GB2310226A

GB2310226A - Cavity wall closer; attaching door or window sub - frame

Info

Publication number: GB2310226A
Application number: GB9708889A
Authority: GB
Inventors: George Molyneux
Original assignee: EDGBASTON IND Ltd
Current assignee: EDGBASTON IND Ltd
Priority date: 1994-01-04
Filing date: 1994-01-04
Publication date: 1997-08-20
Anticipated expiration: 2014-01-04
Also published as: GB2285273A; GB9708889D0; GB2285273B; GB2310226B; GB9400043D0

Description

CAVITY WALL BUILDING CONSTRUCTION This application is divided from patent application no.

9400043.7 Where a functional frame (door or window) has to be fitted in a building of cavity wall type construction, it is sometimes the practice to fit a subframe to the wall structure, and then fit the functional frame into the subframe. This procedure is particularly useful when a plastics (polyvinyl chloride PVC) functional frame is used, because it is undesirable to build the plastics frame into the wall, as that would leave it exposed to damage during the building operations. Recently, there have been various proposals for push-in functional frame systems, in which the functional frame can be fitted into the subframe simply by pushing it into the subframe.

It is also now conventional to employ cavity closers at the end of a cavity wall adjacent to an opening for a functional frame. A cavity closer may be formed as a plastics extrusion and is built into the wall so that it is secured to the bricks; blocks or timber frame of either or both the inner and outer leaves of the wall. The cavity closer closes the end of the cavity, to avoid the use of, for example, cut bricks laid across the end of the cavity; it prevents moisture crossing the cavity and it provides a moisture barrier between the wall and the functional frame. Frequently the cavity closer has a hollow cavity entering part which can be filled with thermal insulation material.

A first aspect of the present invention provides a specially versatile cavity closer for use with a subframe or with any other frame element. Although it is expected that the cavity closer in accordance with this aspect of the invention will generally be used in conjunction with subframes, it is to be understood that it could be used with other frames, e.g. window or door frames (i.e. a construction in which the window or door frame is connected directly to the cavity closer, without the intervention of a subframe). Hence, this specification refers to a subframe or other frame elements.

According to this aspect of the invention a cavity closer for use in building construction comprises a first part adapted to enter the cavity between the inner and outer leaves of a cavity wall; a second part adapted to locate on the end of one or both of the inner and outer leaves of the wall and two or more anchorages on the second part adapted to connect a subframe or other frame element to the cavity closer in any one of two or more locations in the interior/exterior sense relatively to the first cavity entering part in which each anchorage comprises a formation upstanding from the face of the second part, opposite to the face which locates on the end of the wall, with an enlarged head adapted to engage with an abutment on the subframe or other frame element, to establish the connection between the cavity closer and the subframe or other frame element and in which the anchorages are resilient to provide a snap-fit connection for the subframe or other frame element.

The expressions "exterior" and "interior" are used to refer to the interior and exterior of the cavity wall, in which the cavity closer is to be used. Any other directional indications such as "inner" and "outer" or "top" and "bottom" used herein refer to components as they are seen in the drawings. It will be appreciated, however, that in practice, the components will not always be orientated in the sense in which they appear in the drawings.

The advantage of being able to connect the subframe to the cavity closer at alternative locations is that it enables the functional frame to be fitted into the wall at different locations, e.g. aligned with the cavity; entirely within the outer leaf of the wall; partly in the outer leaf and partly aligned with the cavity. This is important because building design calls for a variety of functional frame positions and it is obviously an advantage if a single form of cavity closer can be used with them all.

According to a preferred feature of the invention, the first part comprises a box section of a width such that it is adapted to fit closely within a cavity of minimum width (say 50 mm) and a lateral extension part or the whole of which can be removed, the width of the extension being such that together with the box section it enables the first part to fit closely within a cavity of maximum width (say 100 mm).

Given that the first part may have its lateral extension removed so that the first part will fit a 50 mm cavity; or left intact, so that the first part will fit a 100 mm cavity; or have its lateral extension partly removed so that the first part will fit a 65 mm or a 75 mm cavity, the versatility of the closer appears. In fact, if the cavity closer has three frame fixing positions and can fit 50 mm, 65 mm, 75 mm and 100 mm cavities then it provides for 18 different designs; with the one extrusion.

