GB2103680A - Lintel and wall comprising same - Google Patents

Abstract

A lintel in the outer leaf of a cavity wall comprises a horizontal limb (11) with a drip lip (13) and a vertical limb (12) which abuts the inner face of the outer leaf. The lintel is not connected to the inner skin (21), which includes a separate concrete lintel (19). <IMAGE>

Description

SPECIFICATION Lintel and wall comprising same This invention relates to a lintel for use in bridging an opening, such as a door or window opening, in a wall of a building.

Many different types of lintel have previously been proposed for use in cavity walls, for example concrete lintels, rolled steel T or I-section beams -and hollow box lintels fabricated from galvanized steel sheet.

However, cavity wall lintels generally suffer from the disadvantage that they are capable of use only in cavity walls with cavities of a particular width, to which the appropriate dimensions of the lintel correspond. Specific portions of the lintel lie within, or span the cavity.

Where an unusually large or unusually small cavity is provided, specially made lintels have to be used, which increases cost. Furthermore, in the case of a building of timber-framed construction with a masonry outer leaf, a conventional cavity wall lintel is unsuitable because the outer leaf needs to be supported independently of the timber frame. The width of any cavity between the timber frame and the outer leaf may be determined during construction of the building and use of a lintel designed for a wall having a cavity of predetermined width may give rise to difficulty.

It is an object of the present invention to provide a lintel of a simple form which is capable of being used in building constructions of a variety of kinds, to support an outer leaf of masonry.

According to the invention there is provided a lintel comprising a one piece sheet metal member having a substantially constant cross-section comprising first and second limbs disposed substantially at right angles to each other and having respective edge flanges which present free edges of the limbs, each edge flange extending from the remainder of its limb in a direction away from the included right angle between the limbs.

The lintel is preferably formed by pressing.

Alternatively, it may be formed by cold rolling.

The lintel may be made of pre-galvanized steel sheet. The preferred range of thickness of the sheet is between 2.5 mm and 3.5 mm. Additional corrosion resistance may be provided by a coating of for example chlorinated rubber paint applied to the lintel.

A lintel embodying the invention will now be described in more detail by way of example only with reference to the accompanying drawings in which: FIGURE 1 is a scrap perspective view of a lintel embodying the invention shown in situ in a cavity wall; and FIGURE 2 is a sectional view of the lintel illustrating possible modifications.

Referring firstly to Figure 2 of the drawings, a lintel is generally indicated at 10. It is of constant transverse cross-section throughout its length and is formed as a pressing, or as a cold rolled section, from a single sheet of pre-galvanized steel.

The lintel 10 has a transverse cross-section which is generally L-shaped. It comprises a first limb 11 and a second limb 12, disposed substantially at right angles to each other. The first limb 11 has a length measured in a direction at right angles to the second limb from the second limb to the free edge of the first limb which is approximately equal to the width of a standard brick or block used in building. Typically the length of this limb is 3;0 mm. The second limb 12 has a height which is determined only by the free span and the design loading to be placed on the lintel. It is not restricted by the height of the masonry elements of the outer leaf or their coursing because the outer leaf merely abuts the second limb and does not have any connection with it. A deep second limb is used for relatively long spans or heavy design loads.

The first limb includes an integral first edge flange 1 3 which presents a free edge of the first limb and which is inclined at a shallow obtuse angle with respect to the remaining, flat part of the limb 11. This angle as indicated is approximately 1 700 in the drawings but may be of any size between approximately 1200 and 1750.

In use, the first edge flange 13 forms a drip lip for the lintel.

The second limb 12 also includes an edge flange, this being the second edge flange 1 4 and presenting a free edge of the second limb. In the drawings, the second edge flange 14 extends substantially at right angles to the remaining, flat part of the second limb 12. However, it could extend at an acute or an obtuse angle with respect to the remaining part of the second limb 12, the angle lying between approximately 400 and approximately 1400. The range of alternative positions is as illustrated in dotted lines at 1 5 and 16.

Figure 1 illustrates a cavity wall incorporating the lintel shown in Figure 2. The wall comprises an outer leaf 9 which is formed primarily of masonry and an inner leaf 21 which may also be formed of masonry or may have some other construction.

For example, the inner leaf may comprise a timber frame of a building. There would normally be a cavity between the inner and outer leaves. The inner and outer leaves define an opening 1 8 for a doorway or window and the lintel spans the opening in the outer leaf only. As shown in Figure 1, the lintel is arranged with its first limb 11 generally horizontal to form a base surface on which masonry of the outer leaf 9 is supported.

Opposite end portions of the first limb rest on bearing portions 1 7 of the outer leaf on opposite sides of the opening 18. The second limb 12 extends upwardly from the horizontal limb 11 and is generally vertical.

The first edge flange 1 3 lies adjacent to the outer face of the outer leaf 9 of the wall.

Because of the relatively thin gauge of the first limb 11, no interruption to the coursing of the masonry occurs and the lintel is virtually invisible except from below, the drip lip formed by the first edge flange 13 projecting down slightly below the masonry elements to allow water to drip clear of the window or door opening below the lintel.

The masonry is laid against the upright second limb 12, which therefore defines the forward or outer boundary of the cavity of the wall. The second edge flange 14 provides a stiffening formation which reduces the tendency of the upright second limb to bend under load.

It will be noted that the free edge of the second limb 12 lies nearer to the outer leaf 9 than to the inner leaf 21. The edge flange 14 protrudes only slightly into the cavity between the leaves and can therefore be accommodated in any cavity which is likely to be provided between the leaves of a wall of a building. The distance which the second edge flange projects into the cavity from the outer leaf is preferably within the range 7 mm to 21 mm.

