GB2255124A - Self-supporting subframe with cavity closers - Google Patents

Abstract

A subframe for a window is formed from a plurality of subframe members 4, some or all of which may be cavity closers. An auxiliary support 17 is provided at each lower corner of the subframe, which locates in the channel 8 of the cavity closer, and serves to provide a self-supporting junction between two subframe members. <IMAGE>

Description

WINDOW AND LIKE CONSTRUCTIONS This invention relates to the construction of window openings and window subframes and to an assembly of components, and method of assembly and use of such components, which facilitates such construction.

It is known, for example from British patent 1 469 228 to provide a closure for the space between the leaves of a cavity wall, to constitute a damp-proof barrier as between the two leaves and (as a component in a window structure) between the brickwork and the window frame.

Such cavity closers, as described therein, are formed as lengths of extruded polymeric material having parallel walls to extend contiguous with the brickwork within the cavity, and opposed outwardly extending flange portions to lie one on each inner margin of the respective leaves.

It has been proposed that such cavity closers may be used in window construction to constitute a window subframe. To achieve this, a cavity closure constituting a sill member is mitred at each end to accommodate the lower ends of two like members extending vertically. A metal, wood or polymeric window frame is attached within the subframe thus formed to give an assembly which can be located where desired along the horizontal cavity with its sides vertical. The brickwork or blockwork is then built up at each side to fit the vertical cavity closers, metal or polymeric ties being used where necessary to ensure adequate interengagement of the brickwork and subframe.

The subframe may be filled with an insulating material to improve insulation. The insulating material may be of such a type as to further improve the stiffness of the subframe.

The present invention is also concerned with the building up of window frames and windows by cavity closure members erected as a subframe during the construction procedure. We have observed that it can be a disadvantage to erect the subframe together with the window frame assembly prior to wall construction since the window frame can be subject to damage, or accumulation of drops of mortar, etc, during the subsequent building of the adjacent wall, and we have devised a form of cavity closer which can be used inter alia to overcome this disadvantage.

A first aspect of the invention consists in a synthetic polymeric cavity closer extrusion which possesses an open longitudinal channel directed into the cavity.

The inwardly open channel will preferably have a retaining or gripping configuration conferred by its cross-sectional shape and/or the material from which the closer is constructed; it can for example be a channel deeper that it is wide, with somewhat flexible walls.

The closer can also comprise an outwardly directed open longitudinal channel, again preferably of a gripping configuration or nature.

Thus according to a first aspect of the invention there is provided an elongate cavity closer for use in the formation of a subframe for a window, comprising an inner portion comprising a first open longitudinal channel for direction into a cavity formed between leaves of a cavity wall, and an outer portion comprising a second open longitudinal channel for direction into a window opening.

Preferably, the closer will also comprise outwardly extending, longitudinal support flanges for positioning along respective inner margins of the two leaves of the cavity wall to locate a closer body between the leaves.

In such a case, the flanges will preferably be provided integrally with the closer. However, in some situations it is envisaged that it will be preferable for the closer extrusion not to be provided with such flanges, for example, where the closer is intended to be used in a situation in which it is entirely received within the wall cavity.

The flanges can be provided separately, if so desired.

In this case, the flanges could be affixed to the closer by means of a lug which is received within the outwardly directed open channel of the closer. This provides an adaptable arrangement in which the user can provide flanges, as desired, without needing to obtain two different types of closer.

The outwardly directed open longitudinal channel can be used to support a wide variety of fixtures. Such fixtures can include, inter alia, components for defining application regions for plaster and/or for providing an anchor for plaster applied thereto; decorative or finishing components; or components defining clips, channels or other engaging means for securing another component thereto. Such components can be made from any suitable material and may be rigid or flexible or even made from silicone rubber, for example.

If the channel is to be used for a variety of purposes, then it may be desirable to provide an internal configuration which includes two distinct types of gripping means. These could be for engaging features received therein of varying thicknesses, or for receiving a generally planar component such as a corner piece, whilst still being capable of receiving a lug provided on, for example a plaster support or a flange.

To assist in optional fixing to the wall the closer may possess along each side of its body portion a longitudinal configuration engageable with a tie member for tying to the wall structure.

Such configuration can be a channel with inturned lips, to engage where desired with the T-shaped end of a metal or polymeric tie.

In another aspect the invention consists in a window subframe construction composed of three or four lengths of such closer extrusion.

