described embodiment, the overall front-to-rear dimension of the nose portion 24 of the transom is about 6θmm, whilst the corresponding dimension of the body portion 22 is about 30mm. This latter dimension can be varied depending on the loading for which the curtain walling is designed. For very light loading, the body portion 22 can be a plate provided with reinforcing ribs rather than a box structure. For higher loadings the front-to-rear dimension of the body portion can be increased, for example up to l4θπ_m. To seal the junction between the body 22 of each transom 20 and the body 122 of the adjacent mullion 10, a gasket 90, for example of EPDM foam, is positioned between the end of the body 22 and the mullion Each gasket 90 consists of a sheet of material, formed along its upper and lower edges with beads 92 which project over the upper and lower faces of the bpdy 22 of the junction between the transom and mullion and also provide a decorative finish to the junction. Where an additional spigot 88 is used, the gasket 90 is provided with holes to receive the mounting screws for the spigot. The body 22 of each transom 20 engages the side face of the body 122 of the adjacent mullion 10, and a gap is therefore left between the end face of the nose portion 24 of the transom and the nose portion 124 of the mullion, this gap being bridged by the spigot 80. In accordance with another aspect of this invention, to prevent the passage of moisture through this gap, a dam block 94 is positioned in the gap. The dam block has a portion 96 shaped to fit over the upper face of the spigot 80. The face 98 of the dam block adjacent the mullion is inclined so as to fit closely against the face of the nose portion 124 of the mullion. After insertion of the dam block, a mastic is applied to seal the joints between the dam block and the mullion and transom. The dam block is held in place by the pressure plate 40. A similar dam block may be used at the bottom of each mullion to bridge the gap between the nose portion of the mullion and the cill. The dam block may be of suitable plastics or rubber, or may be an aluminium extrusion. The self-tapping screws 84 used to secure each spigot 80 to a mullion 10 may in some circumstances be replaced by bolts arranged to pass through one spigot, through the nose portion 124 of the mullion to which the spigot is to be secured, and through the corresponding spigot on the other side of the nose portion, each bolt being secured by a nut engaging the corresponding spigot. Figure 5 is a cross-section through an alternative form of spigot l8θ specifically designed to receive bolts in the slots l82. Securing the spigots with bolts provides a stronger structure and is particularly useful where relatively large weights are to be supported, for example where each transom spans a relatively long distance between adjacent mullions. Figures 6 to 8 illustrate an alternative embodiment of the invention suitable for use in light-weight structures. The nose portion 224 of each transom 220 (Figure 6) consists of a sloping upper wall 226, and a solid outer portion 230, but, unlike the previously described embodiment, it has no lower wall. The nose portion 324 of each mullion 310 (Figure 7) consists of a single wall, extending at right angles to the body 322, and a solid outer portion 330. The mullions and transoms are joined by cleats 38O each having two arms 382 and 384 at right angles to one another. The vertical arm 382 of each cleat is secured to the nose portion 324 of a mullion 3 0 by suitable means, such as bolts or rivets 386. Two cleats may be fixed back-to-back to each mullion, to support transoms on each side of the mullion. The horizontal arm 384 of each cleat extends beneath the nose portion 226 of a transom 220 to support the transom. Ribs 228 formed on the lower face of the nose portion 226 engage and locate the horizontal arm 38 of the cleat 38O, and a rib 229 in the body portion 222 engages the vertical arm 382. The arm 384 is secured to the wall 224 by means of a screw 385- The outer portion 230 and 330 of the transom 220 and mullion 3 0 are formed with screw grooves to receive screws 370 holding pressure plates 372 in position. The pressure plates 372 act in the same way as those of the previously described embodiment, to clamp panels between the pressure plates and the body portions of the transoms and mullions, and may be constructed in the same way. Figures 6 and 7 show alternative forms of pressure plates which do not require decorative cappings. A central recess 37^ in each pressure plate 372 may be closed by a decorative section 37 snap-fitted into the recess. As shown in Figure 7. the body portion 322 of mullion 310 is fixed to an adaptor 350 by means of which the mullion can be fixed to a structural member of the building, the adaptor being held by a clamp plate 352 bolted to the structural member. The adaptor 350 could be formed in one with the body portion 322. Alternatively, the body portions of the transoms and mullions could be formed with sections of different depths, as in the previously described embodiment. The transoms and mullions are designed to receive carriers and setting blocks for the panels to be supported, and gaskets, as in the previously described embodiment. The embodiment shown in Figures 6 to 8 has the advantages that it largely avoids components having hollow sections, and that it is relatively light and inexpensive to manufacture. In accordance with another aspect of this invention, each inner gasket 52 used to provide a seal between the bodies of the transoms and mullions and each panel 12 or 14 is a rectangular gasket prefabricated to fit around the four sides of the panel, as shown in Figures 9 and 10. The gasket is formed from extruded lengths, for example of synthetic rubber, the lengths being cut to size and mitred to form the corners, which are welded or bonded by means of a suitable adhesive. The cross-sectional shape of the gasket shown in Figure 6 is illustrative only and will vary to suit the requirements of each particular installation. The use of factory-made gaskets avoids the need to make corner joints in the gaskets on-site.

