GB2292171A - Preventing the occlusion of an air path defined between the skins of a cavity wall - Google Patents

Abstract

A method of preventing the occlusion of an air path defined between the skins of a cavity wall when a material is introduced into the cavity defined by the skins comprises, prior to the introduction of the material, locating an opening eg in an air brick, provided in one of the skins which communicates via the cavity with another opening provided in the other of the skins to define an air path therebetween and inserting into one or both of said openings a device 20 which is sized so as to extend into the cavity and which is adapted to form all or part of a barrier which extends between the two skins and encloses a volume which communicates with the respective openings while still allowing air to pass therethrough. The device comprises a first portion adapted for insertion into the cavity through one of said through holes, a retaining portion 26 connected to said first portion and adapted for engagement with the airbrick so as to retain said first portion with respect thereto and one or more resilient elements 24 connected to said first portion and extending transversely thereof, the or each element is so sized as to form, with one or more similar devices inserted into other of the through holes, a barrier which extends between the two skins and encloses a volume which communicates with at least one of the through holes provided in the airbrick while still allowing air to pass therethrough. <IMAGE>

Description

DEVICE AND METHOD FOR PREVENTING THE OCCLUSION OF AN AIR PATH DEFINED BETWEEN THE SKINS OF A CAVITY WALL The present invention relates to a device and method for preventing the occlusion of an air path defined between the skins of a cavity wall when a material, such as an insulation material, is introduced into the cavity defined by the skins. The present invention also relates to a cavity wall which includes the aforementioned device.

Many buildings have been constructed with a cavity wall comprising an outer and an inner skin which are spaced apart to define a cavity therebetween. In order tp provide ventilation to an inner space bounded by the cavity wall the outer skin typically includes one or more airbricks each having a plurality of through holes which communicate with the cavity. The inner skin may also be provided with one or more airbricks although these are sometimes replaced by more aesthetically pleasing features such as grills, diffusers or some other form of opening such as that created by a missing brick. Whatever form of opening is provided, it is usually in alignment with an airbrick provided in the outer skin so that ventilation air may pass both into and out of the interior space through the cavity wall by way of the shortest possible path.

Clearly, when it is desired to introduce material into the cavity defined between the outer and inner skins so as, for example, to improve the insulation characteristics of the wall it is necessary to do so in such a way as to not block the air path defined between the airbricks and/or other openings provided in the two skins. In the past this has been achieved by physically removing each airbrick in the outer skin, inserting the airbrick in one end of a relatively stiff, open-ended sleeve of substantially the same cross-section as the airbrick so that a portion of the sleeve projects beyond the airbrick by an amount equal to the width of the cavity, and re-introducing the airbrick and the sleeve into the outer skin so that the sleeve defines a barrier which surrounds the air path between the two skins.Insulation material may then be pumped or blown into the cavity wall to fill the cavity with the exception of the volume defined by the or each sleeve. As a result the various air paths between the two skins are not occluded. This however, is clearly a time consuming process since a typical cavity wall may include a number of such airbricks. Furthermore, the initial removal of an airbrick often results in damage either to it or the surrounding brickwork and so necessitates the use of a replacement airbrick.

The present invention seeks to address the problems of the prior art method and to provide a means of maintaining an air path between the outer and inner skins of a cavity wall when the cavity between the two is to be filled with a material, whether for insulation purposes or otherwise, without the necessity of having to first remove an airbrick or similar element from one or both of the outer and inner skins.

According to a first aspect of the present invention there is provided a method of preventing the occlusion of an air path defined between the skins of a cavity wall when a material, such as an insulation material, is introduced into the cavity defined by the skins, the method comprising the step, prior to the introduction of the material, of locating an opening provided in one of the skins which communicates via the cavity with another opening provided in the other of the skins to define an air path therebetween and inserting into one or both of said openings a device which is sized so as to extend into the cavity and which is adapted to form all or part of a barrier which extends between the two skins and encloses a volume which communicates with the respective openings while still allowing air to pass therethrough.