According to a second aspect of the invention there is provided a subframe for a window comprising a plurality of elongate subframe members, at least one of which is a cavity closer, and at least one first auxiliary support means, the or each said cavity closer comprising a first open longitudinal channel for direction into a cavity formed between leaves of a cavity wall, the said channel being adapted to receive the auxiliary support means, the said auxiliary support means providing, in combination with the said cavity closer or a respective one of the said cavity closers and one of the other of said subframe members, a substantially self-supporting arrangement.

Where the subframe is to be used in conjunction with a standard lintel having a generally downwardly directed open channel, the subframe can comprise four lengths of closer extrusion, since the upper portion of the subframe can be received within the lintel. However, if the subframe is to be used in conjunction with a lintel which does not comprise such an open channel, or a lintel in which the channel has too narrow a width to accommodate the subframe, then the subframe will be constructed from three lengths of closer according to the foregoing and a fourth component.

According to a further aspect of the invention there is provided an elongate head strip for use in forming a window subframe, comprising a base strip having a generally flat first surface for locating adjacent a lintel when in use and a plurality of v-shaped elongate grooves formed in the said first surface.

Thus, by means of the immediately foregoing aspect of the invention, the upper horizontal part of the subframe can be provided in the form of a head extrusion which, in cross-section, comprises a generally planar base and may be provided with appropriate, outwardly directed, surface features, such as tongues or flanges, for acting as plaster guides or receiving other components such as trim strips. The planar base of the head extrusion merely juxtaposes the lintel during use, and may be reversible.

It is envisaged that, where the construction includes four lengths of closer extrusion, it shall comprise, outside each lower subframe corner, a flat L-shaped configurationally stabilising metal strap held in the inwardly open longitudinal channels of at least the two end regions of the two closer extrusions forming that corner. The horizontal portion of the metal strap typically extends behind only a minor part of the horizontal length but the strap can if desired extend behind all of the vertical length, depending upon the application. The subframe can further comprise or receive temporary top internal corner pieces held in the internal corners in the outwardly directed open longitudinal channels of the end regions of the two closer extrusions forming those respective internal corners.These internal corners provide rigidity and stability during the building process and may be removed upon completion.

Where the subframe is constructed from three lengths of closer extrusion, with the upper horizontal part of the subframe being formed from a generally flat extrusion member, the construction will be generally as described in the preceding paragraph, but will differ in that the temporary top internal corner pieces would need to be supported by a formation provided on the outwardly directed surface of the upper horizontal extrusion.

This is because the upper horizontal extrusion will not comprise the outwardly directed open longitudinal channels.

The internal corner pieces may be provided only at the top of the subframe, or can be provided alternatively or additionally at the bottom of the subframe. These corner pieces may retain polyethylene film or some other suitable, generally lightweight, but reasonably strong material in order to generally close the opening. The closure of the opening in this manner serves to prevent the ingress of water and reduce the likelihood of damage to the internal structure of the building. Furthermore, the provision of such a closure will tend to render the inside of the buiding more comfortable for workmen.

Generally, it will be preferable for the closure to be transparent, or at least translucent, in order to allow daylight to enter the building, enabling those inside the building to see. However, it is envisaged that this may not always be absolutely necessary.

The invention extends moreover to the assembly of such a subframe held in a window opening, preferably beneath a lintel itself enclosing an uppermost length of closer extrusion, and to the accumulation of component parts used for such subframe assembly. Alternatively, the subframe assembly may be of the type which comprises three lengths of closure extrusion and one length of the above-described flat extrusion. In this case, the lintel does not enclose the subframe assembly, but is merely provided in juxtaposition.

The invention still further extends to a method of constructing a window opening internally surrounded by a window subframe, in which a subframe as defined above, configurationally stabilised by the two L-shaped members, is located over a horizontal run of cavity wall with its lowermost closer extrusion closing the cavity; courses of bricks or blocks are laid at the vertical edges of the subframe, up to the upper level thereof; and a lintel is located over the window opening either to enclose the top length of closer extrusion or to locate adjacent the upper part of the assembly, as appropriate.

