GB2250769A

GB2250769A - Building construction and a template for use therein

Info

Publication number: GB2250769A
Application number: GB9125741A
Authority: GB
Inventors: George Molyneux
Original assignee: Radway Plastics Ltd
Current assignee: Radway Plastics Ltd
Priority date: 1990-12-04
Filing date: 1991-12-03
Publication date: 1992-06-17
Anticipated expiration: 2011-12-03
Also published as: GB9026313D0; GB9125741D0; GB2250769B

Abstract

A template 20 for use in a door or window opening of a building structure, comprises a temporary frame 22 and two permanent jamb elements 24. Four corner pieces 28 are joined by two vertical struts 30 and 32 and two horizontal struts 34 and 36 to form a rectangular frame. The height and width of the rectangular frame may be adjusted by telescopic engagement of the struts with the corner pieces, to accommodate differently sized door or window openings. The permanent jamb elements are releasably attached to the struts 30, 32, eg by bolts, so that the template can be removed after completion of the wall of the building structure. <IMAGE>

Description

Building construction and a template for use therein In traditional building methods, where a window or door frame has to be fitted into a wall, the actual, permanent window or door frame is placed in position at the stage when the brickwork or blockwork of the wall has reached the level of the sill and then the brickwork or other blockwork is built up around the door or window frame.

The only purpose served by the frame at that stage in the construction work is to provide an effective "template", to ensure that the frame is a good fit in the finished wall.

This traditional method is becoming unpopular for a variety of reasons. In particular:1) It requires that the door and window frames are purchased by the builder at a very early stage in construction, long before the frame is required for its permanent function. Besides tying up capital, if there are delivery problems with the frame, then the whole construction is delayed.

2) It means that the frames are susceptible to damage during building construction.

3) Any fittings provided on the frame (including items such as anti-burglar locks) are exposed to the weather from the stage at which the frames arrive on site (sometimes before building has commenced) to the time, near the end of construction, when the glazing is fitted.

4) In practically all cases, where timber window frames are used, the frame is built into the wall with only a priming coat of paint. Hence, the surfaces of the frame exposed to the brickwork (which can be wet for long periods) are inadequately protected; this is a source of frame rotting.

Some of these problems become more acute when plastics or ready-finished high-quality timber frames are specified and, although plastics window frames are now widely employed in buildings, they are rarely fitted in new buildings during construction.

For all these reasons, it is becoming quite common to use a temporary timber frame which provides a template for the brickwork during building, but which is removed from the brickwork when the permanent door or window frame is fitted. The temporary timber frame is constructed on site by a carpenter, who is able to make a reasonably accurately sized and squared template from cheap timber.

Although the temporary frame overcomes most of the disadvantages of the traditional method previously described, it has its own disadvantages - for example:1) The temporary frame is frequently manufactured from materials ordered for other purposes, and this can cause problems on a site if the temporary frame is still in situ when the timber, from which it is made, is required for the other purpose.

2) In order to ensure that the temporary frame maintains its rigidity and remains "squared up", it has to be made of substantial timbers, including bracings, and this increases its weight, making it cumbersome to handle.

3) The rough construction techniques relying solely on nailing to maintain the squared shape, means that the temporary frame is seen by workmen as a rough piece of equipment, rendering it liable to correspondingly rough treatment. Any rough handling may cause the temporary frame to lose its shape, so that it is no longer properly effective.

4) In practice, because of their rough construction, such temporary frames are rarely used more than once, and in any event, they can only be re-used if a second window or door opening of exactly the same dimensions as the first is required. The method of construction does not lend itself to dismantling and re-building, even if a smaller temporary frame is needed. If a temporary frame is only used once, it becomes relatively expensive.

There have been proposals for more sophisticated temporary frames, which can be adjusted to various sizes of opening, but these have been either too flimsy, or else have been made of substantial metal box sections, which are not only expensive, but very difficult to handle - especially if the temporary frame has to be removed from a first floor or higher level, after the scaffolding has been removed.

A further problem with previous proposals for temporary frames is that they either do not provide true vertical planar faces for locating the ends of the brickwork, or such a face is only obtained by a relatively complicated construction.

It is the object of the invention to provide a template for use in a door or window opening of a building structure, which avoids some or all of the problems of the known temporary timber frame template, and which is more economical and more effective than other proposed types of temporary frame. The invention also includes a method of building employing a template, and a structural assembly incorporating such a template.

According to a first aspect of the present invention there is provided a template for use in a door or window opening of a building structure, comprising a rectangular temporary frame having a sill, a head and two jambs, and permanent jamb elements, each adapted for securing to a respective vertical end of a wall, the template providing a locating jamb for the window or door frame, each of the permanent jamb elements being releasably attached to the temporary frame, so that when the part of a wall surrounding the window or door opening has been built, the temporary frame can be released from the permanent jamb elements and removed from the wall, leaving the permanent jamb elements secured to the wall, wherein at least one of the jambs comprises at least one substantially hollow corner location member and at least one strut, inserted in the hollow corner location member, said strut being clamped against at least one of the inside or outside walls of said corner location member.

Preferably the strut is clamped by screw-and-nut means.

In a preferred arrangement the screw is arranged to pass through the strut.

Alternatively the screw may be arranged to abut the strut.

Preferably at least one of the corner location members is provided with one or more internal projections to provide one or more location surfaces inside the corner location member, which surfaces, in use, provide locations for the strut.

Each of the internal projections may provide a limited area location surface.

The projection may be a channel, which channel is arranged to receive the head of a screw or bolt used for securing the strut to the corner location member, the depth of the channel being such that the head of the screw or bolt is entirely housed within the channel.

Preferably the location surface is provided on an inner wall of the corner location member.

Alternatively or additionally, the location surface may be provided on an outer wall of the corner location member.

At least one of said permanent jamb elements may be arranged, in use, to enter, at least partially, a cavity of the wall.

According to a second aspect of the present invention there is provided a template for use in a door or window opening of a building structure, comprising: a rectangular temporary frame having a sill, a head and two jambs, and permanent jamb elements, each adapted for securing to a respective vertical end of a wall, in which the template is used, so as to provide a locating jamb for the window or door frame, each of the permanent jamb elements being releasably attached to the temporary frame, so that when the part of a wall surrounding the window or door opening has been built, the temporary frame can be released from the permanent jamb elements and removed from the wall, leaving the permanent jamb elements secure to the wall, wherein at least one of the jambs comprises at least one substantially hollow corner location member and a strut fitted into the corner location member, the latter having one or more internal projections to provide one or more location surfaces inside the corner location member, which surfaces, in use, provide locations for the strut.

Preferably each of the internal projections provides a limited area location surface.

The projection may be formed by a channel in the corner location member, open on the outside, which channel is arranged to receive the head of a screw or bolt used for securing the strut to the corner location member, the depth of the channel being such that the head of the screw or bolt is entirely housed within the channel.

The channel may be formed in a "jamb" element of each corner location member.

In a preferred arrangement the location surface is provided on an inner wall of the corner location member.

According to a third aspect of the present invention there is provided a template for use in a door or window opening of a building structure, comprising: a rectangular temporary frame having a sill, a head and two jambs, and a permanent jamb element which, in use, is arranged to be temporarily attached, at spaced locations, to the jamb during the forming of a wall portion of the building structure, and subsequently released from the jamb upon completion of the wall portion and secured to the wall portion, the template further comprising at least one support member attached to the jamb between the spaced apart locations and arranged to provide support against deflection for the permanent jamb element.