According to a second aspect of the present invention there is provided a device for use with an airbrick forming part of either an outer or an inner skin of a cavity wall, the airbrick comprising a plurality of through holes and the device serving to prevent said through holes from becoming occluded upon the introduction of a material, such as an insulation material, into the cavity defined between said outer and inner skins, the device comprising a first portion adapted for insertion into the cavity through one of said through holes; a retaining portion connected to said first portion and adapted for engagement with the airbrick so as to retain said first portion with respect thereto; and one or more resilient elements connected to said first portion and extending transversely thereof, the or each element being deformable from its transversely extending position for insertion into said through hole but urged to return to its transversely extending position upon emerging into the cavity, the or each element being so sized as to form, with one or more similar devices inserted into other of the through holes, a barrier which extends between the two skins and encloses a volume which communicates with at least one of the through holes provided in the airbrick while still allowing air to pass therethrough.

According to a third aspect of the present invention, there is provided a cavity wall comprising an inner and an outer skin with a cavity defined therebetween, each of said skins having an opening throughthrough which communicates with the cavity and which, with the opening provided in the other of the skins, defines an air path through the cavity wall, at least one of said openings having a device inserted therein which is sized so as to extend into the cavity and which is adapted to form all or part of a barrier which extends between the two skins and encloses a volume which communicates with the respective openings while still allowing air to pass therethrough.

A number of embodiments of the present invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a schematic view of a typical airbrick which might form part of either an outer or an inner skin of a cavity wall; Figure 2 is a schematic perspective view of a device in accordance with a first embodiment of the present invention; Figure 3 is a plan view of the device of Figure 2; Figure 4 is a lateral side view of the device of Figure 2; Figure 5 is an end view of the device of Figure 2; Figure 6 is a schematic perspective view of a cavity wall in which a number of devices of the type shown in Figure 2 are illustrated but in which the tines have been omitted for the same of clarity; Figure 7 is a schematic perspective view of a device in accordance with a second embodiment of the present invention; ; Figure 8 is a schematic view of the devices of Figure 7 when inserted into the through holes of an airbrick; Figure 9 is a schematic view of a device in accordance with a third embodiment of the present invention; Figure 10 is a schematic view of the devices of Figure 9 when inserted into the through holes of an airbrick; Figure 11 is a schematic view of a device in accordance with a fourth embodiment of the present invention; and Figure 12 is a schematic view of a cavity wall illustrating a situation that can arise when the openings provided in the two skins are not in complete alignment.

A typical airbrick 10 is shown in Figure 1 to comprise a plurality of through holes 12 which communicate between two opposed surfaces of the airbrick 14 and 16. When the airbrick 10 is built into the outer skin of a cavity wall these two opposed surfaces 14,16 will respectively form part of the exterior and interior surfaces of the skin so that each through hole 12 defines an air path between the outside world and the cavity defined between the outer and inner skins. A similar airbrick 10', again having a plurality of through holes 12', may also be provided in the inner skin in alignment with the airbrick 10 provided in the outer skin. Alternatively, the airbrick in the inner skin 10' may be replaced by a more aesthetically pleasing feature such as a grill, diffuser or some other form of opening such as that created by one or more missing bricks.In this way the air path defined by the airbrick 10 in the outer skin may communicate with that provided through the inner skin to allow ventilation air to pass both into and out of an interior spaced bounded by the cavity wall.

In order to prevent material introduced into the cavity from blocking the air path defined between the outer and inner skins a suitable device may be inserted into some or all of the through holes 12 provided in the airbrick 10. One such device 20 is shown in Figure 2 to comprise an elongate spine 22 from which there project a plurality of resilient, laterally-extending tines 24. These tines 24 extend to both sides of the spine 22 in a common plane and are each equidistantly spaced from its neighbours. At one end the spine 22 flares outwardly to form a parallel sided web 26 of increased lateral width. From opposite sides of this web 26 there depend two mutually spaced, parallel side walls 28,30 which with the web 26 form a retaining portion 32 and define a channel of inverted U shape.