According to yet another aspect of the invention there is provided a method of constructing a window opening comprising, in any appropriate order, the steps of: (i) connecting respective lower ends of two upright cavity closer lengths to respective opposite longitudinal ends of a first horizontal cavity closer length; (ii) attaching an auxiliary support member to the junction of each upright cavity closer with the horizontal cavity closer, in order to provide, in each case, a self-supporting connection; (iii) connecting the respective upper ends of the upright cavity closers to respective ends of a second length of horizontal cavity closer or connecting the said respective upper ends of the upright cavity closers to respective ends of a length of head strip;; (iv) attaching an auxiliary support member to the junction of each upright cavity closer with the second horizontal cavity closer or length of head strip; (v) locating the assembled structure over a run of cavity wall with its lowermost closer extrusion substantially closing the cavity; (vi) laying courses of bricks or blocks at the vertical edges of the assembled structure, up to the upper level thereof; and (vii) locating a lintel over the window opening to either enclose an upper portion of the assembly or juxtapose the assembly.

Typically, of course, the courses of bricks or blocks are during construction tied to the vertical closer sides by interengaging metal or polymeric ties, and further courses of bricks or blocks are laid above and supported on the lintel.

The invention still further consists in a window construction including a window held within the incorporated subframe assembly as described above, and in a method of providing a window in which a window frame is inserted into the subframe subsequent to the location of the subframe and the construction of the surrounding wall.

According to a still further aspect of the invention there is provided an elongate cavity closer extender comprising an elongate formation on one side thereof for engagement with a corresponding formation on a side portion of a cavity closer, the said cavity closer extender serving, in use, to extend the effective width of a cavity closer to which it is attached.

According to yet another aspect of the invention there is provided an elongate plaster guide strip for affixation to an elongate cavity closer, comprising elongate guide means for serving as a guide for plaster and an elongate formation for connection to a corresponding formation located upon a cavity closer.

According to another aspect of the invention there is provided an elongate trim strip for use in conjunction with a cavity closer, the said trim strip comprising a generally flat cover member and a formation for interaction with a corresponding formation located in a cavity closer.

The invention will be further described, by way of example, and with reference to the accompanying drawings, in which: Figure 1 shows in perspective a lower corner of a partially constructed window opening and subframe assembly comprising cavity closers, Figure 2 shows diagrammatically the general arrangement of a completed window opening and subframe assembly, Figure 3 shows in perspective part of the upper portion of such an assembly including a conventional lintel, Figure 4 is a cross section through an alternative embodiment of a cavity closer, Figure 5 shows a detail of an alternative outwardly directed open longitudinal channel of a cavity closer, Figure 6 shows a cross section through another alternative cavity closer, Figure 7 shows a cross section through a trim member for use with the cavity closer shown in Figure 6, Figure 8 shows a cross section through a head section for use in a subframe assembly to be used with a closed lintel, Figure 9 shows a cross section through an extender for use with a cavity closer, Figure 10 shows a cross section through a cavity closer of the type shown in Figure 13 (see below), in position in a cavity wall configured to comprise a typical English reveal in combination with a typical wooden window frame and a trim member similar to that shown in Figure 7, Figure 11 is a view similar to Figure 10 except differing in that the plaster guide provided on the trim member is moulded in a different position, Figure 12 is a view similar to Figures 10 and 11 except the wall comprises a typical Scottish reveal and the trim member does not comprise a plaster guide strip.

Figure 13 shows an alternative embodiment of a cavity closer, similar to that shown in Figure 6, but differing in that it does not include longitudinal support flanges, Figure 14 shows a cross section through an alternative embodiment of a cavity closer, Figure 15 shows a cross section through an internal trim member for use with the cavity closer shown in Figure 14, Figure 16 shows an internal trim similar to the one shown in Figure 15, but having an alternative lug profile, Figure 17 is a view of an alternative embodiment cavity closer, Figure 18 shows a cross section through a cavity closer of the type shown in Figure 14 in position in a cavity wall configured to comprise a typical English reveal in combination with a typical PVCU window frame and an internal trim of the type shown in Figure 15, Figure 19 is a view similar to Figure 18 except the cavity wall is configured as a typical Scottish reveal and the internal trim shown in Figures 15 and 18 is not used, and Figure 20 is a view similar to Figures 18 and 19, wherein the cavity wall is configured with a typical English reveal, but with a wider cavity than that shown in Figure 18, and differing in that a cavity extender such as the one shown in Figure 9 is provided and in that the window frame is a typical wooden frame.

Figure 1 shows a cavity wall with an outer leaf of brickwork 1, an inner leaf 2 and a cavity 3 between the leaves. Such walls are commonplace and built to a variety of standard cavity spacings and configurations.