The position of the support member between the spaced apart locations may be ajustable.

Preferably the support member is slideably attached to the jamb.

In a preferred arrangement the support member is arranged to be attached to the jamb by means of a snap-on fitting.

The support member may comprise a clip arranged to at least partially embrace the jamb, the clip having at least one resiliently biased portion which, in use, bears against the jamb.

Preferably the support member comprises two resiliently biased portions, each being arranged, in use, to bear against the jamb.

The support member may comprise a clip made of spring steel.

Each corner location member may comprise a pair of straight hollow elements jointed in an "L" configuration.

In a preferred arrangement the two hollow elements are each located on a corner piece, comprising two arms secured together in a right-angular "L" configuration, each of the arms locating in a respective one of the two straight hollow elements.

The two straight hollow elements may abut one another so as to form a complete corner location on the outside of the corner location member.

Preferably the two straight hollow elements abut each other in a mitred joint.

Each strut may be received at its ends in one of the straight hollow elements of the corner location members at two adjacent corners.

In a preferred arrangement a connection is established between each strut and each of the corner location members into which it is fitted by means of a bolt or like releasable fastening passing through the straight hollow element of the corner member and through that part of the strut which is within that straight hollow element.

Each releasable fastening may have a head received in but not projecting from the open channel in the outside of its respective straight hollow element.

Preferably there are two bolts or like releasable fastenings connecting each end of each strut in its respective straight hollow element, the two fastenings being spaced apart longitudinally of the strut.

In a preferred arrangement each corner member includes angular bracing.

A diagonal brace may extend between the two straight hollow elements of each corner member.

The brace may comprise a triangular plate secured to the two straight hollow elements in the angle between them.

Preferably each of the straight hollow elements of each corner member has a location rib projecting from and extending along the length of its inside face and the brace is secured at its ends or longitudinal margins to the same face of the two ribs of the two straight hollow elements.

The straight hollow elements of the corner member may be made of plastics material.

The straight hollow elements of the corner members may be made as plastics extrusions.

Alternatively or additionally each strut may be made of timber.

Each strut may be made in plastics material.

Each strut may be made as an extrusion.

In a preferred arrangement each permanent jamb element comprises: a flange engaging on the outside face of its respective jamb of the temporary frame and a cavity entering portion, adapted to enter the cavity between the two leaves of a cavity wall at an end of the wall adjacent to an opening for a door or window frame.

The flange of the permanent jamb element may be formed with a rib, against which the front or rear face of the jamb of the temporary frame engages to provide front and rear location of the temporary frame.

Preferably the flange of the permanent jamb element extends on the opposite side of the ribs to the jamb of the temporary frame, to provide a location face for the outside face of the jamb of a door or window to be fitted between the two permanent jamb elements.

One or more undercut recesses may be formed in the inner face of the flange of the permanent jamb element, to form a plaster key after the temporary frame has been removed.

An undercut recess may be formed in and extend along the length of a face of the cavity entering portion of the permanent jamb element, to provide an anchorage for wall ties or an anchorage for mortar squeezed out from the courses of bricks or blocks in the leaves of a wall into which the cavity entering portion can be received at any location along the length of the permanent jamb element.

Preferably a moisture barrier is formed on the cavity entering portion of the permanent jamb element, to resist migration of moisture across the cavity when the permanent jamb element is built into a cavity wall.

In a preferred arrangement at least part of the flange of the permanent jamb element extends beyond the width of the cavity entering part and is adapted to engage with the end of one of the leaves of the wall when the permanent jamb element is built into a cavity wall.

An undercut recess may be formed in and extend along the length of the outer face of that part of the flange of the permanent jamb which is adapted to engage with the end of one leaf of the cavity wall, to provide an anchorage for wall ties or to receive mortar squeezed out from between the courses of bricks or blocks in the cavity wall at any position along its length.

Each permanent jamb element may be made of plastics material.

Preferably each permanent jamb element is made as an extrusion.

In a preferred arrangement each permanent jamb element is attached to its respective jamb of the temporary frame by a bolt or like fastening passed through the jamb and through the permanent jamb element, there being a nut on the outside of the permanent jamb element and means inhibiting rotation of the nut.

The nut may be a toggle-type nut.

Alternatively or additionally each permanent jamb element may be attached to its respective jamb of the temporary frame by an adhesive tape.

Each of the flange and the cavity entering portions of each permanent jamb may be of flat planar form, the cavity entering portion projecting at right-angles from the outer face of the flange.

The template may further comprise a draught screen, closing at least the major part of the opening through the temporary frame.

The draught screen may be attached to the braces of all the corner members of the temporary frame.

Preferably there is at least one space between one of the struts of the temporary frame and the draught screen, large enough to permit the passage of a plank as used on scaffolding.

According to a fourth aspect of the present invention there is provided a method of building a wall, having an opening to accept a preformed door or window frame, comprising: building the wall up to the level of the door or window sill; placing on the partly built wall a template which comprises a temporary frame, to which are releasably attached permanent jamb elements; continuing to build up the wall, so that the permanent jamb elements become secured to the wall; fixing a lintel over the head of the template; releasing the temporary frame from the permanent jamb elements and removing the temporary frame from the wall, leaving the permanent jamb elements in situ in the wall, whereby a door or window opening is defined by: the wall below the opening; the two permanent jamb elements and the lintel.

The method may comprise constructing a template substantially as herein described with reference to the accompanying drawings.

According to a fifth aspect of the present invention there is provided a structural assembly, comprising: a wall built of bricks or other building blocks; a template built into the wall to define an opening for a door or window frame; the template comprising a temporary frame, to which are releasably attached permanent jamb elements; the permanent jamb elements being secured to the wall, whereby the temporary frame can be removed from the structure by releasing it from the permanent jamb elements.

The structural assembly may comprise a template substantially as herein described with reference to the accompanying drawings.

The invention also includes a method of building, substantially as herein described with reference to Figures 1 to 16 of the accompanying drawings.

The invention also includes a structural assembly, constructed and arranged substantially as herein described, with reference to Figures 1 to 16 of the accompanying drawings.

The template therefore differs from the conventional temporary frame and the proposed variable dimension temporary frames, in that it employs the permanent jamb elements which remain in situ in the wall when the temporary frame is removed, so that the permanent jamb elements provide the location surfaces for the outsides of the jambs of the door or window frame, which will be fitted into the wall after the temporary frame is removed.

This is important, because it is the permanent jamb elements which provide the vertical planar faces, against which the ends of the bricks or blocks of the wall have to abut when the window or door opening is being formed in a wall. Consequently, it is not necessary to provide the vertical planar surfaces on the outs ides of the temporary frame, and this facilitates the provision of an adjustable sized temporary frame. Furthermore, the permanent jamb elements may perform useful functions in the building structure.For example, each such jamb element may provide a damp-proof course between the two leaves of a cavity wall at the end of the wall adjacent to the opening; it may provide a damp-proof course between the end of the wall (which is frequently wet for long periods) and the jamb of the door or window frame; it may provide a closure for the end of a cavity in the wall; it may provide a means of tying together the two leaves of the cavity wall in the vicinity of the opening (where the traditional construction is usually weak); and it may provide thermal insulation at the end of the cavity.

Indeed, it is possible to use as the permanent jamb elements any of the cavity closer and damp-proof course elements described, for example, in United Kingdom Patents Nos. 1 302 694; 1 302 695; 1 302 696 and 1 388 608, sold under the Registered Trade Mark DACATIE.