Thus, in one arrangement, each anchorage comprises a flange with an arrowhead cross-section head. In another arrangement, each anchorage comprises a rib and a head of mushroom-shaped cross-section.

According to a preferred feature of this aspect of the invention, there are three or more anchorages spaced apart laterally of the second part, so that a subframe or other frame element can be engaged simultaneously with two of the anchorages.

It is preferred that the first part is constructed so as to provide a moisture barrier to prevent the migration of water across the width of a cavity into which the first part is inserted. It is also preferred to provide undercut recesses providing anchorage for mortar and/or wall ties at any position along the length of the closer.

Further, it is preferred that the first part of the closer is at least partly hollow and filled with thermal insulation material. Preferably, the cavity closer is made of extruded plastics section.

According to yet another preferred feature of this aspect of the invention, a cavity closer in accordance with the invention is connected to a subframe or other frame element by engagement of at least one of its anchorages with abutment means on the subframe or other frame element. Preferably, the subframe or other frame element is at least partly hollow, and has inturned flanges with upstanding lips, the ends of which provide the abutments for engagement with the anchorages on the cavity closer.

In the preferred construction, the subframe or other frame element is made in metal. However, in another form of the invention, the subframe or other frame is made in extruded plastics material.

Second and third aspects of the invention provide structural assemblies incorporating cavity closers, and are aimed at providing assemblies which are relatively easy to construct and meet modern building requirements.

According to a second aspect of the invention, a structural assembly for use in a building comprises a frame element for a window or door frame, or a window or door subframe and a cavity closer snap-fitted to the frame element, the cavity closer having a first part which is adapted to enter the cavity of a cavity wall, so as to provide a damp course between the inner and outer leaves of the cavity wall and further comprising means for retaining thermal insulation in a location such that it provides a thermal break between the two leaves of the wall, and a second part adapted to locate on an end of at least one of the inner and outer leaves of the wall and to provide a damp course between the wall and the frame element in which an anchorage is provided on one of the cavity closer and the frame element, the anchorage entering a recess in the frame element or the cavity closer, as the case may be, and having an enlargement which snaps behind an abutment on the frame element or the cavity closer.

According to a third aspect of the invention, a structural assembly comprises a cavity wall, having inner and outer leaves with a cavity between them; a frame which comprises a window frame, a door frame or a subframe for a window or door frame, built into the cavity wall and at least one cavity closer snap-fitted to the outside of one of the frame elements (head, sill or jamb) of the frame, the cavity closer having: a first part which enters the cavity of the wall, so as to provide a damp course between the inner and outer leaves; a second part locating on an end of at least one of the inner and outer leaves and providing a moisture barrier between the leaves of the wall and the frame element and thermal insulation retained in the first part providing a thermal break between the two leaves of the wall in which an anchorage is provided on one of the cavity closer and the frame, the anchorage entering a recess in the frame or the cavity closer, as the case may be, and having an enlargement which snaps behind an abutment on the frame or the cavity closer.

Various preferred features of the first aspect of the invention also constitute preferred features of the second and third aspects of the invention, and therefore need not be separately specified.

The invention in all three aspects will be better understood from the following description of certain specific constructions which are described here by way of examples only, with reference to the accompanying drawings, in which: Figure 1 is a cross-section through a cavity closer; Figure 2 is a section through a cavity wall at an end of an opening for a functional frame such as a window frame, showing a cavity closer fitted to the end of the wall, with a subframe fitted to the cavity closer; Figure 3 is a cross-section through a subframe element; Figure 4 is a detailed view of a corner of a subframe constructed from elements as shown in Figure 3, and including a mitred joint; Figure 5 is a view similar to Figure 4, but showing a butt joint at the corner; Figure 6 shows a cross-section through a cavity closer of the kind illustrated in Figure 1, during the fitting of the subframe of the kind illustrated in Figure 3; Figure 7 is a cross-section through a cavity wall at an opening for a window frame, showing the fitting of a cavity closer in accordance with Figure 1, to which has been connected a wall tie, and showing the fitting of the subframe in a location where the subframe, and therefore the functional frame, is substantially within the outer leaf of the wall; Figure 8 is a view similar to Figure 7, but showing an alternative position for the subframe on the cavity closer, wherein part of the subframe is located within the outer leaf of the wall, and part of the subframe overlies the end of the cavity; Figure 9 is a horizontal cross-section through the end portion of a cavity wall adjacent to an opening for a functional frame, wherein there is a very wide cavity, and showing the fitting of a cavity closer in accordance with Figure 1, so as to effect the closure of the end of the cavity; Figure 10 is a view similar to Figure 9, excepting that in this construction the cavity is somewhat wider than the narrowest cavity, but not so wide as the cavity illustrated in Figure 9; Figure 11 illustrates the fitting of an alternative construction of cavity closer into a cavity wall; Figure 12 shows a stage during the fitting of a subframe which is shaped to fit the cavity closer of the kind shown in Figure 11, and Figure 13 is a view similar to Figure 12, but showing the subframe in the fully fitted condition.