Claims: Claims 1. Curtain walling comprising a framework of mullions and transoms adapted to support panels, each transom consisting of a body portion and a nose portion extending outwards from the body portion and positioned to receive the weight of the panel supported by the transom, each transom being connected to each adjacent mullion by means of a connecting member secured to the mullion and projecting laterally so as to engage and support the transom, characterised in that the connecting member is positioned to engage the nose portion of the transom. 2. Curtain wall as claimed in Claim 1, characterised in that the nose portion of the transom is shaped to define a cavity and each connecting member is a spigot shaped to fit into the cavity of the nose portion. 3. Curtain walling as claimed in Claim 1, characterised in that each connecting member is a bracket having one arm secured to the adjacent mullion and another arm engaging the nose portion of the transom. 4. Curtain walling as claimed in any one of Claims 1 to 3. in which a pressure plate is attached to the nose portion of each of the transoms and mullions in such a manner that peripheral portions of panels supported by the framework are clamped between the pressure plates and the body portions of the transoms and mullions, characterised in that each pressure plate is connected to the adjacent nose portion in such a manner that air can circulate between the pressure plate and the nose portion, and in that the pressure plate is provided with holes to allow ventilation of the cavity defined by the body portion of the mullion or transom, the pressure plate, and the edges of the panels clamped between them. 5- Curtain walling as claimed in Claim 4,, characterised in that the upper surface of the nose portion of each transom slopes downwards away from the body portion, carriers being interposed between the upper surface of the nose portion and the lower edge of a panel supported thereon, the carriers being arranged so that water can drain off the upper surface, the pressure plate fixed to the transom having holes in its lower peripheral portion so that water can drain out of said cavity. 6. Curtain walling as claimed in Claim 5. characterised in that the lower peripheral portion of the pressure plate connected to the transom is shaped to form a channel to receive water draining from the nose portion of the transom, the face of the channel nearest the body portion of the transom being formed by an upwardly projecting wall on the pressure plate, the upper edge of said wall lying nearer the body portion than the outer edge of the nose portion, the said holes in the pressure plate being formed in the said channel. 7. Curtain walling as claimed in any preceding claim, in which a gasket is positioned between the body portion of each mullion and the body portion of each adjacent transom. 8. Curtain walling as claimed in any preceding claim, characterised in that each connecting member between a transom and an adjacent mullion extends across a gap between the end of the nose portion of the transom and the nose portion of the adjacent mullion, and a dam block is positioned to cover the upper surface of the exposed portion of the connectitjg member to prevent the passage of moisture through the gap. 9. Curtain walling as claimed in any preceding claim, characterised in that each connecting member slidably engages the nose portion of the adjacent transom to allow slight movement between the transom and the mullion to which it is connected, the connecting member being provided with a friction-reducing plastics coating. 10. Curtain walling as claimed in any preceding claim, characterised in that a gasket is interposed between the peripheral edges of each panel and the body portions of the adjacent transoms and mullions, each gasket comprising lengths of gasket material, each length extending along an edge of a panel, , the lengths being welded or bended to one another at each corner of the panel. 11. Curtain walling comprising a framework of transoms and mullions, each transom consisting of the body portion and a nose portion extending outwards from the body portion and positioned to receive the edge of a panel supported by the transom, in which the overall front-to-rear dimension of the nose portion is greater than 20mm.

Inventors: BORLEY HOWARD, BORLEY, HOWARD
Applicants: CONST UTILITIES GROUP LTD
Application year: 1987
Main classification: E04B2
IPC codes: E04B2, E06B7