The invention is partly based on the appreciation that a door or window template is not required to provide planar location surfaces for the brickwork above and below the opening. This is because the sill is built before the template is placed in position, and the head of the opening is provided by the lintel. Hence, it is only necessary to provide permanent jamb elements to create the vertical planar location surfaces for the brickwork.

In a preferred construction of the temporary frame, each strut is received at its ends in one of the straight hollow elements of the corner location members at two adjacent corners. This construction allows struts of different lengths to be used with a set of the corner members to produce temporary frames in a wide variety of sizes. It also allows for some telescoping of each strut in one or both of the corner members into which it is fitted. However, this very convenient method of construction has the drawback that the outer face of a strut is not in the same plane as the outer face of the corner pieces. This problem is obviated by the use of the permanent jamb elements, which can rest on the outer faces of the jamb parts of the corner members without engaging with the struts themselves.As has been shown, the fact that the top and bottom struts do not have their outer faces in the same plane as the top and bottom faces of the corner members does not matter, because the top and bottom faces of the temporary frame do not define the top and bottom edges of the wall at the opening.

The struts may be made of timber or of plastics material.

A plastics strut may conveniently be made as an extrusion, as this permits the manufacture of relatively long lengths of material, which can then be cut to the required strut length on site.

According to a still further preferred feature of the invention, each permanent jamb element comprises: a flange engaging on the outside face of its respective jamb of the temporary frame and a cavity entering portion adapted to enter the cavity between the two leaves of a wall at the end of the wall adjacent to an opening for a door or window frame. The use of a permanent jamb element having a cavity entering portion enables that portion to be used as a means of securing the jamb element to the cavity wall. It also allows the cavity entering portion to be used to provide a damp-proof course between the two leaves of the cavity wall and it allows the jamb element to extend across the width of the cavity, so that it forms a cavity closer, thereby obviating the need for cutting bricks to close the end of the cavity in the traditional manner. Furthermore, it can provide location for thermal insulation at the end of the cavity.

Preferably, the flange of the permanent jamb element is formed with a rib, against which the front or rear face of the jamb of the temporary frame engages to provide front and rear location of the temporary frame. It is further preferred that the flange of the permanent jamb element extends on the opposite side of the rib to the jamb of the temporary frame, to provide a location face for the outside face of the jamb of the door or window to be fitted between the two permanent jamb elements.

In the preferred construction, one or more undercut recesses is or are formed in the inner face of the flange of the permanent jamb element to form a plaster key after the temporary frame has been removed. Preferably an undercut recess is formed in and extends along the length of a face of the cavity entering portion of the permanent jamb element to provide an anchorage for wall ties or an anchorage for mortar squeezed out from the courses of bricks or blocks in the leaves of a wall into which the cavity entering portion can be received at any location along the length of the permanent jamb element.

Also in the preferred construction, a moisture barrier is formed on the cavity entering portion of the permanent jamb element to resist migration of moisture across the cavity when the permanent jamb element is built into a cavity wall.

Another preferred feature of the invention is that at least part of the flange of the permanent jamb element extends beyond the width of the cavity entering part and is adapted to engage with the end of one of the leaves of the wall when the permanent jamb element is built into a cavity wall. Preferably, an undercut recess is formed in and extends along the length of the outer face of that part of'the flange of the permanent jamb which is adapted to engage with the end of one leaf of the cavity wall, to provide an anchorage for wall ties or to receive mortar squeezed out from between the courses of bricks or blocks in the cavity wall at any position along its length.

It is preferred that each permanent jamb element is made of plastics material, and it is further preferred that each permanent jamb element is made as an extrusion. As with the struts, the extrusion method of production allows the manufacture of long lengths of the permanent jamb sections, so that it can be cut to the required length on site.

Preferably, each permanent jamb is attached to its respective jamb of the temporary frame by a bolt or like fastening passed through the jamb and through the permanent jamb element, there being a nut on the outside of the permanent jamb element and means inhibiting rotation of the nut. The nut may be a toggle-type nut.

Alternatively, each permanent jamb element may be attached to its respective jamb of the temporary frame by an adhesive tape.

According to an alternative feature of the invention, each of the flange and the cavity entering portion of each permanent jamb is of flat planar form, the cavity entering portion projecting at right angles from the outer face of the flange. Such a permanent jamb may be made of plastics material, and may be made by an extrusion process.

The template may be provided with a draught screen, closing at least the major part of the opening through the temporary frame. Such a draught screen may be attached to the braces of all the corner members of the template frame. Preferably, there is at least one space between one of the struts of the temporary frame and the draught screen large enough to permit the passage of a plank as used on scaffolding.

The invention will be better understood from the following description of various practical embodiments of it, which are given here by way of examples only. In the drawings: Figure 1 is a somewhat diagrammatic front view of a template for a window opening, shown placed in a brick wall at the stage in the building when the wall is at the height of the window sill; Figure 2 is an elevation of a corner member for a temporary frame forming part of the template; Figure 3 is a perspective view of the corner member shown in Figure 2; Figures 4A and 4B are cross-sectional views of two different embodiments of corner members, each having a strut located therein; Figure 5 is a perspective view of a corner part of a temporary frame, employing a corner member and strut as shown in Figure 4A;; Figure 6 is a perspective view showing a method of securing a timber strut in a corner member; Figure 7 is an elevation of a window template, including a central brace; Figure 8 is a perspective view showing a method of providing a frame brace at a position between the corners, using a timber strut; Figure 9 is a section through part of a corner member, with one form of permanent jamb element attached to it; Figure 10 is a view similar to Figure 9, but showing an alternative form of permanent jamb element; Figure 11 is an elevation of a template with a draught screen fitted to it; Figure 12 is a section through part of a corner member showing another form of permanent jamb element fitted to it; Figure 13 illustrates a jamb element of the type shown in Figure 12 used in the end of a cavity wall closed by the traditional method;; Figure 14 is a view similar to Figure 13, but showing the permanent jamb element in an alternative orientation; Figure 15 shows an alternative means of locating a strut against a face of a corner member; and Figure 16 shows an adjustable support releasably attached to a strut.

In Figure 1, there is illustrated a partly built brick wall 10, at the stage in building construction when the top surface of the top course of bricks is at the level of the sill for a window opening. Sometimes, of course, a preformed concrete sill will be positioned in the brick wall, the top surface of the sill then providing the surface on which the window frame (not shown) eventually rests. Alternatively, the sill may be incorporated in the actual window frame, but in that case the sill rests on the top course of bricks under the window frame, the top surface of which can still be regarded for present purposes as being at sill level. In this specific example, it is assumed that an opening has to be formed in the brick wall, to accept a window frame, which is square and may be, for example, 900 mm square.

In accordance with the invention, a template 20 is provided, which comprises a temporary frame 22, and two permanent jamb elements 24. The construction of the template 20 will be described in greater detail, but it will be noted from Figure 1, that the template is stood upright on the sill provided by the top course of bricks in the wall 10, and it is positioned in precisely the position which is to be occupied by the eventual window frame. Once the template 20 is thus located on the brick wall, the wall can then be built up on both sides of the template 20, and a lintel, indicated in dotted lines at 26, can be positioned across the head of the template 20, and built into the brick wall in conventional fashion. In this manner, the template is incorporated into the wall construction-during building, and forms an opening in the brickwork, which is of the required shape and size for occupation by the preformed window frame at a later stage in the construction work It will be observed from Figure 1 that the temporary frame 22 itself comprises four corner pieces 28, joined by two vertical struts 30 and 32 and two horizontal struts 34 and 36, to form a rectangular (in this case square) frame.