The cavity closer 100 which is shown in Figure 1 is made in extruded polyvinyl chloride (PVC) of a grade such as is now commonly used for PVC windows, and the material is particularly useful, because it is water resistant and moisture impermeable. By virtue of its extrusion, the cavity closer is in the form of a strip of constant crosssection, as shown in Figure 1, and it can be manufactured in long lengths and then cut to required lengths either on site or at a window and door assembly factory.

The strip comprises a cavity entering part 101 and a wall engaging part 102. The wall engaging part is essentially a flat plate which is intended to rest against the end of the leaves of a cavity wall and to separate and provide a moisture barrier between the wall and the door or window frame at the end of the wall which forms a boundary of a door or window opening. Figure 2 shows the inner leaf 103 and outer leaf 104 of a cavity wall at such an end position, with a cavity closer 100 fitted. In this construction there is a cavity 106 between the inner and outer leaves and this cavity is of the recommended (United Kingdom) minimum width of 50 mm. It will be seen that the flat underside of the wall engaging part 102 rests on the end faces of the blocks and bricks of the leaves 103 and 104.

Throughout the following description directions (right, left, top, bottom, inside, outside and the like) refer to directions as seen in the drawing under description. In practice, since the arrangement fits all round the opening for the functional frame, components will sometimes be inverted from the position illustrated.

Reverting to Figure 1, there are two laterally spaced T-shaped ribs 108 and 110 projecting outwardly from the left hand part of the part 102 and at the left hand end of this part there is an L-shaped rib 112, the ribs 108, 110 and 112 forming between them two undercut recesses 114 and 116 in which plaster or mortar can engage to anchor the plaster or mortar to the cavity closer.

On the right hand part of the wall engaging part 102 there are four laterally spaced subframe anchorages 118, 120, 122 and 124. Each of these anchorages comprises an upstanding flange 126 with a bulbous head 128 at its upper end, the head being of arrowhead cross-section but with a rounded nose. The purpose of these anchorages will become apparent later.

Turning now to the cavity entering part 101, this essentially comprises a rectangular box section 130 and a bottom extension flange 132. The box section 130 is formed by a pair of side walls, a bottom wall and part of the plate-like wall engaging part 102. The overall width of this box section is 50 mm, so that it is a snug fit in a 50 mm wide cavity. The flange 132 projects another 50 mm to the left of the box section and is a continuation of the bottom wall of the box section. A series of ribs projects downwardly from the flange 132 and the bottom wall of the box section at laterally spaced positions.

The outer ribs 134 and 136 are L-shaped and are inturned whilst the intermediate ribs 138, 140 and 142 are all Tshaped. Thus, a series of four undercut recesses 144, 146, 148 and 150 is formed across the bottom of the cavity closer. These recesses can accept the root portions of plastics wall ties, as shown for example in Figures 7 to 11. The use of wall ties of this kind for firmly securing cavity closers to the wall of a building is now well understood and need not be described in detail. Also, it is to be understood that such wall ties can be used with the cavity closer 100 wherever it is employed, but they have not been illustrated in all the cavity wall constructions shown in the drawings.

A series of shallow arcuate cross-section grooves 152 is formed in the bottom face of each leg of the ribs 134, 136, 138, 140, 142. The purpose of these grooves is to provide a series of sharp edges extending longitudinally of each rib. These edges provide a moisture barrier inhibiting flow of water across the bottom face of the cavity closer. The recesses 144, 146, 148 and 150 also provide moisture traps and it is practically impossible for water to migrate from the outer leaf 104 of a wall (which may be wet for long periods of time) across the bottom face of the cavity closer. This is important, because one of the characteristics of the cavity closer is that it prevents water crossing from the outer leaf to the inner leaf. Since the closer is itself made of water impervious material, water cannot travel through the cavity entering part from one leaf of the wall to the other, and the moisture resistant nature of the PVC ensures that the cavity entering part does not corrode or otherwise decay.

