This invention relates to elongate structural members, and has particular, though not exclusive application to such members to provide support in confined spaces, for example when converting the loft of a domestic residence into a living area. BACKGROUND ART

When converting a loft in a domestic residence into a living area, it is necessary to locate elongate structural members, for example I-section steel beams, within the loft area to provide support for the subsequently introduced floor joists, and, if appropriate, for the additional rafters required.

Heretofore this has commonly been achieved either by providing scaffolding externally of the building and feeding the members into the loft area through a hole formed in the roof of the building, or by forming a hole in the ceiling below the loft area and feeding the members into the loft area through said hole in the ceiling.

In both cases large scale disruption to the existing structural supports of the building results, while the use of access equipment such as scaffolding towers, temporary supports for the affected part of the building and the like, adds significantly to the cost of the exercise as well as being time consuming to erect .

Additionally, the roof and/or ceiling have to be repaired, while damage is often caused to existing structural members and building fabric, with unwanted debris resulting. This can lead to unnecessary increases in accident risk during the lifting and

manoeuvring of the conventional structural members to the heights necessary for installation into the loft space. DISCLOSURE OF THE INVENTION

It would be desirable to be able to provide an elongate structural member capable of providing substantial support for loads applied thereto, and of such a construction that it can be more readily accessed into confined spaces than a conventional member.

According to the present invention there is provided an elongate structural member characterised by at least one lattice frame the elements of which are pivotally mounted to one another whereby the length of the frame can be adjusted, opposed support means which, in use, are rigidly secured one to each of two opposed surfaces between which the member is to extend, the ends of the or each extended frame being secured to the associated support means, and, for the or each frame, a pair of rigid, elongate locking bars secured one to each edge of the extended frame to extend the length of the frame.

Such a member is of substantial structural strength, and can readily be used in substitution for the l-section steel girders used in, for example, loft conversions.

The locking bars may each comprise a plurality of interconnected sub-elements, which, on securing to the lattice frame, are interconnected with one another to constitute the associated locking bar.

It will thus be appreciated that the elongate structural member of the invention comprises a plurality of components each of which is of relatively compact size, and which can therefore

be readily manoeuvred into the desired location, for example through a loft hatch, and then erected into its operative condition.

In this respect, the lattice frame may comprise a plurality of sub-frame elements which can be interconnected to constitute the frame proper.

The lattice frame preferably comprises a plurality of parallel first struts, a corresponding plurality of parallel second struts, each first strut intersecting an associated second strut and being pivotal relative thereto about a first pivot point central of the first and second struts, one end of each first strut being pivotally mounted at a second pivot point to one end of the adjacent second strut to one side of said associated second strut, and the other end of each first strut being pivotally mounted, at a third pivot point, to one end of the adjacent second strut to the other side of the associated second strut to constitute a frame extensible between a retracted position and any one of a number of extended positions.

Conveniently each second and third pivot point is constituted by a pivot pin and associated nut, each locking bar having a longitudinal slot therein extending the length of the bar to receive therein the nuts of the associated pivot pins, locking means reacting between the nuts and the bars to secure the bars to the lattice frame.

In a preferred embodiment of the invention, adjustment means are provided to react between the support means and the ends of the lattice frame to enable the final position of the ends of the lattice frame relative to the support means to be finely

adj usted .

Said adjustment means may each comprise a screw-threaded arrangement rotation of which achieves the desired adjustment, or may each comprise a plurality of elongate slots in the support means to receive therethrough bolts by which the associated end of the lattice frame is secured to the support element. BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a perspective view of a structural member according to the invention installed in the loft of a domestic residence;

Fig. 2 shows the member of Fig. 1 in more detail;

Fig. 3 is a vertical cross-section through the member of Fig. 2;

Fig. 4 is a side view of the region of connection of one end of the lattice frame with a support element of a structural member according to the invention, and

Fig. 5 is a side view of the lattice frame of a structural member according to the invention in its retracted condition. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In Fig. 1 there is shown a domestic residence having a loft which is to be converted to a living area and in which has been located a structural member according to the invention indicated generally at 2. Rafters 4, floor joists 6 and ceiling joists 8 are shown.

Referring to Fig. 2, a structural member 2 is shown in more detail. Two such members 2 are located in position one to each side of the loft to define the floor area of the conversion, the members 2 so installed serving to support the existing rafters 4

and any other rafters incorporated on conversion of the loft. Additionally, hangers 10 are mounted on and secured to each member 2, the floor joists 6 to constitute the basis of the floor of the converted loft, as well as additional ceiling joists as required, being carried by, to extend between, the opposed hangers 10.

The support member 2 includes an extensible lattice frame indicated generally at 12, a sectional top support rail indicated generally at 14, and a sectional bottom support rail indicated generally at 16.

