GB2450801A

GB2450801A - A moisture barrier, and a method for placing it between roof element and a cavity wall.

Info

Publication number: GB2450801A
Application number: GB0812146A
Authority: GB
Inventors: John Patrick Byrne; Mary Margaret Byrne
Original assignee: Individual
Current assignee: Individual
Priority date: 2007-07-02
Filing date: 2008-07-02
Publication date: 2009-01-07
Also published as: GB0812146D0; IE20080542A1

Abstract

A moisture barrier (1) for mounting on top of a gable end cavity wall (3) of a building (4) prior to casting a concrete barge element (5), preventing the passage of moisture permeating through the barge element to the inner leaf (6) of the cavity wall (3). The barrier (1) comprises a barrier plate (25) having a central channel (26) and side wings (27, 28) extending along it, for locating on the top of the inner and outer leaves (6,8) of the cavity wall (3). The central channel (26) is of width similar to the width of the cavity (7) and extends downwardly into a cavity (7) of the cavity wall (3). A sheet (33) of galvanised metal mesh secured to the side wings (27, 28) of the barrier plate (25) keys the concrete of the barge element (5) to the moisture barrier (1). The moisture barriers (1) may be provided of length to extend the full length of the cavity wall (3), or may be of length such that a plurality of overlapping barriers (1) is required.

Description

"A moisture barrier, and a method for minimising the passage of

moisture from a concrete roof barge element to an inner leaf of a wall of a building" The present invention relates to a moisture barrier, and the invention also relates to a method for minimising the passage of moisture from a concrete roof barge element to an inner leaf of a cavity wall of a building.

In the construction of buildings, for example, houses which have gable ends whereby the gable end wall is of cavity construction and extends upwardly to an apex, in general, roof tiles are laid on the roof and partly overlap the inner load bearing leaf of the gable end wall. A concrete barge element is then cast in situ along the top of the gable end wall which spans a cavity between the inner and outer leaves of the gable end wall and extends over the inner and outer leaves to terminate in an outer edge portion extending beyond the outer leaf of the gable end wall, and in an inner edge portion extending beyond the inner leaf of the gable end wall to overlap a portion of the tiles adjacent the gable end wall. Typically, a base element provided by a sheet of expanded metal mesh is placed on the top of the gable end wall spanning the cavity to act as a base for the concrete barge element while being cast and during curing of the concrete thereof. A problem with such known constructions is that concrete, being a porous material, is not impervious to moisture, and over time, particularly in areas prone to relatively high rainfall, moisture penetrates through the barge element to the inner leaf of the cavity wall, thus resulting in damp patches forming on the inside of the inner leaf of the cavity wall, which is unacceptable. Indeed, in areas of particularly high rainfall, moisture may penetrate through the barge element to the extent that the rainwater may actually run down the surface of the inner leaf within the cavity, thus leading to moisture penetrating through the inner leaf leading to deterioration of internal plasterwork.

There is therefore a need for a moisture barrier to address this problem.

The present invention is directed towards such a moisture barrier, and the invention is also directed towards a method for minimising the passage of moisture from a concrete roof barge element to an inner leaf of a wall of a building. I0

According to the invention there is provided a moisture barrier for minimising passage of moisture from a concrete roof barge element to an inner leaf of a gable end cavity wall of a building on which the roof barge element is located, the moisture barrier comprising a barrier plate of moisture impervious material for placing on the cavity wall adjacent the top thereof and extending across a cavity of the cavity wall from the inner leaf thereof to the outer leaf, the barrier plate being adapted for securing to at least one of the inner and outer leaves of the cavity wall, and a keying means being provided for keying the roof barge element to the barrier plate.

In one embodiment of the invention the keying means is a passive keying means, and is adapted for integration into the concrete of the barge element as the concrete is being poured, and preferably, the keying means comprises expanded metal mesh.