Another function of the cavity closer is to provide a thermal insulation between the two leaves of the wall at the end of the wall, thereby reducing the possibility of a cold bridge across the cavity.

In Figure 3 there is illustrated a strip 160 formed by rolling steel plate, this strip being used in the formation of the head, sill and jamb elements of a subframe for a door or window. The use of such subframes is also well understood and need not be described in detail. They are particularly required where the functional frame (i.e. door or window frame) is to be push-fitted into place as one of the later operations in the construction of a building. As with the cavity closer 100, the steel strip is manufactured in long lengths and can be cut to the required lengths on site or at a window and door factory. The steel plate should be water resistant and may be stainless steel or mild steel which has been given a good water resistant surface treatment.

The strip 160 is generally of dumbbell cross-section, with an open bottom and with deep end parts 178 and 180. (As with the description of the cavity closer, directional indications apply to the subframe strip as it appears in Figure 3). Hence, the strip has a top wall in which there is a wide channel 162, but its bottom wall comprises only short end pieces 164 and 166, on which there are upturned reentrant flanges 168 and 170 respectively, so that the bottom side of the strip is open. The end walls 172 and 174 of the strip are flat, except that there is a groove 176 in the wall 174 and all the corners on the end parts 178 and 180 are rounded. The groove 176 provides a plaster guide for the tool of a plasterer when plaster rendering the end of the inside leaf of the wall. The thickness of the steel plate from which the subframe strip is formed is substantial (e.g. 1.5 mm in the case of treated mild steel) and the cross-section gives it additional strength, so that the strip is quite rigid in character.

A subframe for reception of a functional frame is constructed from four lengths of the strip 160, welded together to form head, sill and jamb elements of the subframe. The frame elements are welded together and the corner joints may be mitred, as shown at 182 in Figure 4, or butt jointed as shown at 184 in Figure 5.

The method of constructing part of a cavity wall building incorporating a steel subframe made of the strip material shown in Figure 3 will now be described with reference to Figure 2.

The subframe is first manufactured by cutting the required lengths of the steel strip 160 and welding them together.

It is to be noted that, although the welding process is carefully controlled, there have to be reasonable manufacturing tolerances and therefore the inside dimensions of the subframe can vary by up to 2 mm. It is failure to appreciate this fact which has created window securing problems with some known push-in window arrangements.

Lengths of the cavity closer 100 are cut as required for the sill and two jambs of the subframe. If some types of metal lintel are fitted over the window or door space, then the cavity closer 100 cannot be used across the head of the subframe, in which case a length of the cavity closer is not cut for the head of the subframe. In Figure 2, the cavity 106 is the (United Kingdom) recommended minimum 50 mm width. So that the cavity entering part 101 can fit into the cavity, the extension flange 132 is cut off. Also, it will be noted that in Figure 2, the subframe 160 is aligned with the cavity: for this location, only the two left hand anchorages 118 and 120 are required, so the anchorages 122 and 124 are cut off each of the three or four strips. One of the useful features of the cavity closer 100 is that parts of it can be easily removed by cutting so that it can be used with a variety of building details.

Next, the strips of cavity closer are secured to their respective sill, jamb and head elements of the subframe, by engaging the upstanding lips 168 and 170 with the anchorages 118 and 120. The method of fitting is described later with reference to Figure 23. This automatically locates the subframe in alignment with the box section 130 of the cavity closer 100.

In essence the subframe strip 160 is snap-fitted to the anchorages 118, 120 and it will be observed from Figure 2, for example, that in this fitted position, the reentrant flanges 168 and 170 are nipped between their respective arrowhead ribs and the top surface of the wall engaging portion 102 of the cavity closer. In other words, the cavity closer is then tightly attached to its respective subframe strip. This is done on all three or four sides of the subframe, so that as a result, the subframe carries the cavity closers.