More particularly, the lattice frame 12 comprises a first series of parallel struts 18 and a second series of parallel struts 20, associated struts 18,20 of the first and second series intersecting one another and being pivotal relative to one another about a first pivot point 22 central of each strut 18,20.

The upper ends of the struts 18 and 20 of the first and second series are pivoted together at second points 24, while the lower ends of the struts 18 and 20 are pivoted together at third points 26 to constitute a frame extensible between a fully retracted condition as shown in Fig. 5 to any one of a number of extended conditions one of which is shown in Fig. 2.

Each pivot point 24,26 is constituted by a pivot pin 28 and a nut 30 as best seen in Fig. 3.

Each support rail 14,16 comprises a plurality of sections 32 which, in use, are secured together by plates 34 to constitute the continuous rails 14,16.

Each support rail 14,16 is formed, in its inner face, with an elongate slot extending the length of the rail 14,16 and

adapted to receive therein the nuts 30 of the second and third pivot points 24,26, attachment means within the slots, for example locking nuts, co-operating with the nuts 30 to secure the rails 14,16 to the lattice frame 12.

The support member of the invention further includes a pair of opposed support brackets 36 one rigidly secured to each of two opposed defining end walls of the loft, and to which the end struts of the lattice frame 12 are attached.

One or both of the brackets 36 may be provided with adjustment means, best seen in Fig. 4, for varying the precise final fixed position of the frame 12.

More particularly, the bracket 36 includes a lower element 38 rigidly secured to the body of the bracket 36 to which the lower end of the endmost strut 18 is connected, and an upper element 40 to which the upper end of the endmost strut 20 is connected. The element 40 is integral with an internally threaded nut 42 mounted for axial movement along a threaded shaft 44 secured to the bracket 36, the nut 42 and shaft 44 constituting adjustment means indicated generally at 46.

Thus it will be appreciated that, once the lattice frame is secured to the brackets 36, any slack in the frame due to, for example, any distortion in, or non-verticality of, the supporting walls, can be accommodated by appropriate actuation of the adjustment means 46.

In an altemative embodiment, the brackets 36 may incorporate vertically and horizontally elongate slots therein to enable their precise position relative to the lattice frame 12 to be varied.

It will be appreciated that the described structural member, prior to installation, can adopt an extremely compact form, the member effectively comprising the two end brackets 36, the lattice frame 12 compacted to the retracted condition of Fig. 5, and the modular sections 32 to constitute the upper and lower support rails 14,16. Furthermore, the lattice frame 12 may itself be broken down into a series of modular lengths for interconnection on location in the loft, thereby further compacting the overall arrangement prior to installation.

On installation, the individual components of the structural member can readily be located in the loft through the conventional hatch and without the necessity for any substantial alteration to the structure of the building.

The support brackets 36 are mechanically secured to the opposed end walls of the loft, and one end of the lattice frame 12 is secured to one of the brackets 36. If the lattice frame 12 is of modular construction, the individual lengths are interconnected as required, and the frame 12 is extended across the length of the loft.

The other end of the frame 12 is secured to the other bracket 36, and the adjustment means 46 are actuated to achieve the final position of the frame 12.

The sections 32 of the top and bottom support rails 14,16 are then secured to the frame 12 and to each other by the plates 34, thereby completing the formation of an elongate member with substantially structural rigidity.

As previously mentioned, two such members are located one to each side of the loft area, hangers 10 being secured to the

bottom rail 16 to support floor joists 4 between the existing ceiling joists 8, and, if appropriate, additional ceiling joists.

The height of the structural member is such that the top rail 14 supports the existing rafters 4 and any additional rafters that may be required.

The finite height to the member, as determined primarily by the depth of the frame 12, enables the members themselves to constitute sidewalls to the living area of the converted loft. More particularly, the inner faces of the members can be clad with plasterboard or the like and insulated.

Each bracket 36 may be replaced by a pair of brackets, the free end of the associated endmost first strut 18 being secured to one of said brackets of the pair, and the free end of the associated endmost second strut 20 being secured to the other bracket of said pair.

The brackets of each pair may be movable relative to one another, for example by being slidable one on the other, whereby the distance between the brackets can be varied to accommodate lattice frames of different extended depths.

The brackets 36 are conveniently of metal, while the struts 18,20 and sections 32 of the rails 14,18 may be of wood or metal, although other materials such as glass reinforced plastic, carbon fibre and the like may be used.

Although described in relation to the conversion of a loft space into a living area, the elongate structural member of the invention has numerous other applications where support is required and whether access to the region of support is restricted or otherwise.

Such applications may be associated with the construction industry, the rescue services, the provision of emergency relief or aid, military and shipping situations, and the offshore oil industry.

Instead of incorporating a single extensible lattice frame, the structural member of the invention may be of, for example, hollow triangular or rectangular shape in transverse section with a lattice frame extending along each side of the member and a locking bar along each corner edge of the member.

Other modifications and variations from the described and illustrated arrangements will be apparent to those skilled in the art.