GB2027100A - Lathing Formations in Lintels - Google Patents

Abstract

Plaster keying formations are provided integrally with a structural sheet metal member forming part of a lintel of generally box section. The keying formations each comprise a strip of metal having both its ends integrally connected with the main sheet of metal but having its central portion pressed out of the plane of the metal in a generally V-shape with the metal strip having been plastically deformed. Because the force causing plastic deformation is then removed, the deformed metal strip has some rigidity and contributes to the overall strength of the sheet metal member, in spite of having been deformed out of the plane of the sheet. By use of such plaster keying formations integral with the structural parts of the lintel, it is possible to avoid having to attach separate conventional plaster keying material such as mesh. <IMAGE>

Description

SPECIFICATION Lintel This invention relates to lintels which are wholly or partly of metal, and more particularly to lintels provided with keying for assisting in securing plaster, mortar or like materials to the lintel.

It is known to provide some form of keying to enable the inwardly and downwardly presented faces of the lintel to be concealed in use by a coating of plaster. This has previously been done by attaching a wire mesh or expanded metal mesh or by welding on small keying members which are additional to the structural components of the lintel. This of course requires an extra assembly operation and increases the weight of the lintel because the keying material is provided in addition to the basic lintel. Alternatively, holes can be punched in the structure but this provides poor keying and causes weakness.

It is an object of the invention to provide a lintel which overcomes or reduces these disadvantages.

According to the invention there is provided a lintel comprising at least one structural sheet metal member having a plurality of integral keying formations, each formation comprising a strip of the sheet metal of said member, both ends of the strip being integral with the remainder of the sheet and the strip being bounded on opposed edges by openings in the sheet, the strip having been plastically deformed out of the plane of the remainder of the sheet at a portion intermediate its said ends.

The lintel may include a sheet metal box section comprising a base plate, front and rear walls and a top plate rigidly secured together to define a box section, the rear wall constituting said sheet metal member having keying formations.

At least a portion of the base plate may also include keying formations. The lintel will now be described in more detail by way of example only with reference to the accompanying drawings in which Figure 1 is a perspective view of a portion of sheet metal incorporating keying formations; Figure 2 is a similar view of an alternative form of sheet metal having keying formations; Figure 3 is a side elevational view of a lintel embodying the sheet metal of the type shown in Figures 1 and 2.

Referring firstly to Figures 1 and 2 of the drawings, each of these figures shows a portion of sheet metal generally indicated at 10 and 11 respectively. In Figure 1, the sheet 10 is in the form of a strip provided with a plurality of keying formations generally indicated at 12 disposed side by side. The sheet 11 of Figure 2 shows keying formations 1 3 disposed in staggered rows.

The formations 12 and 13 are substantially identical except for questions of scale and hence only the formations 12 will be described in detail.

Each of the formations 12 is formed by making a pair of parallel slits in the sheet metal 10, thereby isolating a strip 14 of the sheet metal which is integral with the main sheet at its ends 15 and 16.

A pressing operation is then carried out on the strip 14 so as to press its central portion intermediate the ends 1 5 and 1 6 out of the plane of the sheet 10. In the configuration shown in the drawings, the strip 14 adopts a V-shape as seen in side elevation looking along the plane of the sheet 10. However, this particular shape need not be adopted and the strip could be formed to an arcuate or oblong shape for example.

The V-shape can be seen more clearly with reference to Figure 3 of the drawings which shows a lintel generally indicated at 1 7 having a back plate 1 8 formed from a sheet of metal 10 having keying formations 12. Each formation comprises a strip 14 having the V-shaped profile shown.

It will be appreciated that, in order to form the strip 14 to the shape shown, sufficient pressure must be exerted to deform the metal plastically.

When the plastic deformation has been carried out by a pressing operation, the deformed metal will retain its shape and will have certain modified load bearing characteristics.

Considering a sheet of metal from which the strips 14 have been removed completely by severing their ends 1 5 and 16, the load bearing characteristics of the sheet are greatly reduced by the openings which remain. Since the strips 14 remain integral with the main sheet 10 as described with reference to Figure 1, they do contribute some structural strength to the sheet because, although deformed out of the plane of the sheet, the strips 14 are rigid.

The lintel 1 7 includes a base plate 1 9 which is formed from a sheet 11 simiiar to that shown in Figure 2. This is provided with a plurality of plaster keying formations 1 3 as described above disposed in relatively staggered rows and of a relatively smaller dimension than those 14 of the sheet 10.

The remainder of the lintel is of a generally conventional box type including a top plate 20 and a front plate 21. A damp resisting element 22 extends over the forward edge of the base plate 19 and slopes downwardly and outwardly to resist damp penetration across a cavity of a cavity wall.

The formations 12 and 13 provide a plaster key which is integral with the structural parts of the lintel without excessively reducing the strength and load bearing characteristics. Mortar or plaster will key soundly to the lintel by penetration into the openings 23 behind the deformed strips 14.

Thus, a firm mechanical interlock is provided. The keying effect is greater than is achieved by simply perforating the metal sheet 10 and in addition the structural strength of the sheet is greater, as referred to above, than in the case of a perforated sheet. Additionally, since the keying formations are derived from the material of which the lintel is constructed, and are not attached subsequently, assembly operations and time are reduced and no extra weight is added to the lintel to provide the plaster or mortar key.

It will be appreciated that the keying formations can be provided on other types of lintel than that shown in Figure 3, which may include lintels which are not wholly formed of metal. It is applicable both to cavity wall lintels as shown and to lintels used in internal walls which are not of the cavity type.

Claims (6)

Claims

1. A lintel comprising at least one structural sheet metal member which is planar except for a plurality of integral keying formations, each formation comprising a strip of the sheet metal of said member, both ends of the strip being integral with the remainder of the sheet and the strip being bounded on opposed edges by openings in the sheet, the strip having been plastically deformed out of the plane of the remainder of the sheet at a portion intermediate its said ends.

2. A lintel according to Claim 1 and including a sheet metal box section comprising a base plate, front and rear plates and a top plate rigidly secured together to define a box section, at least one of said plates constituting said sheet metal member having keying formations.

3. A lintel according to Claim 2 wherein the rear wall constitutes said sheet metal member having keying formations.

4. A lintel according to Claim 2 or Claim 3 wherein at least a portion of the base plate constitutes said sheet metal member having keying formations.

5. A lintel substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

6. A lintel having any novel feature or combination of features set out in the associated description.