During the construction of the building, the inner and outer leaves 103 and 104 (see Figure 2) are built up in the conventional manner, until the wall reaches sill height at the opening for the functional frame. The subframe to which the cavity closers 100 have been attached is then lowered onto the leaves of the wall below the window or door opening, and this causes the cavity entering portion 130 to enter the cavity between the inner and outer leaves of the wall. The cavity entering portion 130 should be a snug fit within the cavity.

Then the wall is built upwards alongside the opening for the door or window frame, and the resulting construction is as illustrated in Figure 2. At various levels between horizontal courses of bricks or blocks, wall ties (not shown) may be anchored in the undercut recesses 148 and 150 of the cavity entering portion of the cavity closer, and these wall ties extend into the mortar on opposite sides of the cavity closer, and tie the cavity closer in the position illustrated in Figure 2. The wall engaging part 102 provides end locations for the blocks and bricks of the inner and outer leaves 103 and 104 of the building, and this helps to maintain the accuracy of the window opening. It will be appreciated that the construction which is illustrated in Figure 2 occurs at both sides of the window opening.

When the brickwork reaches the level of the top of the subframe, then a steel lintel is laid across the top of the subframe. The blocks of the inner leaf and the bricks of the outer leaf continue to be built up above the level of the opening. As a result of this building technique, the subframe comprising the strips 160 welded together is properly located in the window or door opening, and because of its alignment with the box section 130 of the cavity closer, the subframe will be aligned with the cavity. It is then possible to leave the window or door opening unattended until a late stage in the building process, when the window or door frame has to be fitted.

Consequently, the opening is available for the passage of materials or workmen, and the steel subframe is unlikely to suffer any significant damage during the building process, partly because of its inherent strength, and partly because in any case it provides only a narrow projection into the window or door opening. Moreover, the cavity closer 100 offers a very rigid fixing of the subframe to the wall.

At some stage, thermal insulation foam 180 is introduced into the box section 130. This can be done at an early stage by cutting a strip of preformed foam filling material and sliding it into the end of the box section, or alternatively it can be done either at an earlier or a later stage by blowing liquified foam into the box section 130.

Figure 6 shows the fitting of the subframe onto two of the anchorages 122 and 124. These anchorages are first aligned with the gap between the upturned flanges 168 and 170 of the subframe, and then the cavity closer is pushed towards the subframe. Engagement of the rounded corners at the bottoms of the flanges 168 and 170 with the outsides of the arrowhead formations on the anchorages 122 and 124 causes the anchorages to deflect towards each other, to allow the anchorages to pass through the space between the flanges 168 and 170. This deflection of the anchorages 122 and 124 is permitted by the inherent nature of the polyvinyl chloride from which the cavity closer is manufactured. As soon as the arrowhead devices pass the top edges of the flanges 168 and 170, however, the anchorages spring outwardly into their free vertical positions, and the shoulders provided by the outwardly facing parts of the arrowhead devices engage with the extremities of the flanges 168 and 170. In fact, the lower parts of the sections 178 and 180 of the subframe are then nipped between the top surface of the wallengaging flange 102 of the cavity closer and the arrowhead formations on the anchorages 122 and 124. It is then virtually impossible to detach the cavity closer from the subframe, and hence, when the cavity closer is then built into the wall structure, the subframe is tightly held in the wall.

It is also to be understood that, whilst a steel subframe has been described, the invention could be applied to a plastics subframe, which have much the same shape as the steel subframe 160.

In Figure 2 the subframe is shown secured by the anchorages 118 and 120, which ensure that the subframe is substantially aligned with the box section 130 of the cavity entering portion of the cavity closer. This will provide an arrangement, in which the window frame itself is substantially aligned with the cavity in the interior/exterior sense. Turning to Figure 7, an arrangement is illustrated in which the outer leaf of a wall is shown at 500, and a cavity closer 100 is shown with its cavity entering portion 101 abutting the internal face of the external leaf of the wall, and with the wall engaging element 102 locating on the end of the external leaf. In this arrangement, all the anchorages 118, 120, 122 and 124 are left in position. In practice, if the cavity is only 50 mm wide, then the lower extension flange 132 will be cut off the cavity closer, before the closer is inserted into the wall structure. That will enable the left hand part of the wall-engaging element 102 to engage with the end face of the inner leaf of the cavity wall.