An extruded polymeric cavity closer 4 according to a first embodiment of the invention is located over a top or side edge (or underside) of such a wall. It possesses coplanar inner and outer flanges 5 and 6 respectively, separated by a channel 7 facing outwards.

A similar somewhat deeper channel 8, in the body of the cavity closer, faces inwards. Two shallow inclined channels 9 and 10, defined by walls 11 with inturned lips 12, occupy the sides of the closer. In contrast to the known type of closer, discussed above, the closer shown in Figure 1 is spaced from the inner walls of the cavity, and is somewhat V-shaped in cross-section.

To use such a cavity closer in fabrication of a window opening and subframe, the wall 1, 2, 3 of the building is first built to the desired lower level. A desired length of the closer to form the lower end 13 (figure 2) is cut from the original extrusion and mitred at 45 at each end. A second such length is cut and mitred to form the top 14 of the frame, and two lengths are cut and mitred to form the sides 15, 16. As an alternative to mitreing, the end of one closer length could be cut square and a complementary notch could be cut in the end of the length to be fitted thereto.

Each lower subframe corner is then formed by fitting within the channels 8 at the ends of two lengths of closer a flat L-shaped configurationally stabilising metal strap 17. Each such strap extends for part of the way along the channel 8 in the lower edge 13 and for part or all of the way up the channel 8 in side edge 15 or 16 (see Figure 2). It can if desired be adhered, or be held by the resilience of the walls of the channel 8.

The top 14 is then fitted, using two temporary plywood gussets 18, 19 wedged, one in each internal upper subframe corner, within channels 7 in the adjacent side and top lengths. If, so desired, similar plywood gussets could be used in the bottom corners rather than the above-described straps. Where such a gusset is used in all four of the corners, a panel may be mounted upon the gussets for closing the window aperture. Normally, such a panel would be transparent or translucent to allow light to pass and serve as a temporary seal for preventing rain or debris from entering the building under construction.

Alternatively the subframe members could simply be welded together - at top and/or bottom corners - to form rigid corners.

This subframe is laid upon the wall 1, 2, 3 at a desired location, with the horizontal portion of each metal stabilizing strap 17 lying within the cavity and accurately locating, both as to verticality and spacing, the upright sides 15 and 16. The side walls of brickwork can then be built accurately to the side pieces 15, 16, using metal wall ties 20 at desired locations to connect between the mortar in the joints of the brickwork and the shallow channels 9, 10 on the closer. When the upper level of the window is reached a conventional lintel 21 can be laid across the opening (see Figure 3), to cover and accommodate the closer 3 create a thermal barrier and provide the usual support for further courses of brickwork.

In this way the necessity of using the actual window frame as a connecting and stabilizing member for the subframe units, so that they may present an accurate external periphery, is avoided. The window opening and subframe can be erected as described above and the actual window frame incorporated later (first of course removing the temporary plywood gussets) after any risk of damage has passed.

Channel 7 is an important feature for such subsequent mounting. For completeness, therefore, Figure 1 also shows some of the components of a subsequently mounted window frame assembly.

The periphery of the channel 7 can be given any suitable configuration, depending upon which components are intended to be inserted into the channel 7. The channel 7 shown in Figures 1 to 3 is generally rectangular in cross section and may, as shown in Figure 17, for example, comprise a series of fine ribs on each of its side walls. Such ribs serve to assist in the securing of a component fitted within the channel. In the case of the embodiments shown in Figures 1 and 3, the channel 7 is used primarily for receiving the peripheral strip 22 and also for receiving corner pieces 18. In this case, the peripheral strip 22 is provided with a lug of generally similar thickness to the corner piece 18.

However, it may be that the channel 7 will be required to receive and support components having differing thicknesses. Therefore, Figures 4, 5 and 6 show alternative profiles for the channel 7.

In Figure 4, the channel 7 can be seen to include an outer region 71 of relatively broad cross section and an inner region 72 of relatively narrow cross section. The two are configured so that the channel 7 is generally symmetrical when viewed in cross section. The two regions 71 and 72 are connected by a pair of sloping walls 73 and 74 which lead from the broader region 71 into the narrower region 72. These walls 73 and 74 serve to assist in the location of a component such as a trim, for example, having a relatively narrow lug into the relatively narrow region 72 of the channel 7. Figure 5 shows an alternative cross section for a channel 7, once again comprising an inner relatively narrow region 77 along with an outer relatively broad region 76. In this case, however, the two are not symmetrically aligned but instead they share a common straight wall 78.A feature, such as an engagement lug, of a component having a relatively narrow cross section may be inserted into the relatively narrow portion 77 of the channel 7 by first locating the feature up against wall 78, which can then be used to guide the connector into the narrow portion 77 of the channel 7.