The struts 30, 32, 34 and 36 are indicated by dotted lines in Figure 1, because, as will hereinafter appear, they can take various forms.

Turning to Figures 2, 3 and 5, there is illustrated a single corner piece, which itself comprises a pair of straight hollow elements 38 and 40, disposed at 900 to each other, and joined in abutting relationship at a mitred joint 42. The cross-sectional shape of the hollow elements 38 and 40 is apparent from Figures 3, 4 and 5, and is essentially that of a rectangle, with an open channel 44 extending along the outer wall. There is also a rib 46 in extension of one of the side walls of the hollow box construction. Figure 4B shows the crosssection of an alternative embodiment of hollow element, having grooves 44b extending along the outer wall.

The hollow longitudinal elements are manufactured in unsaturated polyvinylchloride (uPVC) of similar grade to that which is used for the manufacture of many building products, such as gutters and drainpipes. One of the advantages of this material is that it is completely weather-resistant, which, of course, is of advantage, since the template 20, which incorporates the corner members 28, will be required to stand in the building during the period of construction, and will therefore be exposed to all weather conditions. In practice, the hollow section is made by an extrusion process, since it is of constant cross-section throughout its length, and then the lengths of the hollow section required to form the longitudinal members 38 and 40 of the corner member are cut from the extruded length, mitred and secured together by conventional plastics welding techniques.

In order to facilitate construction of the corner member 28, and, in particular, to ensure that the two longitudinal elements 38 and 40 are properly disposed at right-angles to each other, a small corner piece 50 is employed. This corner piece is, itself, made from extruded plastics hollow sections similar to those used for the longitudinal elements 38 and 40, but of slightly smaller external dimensions, so that the legs of the corner piece are a sliding fit within the longitudinal elements 38 and 40. It will be appreciated that it is relatively easy to manufacture the corner piece 50 in an accurate right-angular form, and this then provides location for the elements 38 and 40 when they are being assembled, and also strengthens the corner member 28.The corner member is completed by a triangular bracing plate 52, which is a snug fit in the angle between the elements 38 and 40, and which is secured by solvent welding to the faces of the ribs 46 on the elements 38 and 40, and if desired, by welding to the inside walls of the elements 38 and 40. Once the brace plate 52 is secured in position, it ensures that the longitudinal hollow elements 38 and 40 are held rigidly in their right-angular disposition. As will appear, it is of importance that the corner members 28 should form accurate right-angles, and should be able to withstand a certain amount of rough usage.

When one end of a strut 54 has been engaged in one of the hollow elements 38 or 40, it can be secured in the required position by a square-headed bolt 62, the head 64 of which is received entirely within the channel 44, so that it does not project from that channel, the square shape of the head 64 enabling it to engage with the sides of the channel 44, so as to prevent rotation of the bolt 62. A wing nut 66 completes the means for fastening the strut to the element 38 or 40 of the corner member.

An alternative means of locating the strut 54 in a hollow element 38 is shown in Figure 15. A nut 220 is welded onto the outside of a wall 38a of the hollow element 38.

A screw 221 threadably engages the nut 220 and abuts the strut 54, locating it firmly against the wall 38b of the hollow member 38.

It will be appreciated that the ends of a strut 54 can be engaged in a longitudinal hollow element of each of a pair of adjacent corner members 28, so as to provide a strut extending between and bracing the two adjacent corner elements, the strut 54 thus providing one of the struts illustrated diagrammatically in Figure 1 at 30, 32, 34 or 36. Since it is an important feature of the present invention that the size of the temporary frame 22, which is constructed from the corner members 28, and the struts is variable, the fact that the struts 54 can slide in the longitudinal elements 38 and 40 is of importance, as it provides a telescopic effect. Each of the elements 38 and 40 is preformed with slots, as illustrated at 68 and 70 in Figure 5, to receive the securing bolts 62.The carpenter, who has to assemble the temporary frame, would be able to drill out suitable clearance holes (not shown) in the strut for the bolts 62 during assembly of the frame. It will be appreciated that other arrangements of slots and holes could be employed, and, in particular, the slots could be formed in the strut and clearance holes in the corner member, if that were found more convenient.

Obviously, however, with this construction, the smallest size of temporary frame which can be constructed is that in which the ends of the longitudinal elements 38 or 40 engage with each other, so that the temporary frame has a width equal to the sum of the lengths of the longitudinal elements 38, which abut each other, and the depth of the frame is equal to the sum of the lengths of the elements 40, which abut each other. Indeed, even smaller temporary frames could be produced by cutting off part of the longitudinal elements 38 or 40. In a practical embodiment, each of the longitudinal elements 38 and 40 is 380 mm long, and it is unlikely that they will need to be reduced for most purposes.Indeed, it is much more likely that part of each strut 30, 32, 34 and 36 will be exposed between two adjacent corner members, as illustrated, for example, in Figure 1 Since the struts 54 are of planed timber they can be supplied on site in long lengths, and cut to the required length by the carpenter as necessary, when he has to produce one of the temporary frames 22.

The external dimensions of the timber strut 54 are a sliding fit within the hollow element 38 or 40. A timber strut has been found to be satisfactory, and one of the advantages of using a timber strut is that timber for this purpose is likely to be available on most building sites, and therefore it may not always be necessary to supply timber specially prepared for use in the temporary frames.

Moreover, the part of the element 38 or 40 which forms the open channel 44, can be deflected slightly under the applied load provided by the bolt 62 and wing nut 66, to nip the timber strut 54, as illustrated in Figure 6, and this provides a very good location for the timber strut.

In some instances, very wide templates may be required, as illustrated, for instance, in Figure 7. The same struts 30, 32, 34 and 36 are employed with four corner pieces 28, and, of course, the struts may be made either from extruded plastics material, or from planed timber, as illustrated at 54. However, whilst the struts 30 and 32 in the frame illustrated in Figure 7 are relatively short, it will be seen that the horizontal struts 34 and 36 are very long, to create the wide temporary frame. Indeed, the struts 34 and 36 are so long, that in the construction shown in Figure 7, it has been thought necessary to have a central additional brace strut 76 between the horizontal struts 34 and 36. Figure 8 shows that where the struts are made of timber, the securing of the central vertical brace 76 is simply a matter of nailing through the horizontal struts, as indicated at 78.

Although, for manipulation purposes, it will probably be advisable to use vertical bracing struts such as that illustrated at 76 (and indeed, in the case of a very wide frame, more than one such bracing strut may be employed), strictly speaking, these are not essential for the template forming function of the construction. This is because, as has already been mentioned, the template does not provide a template function in relation to the formation of the sill and the lintel. Consequently, even if the horizontal struts 34 and 36 were to deflect slightly, that would not in itself detract from the template forming function of the temporary frame. Of course, it is preferable to avoid such deflection, particularly if it brought about any deflection of the corner members 28, since they do fulfil an important template function.Clearly, also, since the temporary frame is likely to be on the building site for some time, it is advisable that the temporary frame should be reasonably rigid, to stand up to weathering and possible rough usage, and for this reason, the additional vertical bracing struts 76 would be employed. It will also be appreciated that, in the case of a door opening, or a very deep window, it would be the vertical struts 30 and 32 which would be of considerable length, and therefore the additional bracing struts would be arranged horizontally between the struts 30 and 32.