An angled plastics wall tie 502 has its root portion engaged in one of the undercut recesses on the inside face of the cavity entering portion of the closer, and extends into a mortar joint of the external leaf of the cavity wall. It will be appreciated that similar wall ties can be provided at various vertical locations.

However, it will be noticed that in Figure 7, the subframe element 160 has been fitted onto the two outer anchorages 122 and 124. The actual method of fitting onto these anchorages is as described, with reference to Figure 6.

Positioning the subframe on the anchorages 122 and 124 has the effect of aligning the subframe substantially within the external leaf of the cavity wall, and hence the window frame will also be within the external leaf. This is a position which is much favoured in modern building techniques. In the case of a timber window frame, it has the disadvantage that the frame is more exposed to the weather than it would be if fitted deeper into the window opening, but on the other hand, with a plastics window frame, this is not so significant.

Turning to Figure 8, again there is an outer leaf 504 of a cavity wall, and a cavity closer 100 is fitted with its cavity entering portion locating against the inside face of the outer leaf. In this arrangement, however, the outer anchorage 124 has been cut off, leaving only the anchorages 118, 120 and 122. The subframe 160 is fitted to the anchorages 120 and 122, that is to say the two intermediate anchorages, and this has the effect of locating the subframe and therefore the window frame partly within the outer leaf of the wall, and partly in alignment with the cavity of the wall.

Thus, it will be seen that by providing four spaced apart anchorages, such as 118, 120, 122 and 124, it is possible to locate the subframe 160 in three positions relatively to the cavity wall itself. This renders the arrangement very versatile.

In Figure 9, there is illustrated a cavity wall, which comprises an outer leaf 506 and an inner leaf 508, with a wide cavity between them. This figure shows the widest cavity which is normally employed, having a width of 100 mm. A cavity closer 100 is fitted, but in this construction, the extension flange 132 is left in position, and therefore the cavity entering part of the closer comprises the box section 130 and the channel section provided by the inner part of the wall-engaging flange 102, the left hand end wall of the box section 130 and the extension flange 132. Hence, the cavity entering portion is able to fill the full width of the cavity, and as illustrated in Figure 9, the two hollow portions of the cavity closer may be filled with foam thermal insulation material.

This construction also shows angled wall ties 512, the root portions of which are fitted into undercut recesses of the box section 130 and the extension flange 132, the main portions of the ties 512 extending respectively into the inner and outer leaves of the cavity wall.

Figure 10 shows an arrangement which is quite similar to Figure 9, in that it has an outer leaf 520 and an inner leaf 522 of the wall, with a cavity 524 between them, and the cavity closer 100 is fitted to the end of the wall.

However, in this arrangement, the cavity is 75 mm wide, so that the extension flange 132 is cut short, so that the cavity entering part of the closer just fills the width of the cavity, and again the hollow box section 130 and the channel formed at one side of the box section are filled with thermal insulation material. This construction also shows that part of the wall-engaging flange 102 has been cut off at the left hand end, although there is a sufficient width of this flange to engage on the end face of the inner leaf of the wall.

Turning now to Figure 11, there is shown another arrangement in which there is an external leaf 530 and an internal leaf 532 with a cavity 534 between them. There is also a cavity closer 540, which in many respects is similar to the cavity closer 100, in that it has a box section cavity entering portion 542 and an extension flange 544 which can be cut off if required (as has been done in the Figure 11 structure). In this cavity closer, however, instead of the flange-type anchorages 118, 120, 122 and 124, there are mushroom cross-section anchorages 546, 548, 550 and 552, which are at similar locations on the cavity closer to the flange-type anchorages, but which project only quite a short distance from the face of the wall-engaging flange 554. This construction of cavity closer can be employed with a subframe of the crosssection which is illustrated in Figures 12 and 13, that is to say generally a rectangle, with part of the bottom wall cut away, to leave inturned lips 556 and 558. In practice, the top portion of the subframe may have a recess, so as to provide shoulders for engagement by spring clips for retaining the window on the subframe, but this has not been illustrated for simplicity in Figures 12 and 13.