Figure 6 shows yet another alternative profile for channel 7. In this case, each of the side walls of the channel is provided with a rib 79. These ribs 79 divide the channel 7 into an inner region 81 and an outer region 80. In use, the ribs 79 will serve as a stop to prevent further insertion of any component of a generally rectangular profile which is inserted into the channel 7.

Figure 7 shows a component 100 in the form of a trim member. The trim member 100 includes a lug 102 having a pair of elongate grooves 110, one of which runs along each side of the lug near to its distal end. The distal end of the lug is rounded-off to form a tip 112 which is part-circular in cross-section. If a lug such as the lug 102 of the trim 100 shown in Figure 7 is inserted into the channel 7, the tip can be forced past the ribs 79 which then engage respective ones of the grooves 110 to provide for a snap-fit engagement between the lug 102 and the channel 7.

It is to be understood that the various illustrated profiles for channel 7 are merely preferred embodiments and many other useful profiles could be used, depending upon the circumstances of use.

A peripheral strip 22 (see Figure 1) can be fixed in channel 7 to provide a guide and edge for finishing plaster 23. Strip 22 in turn presents an outwardly facing narrow channel 24, in which adjusting trim members 25 or window frame uprights can be fixed.

Internal and external sill structures 26, 27 can also be fitted with the closer profile as extending along the bottom of the subframe.

The lintel shown in Figure 3 can be seen to be open in cross section and, therefore, capable of receiving the upper horizontal cavity closer 4 within its body.

However, not all lintels commonly in use are open in this manner. Sometimes the bottom plate 32 of the lintel extends completely across the width of the lintel, and sometimes the lintel cavity 30 is filled, for example, with insulating material. Alternatively, it is not uncommon for such lintel cavities to be very narrow, thus providing insufficient space for receiving a cavity closer according to the present invention.

In such circumstances, a head section 40 such as the one shown in Figure 8 is used for the upper horizontal part of the subframe assembly, rather than a length of closer extrusion.

The head section 40 includes a base portion 41 comprising plurality of generally V-sectioned, shallow recessed channels 42 for locating fixation means, such as screws, for fixing the head section to other subframe components. The position of the recessed channels 42 corresponds with the transverse position of channels 44 provided in the cavity closer 4 shown in Figure 4, for example. Thus, when a strip of head section is placed with its base portion 41 against the end of a vertical closer, the vertical closer and the head section 40 can be fixed to be correctly aligned. It would, of course, be necessary to remove part of tongues 160 and 162 before fitting, to enable the end of the vertical section to contact the base portion 41 of the head section 40.

The width of a cavity in a cavity wall will vary from building to building. This can be observed by a comparison of Figures 18 and 20, for example. In order to account for this, an additional cavity extender 50 is provided. An example of such a cavity extender is shown in Figure 9. The cavity extender shown in Figure 9 is designed for use with a cavity closer such as the one shown in Figure 4.

The cavity extender 50 is provided with a pair of spaced resilient lugs 52 which fit within open channel 60 positioned on one side of the cavity closer 4. In order to fit the cavity extender within the cavity closer, the two lugs 52 are pushed against the lips 62 of the channel 60. The resilient lugs 63 each comprise an inclined surface 63 which slides across a corresponding inclined surface on each of the lips 62. The angled surfaces serve to deflect the two lugs towards each other and once the lugs are fully received within the channel 60, their resilience causes them to spring back out, thus locking the cavity extender in engagement with the cavity closer 4. The inclined surface 56 on the cavity extender mates with inclined surface 58 on the cavity closer, thus providing a stable assembly.The cavity extender is provided, in this case, with a flange 54, which corresponds to the flanges 5 and 6, although this is not necessary and could be omitted, if desired.