The device 20 is dimensioned for use with the airbrick 10 of Figure 1. Thus, the length of each of the tines 24 is equal to at least half the distance between the centres of adjacent through holes 12 whereas the length of the spine 22 is such that it may extend between the outer and inner skins of the cavity wall. In order to find use in cavity walls where the spacing between the two skins varies the spine 22 may be formed over size and cut to suit a particular application. Alternatively, the spine 22 may be formed with one or more frangible zones 23 disposed at intervals along its length so that the spine may be snapped to a length to suit a particular application without requiring the use of a cutting tool.

In a similar way the lateral width of the parallel sided web 26 and the downward extent of the mutually spaced, parallel side walls 28, 30 are also dimensioned with respect to the airbrick 10 and are such as to enable the retaining portion 32 to be received and retained within a respective one of the through holes 12. The reception of the retaining portion 32 within any of the through holes 12 is preferably a press, but nevertheless tight, fit. To this end the parallel sided web 26 and the mutually spaced, parallel side walls 28, 30 are preferably formed of a resilient material that may be deformed sufficiently to introduce the retaining portion 32 into the through hole 12 but which, when released, are urged outwardly to retain the device 20 in position with respect to the airbrick 10.

Alternatively, one or more of the parallel sided web 26 and the mutually spaced, parallel side walls 28,30 may be provided on an outwardly directed surface with a strip of crushable material which is crushed upon the introduction of the retaining portion 32 into the through hole 12 to hold the retaining portion in place. In yet another arrangement, the two mutually spaced side walls 28,30 may be formed so as to be inclined outwardly from the parallel sided web 26 from which they depend. Thus, provided the side walls 28,30 can flex resiliently about their respective lines of intersection with the parallel sided web 26, they may be deformed inwardly to allow the introduction of the retaining portion 32 into one of the through holes and then, when released, flex back outwardly to engage the surfaces of the through hole to again retain the device 10 with respect to the airbrick 10.

Whichever means of retaining the device 10 is selected, the parallel sided web 26 and the mutually spaced, parallel side walls 28,30 preferably have a longitudinal dimension approximating to the thickness of the airbrick 10. In this way the retaining portion 32 can provide the maximum cantilever support for the spine 22.

In use and prior to the introduction of material into the cavity between the two skins of the cavity wall, a separate device of the type shown in Figure 2 is inserted into each of the peripheral through holes 12 of the airbrick 10. In order to do this the device 20 is orientated so that the parallel sided web 26 and the mutually spaced, parallel side walls 28,30 are aligned parallel to the surfaces of the through hole 12 with the parallel side walls 28,30 extending from the parallel sided web 26 toward a longitudinal centre line of the airbrick 34. In this way, when the retaining portion 32 is inserted into the through hole 12 the parallel sided web 26 is disposed parallel to the longitudinal centre line 34 and in engagement with the surface of the through hole which is closest to the adjacent external surface of the airbrick 10.

The device 20 is held by the user by means of the parallel sided web 26 and the side walls 28,30 and inserted into the through hole 12 spine first. As the spine 22 is introduced into the through hole the laterally-extending tines 24 engage the surface of the airbrick 14 adjacent the through hole 12 and are bent rearwardly toward the user in order to pass through the through hole. As the device 20 continues to be pressed into the through hole 12 the tines 24 furthest from the user emerge from the through hole 12 into the cavity between the outer and inner skins whereupon they spring forward by virtue of their resilience to assume their original, laterally-extending configuration. The device is pressed home until the parallel sided web 26 and the mutually spaced, parallel side walls 28,30 are wholly received within the through hole 12.At the same time the end of the spine 22 furthest from the user either abuts the opposing surface of the inner skin or else is received within whatever form of opening is provided therein.