The subframe can be secured to any adjacent pair of the mushroom-shaped cross-section anchorage ribs 546, 548, 550 and 558, in order to locate the subframe in alignment with the cavity; partly in alignment with the cavity and partly in alignment with the outer leaf, or substantially entirely within the outer leaf. Engagement is effected by hooking one of the lips 558 under the outer mushroom head of the rib 552, and then pressing the other side of the subframe downwardly. During this downward movement, it will distort the mushroom head on the rib 550 slightly, to allow the interned flange 556 to pass the mushroom head, and once the subframe arrives at the fully fitted position, as illustrated in Figure 13, the rib 550 reverts to its original upright condition, so that the inner edges of the flanges 556 and 558 are secured under the outwardly projecting parts of the mushroom head 550 and 552.

Claims

1. A cavity closer for use in building construction comprising a first part adapted to enter the cavity between the inner and outer leaves of a cavity wall; a second part adapted to locate on the end of one or both of the inner and outer leaves of the wall and two or more anchorages on the second part, adapted to connect a subframe or other frame element to the cavity closer in any one of two or more locations in the interior/exterior sense relatively to the first cavity entering part in which each anchorage comprises a formation upstanding from the face of the second part, opposite to the face which locates on the end of the wall, with an enlarged head adapted to engage with an abutment on the subframe or other frame element to establish the connection between the cavity closer and the subframe or other frame element and in which the anchorages are resilient to provide a snap-fit connection for the subframe or other frame element.

2. A cavity closer as claimed in Claim 1, in which the first part comprises a box section of a width such that it is adapted to fit closely within a cavity of minimum width (say 50 mm) and a lateral extension part or the whole of which can be removed, the width of the extension being such that together with the box section it enables the first part to fit closely within a cavity of maximum width (say 100 mm).

3. A cavity closer as claimed in claim 1 of claim 2, in which anchorage comprises a flange with an arrowhead cross-section head.

4. A cavity closer as claimed in any preceding claim, in which anchorage comprises a rib and a head of mushroom-shaped cross-section.

5. A cavity closer as claimed in any one of claims 1 to 4, in which there are three or more anchorages spaced apart laterally of the second part, so that a subframe or other frame element can be engaged simultaneously with two of the anchorages.

6. A cavity closer as claimed in any one of claims 1 to 5, in which the first part is constructed so as to provide a moisture barrier to prevent the migration of water across the width of a cavity into which the first part is inserted.

7. A cavity closer as claimed in any one of claims 1 to 6, in which there are undercut recesses providing anchorage for mortar and/or wall ties at any position along its length.

8. A cavity closer as claimed in any one of claims 1 to 7, in which the first part of the closer is at least partly hollow and filled with thermal insulation material.

9. A cavity closer as claimed in any one of claims 1 to 8 which is made of extruded plastics material.

10. A cavity closer for use in building construction as claimed in any one of claims 1 to 9, connected to a subframe or other frame element by engagement of at least one of its anchorages with abutment means on the subframe or other frame element.

11. A cavity closer and subframe or other frame element as claimed in claim 10, in which the subframe or other frame element is at least partly hollow and has inturned flanges with upstanding lips, the ends of which provide the abutments for engagement with the anchorages on the cavity closer.

12. A cavity closer and subframe or other frame element as claimed in claim 9 or claim 10, in which the subframe or other frame element is made in metal.

13. A cavity closer and subframe or other frame element as claimed in claim 9 or claim 10, in which the subframe or other frame element is made in extruded plastics material.

14. A cavity closer for use in building construction constructed and arranged substantially as herein described with reference to Figure 1 or Figure 11 of the accompanying drawings.

15. A cavity closer and a subframe or other frame element constructed and arranged substantially as herein described with reference to any one of Figures 2, 7, 8 or 13 of the accompanying drawings.

16. A structural assembly comprising a cavity wall, having inner and outer leaves, and a cavity closer as claimed in any one of claims 1 to 9 or claim 14, with the first part of the cavity closer built into the cavity of the wall.

17. A structural assembly for use in a building comprising a frame element for a window or door frame, or a window or door subframe and a cavity closer snap-fitted to the frame element, the cavity closer having a first part which is adapted to enter the cavity of a cavity wall, so as to provide a damp course between the inner and outer leaves of the cavity wall and further comprising means for retaining a thermal insulation in a location such that it provides a thermal break between the two leaves of the wall, and a second part adapted to locate on an end of at least one of the inner and outer leaves of the wall and to provide a damp course between the wall and the frame element in which an anchorage is provided on one of the cavity closer and the frame element, the anchorage entering a recess in the frame element or the cavity closer, as the case may be, and having an enlargement which snaps behind an abutment on the frame element or the cavity closer.