The inner and outer flanges 5 and 6 of the cavity closers shown in, for example, Figures 1, 4, 14 or 17 are optionally provided. In some circumstances it may be desirable for one or both of the flanges to be absent. For instance, where a wooden framed window is to be used, it is desirable for plaster to be provided right up to the window frame. Figures 10, 11 and 12 show three arrangements in which a flangeless cavity closer, as shown in Figure 13, is used. In each case, use is made of a trim piece such as the one shown in Figure 7. The trim piece includes a plaster guide 104 in each case. The trim piece may be manufactured to have a guide location or flange length to suit a particular circumstance of use. For instance, it can be seen that the plaster guide shown in Figure 11 is located inwardly relative to the plaster guide shown in Figure 10, whereas the trim shown in Figure 12 does not include a plaster guide at all. Furthermore, the trim shown in Figure 12 only comprises one flange.

As explained above, the channel 7 may be used to provide a fixing means for any appropriate accessory or component. It is not limited merely to use for supporting trims or gussets.

The embodiment shown in Figure 14 includes a pair of outwardly projecting flanges 150, 150. These can be used in a similar fashion to the relatively narrower region 72 of the channel 7 shown in the embodiment of Figure 4 or the relatively narrow region 77 shown in Figure 5. That is to say they will provide a means for connecting a component having a relatively narrow thickness to the cavity closer. In this particular embodiment, however, the innermost of the two flanges also comprises a lip 152 which serves as a guide when plaster is applied. The head section shown in Figure 8 is provided with a similar pair of flanges 160, 160, these are optionally provided.

The plaster guide need not necessarily be provided exactly in this position but could be provided at any transverse position on the outwardly directed face of a closure member. Furthermore, such a plaster guide may be provided directly on the closure member, as in Figure 14 or, alternatively, on a trim member such as the one shown in Figure 7, or on a strip such as the strip 22 shown in Figure 1. A lip, such as lip 152, may or may not be provided, as preferred.

The outwardly directed face of the cavity closer 4 or any appropriate surface of a trim or plaster guide may comprise contoures (such as ridges 208 shown in Figure 19) to facilitate the adhesion of plaster thereto.

Alternatively, a member with a textured surface may be affixed to the cavity closer 4 by means of, for example, channel 7.

A trim strip such as strip 200, shown in Figure 15 may be'provided for finishing purposes and also to serve as a plaster guide. Figure 16 shows a similar strip, bu#t with a lug 202 having a different configuration of the so-called 'Christmas tree' type. The lug would fit within a complementary channel provided in a closer, the channel comprising internal ridges spaced along its sides, an example of this is channel 204, shown in Figure 17.

Channel 7 shown in Figure 17 also includes a series of fine ribs 220 located on each of its side walls. These serve to anchor any component, such as a trim member or gusset fitted therein.

Many variations and modifications of the present invention will suggest themselves to a skilled addressee upon making reference to the foregoing description, which is given by way of illustrative example only, and which is not intended to limit the scope of the invention.

Claims (54)

1. A subframe for a window comprising a plurality of elongate subframe members, at least one of which is a cavity closer, and at least one first auxiliary support means, the or each said cavity closer comprising a first open longitudinal channel for direction into a cavity formed between leaves of a cavity wall, the said channel being adapted to receive the auxiliary support means, the said auxiliary support means providing, in combination with the said cavity closer or a respective one of the said cavity closers and one of the other of said subframe members, a substantially self-supporting arrangement.

2. A subframe according to claim 1, wherein two of the subframe members are upright cavity closers, each one defining a respective side portion of the subframe, and another of the subframe members is a horizontal cavity closer, defining the lower portion of the subframe, the said horizontal cavity closer being connected, at each of its longitudinal ends, to a respective one of the said upright cavity closers by means of a said first auxiliary support means.

3. A subframe according to claim 2, wherein a further of the subframe members is a horizontal cavity closer defining an upper subframe portion, the said upper subframe portion being connected at each of its longitudinal ends to a respective one of the said upright cavity closers.

4. A subframe according to claim 2, comprising an upper subframe portion connected at each of its longitudinal ends to a respective one of the said upright cavity closers, the said upper subframe portion comprising a substantially flat upper surface.

5. A subframe according to claim 3 or 4, wherein each said first auxiliary support means is in the form of an L-shaped former, one limb of each former being received in the said first longitudinal channel located in a respective one of the cavity closers to be connected by the said former.

6. A subframe according to any preceding claim, further comprising second auxiliary support means for providing support between connected subframe members, wherein at least two of the said subframe members comprise second longitudinal channels for receiving the second auxiliary support means, each said second longitudinal channel being adapted to be directed away from the said cavity, during use.