Having inserted a device 20 into one of the through holes 12, similar devices are then inserted into each of the remaining peripheral through holes in turn. As a result there is formed within the cavity two mesh-like surfaces, one of which occupies a first plane level with the top of the upper row of through holes while the other occupies a parallel plane level with the bottom of the lower row of through holes. By rotating the devices inserted in the through holes located at the corners of the airbrick through 900 these two mesh-like surfaces may be joined to form a barrier which surrounds the through holes in the airbrick and which extends from the outer skin to whatever form of opening is provided in alignment therewith in the inner skin. Because air may still pass through each of the through holes 12 by way of the respective U shaped channels defined by the retaining portions 32 and because the mesh-like barrier is effective to prevent the occlusion of either the U shaped channels or the through holes by the material that is subsequently introduced into the cavity, even when this material is introduced, the air path through the cavity wall is not impaired.

The mesh-like barrier is formed by the close proximity into which the tines 24 of adjacent spines 22 are brought following their insertion into adjacent through holes 12.

It will be apparent however, that not only is the length of the tines 24 important in determining the effectiveness of the mesh-like barrier but so to is their spacing along their respective spines 22. The size of the spacing is dependent upon the nature of the material to be excluded from the volume adjacent the through holes 12, but for a typical insulation material this spacing may be of the order of 3 x 10 3m.

Looking now at the length of the tines, it will apparent that the tines 24 may be sufficiently long so as to require the insertion of the devices 20 in only selected of the peripheral through holes 12. For example, if the tines 24 had a length equivalent to the distance between the centres of adjacent through holes 12, the devices 20 need only be inserted in every other peripheral through hole of the airbrick 10 to form the same mesh-like barrier.

Furthermore, it will be apparent that the tines 24 on opposite sides of any particular spine 22 may be offset with respect to each other by a distance equal to half the spacing between adjacent tines. In this way when two such devices 20 are inserted into adjacent through holes 12 the tines 24 of one of the devices will be interdigitally received within the tines of the other, further reducing the spacing between adjacent tines in the mesh-like barrier.

It will also be apparent that whereas the tines 24 on opposite sides of any particular spine 22 have been described as occupying a common plane, this need not necessarily be the case. Indeed, in order to provide a device which is particularly adapted for insertion into the through holes 12 located closest to the corners of the airbrick 10, the tines 24 on one side of the spine 22 may extend at right angles to those on the other.

It will apparent to those skilled in the art that the device illustrated in Figure 2 may be inserted into any one of the through holes 12 in an incorrect as well as a correct orientation. For example, if the device 20 were inserted with the mutually spaced, parallel side walls 28,30 extending from the parallel sided web 26 away from the longitudinal centre line 34, the resulting mesh-like barrier would no longer surround, and the enclosed volume, no longer communicate with, the peripheral through holes 12. As a consequence the mesh-like barrier would not be effective in preventing the occlusion of the peripheral through holes by a material that was subsequently introduced into the cavity.This may not matter if, for example, the air brick contains three or more rows of through holes so that in addition to the occluded peripheral through holes the air brick also defines one or more central through holes that are surrounded by the mesh-like barrier and which do communicate with the enclosed volume thereby defined. Nevertheless in order to counteract the incorrect insertion of the device 20, the device may be provided with an identifying mark to indicate its correct orientation with respect to the airbrick 10.

Alternatively, the device may be made symmetrical about a rotation through 900. The device may even be provided with more than one spine 22.

In an alternative embodiment illustrated in Figure 7 the device 20' is provided with a plurality of further tines 24' which depend from the spine 22 and extend generally perpendicularly to the laterally-extending tines 24. In this way the tines 24 and 24' define a plurality of T-shaped projections which are spaced at intervals along the spine 22. As a result this alternative embodiment is less sensitive to the incorrect orientation of the device 20' with respect to the through holes as is shown in Figure 8.