The fitting together of the corner members 28 and the struts 30, 32, 34 and 36 produces the temporary frame, which is an essential part of the template. However, reverting to Figure 1, the template also includes the permanent jamb elements 24. One such jamb element 24 is illustrated in Figure 9, attached to a corner member 28.

In this arrangement, the jamb element 24 is produced in extruded uPVC material of the type which is used to produce gutters and drainpipes for building construction, and this is important, because besides providing a relatively cheap construction, it also ensures that the jamb element is water-resistant and moisture impermeable, characteristics which play an important role in the function of the jamb element. One important part of the jamb element 24 is a location flange 82, which is generally a flat planar element, from the inside of which there projects a window frame locating rib 84. In use, the part of the flange 82 on the internal side of the locating rib 84 rests against the outside face of the two vertical hollow members 40 of the two corner members 28 at one side of the frame 22.The locating rib 84 engages against the external faces of the same two longitudinal elements 40, so that the permanent jamb element 24 is snuggly located on the elements 40 of the upper and lower corner members 28 at one side of the temporary frame.

The permanent jamb element also includes a substantially box-shaped cavity entering portion 86, which extends from the outside of the flange 82. The cavity entering portion 86 is of such a width that it will fit within the width of the cavity of a cavity wall. In fact, in a specific embodiment illustrated in Figure 9, the overall width of the cavity entering portion 86 is 50 mm, so that it is a good fit within a 50 mm wide standard cavity.However, it will be appreciated that if the template is used with a cavity wall having a wider cavity, for example 75 mm width, then it is still possible to employ the permanent jamb element 24, because the cavity entering portion can fit in the wide cavity, either by leaving a space on the internal or external sides of the cavity entering portion, or by filling the space which would otherwise exist between the cavity entering portion and one of the internal surfaces of the cavity wall, by thermal insulation material. In any case, however, it will be noted that the flange 82 is sufficiently wide to extend across the full width of a cavity in a cavity wall construction, and therefore the permanent jamb element 24 can be described as a cavity closer because it will effectively close the end of the cavity when it is in position.

In the construction illustrated in Figure 9, the cavity entering portion 86 of the permanent jamb element 24 has a pair of undercut recess formations 88 and 90 in its outer face, and there is a similar undercut recess formation 92 in its internal face. It is possible to engage the root portions of plastics wall ties in any or all of these undercut recesses 88, 90 and 92, the plastics wall ties themselves extending into the inner and/or outer leaves of the cavity wall, where they rest between adjacent courses of the wall and become embedded in the mortar.In fact, the permanent jamb element, which is illustrated at 24, is of a type which is-described in the specification of United Kingdom Patent Application No. 90 16674.5, and full details of the manner in which the element 24 is constructed, the manner in which it is secured in a cavity wall and its function are described in that specification. It will be mentioned here, however, that, besides closing the end of the cavity, the permanent jamb element 24 also provides a damp-proof course between the internal and external leaves of the cavity wall (which are illustrated diagrammatically by the chain-dotted lines 94 and 96 in Figure 9). Furthermore, the undercut recesses 88 and 90 form effective moisture traps, preventing the migration of moisture from the external leaf 94 to the internal leaf 96 across the width of the cavity.In addition, if wall ties are provided engaging in one or more of the undercut recesses 88, 90 and 92, they will tie the permanent jamb element 24 to the external and internal leaves 94 and 96, and, in any event, mortar squeezed out from between the courses of blocks in the internal leaf 96 will engage in the undercut recess 92 and secure the permanent jamb element 24 to that leaf.

Consequently, the jamb element 24 also acts to tie the two leaves 94 and 96 to each other, at a position where, in traditional building construction, the method of closing the end of the cavity adjacent to the window or door opening normally provides a rather weak detail. The boxlike cavity entering section can be filled with thermal insulation material if required.

It will also be seen that part of the flange 82 extends externally of the locating rib 84, and engages with the ends of the bricks in the external leaf 94.

In order to complete the template 20 after the temporary frame 22 has been built up, it is necessary to cut two jamb elements 24 to the correct length, and then attach them to the jambs of the temporary frame 22. Figure 9 illustrates a method of attachment, utilising a cup-headed screw 98 passing through slots in the element 40 of one of the corner members 28, and then through the cavity entering portion 86 of the permanent jamb element, the attachment being completed by a square nut 100, which locates in one of the undercut recesses 90, and engages with the walls of that recess, so that it cannot rotate.

However, it has been found that, in practice, it is possible to provide a satisfactory attachment of the permanent jamb element 24 to the corner members 28, using permanently adhesive packaging tape, particularly if that tape is of the type used for industrial packaging. A strip of adhesive packaging tape is secured to the outside face of the flange 82 of the jamb element 24; from there it is taken around the internal end of the flange 82, along and in contact with the internal face of the hollow element 40, over and in engagement with the inside face of the element 40, over and in engagement with the external face of the element 40, over the external face of the rib 84 and on to the external part of the flange 82, where it terminates. The adhesive tape, therefore, binds the element 40 to the jamb element 24.It will usually be desirable to employ two or more such adhesive tape securing arrangements along the length of the jamb element 24. It will be understood, however, that if adhesive tape is used, there are various locations where it could be attached to the temporary frame and the permanent jamb elements. The only essential features of the attachment means, whether by, for example, the screw and nut method illustrated in Figure 9, or the use of adhesive tape, are that the attachment shall be secure enough to allow the entire template, comprising the temporary frame 22 and the permanent jamb elements 24 to be manipulated as a unit, and that it permits the temporary frame to be detached from the jamb elements when required.

It is now possible to describe the completion of the wall to provide the window frame opening, after the template 20 has been placed on the lower courses of bricks, as illustrated in Figure 1. In constructing the temporary frame, the connections between the corner members 28 and the struts 30, 32, 34 and 36 will have been established so that the corner members define the shape and size of the eventual window opening. It is important to note that the permanent jamb elements 24 are discounted when determining the size of the template. It is also to be noted that, although the struts do not form planar continuations of the outside faces of the corner members 28 (as appears clearly, for instance, in Figure 8), this is immaterial, because the struts do not have a template-forming function.

The remaining courses of bricks are then built up in conventional manner above the courses shown in Figure 1, the ends of the bricks engaging with the outside faces of the flange 82, as illustrated in Figure 9. During this construction of the upper courses of bricks and blocks, the permanent jamb elements 24 will become firmly secured to the cavity wall, as described in the specification of United Kingdom Patent Application No. 90 16674.5.

Eventually, when the brickwork reaches the level of the top of the template, the lintel 26 can be added in conventional manner, and the brickwork can then continue above the window frame opening. At that stage, the wall can be completed, leaving the template 20 in situ.

When it is eventually required to fit the actual window frame (not shown), the temporary frame 22 is disconnected from the two permanent jamb elements 24, either by unfastening the screws 98, or by cutting through the exposed parts of the adhesive tape which has been used to secure the temporary frame to the jamb elements 24. The temporary frame 22 can then be completely removed from the window space. This leaves a window opening, the depth of which is equal to the depth of the temporary frame, between the horizontal elements 38 of the corner members.

The fact that the struts 34 and 36 did not engage with the lintel and sill, respectively, makes no difference. The width of the window opening which is left when the temporary frame is removed is equal to the horizontal distance between the internal faces of the flanges 82 of the two permanent jamb elements 24, since those elements, of course, remain secured in the brickwork at each side of the window opening. The actual window frame has exactly the same external dimensions as the temporary frame, and can therefore be placed in position between the two permanent jamb elements 24, by engaging the jamb elements of the actual window frame with the inside faces of the flanges 82, and with the external face of the locating rib 84 on each of those flanges.