7. A subframe according to claim 6, wherein the said second auxiliary support means is in the form of a former comprising two mutually perpendicular edges for receipt within the said outwardly directed channels.

8. A subframe according to claim 7, wherein the said second auxiliary support means is in the form of a right-angled triangle.

9. A subframe according to claim 7, 8 or 9, wherein the said second auxiliary support means serve to provide support for a sheet for closing the window aperture about which the subframe is provided.

10. A subframe substantially as herein described with reference to any of figures 1, 2 and 3; or any one of 4 to 20 of the accompanying drawings;

11. An elongate cavity closer for use in the formation of a subframe for a window, comprising an inner portion comprising a first open longitudinal channel for direction into a cavity formed between leaves of a cavity wall, and an outer portion comprising a second open longitudinal channel for direction into a window opening.

12. A cavity closer according to claim 11, wherein the said second channel is adapted to receive two different subframe components, each having a formation for engaging with the channel, each said formation having a different thickness from the other.

13. A cavity closer according to claim 11 or 12, wherein the said second channel is adapted to receive components in a snap-fit engagement therewith.

14. A cavity closer according to any one of claims 11 to 13, wherein the said second channel is provided with a series of ribbed formations on an internal surface thereof.

15. A cavity closer according to claim 12, wherein the said second channel comprises an inner portion of relatively narrow cross-section and an outer portion of relatively broad cross-section, the two said portions being connected by an intermediate portion comprising walls which slope generally from the said outer to the said inner portion.

16. A cavity closer according to claim 12, wherein the said second channel comprises an inner portion of relatively narrow cross-section and an outer portion of relatively broad cross-section, the two said portions sharing a common substantially planar side wall.

17. A cavity closer according to claim 12, 13 or 14, wherein the said second channel is generally rectangular in cross-section and comprises a pair of longitudinal opposed ribs, a respective one of the said ribs extending along the length of each of the side walls of the said channel.

18. A cavity closer according to any one of claims 11 to 17, further comprising a longitudinal flange for locating against a wall of a window aperture and serving to control the depth of location of the cavity closer within a cavity formed between leaves of a cavity wall.

19. A cavity closer according to claim 18, wherein the said flange is integrally formed with the cavity closer.

20. A cavity closer according to claim 18, wherein the said flange is releasably mounted upon the said cavity closer by means of a lug connected to the flange which lug is received within the said second channel.

21. A cavity closer according to any one of claims 11 to 20, further comprising a third open longitudinal channel formed in one side portion of the said cavity closer, the said third channel being adapted for engagement with a portion of a cavity closer extender portion for affixation to the said cavity closer.

22. A cavity closer according to any one of claims 11 to 20, further comprising an elongate formation extending along one side portion of the cavity closer, the said formation being adapted for engagement with an elongate open channel formed in a portion of a cavity closer extender for affixation to the said cavity closer.

23. A cavity closer according to any one of claims 11 to 21, further comprising a pair of elongate tongues for projecting into a window opening.

24. A cavity closer according to claim 23, wherein at least one of the said tongues is adapted to serve as a plaster guide when in use.

25. A cavity closer according to claim 23 or 24, wherein the said tongues are adapted to engage a window component fitted therebetween during use.

26. A cavity closer according to any one of claims 11 to 25, wherein at least a major portion of the cross-section of the said cavity closer is generally V-shaped.

27. A cavity closer according to any one of claims 11 to 26, wherein the said cavity closer comprises an elongate chamber filled or partially filled with insulation material.

28. A cavity closer according to any one of claims 11 to 27, wherein the said cavity closer comprises an elongate reinforcement.

29. A cavity closer according to any one of claims 11 to 28, formed generally from extruded polymeric material.

30. A cavity closer according to any one of claims 11 to 29, further comprising a pair of fourth open longitudinal channels, one being disposed on each side of the said cavity closer for securing wall ties thereto.

31. A cavity closer according to claim 30, wherein each of the said fourth channels is configured such that, in use, a wall tie can be secured thereto so as to extend generally obliquely into the leaf of a cavity wall.

32. A cavity closer substantially as herein described with reference to any of figures 1, 2 or 3; or 4, 7, 8, 10 or 12; or 13, 14 and 15; or 16, 17 and 18 of the accompanying drawings.

33. An elongate head strip for use in forming a window subframe, comprising a base strip having a generally flat first surface for locating adjacent a lintel when in use and a plurality of v-shaped elongate grooves formed in the said first surface.