In yet another embodiment, this tine illustrated in Figure 9, the device 20" is provided with a plurality of yet further tines 24" which extend from the opposite side of the spine 22 but in the same plane as the further tines 24' of the previous embodiment. Thus the yet further tines 24", like the further tines 24', extend generally perpendicularly to the laterally-extending tines 24 to define a plurality of cross-shaped projections at intervals along the spine 22. As a result this embodiment is still less sensitive to the incorrect orientation of the device 20" as shown in Figure 10.

In still another alternative embodiment illustrated in Figure 11, the device 36 may simply comprise a tubular, hose-like member having a through bore 38 to define a path for the passage of air. As with the previous embodiments the hose-like member 36 may, in use, be inserted into a through hole of an airbrick provided in the outer skin of a cavity wall so that it projects into the cavity and communicates with whatever form of opening is provided in the inner skin. As before the hose-like member 36 may be retained in position in a cantilever fashion by the engagement of one end with the surfaces of the through hole. To this end the hose-like member is preferably formed of a resilient material which is capable of being deformed sufficiently to be inserted into one of the through holes and which, when released, is urged outwardly to engage its surfaces.

In each of the foregoing embodiments it has been assumed that the airbrick in the outer skin is in alignment with whatever form of opening is provided in the inner skin. This however, is not always the case. Even so, the embodiments of Figures 2 to 10 still provide significant advantages even when the openings in the two skins are not in alignment. For example, in the situation shown schematically in Figure 12, a mesh- like barrier may still be created which surrounds the respective openings by inserting devices of a kind illustrated in any of Figures 2 to 10 into the through holes of the airbrick in the inner skin as well as those of the airbrick in the outer skin.

Where the openings in the respective skins are laterally or vertically spaced to a still greater extent, a useful result may still be obtained by creating a new airbrick in the outer skin in alignment with the opening provided in the inner skin by drilling a number of suitable through holes in the existing brickwork.

Clearly the effectiveness of the embodiment of Figure 11 does not in principle depend on the relative alignment or otherwise of the openings in the two skins of the cavity wall. It is anticipated however, that the difficulties of inserting the hose-like member 36 into a through hole in an airbrick in one skin and guiding it within the cavity so that it is received in whatever form of opening is provided in the other skin will limit its use to situations where the two sets of openings are within a few bricks of complete alignment. In other situations the option of creating a new airbrick by drilling through the existing brickwork of the outer skin still remains a possibility.

Claims (28)

1. A method of preventing the occlusion of an air path defined between the skins of a cavity wall when a material is introduced into the cavity defined by the skins, the method comprising the steps, prior to the introduction of the material, of locating an opening provided in one of the skins which communicates via the cavity with another opening provided in the other of the skins to define an air path therebetween and inserting into one or both of said openings a device which is sized so as to extend into the cavity and which is adapted to form all or part of a barrier which extends between the two skins and encloses a volume which communicates with the respective openings while still allowing air to pass therethrough.

2. A method in accordance with claim 1, wherein the device comprises a hose-like member having a throughbore for the passage of air.

3. A method in accordance with any preceding claim, wherein the device is retained in position by the engagement of a portion of the device with the surface or surfaces of the opening into which it is inserted.

4. A method in accordance with any preceding claim wherein the opening through which the device is inserted comprises a through hole of an airbrick.

5. A method in accordance with claim 4, wherein the airbrick comprises a plurality of through holes and a separate device is inserted into two or more of said through holes.

6. A method in accordance with claim 4 or claim 5, wherein the device is in accordance with any of claims 10 to 24.

7. A method in accordance with any preceding claim, wherein the opening through which the device is inserted is provided in an outer of the two skins.

8. A method in accordance with any preceding claim, wherein the openings provided in the two skins are significantly out of alignment and the method comprises the additional steps of creating a fresh opening in one of the skins in substantial alignment with the existing opening provided in the other of the skins and inserting the device into one or both of the fresh and existing opening.

9. A method of preventing the occlusion of an air path defined between the skins of a cavity wall when a material is introduced into the cavity defined by the skins, the method being substantially as herein described with reference to the accompanying drawings.