When the actual window frame has been placed in the correct location, it can then be secured to the cavity wall by, for example, passing expanding type bolts through the jambs of the window frame into holes drilled in the outer leaf 94 of the cavity wall. Alternatively, and especially if the actual window frame is itself made of plastics material, the window frame can be secured by the use of a known type of window frame cramp, which is clipped on to the window frame jambs and extends to the inside leaf of the cavity wall, to which the cramp is attached by means of expanding bolts. If this cramp method of fixing is employed, then it will be necessary to cut notches for the cramps in the location rib 84. The cramps are concealed by the plasterboard or plaster applied over the reveal of the window opening on the inside of the location rib 84.It is to be understood, however, that any method of securing the actual window frame could be employed, since this does not in itself form a part of the present invention.

In Figure 10, there is illustrated an alternative form of permanent jamb element 110, which is of a type known as a combined cavity closer and damp-proof course, already employed in building construction and sold under the Registered Trade Mark DACATIE. This permanent jamb element 110 has an external flange 112, against which is abutted the jamb of the actual window frame; an internal flange 114 provided with a series of three T-shaped ribs 116, which provide undercut locations for plaster in the reveal of the window opening, and the heads of which locate the permanent jamb element 110 on the jamb elements 40 of the corner members 28 of the temporary frame, and a pair of flanges 118 and 120, extending at right-angles from the outside face of the flange 114 and forming a cavity entering portion of the element 110.The external flange 112 is formed with a pair of reversed longitudinal dovetail-shaped recesses 122 and 124. The recess 122 receives mortar squeezed out from between the courses of bricks at the end of the external leaf of the cavity wall, whereby the flange 112 becomes anchored to the external leaf. Additionally, the roots of plastics wall ties (not shown) can be engaged in the longitudinal recess 122, the wall ties then extending between courses of the bricks in the external leaf 94 as an additional means of securing the flange 112 to the external leaf.

The flange 118 has an internal extension 126, which provides a locating rib, having the same function as the rib 84, described with reference to Figure 9. It is also to be noted that the flange 114 is formed with a series of closely juxtaposed longitudinally extending shallow grooves 128 on the outside, between the cavity entering flanges 118 and 120. This provides a very effective moisture trap, to prevent the migration of moisture from the external leaf to the internal leaf, across the inside of the cavity entering portion.In addition, it will be seen that the cavity entering flange 120 is formed with a dovetail-shaped, longitudinally extending undercut recess 130, and in use, if the cavity entering portion engages in a cavity which is only just wider than the cavity entering portion (e.g. 50 mm), it receives mortar squeezed out from between the courses of blocks in the inner leaf of the wall, to provide a means of anchoring the cavity entering portion of the permanent jamb element 110 to the internal leaf. Alternatively, or in addition, the root portions of wall ties (not shown) can be received in the undercut recess 130, the ties then extending between courses of the blocks in the inner leaf of the wall.

Figure 10 also illustrates a method of attaching the permanent jamb element 110 to the corner members 28, employing a cup-headed screw 132, which, in a similar fashion to the cup-headed screw 98 shown in Figure 9, passes through the vertical element 40 of one of the corner members 28, and engages with a toggle nut 134 on the outside of the element 110. Such toggle nuts are well-known, and need no further description. It is sufficient to say that the arms of the toggle engage with the surface of the flange 114, and spread as the screw 132 is tightened. Again, however, it should be appreciated that it is possible to secure the permanent jamb elements 110 to the temporary frame 22 by means of adhesive tape, as described with reference to Figure 9.

The method of constructing the wall and fitting the actual window frame, utilising the construction illustrated in Figure 10, is exactly the same as that described with reference to Figures 1 and 9, and therefore need not be repeated.

Turning now to Figure 11, there is illustrated the temporary frame 22, fitted with a draught screen 136. The draught screen simply comprises a rectangular timber frame 138, to which is secured a sheet of plastics film, such as polyethylene. This draught screen is secured by screws or clamps to the four triangular braces 52 of the corner members 28 of the temporary frame. The purpose of the draught screen, which is an optional feature, is to protect the interior of the building during construction from rain or snow, and, in some instances, the draught screen may actually fill the internal space bounded by the longitudinal elements 38 and 40 of the four corner members 28.However, it is preferred that the draught screen should be somewhat smaller in its external dimensions than the internal dimensions of the corner members, so that there is an open margin 140 between the draught screen and the top, bottom and jamb members of the temporary frame 22. This is as illustrated in Figure 11. The purpose of this open margin is two-fold: In the first place, it can be made wide enough to allow planks, as used on scaffolding for instance, to be passed through the window opening between the draught screen and the struts of the temporary frame, and, in the second place, it reduces the sail effect of the draught screen, by allowing wind to pass around the draught screen into or out of the building.It should be explained that, if the temporary frame is completely closed, for example, by a sheet of polythene material, then the sail effect can be strong enough to cause the temporary frame to destroy part of the brickwork structure, particularly if heavy winds are encountered during the early stages, when the wall is only a few courses high above the level of the sill.

The embodiments described with reference to Figures 9 and 10 require the use of special cavity closers and damp proof courses, and any of the now available speciality cavity closers can be employed as temporary jamb elements.

In particular, any of the cavity closers described in United Kingdom Patents Nos. 302 694, 1 302 695, 1 304 696 and 1388 608 could be employed. However, the invention is also capable of use in wall construction, where the ends of the cavity adjacent to the window or door opening are closed in the conventional manner, using bricks extending laterally from the internal leaf towards the external leaf. For this purpose, a permanent jamb element 150 (see Figure 12) is employed, which simply comprises an extruded plastics strip, having two flanges, disposed at rightangles to each other, the flange 152 engaging with and being attached to the jamb elements 40 of the corner members 28, and the flange 150 providing the conventional vertical damp-proof course which is required between the internal and external leaves of the cavity wall.

In Figure 13, there is illustrated a construction comprising an external leaf 156 and an internal leaf 158 with a cavity 160 between them. The end of the cavity is closed by using three-quarter bricks and quarter bricks in a manner well-known in the building industry, so that it is unnecessary to describe it in detail here. However, as the wall is built up, with the template 20 in position, the flange 154 is trapped between the internal face of the external leaf 156 and the external ends of the threequarter and quarter bricks used to form the closure at the end of the cavity 160. Hence, the conventional vertical damp-proof course is effectively provided by the flange 154.The flange 152, on the other hand, provides a dampproof course between the end of the cavity wall and the actual window or door frame, when the latter is fitted between the two permanent jamb elements 150, after the temporary frame 22 has been removed. In the arrangement shown in Figure 13, the major portion of the flange 152 extends over the end of the external leaf, and since the actual window or door frame will be fitted over this flange 152, the window or door frame will lie mainly between the parts of the external leaf of the wall.

However, as shown in Figure 14, the same permanent jamb element 150 can be employed in the reversed orientation, where the major part of the flange 152 extends over the part of the internal leaf which closes the end of the cavity 160, so that with this arrangement, the actual window or door frame will be set further back into the opening when the window or door frame is fitted after the temporary frame 22 has been removed.

In a further alternative (not illustrated), the permanent jamb element may be similar to that illustrated in Figure 12, excepting that its two flanges form a simple right angle cross-section, in which case, the window frame will be located on the flange which does not enter the cavity and in one orientation of the jamb element will lie entirely within the line of the outer leaf of the wall and in the alternative orientation will be in the line of the joint across the end of the cavity and partly across the end of the inner leaf.

