GB2226346A - Lintel - Google Patents

Abstract

A lintel comprises two similar but oppositely facing metal elements 11, 12 of lazy Z section, the upper flanges 11c, 12c of which face towards each other and have interlocking formations 16, 17. A third element 13 spans between, and is secured to, the lower flanges 11b, 12b. The elements have strengthening ribs 11e, 12e, 13e and the third element 13 may have holes for keying plaster. A plastics water shield 19 is clipped to the interlocking formations 16, 17. <IMAGE>

Description

STRUCTURAL BEAM This invention relates to a structural beam of the kind usually referred to as a lintel, for spanning openings such as window or door openings in building walls.

Lintels, for supporting the courses of bricks, blocks, or other constructional materials in a single leaf wall, or in both leaves of a cavity wall, are well known. It is known to manufacture lintels as pre-cast concrete beams, rolled steel joists, and as sheet metal fabrications of box structure. The present invention is concerned with the latter type, that is to say sheet metal fabrications.

The fabricated sheet metal lintel usually exhibits a significant weight saving over the pre-cast concrete and rolled steel joist arrangements. It is an object of the present invention to provide a lintel of the fabricated sheet metal type which can relatively easily be manufactured in a wide variety of sizes, each making use of the optimum amount of metal for a given lintel strength.

In accordance with the present invention there is provided a lintel comprising first and second elongate sheet metal elements, each element having a generally planar web portion and integral therewith, along opposite longitudinal edges of the web portion, first and second generally planar flange portions, said first flange portion of each element lying perpendicular to the respective web portion and said first and second flange portions of each element extending respectively to opposite sides of the plane of their respective web portion, said first and second elements being positioned with their web portions spaced, and generally parallel, their first flange portions generally co-planar, but extending in opposite directions, and their second flange portions extending towards one another, said second flange portions being formed integrally with interlocking regions thereby the second flange portions can interlock along their length, and the lintel further including a third element spanning the gap between the web portions of the first and second elements and secured to the first flanges of said first and second elements, the interlocking means and said third element serving to fix said first and second elements in position relative to one another.

Desirably said third element is an elongate, generally planar, strip aligned with the first and second elements and secured at a plurality of spaced points along its length to the first flanges of the first and second elements.

Conveniently said third element is formed with strengthening ribs extending transverse to the length of the first and second elements.

Preferably said third element is pierced at a plurality of points to provide a plaster key.

Preferably the width of said third element is such that the third element overlies substantially the whole width of the first flanges of the first and second elements.

Conveniently the planar webs of the first and second elements are formed with integral strengthening ribs extending transverse to the length of the first and second elements.

Desirably the interlocking means of the second flanges of the first and second elements project outwardly from the edge of the lintel remote from the third element and are continuous over the length of the lintel so as to add to the beam strength of the lintel.

Preferably the lintel includes a moulded synthetic resin shield extending substantially the full length of the lintel and secured thereto as a snap fit.

One example of the invention is illustrated in the accompanying drawings wherein, Figure 1 is a diagrammatic transverse crosssectional view of a lintel, and Figures 2 and 3 are views in the directions of arrows A and B in Figure 1 respectively.

Referring to the drawings it can be seen that the lintel is constructed from three elongate sheet metal elements 11, 12, and 13 respectively. All three elements conveniently are produced by roll-forming thin mild steel strip. The element 11 includes a generally planar web portion lla, and integral, perpendicular first and second flange portions lSk, llc integral with the web portion 11 along opposite longitudinal edges thereof respectively. The flange portions lib and llc extend in opposite directions from the plane of the web portion ila and thus are substantially parallel. At its edge remote from the web portion ila the flange portion lic includes an up turned lip 15 rolled over at its free edge to form a hook portion 16.

The element 12 is basically very similar to the element 11 including a generally planar web portion 12a and oppositely directed first and second flange portions 12, 12c. At its free edge the flange 12b is bent to define an inclined region 12 and the shaping at the edge of the flange portion 12c remote from the web portion 12a differs from that of the element 11. The edge of the flange portion 12c remote from the web portion 12a is bent to a formation 17 which is generally S-shaped transverse cross-section, and which can fit closely within the hook portion 16 of the element 11 when the elements 11 and 12 are positioned with their web portions parallel and their first flange portions extending outwardly, away from one another.

The third element 13 of the lintel is generally in the form of a planar strip the width of which is such that it can overlie substantially the whole of the width of the flange portions llk, 12b and the gap between the web lia 12a when the elements 11, 12 are positioned with the formation 17 received within the hook portion 16 and the web portions 11a, 12a parallel. During construction of the lintel the three elements are arranged in the orientation illustrated in Figure 1 and the element 13 is then welded either continuously, or at a predetermined plurality of spaced locations, to the flange portions llb, 12b.It will be recognised that the interlocking arrangement of the portion 16 and formation 17 interconnects the elements 11, 12 along what will be the top edge of the lintel in use, while the element 13 interconnects the elements 11, 12 along the opposite edge of the lintel. It will be recognised that the upturned portion 15 with the integral hook portion 16, and the formation 17, which are continuous throughout the length of the lintel, contribute significantly to the rigidity (beam strength) of the lintel, as does the element 13.

Furthermore, in use the flanges 11b, 12b receive the courses of brickwork or the like to be supported by the lintel, and these are strengthened by the additional thickness of the element 13.