10. A device for use with an airbrick forming part of either an outer or an inner skin of a cavity wall, the airbrick comprising a plurality of through holes and the device serving to prevent said through holes from becoming occluded upon the introduction of a material into the cavity defined between said outer and inner skins, the device comprising a first portion adapted for inert ion into the cavity through one of said through holes; a retaining portion connected to said first portion and adapted for engagement with the airbrick so as to retain said first portion with respect thereto; and one or more resilient elements connected to said first portion and extending transversely thereof, the or each element being deformable from its transversely extending position for insertion into said through hole but urged to return to its transversely extending position upon emerging into the cavity, the or each element being so sized as to form, with one or more similar devices inserted into other of the through holes, a barrier which extends between the two skins and encloses a volume which communicates with at least one of the through holes provided in the airbrick while still allowing air to pass therethrough.

11. A device in accordance with claim 10, wherein the device is adapted so as to permit the passage of air through the through hole into which the device is inserted.

12. A device in accordance with claim 10 or claim 11, wherein the retaining portion is adapted so as to be received within the through hole into which the device is inserted.

13. A device in accordance with claim 12, wherein the retaining portion is adapted so as to define a path for the passage of air through the airbrick.

14. A device in accordance with any of claims 10 to 13, wherein the retaining portion is formed of a resilient material which is sufficiently deformable to be received within a through hole of the airbrick but which, when released, is urged outwardly to engage the surface or surfaces of the through hole.

15. A device in accordance with any of claims 10 to 14, wherein the retaining portion is provided with one or more crushable projections which are crushed upon inertion into the through hole and which serve to retain the device with respect to the airbrick.

16. A device in accordance with any of claims 10 to 15, wherein said first portion comprises an elongate spine and said elements comprise a plurality of tines which extend laterally therefrom.

17. A device in accordance with any of claims 10 to 16, wherein said elements extend to either side of said first portion and occupy a common plane.

18. A device in accordance with any of claims 10 to 16, wherein said elements extend from said first portion in such as way as to occupy substantially mutually perpendicular planes.

19. A device in accordance with any of claims 10 to 18, wherein each of said elements is equidistantly spaced from its neighbouring elements which extend from the same side of said first portion.

20. A device in accordance with claim 19, wherein the elements which extend from one side of said first portion are offset with respect to those which extend from an opposite side of said first portion by a distance equal to substantially half the spacing between the neighbouring elements of either of said sides.

21. A device in accordance with any of claims 10 to 20, wherein the elements extend from said first portion by a distance equal to half that between the centres of adjacent through holes of the airbrick.

22. A device in accordance with any of claims 10 to 21, wherein said first portion is formed so as to have a length greater than the spacing between the outer and inner skins of the cavity wall and is reduced to size prior to insertion into said through hole.

23. A device in accordance with any of claims 10 to 22, wherein said first portion is formed so as to have a plurality of frangible zones at intervals along its length.

24. A device for use with an airbrick and substantially as herein described with reference to Figures 2 to 10 of the accompanying drawings.

25. A cavity wall comprising an inner and an outer skin with a cavity defined therebetween, each of said skins having an opening therethrough which communicates with the cavity and which, with the opening provided in the other of the skins, defines an air path through the cavity wall, at least one of said openings having a device inserted therein which is sized so as to extend into the cavity and which is adapted to form all or part of a barrier which extends between the two skins and encloses a volume which communicates with the respective openings while still allowing air to pass therethrough.

26. A cavity wall in accordance with claim 25, wherein the cavity, with the exception of the volume enclosed by the barrier, is occupied with a material, such as insulation material.

27. A cavity wall in accordance with claim 25 or claim 26, wherein the device comprises a a hose-like member having a throughbore for the passage of air.

28. A cavity wall in accordance with claim 25 or claim 26, wherein the device is in accordance with any of claims 10 to 24.