It will be appreciated that, whichever construction is employed, once the temporary frame 22 has been removed, it can be re-used in another location. If exactly the same size of window or door opening is required, then it is only necessary to attach two fresh permanent jamb elements to the "jambs" of the temporary frame, and then the temporary frame can be used exactly as previously described. However, if a differently sized window or door opening is required, it is only necessary to adjust the effective lengths of the struts between the corner members, and then to attach two permanent jamb elements.

It is a significant feature of the invention, that the permanent jamb elements completely separate the "jambs" of the temporary frame 22 from the brickwork or other blockwork during the construction of the wall. This is important, because it prevents mortar becoming attached to the temporary frame 22, and in particular, it avoids the problems that would arise if mortar squeezed out from between the courses of bricks in the wall were to engage, for example, in the open channel 44 of the corner members 28.

Referring now to Figure 16, this shows an adjustable support 200, releasably mounted on a timber strut 20, the ends of which are located respectively in corner members 202 and 203. The adjustable support comprises a sprung steel clip having a back face 204, two side faces 205 and two rolled portions 206. Parallel flanges 207 extend along the full length of the back face 204.

In use, the adjustable support 200 is attached to the timber strut 201 in the manner of a snap-fit during assembly of the temporary frame or after assembly of the temporary frame but prior to its positioning in the desired location against the permanent jamb element 24 (shown in Figure 1). The purpose of the adjustable support 200 is to provide a support for the permanent jamb element to resist any inwards deflection of the permanent jamb element which might arise as a result of badly laid, out of plumb brickwork.

In use the flanges 207 provide the points of contact at which the adjustable support 200 supports the permanent jamb element (24 in Figure 1) The adjustable support 200 is therefore attached to the timber strut 201 with the flanges located on an outer wall of the timber strut 201.

The adjustable support 200 may be slid along the timber strut 201 by partly prising apart the rolled portions 206 to relax their grip on the timber strut 201. When the adjustable support 201 is positioned equidistant from two corner members 202 and 203, it provides optimum support for the permanent jamb element (shown in Figure 1). For the jamb element to be made to deflect when supported at its halfway point by the adjustable support 200, the brickwork would have to be so out of plumb that it would be immediately visually detectable and would therefore be corrected.

When a horizontal brace strut is used (eg. 76 in Figure 7) the adjustable support 200 can be simply slid past this by prising apart the rolled portions 206.

The adjustable support 200 never obstructs brick laying and, accordingly, it has been designed so that it cannot be removed when the permanent jamb element is in position. The purpose of this is to reduce the likelihood of the adjustable support being separated from the timber strut and possibly misplaced. However, if the temporary frame has already been assembled the adjustable support 200 can easily be attached prior to attachment of the permanent jamb element by simply prising apart the rolled portions 206.

In the specific examples described above, the creation of window openings has been described. It is to be understood that the same techniques can be used to create door or other openings.

Claims

1. A template for use in a door or window opening of a building structure, comprising a rectangular temporary frame having a sill, a head and two jambs, and permanent jamb elements, each adapted for securing to a respective vertical end of a wall, the template providing a locating jamb for the window or door frame, each of the permanent jamb elements being releasably attached to the temporary frame, so that when the part of a wall surrounding the window or door opening has been built, the temporary frame can be released from the permanent jamb elements and removed from the wall, leaving the permanent jamb elements secured to the wall, wherein at least one of the jambs comprises at least one substantially hollow corner location member and at least one strut, inserted in the hollow corner location member, said strut being clamped against at least one of the inside or outside walls of said corner location member.

2. A template as claimed in claim 1 in which the strut is clamped by screw-and-nut means.

3. A template as claimed in claim 2 in which the screw is arranged to pass through the strut.

4. A template as claimed in claim 2 wherein the screw is arranged to abut the strut.

5. A template as claimed in any of claims 1 to 4 wherein at least one of the corner location members is provided with one or more internal projections to provide one or more location surfaces inside the corner location member, which surfaces, in use, provide locations for the strut.

6 A template as claimed in claim 5 wherein each of the internal projections provides a limited area location surface.

7. A template as claimed in claim 5 or claim 6 wherein the projection is a channel, which channel is arranged to receive the head of a screw or bolt used for securing the strut to the corner location member, the depth of the channel being such that the head of the screw or bolt is entirely housed within the channel

8. A template as claimed in any of claims 5 to 7 wherein the location surface is provided on an inner wall of the corner location member.

9 A template as claimed in any of claims 5 to 8 wherein the location surface is provided on an outer wall of the corner location member.

10. A template as claimed in any of claims 1 to 9 wherein at least one of said permanent jamb elements is arranged, in use, to enter, at least partially, a cavity of the wall.

11. A template for use in a door or window opening of a building structure, comprising: a rectangular temporary frame having a sill, a head and two jambs, and permanent jamb elements, each adapted for securing to a respective vertical end of a wall, in which the template is used, so as to provide a locating jamb for the window or door frame, each of the permanent jamb elements being releasably attached to the temporary frame, so that when the part of a wall surrounding the window or door opening has been built, the temporary frame can be released from the permanent jamb elements and removed from the wall, leaving the permanent jamb elements secure to the wall, wherein at least one of the jambs comprises at least one substantially hollow corner location member and a strut fitted into the corner location member, the latter having one or more internal projections to provide one or more location surfaces inside the corner location member, which surfaces, in use, provide locations for the strut.

12. A template as claimed in claim 11 wherein each of the internal projections provides a limited area location surface.

13. A template as claimed in claim 12 wherein the projection is formed by a channel in the corner location member, open on the outside, which channel is arranged to receive the head of a screw or bolt used for securing the strut to the corner location member, the depth of the channel being such that the head of the screw or bolt is entirely housed within the channel.

14. A template as claimed in claim 13 in which the channel is formed in a "jamb" element of each corner location member.

15. A template as claimed in any of claims 11 to 14 wherein the location surface is provided on an inner wall of the corner location member.

16 A temporary frame as claimed in any of claims 13 to 15 wherein the location surface is provided on an outer wall of the corner location member.

17. A temporary frame as claimed in any of claims 11 to 16 wherein at least one of said permanent jamb elements is arranged, in use, to enter, at least partially, a cavity of the wall.

18. A template for use in a door or window opening of a building structure, comprising: a rectangular temporary frame having a sill, a head and two jambs, and a permanent jamb element which, in use, is arranged to be temporarily attached, at spaced locations, to the jamb during the forming of a wall portion of the building structure, and subsequently released from the jamb upon completion of the wall portion and secured to the wall portion, the template further comprising at least one support member attached to the jamb between the spaced apart locations and arranged to provide support against deflection for the permanent jamb element.

19. A template as claimed in claim 18 wherein the position of the support member between the spaced apart locations is ajustable.

20. A template as claimed in claim 19 wherein the support member is slideably attached to the jamb.

21. A template as claimed in any of claims 18 to 20 wherein the support member is arranged to be attached to the jamb by means of a snap-on fitting.

22. A template as claimed in any of claims 18 to 21 wherein the support member comprises a clip arranged to at least partially embrace the jamb, the clip having at least one resiliently biased portion which, in use, bears against the jamb.

23. A template as claimed in claim 22 wherein the support member comprises two resiliently biased portions, each being arranged, in use, to bear against the jamb.

24. A template as claimed in any of the claims 18 to 23 wherein the support member comprises a clip made of spring steel.