In another embodiment of the invention the barrier plate is of inverted top hat cross-section, having a longitudinally extending central channel and at least one side wing extending sidewardly outwardly from a corresponding side wall of the centre channel, and preferably, a pair of side wings extending sidewardly outwardly from respective opposite side walls of the central channel. Preferably, each side wing extends along the corresponding side wall of the central channel, and advantageously, the respective side wings are adapted for engaging the top of the inner and outer leaves of the cavity wall, and preferably, the central channel is adapted for locating within the cavity wall between the inner and outer leaves thereof and extending downwardly into the cavity. Ideally, the central channel is of width substantially corresponding to the width of the cavity of the cavity wall. I0

Advantageously, the side wing which is adapted for engaging the top of the inner leaf of the cavity wall is of width sufficient to span the width of the inner leaf at the top thereof. Preferably, the side wing which is adapted to engage the top of the outer leaf of the cavity wall is of width sufficient to span the width of the outer leaf at the top thereof.

Ideally, the side wings are of width substantially corresponding to the width of the corresponding ones of the inner and outer leaves of the cavity wall.

Preferably, the keying means extends across an open mouth defined by the central channel, and advantageously, the keying means overlaps the respective side wings of the barrier plate adjacent the open mouth defined by the channel, and ideally, the keying means extends across the respective side wings.

Ideally, the barrier plate is of metal, and preferably, of sheet metal, and advantageously, of galvanised sheet metal.

In one embodiment of the invention the barrier plate is formed by bending.

Ideally, the barrier plate is of thickness of the order of 0.7mm approximately.

In another embodiment of the invention the barrier plate is adapted to co-operate with an adjacent barrier plate, with one end of the barrier plate overlapping a portion of an adjacent end of an adjacent barrier plate.

Advantageously, the keying means extends from one end of the barrier plate and terminates short of the other end thereof for accommodating an overlapping adjacent barrier plate.

Additionally the invention provides a method for minimising the passage of moisture from a concrete roof barge element to an inner leaf of a cavity wall of a building on which the roof barge element is located, the method comprising prior to casting the concrete roof barge element on the top of the cavity wall placing a moisture impervious barrier plate extending across the cavity of the cavity wall from the inner leaf thereof to an outer leaf thereof and providing a keying means on the barrier plate for keying the barge element to the barrier plate.

In one embodiment of the invention the barrier plate co-operates with an adjacent barrier plate on the top of the cavity wall, with one end of the barrier plate overlapping an adjacent end of an adjacent lower barrier plate.

Preferably, the keying means extends from one end of the barrier plate and terminates short of the other end thereof for accommodating an overlapping adjacent barrier plate. Advantageously, at least two barrier plates are located on the top of the cavity wall longitudinally aligned with each other in end-to-end relationship with an end of one of the barrier plates overlapping an adjacent end of an adjacent lower one of the barrier plates. Ideally, the keying means of one of the barrier plates terminates adjacent an end of the keying means of the adjacent overlapping barrier plate.

In another embodiment of the invention the method comprises casting the roof barge element of concrete over each barrier plate, and preferably, the roof barge element is cast of concrete over the overlapping barrier plates on the top of the cavity wall.

The invention will be more clearly understood from the following description of a preferred embodiment thereof, which is given by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is a perspective view of a moisture barrier according to the invention, Fig. 2 is an end view of the moisture barrier of Fig. 1, Fig. 3 is a perspective view of a gable end wall with a plurality of the moisture barriers of Fig. 1 in use, Fig. 4 is another perspective view of the gable end wall of Fig. 3 with one of the moisture barriers of Fig. 1 in use, and Fig. 5 is a transverse cross-sectional end elevational view of the gable end wall of Fig. 3 illustrating the moisture barrier of Fig. 1 in use in conjunction with a portion of a roof adjacent the gable end wall.