34. A head strip according to claim 33, further comprising an integrally formed elongate plaster guide.

35. A head strip substantially as herein described with reference to figure 6 of the accompanying drawings.

36. An elongate cavity closer extender comprising an elongate formation on one side thereof for engagement with a complementary formation on a side portion of a cavity closer, the said cavity closer extender serving, in use, to extend the effective width of a cavity closer to which it is attached.

37. An elongate cavity closer extender according to claim 36, wherein the extender further comprises an elongate flange along one side thereof, for locating against a leaf of a cavity wall during use and serving to control the depth of location of the cavity closer and extender combination within the cavity.

38. An elongate cavity closer extender substantially as herein described with reference to figure 9 or figure 20 of the accompanying drawings.

39. An elongate plaster guide strip for affixation to an elongate cavity closer, comprising elongate guide means for serving as a guide for plaster and an elongate formation for connection to a complementary formation located upon a cavity closer.

40. A guide strip according to claim 39, comprising a generally flat base member, said formation being in the form of an elongate lug projecting generally perpendicularly from a first face of the said base member, and the said plaster guide being in the form of an elongate flange projecting generally perpendicularly from a second face of the said base member and in an opposite direction to the direction of projection of the said lug.

41. A guide strip according to claim 40, wherein the said lug comprises a pair of elongate grooves, each one being disposed on a respective side face of the said lug and being adapted to interact with one of a pair of elongate ribs formed on respective internal side faces of a channel located in a cavity closer.

42. A guide strip according to claim 41, wherein the said lug is adapted to interact with a channel located in a cavity closer in a snap-fit manner.

43. An elongate plaster guide strip substantially as herein described with reference to any one of figures 7, 10, or 11 of the accompanying drawings.

44. An elongate trim strip for use in conjunction with a cavity closer, the said trim strip comprising a generally flat cover member and a formation for interaction with a complementary formation located in a cavity closer.

45. A trim strip according to claim 43, wherein the said formation is in the form of an elongate lug projecting generally perpendicularly from one face of the said cover member and being adapted to interact with a channel located in a cavity closer to secure the said trim in relation thereto.

46. An elongate trim strip substantially as herein described with reference to any one of figures 7, 15 or 16 of the accompanying drawings.

47. A method of constructing a window opening comprising, in any appropriate order, the steps of: (i) connecting respective lower ends of two upright cavity closer lengths to respective opposite longitudinal ends of a first horizontal cavity closer length; (ii) attaching an auxiliary support member to the junction of each upright cavity closer with the horizontal cavity closer, in order to provide, in each case, a self-supporting connection; (iii) connecting the respective upper ends of the upright cavity closers to respective ends of a second length of horizontal cavity closer or connecting the said respective upper ends of the upright cavity closers to respective ends of a length of head strip; (iv) attaching an auxiliary support member to the junction of each upright cavity closer with the second horizontal cavity closer or length of head strip;; (v) locating the assembled structure over a run of cavity wall with its lowermost closer extrusion substantially closing the cavity; (vi) laying courses of bricks or blocks at the vertical edges of the assembled structure, up to the upper level thereof; and (vii) locating a lintel over the window opening to either enclose an upper portion of the assembly or juxtapose the assembly.

48. A method according to claim 47, comprising the additional step of fixing a plaster guide strip to one or more of the cavity closers and/or the head strip.

49. A method according to claim 46 or 47, comprising the additional step of fixing a trim strip to one or more of the cavity closers and/or the head strip.

50. A method according to claim 46, 47 or 48, comprising the additional step of fixing a cavity closer extender to one or more of the cavity closers.

51. A method according to any one of claims 46 to 49, wherein the window opening is closed by means of a closure panel supported by two or more of the auxiliary supports.

52. A synthetic polymeric cavity closer extrusion which possesses an open longitudinal channel for direction into a wall cavity.

53. A window subframe construction comprising three or four lengths of closer extrusion according to claim 52.

54. A method of eonstrueting a window opening internally surrounded by a window subframe, in which a subframe according to claim 53, configurationally stabilized by two L-shaped members, is located over a horizontal run of cavity wall with its lowermost closer extrusion closing the cavity; courses or bricks or blocks are laid at the vertical edges of the subframe, up to the upper level thereof; and a lintel is located over the window opening either to enclose the top length of closer extrusion or to locate adjacent the upper part of the assembly, as appropriate.