25. A template as claimed in any of the claims 18 to 24, in which the template is constructed as claimed in any of claims 1 to 17.

26. A template as claimed in claim 1, in which each corner location member comprises a pair of straight hollow elements jointed in an "L" configuration.

27. A template as claimed in claim 26, in which the two hollow elements are each located on a corner piece, comprising two arms secured together in a right angular "L" configuration, each of the arms locating in a respective one of the two straight hollow elements.

28. A template as claimed in claim 26 or claim 27, in which the two straight hollow elements abut one another so as to form a complete corner location on the outside of the corner location member.

29. A template as claimed in claim 28, in which the two straight hollow elements abut each other in a mitred joint.

30. A template as claimed in any of claims 26 to 29 in which each strut is received at its ends in one of the straight hollow elements of the corner location members at two adjacent corners.

31. A template as claimed in claim 30, in which a connection is established between each strut and each of the corner location members into which it is fitted by means of a bolt or like releasable fastening passing through the straight hollow element of the corner member and through that part of the strut which is within that straight hollow element.

32. A template as claimed in claim 31 in which each releasable fastening has a head received in but not projecting from the open channel in the outside of its respective straight hollow element.

33. A template as claimed in claim 31 or claim 32, in which there are two bolts or like releasable fastenings connecting each end of each strut in its respective straight hollow element, the two fastenings being spaced apart longitudinally of the strut.

34. A template as claimed in any of claims 26 to 33 in which each corner member includes angular bracing.

35. A template as claimed in any one of claims 26 to 33 in which a diagonal brace extends between the two straight hollow elements of each corner member.

36. A template as claimed in claim 35, in which the brace comprises a triangular plate secured to the two straight hollow elements in the angle between them.

37. A template as claimed in Claim 35 or 36, in which each of the straight hollow elements of each corner member has a location rib projecting from and extending along the length of its inside face and the brace is secured at its ends or longitudinal margins to the same face of the two ribs of the two straight hollow elements.

38. A template as claimed in any one of Claims 26 to 37 in which the straight hollow elements of the corner member are made of plastics material.

39. A template as claimed in Claim 38, in which the straight hollow elements of the corner members are made as plastics extrusions.

40. A template as claimed in claim 30 or any one of claims 31 to 39 so far as they depend from claim 30, in which each strut is made of timber.

41. A template as claimed in claim 30, or any one of claims 31 to 39 so far as they depend from Claim 30, in which each strut is made in plastics material.

42. A template as claimed in claim 41, in which each strut is made as an extrusion.

43. A template as claimed in any one of claims 1 to 42, in which each permanent jamb element comprises: a flange engaging on the outside face of its respective jamb of the temporary frame and a cavity entering portion, adapted to enter the cavity between the two leaves of a cavity wall at an end of the wall adjacent to an opening for a door or window frame.

44. A template as claimed in claim 43, in which the flange of the permanent jamb element is formed with a rib, against which the front or rear face of the jamb of the temporary frame engages to provide front and rear location of the temporary frame.

45. A template as claimed in claim 44, in which the flange of the permanent jamb element extends on the opposite side of the ribs to the jamb of the temporary frame, to provide a location face for the outside face of the jamb of a door or window to be fitted between the two permanent jamb elements.

46. A template as claimed in any one of claims 43 to 45, in which one or more undercut recesses is or are formed in the inner face of the flange of the permanent jamb element, to form a plaster key after the temporary frame has been removed.

47. A template as claimed in any one of Claims 43 to 46, in which an undercut recess is formed in and extends along the length of a face of the cavity entering portion of the permanent jamb element, to provide an anchorage for wall ties or an anchorage for mortar squeezed out from the courses of bricks or blocks in the leaves of a wall into which the cavity entering portion can be received at any location along the length of the permanent jamb element.

48. A template-as claimed in any one of claims 43 to 47, in which a moisture barrier is formed on the cavity entering portion of the permanent jamb element, to resist migration of moisture across the cavity when the permanent jamb element is built into a cavity wall.

49. A template as claimed in any one of Claims 43 to 48, in which at least part of the flange of the permanent jamb element extends beyond the width of the cavity entering part and is adapted to engage with the end of one of the leaves of the wall when the permanent jamb element is built into a cavity wall.

50. A template as claimed in claim 49, in which an undercut recess is formed in and extends along the length of the outer face of that part of the flange of the permanent jamb which is adapted to engage with the end of one leaf of the cavity wall, to provide an anchorage for wall ties or to receive mortar squeezed out from between the courses of bricks or blocks in the cavity wall at any position along its length.

51. A template as claimed in any one of claims 43 to 50, in which each permanent jamb element is made of plastics material.

52. A template as claimed in claim 51, in which each permanent jamb element is made as an extrusion.

53. A template as claimed in any one of claims 1 to 52, in which each permanent jamb element is attached to its respective jamb of the temporary frame by a bolt or like fastening passed through the jamb and through the permanent jamb element, there being a nut on the outside of the permanent jamb element and means inhibiting rotation of the nut.

54 A template as claimed in claim 53, in which the nut is a toggle-type nut.

55. A template as claimed in any one of claims 1 to 52, in which each permanent jamb element is attached to its respective jamb of the temporary frame by an adhesive tape.

56. A template as claimed in claim 43, in which each of the flange and the cavity entering portions of each permanent jamb is of flat planar form, the cavity entering portion projecting at right-angles from the outer face of the flange.

57. A template as claimed in claim 56, in which the permanent jamb is made of plastics material.

58. A template as claimed in claim 57, in which the permanent jamb is made as an extrusion.

59 A template as claimed in any one of claims 1 to 58, further comprising a draught screen, closing at least the major part of the opening through the temporary frame.

60. A template as claimed in claim 59, wherein the temporary frame is constructed as claimed in claim 35, or any one of claims 36 to 58 so far as they depend from Claim 35, in which the draught screen is attached to the braces of all the corner members of the temporary frame.

61. A template as claimed in claim 59 or claim 60, in which there is at least one space between one of the struts of the temporary frame and the draught screen, large enough to permit the passage of a plank as used on scaffolding.

62. A template for use in a door or window opening of a building structure, constructed and arranged substantially as herein described with reference to Figures 1 to 16 of the accompanying drawings.

63. A method of building a wall, having an opening to accept a preformed door or window frame, comprising: building the wall up to the level of the door or window sill; placing on the partly built wall a template which comprises a temporary frame, to which are releasably attached permanent jamb elements; continuing to build up the wall, so that the permanent jamb elements become secured to the wall; fixing a lintel over the head of the template; releasing the temporary frame from the permanent jamb elements and removing the temporary frame from the wall, leaving the permanent jamb elements in situ in the wall, whereby a door or window opening is defined by: the wall below the opening; the two permanent jamb elements and the lintel.

64. A method of building as claimed in claim 63, in which the template is constructed in accordance with any one of Claims 1 to 62.

65. A structural assembly, comprising: a wall built of bricks or other building blocks; a template built into the wall to define an opening for a door or window frame; the template comprising a temporary frame, to which are releasably attached permanent jamb elements; the permanent jamb elements being secured to the wall, whereby the temporary frame can be removed from the structure by releasing it from the permanent jamb elements.

66. A structural assembly as claimed in claim 65, in which the template is constructed in accordance with any one of Claims 1 to 62.

67. A method of building, substantially as herein described with reference to Figures 1 to 16 of the accompanying drawings.

68. A structural assembly, constructed and arranged substantially as herein described, with reference to Figures 1 to 16 of the accompanying drawings.