During the formation of the elements 11, 12, 13 the element 13 and the web portions lla, 12a of the elements 11, 12 are preferably formed, by the rollforming process, with integral ribs 11e, 12e, 13e respectively. The ribs are defined by displacing material, and thus a rib on one face of the material is accompanied by a corresponding recess in the opposite face of the material. The ribs lle, 12e are parallel to one another, and are evenly spaced along the length of their respective web portion lla, l2a. The ribs 11, 12e thus extend substantially vertically when the lintel is in use, and preferably are arranged to be on the inner surface of their respective web portions.The ribs 13e similarly extend transversely of the length of the element 13 and are parallel and evenly spaced. The length of the ribs 13e is slightly less than the spacing between the inner faces of the webs lla, 12a and the element 13 is secured to the elements 11, 12 with the ribs 13e presented to the interior of the lintel. The ribs 11e l2e 13e enhance the rigidity of the lintel.

During use of the lintel it is probable that plaster, or other coating material will be applied to the exposed face of the element 13. The element 13 is thus pierced with apertures 18 to provide a key for the plaster or other covering material. Naturally other alternative surface formations could be provided to give a plaster key.

When the lintel is in use in a cavity wall the web portions lla, 12a will extend within the cavity, and in order that any water running down the cavity shall be directed away from the inner leaf towards the outer leaf there is provided a moulded synthetic resin shield 19 generally in the form an elongate substantially planar strip having either a continuous pair, or a series of spaced pairs, of resilient jaws 21 which can be snap engaged with the upwardly projecting portion 16 and the formation 17 to secure the shield 19 in place along the top edge of the lintel. The shield 19 spans the cavity between the inner and outer leaves of the wall, and is inclined so as to shed water from the inner leaf towards the outer leaf of the wall.

It will be recognised that it is not essential that the flange portions llc, 12c extend at-right angles to their respective web portions lla, 12a and the flange portions llc, 12c could be inclined so as to meet at an apex. Moreover, although it is preferred to spot weld the element 13 to the flanges llb, 12b it is to be understood that other securing arrangements could be used. For example the element 13 could be rivetted to the flanges, or could be secured by screws or the like.

The provision of the upstanding portion 15 with an integral hook portion 16, and the upstanding sinuous formation 17 adds rigidity to the lintel, thus permitting a thinner gauge of material to be used for the elements 11, 12 than would have been the case in the manufacture of a lintel of the same dimensions and same strength but using a configuration not embodying the portions 15, 16 and the formation 17. Similar comments apply to the provision of the element 13 rigidly secured to the flange portions lib, 12b. In the absence of the stiffening effect of the element 13 more material would be required in the manufacture of the elements 11, 12 to achieve a lintel of comparable dimensions and strength. The effect is enhanced by the provision of the ribs 11, 12e. 13e which strengthen the lintel without the need to add material.

In a modification at least the element 13 is formed from stainless steel, rather than mild steel, and rather than welding the element 13 to the flanges llb 12b the width of the element 13 is increased, and its edges, which project beyond the flanges llk, 12 are bent around the flanges llb 12b so as to grip the flanges and thus secured the element in position. Where corrosion resistance is of prime importance then of course the whole of the lintel could be formed from stainless steel, or alternatively a mild steel lintel could be given one or more of a number of different surface finishes to enhance its corrosion resistance.

Claims (9)

CLAIMS:

1 A lintel comprising first and second elongate sheet metal elements, each element having a generally planar web portion and integral therewith, along opposite longitudinal edges of the web portion, first and second generally planar flange portions, said first flange portion of each element lying perpendicular to the respective web portion and said first and second flange portions of each element extending respectively to opposite sides of the plane of their respective web portion, said first and second elements being positioned with their web portions spaced, and generally parallel, their first flange portions generally co-planar, but extending in opposite directions, and their second flange portions extending towards one another, said second flange portions being formed integrally with interlocking regions whereby the second flange portions can interlock along their length, and the lintel further including a third element spanning the gap between the web portions of the first and second elements and secured to the first flanges of said first and second elements, the interlocking means and said third element serving to fix said first and second elements in position relative to one another.

2 A lintel as claimed in Claim 1 wherein said third element is an elongate, generally planar, strip aligned with the first and second elements and secured at a plurality of spaced points along its length to the first flanges of the first and second elements.

3 A lintel as claimed in Claim 1 or Claim 2 wherein said third element is formed with strengthening ribs extending transverse to the length of the first and second elements.

4 A lintel as claimed in any one of Claims 1 to 3 wherein said third element is pierced at a plurality of points to provide a plaster key.

5 A lintel as claimed in any one of the preceding claims wherein the width of said third element is such that the third element overlies substantially the whole width of the first flanges of the first and second elements.

6 A lintel as claimed in any one of the preceding claims wherein the planar webs of the first and second elements are formed with integral strengthening ribs extending transverse to the length of the first and second elements.

7 A lintel as claimed in any one of the preceding claims wherein the interlocking means of the second flanges of the first and second elements project outwardly from the edge of the lintel remote from the third element and are continuous over the length of the lintel so as to add to the beam strength of the lintel.

8 A lintel as claimed in any one of the preceding claims including a moulded synthetic resin shield extending substantially the full length of the lintel and secured thereto as a snap fit.

9 A lintel substantially as hereinbefore described with reference to the accompanying drawings.