The second limb 12 contacts the outer leaf at at least some positions spaced from the first limb 11.

In some cases, particularly those in which the edge flange 14 extends upwardly to the free edge of the second limb, the edge flange may extend across the cavity to the inner leaf.

Considering the lintel as a loaded beam in use, the generally horizontal first limb will tend to be extended and the upper edge of the upright second limb to be compressed under load. It has been found that the provision of the second edge flange 14 greatly resists any tendency for the second limb to buckle when the lintel is in use under load.

By means of this second edge flange which provides additional stiffness to the second limb, it is not necessary to make the lintel of excessively heavy gauge metal, which would result in a heavy and expensive construction. The use of heavy gauge metal would also interfere with the coursing of masonry in the outer leaf.

From the point of view of corrosion resistance, it will be noted that the lintel described is made from a single pre-galvanized steel sheet and does not incorporate any welds, which might interrupt the continuity of the galvanic coating. In order to provide additional protection, a coating of a protective agent such as chlorinated rubber paint may additionally be provided on the finished lintel, in order to resist corrosion even in those portions of the lintel which are in contact with the mortar of the outer leaf.

In conventional masonry cavity walls, the inner leaf of masonry can be supported over the opening 18 by any suitable means, for example the concrete lintel shown at 19, a hollow box-section metal lintel or an in-filled lintel. It will be seen that no connection is required between the inner and outer lintels, so that the lintel 10 can be used in a wide variety of types of building construction. For example, it can be used where the cavity between the inner and outer leaves is exceptionally narrow or exceptionally wide, for example to accommodate extra cavity insulation. It can also be used with the timber frame type of construction in which the inner leaf of the wall is in fact a selfsupporting timber frame, requiring no additional lintel.

Where the lintel 10 is used in a cavity wall construction, some form of damp-proof element must be used across the cavity 20 so that any moisture in the cavity is diverted outwardly to the outer skin of masonry and can then be discharged outside the building. The damp proofing can readily be carried out using a suitable flexible damp-proof membrane which is inserted between the masonry elements of the inner leaf 21 allowed to span the cavity downwardly towards the lintel 10 and is then located over the rearwardly extending second edge flange 14, and against the outer face of the second limb 12 of the lintel. Thus, the second edge flange 14 provides a guide for the damp-proof elements to be laid across the cavity.

Before using the lintel, during general handling on site, the second edge flange 14 assists in keeping the lintel in a straight and undistorted form, irrespective of whether the second limb is in compression or tension. Similarly, the first edge flange tends to stiffen the first limb.

It will be noted that the cavity between the inner leaf 21 and outer leaf 9 is open immediately adjacent to the top of the opening 1 8 and that the head of a door or window frame can be accommodated in the cavity adjacent to the second limb 1 2.

As referred to above, the lintel can be used in cavity walls of different cavity sizes or indeed of irregular cavity size, which may occur particularly in the timber frame type of construction. This is made possible because the lintel is not connected in any way to the inner leaf of the wall. This has the additional advantage that the cavity below the gap 1 8 in the wall is accessible and can be used to receive the head of a door or window frame, or other structural elements if desired. Naturally, a plaster retaining key can be mounted in any suitable position in generally known manner to carry plaster as necessary.

The dimensions of the lintel may vary but typically the first limb and first edge flange together will have a length of approximately 90 mm, equivalent to the width of a standard house brick and the second limb will have a height dependent on the free span of the lintel and its design loading in use. The preferred thickness of the metal is 3 mm so as to avoid interference with the coursing of the masonry. The second edge flange, extending into the cavity, is preferably between 10 mm and 15 mm, and typically 12 mm in length so as not to cause any interference with even a narrow cavity.

Claims (1)

1. A wall of a building comprising inner and outer leaves wherein the outer leaf is formed primarily of masonry, the wall defines a doorway or window opening, the outer leaf includes a lintel spanning the opening, said lintel has a crosssection in a plane transverse to its length which includes a horizontal limb lying beneath masonry of the outer leaf and a second limb extending upwardly from the horizontal limb to terminate in a free edge which lies nearer to the outer leaf than to the inner leaf.

2. A wall according to Claim 1 wherein the second limb is substantially vertical.

3. A wall according to Claim 2 wherein the outer leaf contacts the second limb adjacent to the upper extremity of the second limb.

4. A wall according to any preceding Claim wherein there is a cavity between the inner and outer leafs and the second limb does not extend substantially into the cavity.

5. A wall according to any one of Claims 1 to 3 wherein the lintel does not extend into the inner leaf.

6. A lintel for use in a wall according to Claim 1 and comprising a one-piece sheet metal member having a substantially constant transverse crosssection comprising first and second limbs disposed substantially at right angles to each other and having respective first and second edge flanges, each flange extending from the remainder of the corresponding limb in a direction away from the included right angle between the limbs.

7. A wall according to any one of Claims 1 to 5 wherein said limbs have respective edge flanges, each of which extends from the remainder of its limb in a direction away from the masonry of the outer leaf which rests on the horizontal limb of the lintel.

8. A lintel according to Claim 6 or a wall according to Claim 7 wherein the first edge flange is adapted to act as a drip lip and is inclined at an angle within the range 1200 to 1700 to the remainder of the first limb.

8. A lintel according to Claim 6 or a wall according to Claim 7 wherein the second edge flange is inclined to the remainder of the second limb at an angle within the range 400 to 1400.

10. A lintel substantially as herein described with reference to and as shown in the accompanying drawings.

11. Any novel feature or novel combination of features disclosed herein or in the accompanying drawings.