18. A structural assembly as claimed in claim 17, in which the anchorage is provided on the second part of the cavity closer and comprises a flange with an arrowhead cross-section head, the snap-fitting being achieved by deflection of the flange to allow the arrowhead to pass an obstruction as it enters a recess in the frame element.

19. A structural assembly as claimed in claim 17, in which the anchorage is provided on the second part of the cavity closer and comprises a rib and a head of mushroom-shaped cross-section.

20. A structural assembly as claimed in claim 18 or claim 19, in which there are two anchorages spaced laterally on the second part of the cavity closer; the frame element is hollow and the anchorages are adapted to engage with reentrant flanges in the frame element.

21. A structural assembly as claimed in any one of claims 17 to 20, in which the means for retaining the thermal insulation comprises a channel cross-section formation of the first part of the cavity closer.

22. A structural assembly as claimed in any one of claims 17 to 20, in which the means for retaining the thermal insulation comprises a substantially box shaped cross-section formation of the first part of the cavity closer.

23. A structural assembly as claimed in any one of claims 17 to 22, in which the anchorages are resilient.

24. A structural assembly as claimed in any one of claims 17 to 23, in which the first part of the cavity closer is constructed so as to provide a moisture barrier, to prevent the migration of water across the width of a cavity into which the first part is inserted.

25. A structural assembly as claimed in any one of claims 17 to 24, in which there are undercut recesses providing anchorage for mortar and/or wall ties at any position along the length of the cavity closer.

26. A structural assembly as claimed in any one of claims 17 to 25, in which the cavity closer is made of extruded plastics material.

27. A structural assembly comprising a cavity wall having inner and outer leaves with a cavity between them; a frame which comprises a window frame, a door frame or a subframe for a window or door frame, built into the cavity wall and at least one cavity closer snap fitted to the outside of one of the frame elements (head, sill or jamb) of the frame, the cavity closer having: a first part which enters the cavity of the wall so as to provide a damp course between the inner and outer leaves; a second part locating on an end of at least one of the inner and outer leaves and providing a moisture barrier between the leaves of the wall and the frame element and thermal insulation retained in the first part providing a thermal break between the two leaves of the wall in which an anchorage is provided on one of the cavity closer and the frame, the anchorage entering a recess in the frame or the cavity closer, as the case may be, and having an enlargement which snaps behind an abutment on the frame or the cavity closer.

28. A structural assembly as claimed in claim 27, in which the anchorage is provided on the second part of the cavity closer and comprises a flange with an arrowhead cross-section head, the snap-fitting being achieved by deflection of the flange to allow the arrowhead to pass an obstruction as it enters a recess in the frame.

29. A structural assembly as claimed in claim 27, in which the anchorage is provided on the second part of the cavity closer and comprises a rib and a head of mushroom-shaped cross-section.

30. A structural assembly as claimed in claim 28 or claim 29, in which there are two anchorages spaced laterally on the second part of the cavity closer, the frame is hollow and the anchorages are adapted to engage with reentrant flanges in the frame.

31. A structural assembly as claimed in any one of claims 27 to 30, in which the means for retaining the thermal insulation comprises a channel cross-section formation of the first part of the cavity closer.

32. A structural assembly as claimed in any one of claims 27 to 30, in which the means for retaining the thermal insulation comprises a substantially box shape cross-section format ion of the first part of the cavity closer.

33. A structural assembly as claimed in any one of claims 27 to 32, in which the first part of the cavity closer is constructed so as to provide a moisture barrier to prevent the migration of water across the width of the cavity.

34. A structural assembly as claimed in any one of claims 27 to 33, in which there are undercut recesses providing anchorage for mortar and/or wall ties at any position along the length of the cavity closer.

35. A structural assembly as claimed in any one of claims 27 to 34, in which the cavity closer is made of extruded plastics material.

36. A structural assembly for use in a building as claimed in claim 17, constructed and arranged substantially as herein described with reference to Figure 2; Figure 7; Figure 8 or Figure 13 of the accompanying drawings.

37. A structural assembly as claimed in claim 27, constructed and arranged substantially as herein described with reference to Figure 2 or Figure 7 or Figure 8 or Figure 9 or Figure 10 or Figure 11 of the accompanying drawings.