Referring to the drawings, there is illustrated a moisture barrier according to the invention, indicated generally by the reference numeral 1, for mounting on top of a gable end cavity wall 3 of a building 4 prior to casting a concrete barge element 5 (see Fig. 5) on top of the cavity wall 3 for preventing the passage of moisture which permeates through the barge element 5 onto an inner load bearing leaf 6 of the cavity wall 3 and/or into a cavity 7 of the cavity wall 3 defined between the inner leaf 6 and an outer leaf 8 thereof. Before describing the moisture barrier I in further detail, the gable end wall 3 of the building 4, and a roof 10 thereof will first be described, with reference to Fig. 5. The gable end wall 3 comprising the inner leaf 6 and the outer leaf 8 extend upwardly from the foundation (not shown) of the building and terminates in an upper apex 11, see Fig. 3. Rafters 12 of the roof 10 extend downwardly from a ridge (not shown) adjacent the apex 11 of the cavity wall 3 and are supported on an inner leaf (not shown) of a front or rear wall of the building 4.

Tiles 15 are secured to laths 16 which are located on top of roofing felt 17 and are secured to the rafters 12 through the roofing felt 17. The tiles 15 extend sidewardly towards the cavity wall 3 to slightly overlap the inner leaf 6. The roofing felt 17 is folded around edges 20 of the tiles 15 to overlay a portion of the top of the tiles 15 adjacent the edges 20 thereof. The moisture barrier 1, as will be described below, is located and supported on the inner and outer leaves 6 and 8 of the cavity wall 3 and extends beneath the roofing felt 17. The barge element 5 is then cast in situ of concrete above the moisture barrier 1 with a portion 21 of the barge element 5 overlapping the tiles 15 adjacent the edges thereof, and extending on the opposite side over and beyond the outer leaf 8 of the cavity wall 3, and terminating in an overhanging portion 22. The general construction of such a barge element 5 on a gable end cavity wall 3 to overlap the adjacent tiles 15 adjacent the edges 20 thereof will be understood by those skilled in the art.

In this embodiment of the invention a plurality of moisture barriers 1 are located on the top of the cavity waIl 3 in overlapping relationship with each other. Each moisture barrier 1 comprises an elongated barrier plate 25 of galvanised sheet metal of thickness of approximately 0.7mm. The barrier plate 25 is bent to form an inverted top-hat cross-section having a longitudinally extending central channel 26 I 5 and a pair of side wings 27 and 28 extending along and sidewardly outwardly from the central channel 26. The side wing 27 is adapted for engaging the inner leaf 6, and the side wing 28 is adapted for engaging the outer leaf 8. The central channel 26 is of width which substantially corresponds to the width of the cavity 7 of the cavity wall 3 so that the central channel 26 extends downwardly into the cavity 7 between the inner and outer leaves 6 and 8. The side wing 27 of each barrier plate is of width which is substantially similar to the width of the inner leaf 6 so that the side wings 27 of the barrier plates 25 span the width of the inner leaf 6. The side wing 28 of each barrier plate 25 is of width which is substantially similar to the width of the outer leaf 8 so that the side wings 28 of the barrier plates 25 span the width of the outer leaf 8. Four holes 30, two on each side wing 27 and 28 at the opposite ends thereof, are provided for securing the barrier plates 25 to the inner and outer leaves 6 and 8. In general, it is envisaged that the barrier plates 25 will be secured to the inner and outer leaves 6 and 8 by suitable masonry bolts or nails.

A keying means, in this embodiment of the invention provided by a sheet 33 of galvanised expanded metal mesh is secured to the barrier plate 25 of each moisture barrier 1 by pop rivets (not shown) for keying the concrete of the barge element 5 to the moisture barrier 1 The mesh sheet 33 spans the central channel 26 of the barrier plate 25, and overlays and is secured to the side wings 27 and 28 by the pop io rivets (not shown). The mesh sheet 33 acts to support the concrete of the barge element 5 during casting and curing thereof, and becomes integrated with the concrete of the barge element 5 when cured, thereby securing and keying the barge element 5 to the moisture barrier 1. The mesh sheet 33 of each moisture barrier I extends substantially the width of the barrier plate 25, and extends from a lower end 35 to terminate in an upper end 37 short of an upper end 36 of the barrier plate 25 for facilitating overlapping of the barrier plate 25 with an adjacent upper barrier plate at the upper end 36 thereof.

In use, when the cavity wall 3 has been built up to the apex 11 and the roof rafters 12 are in place, the moisture barriers are placed on the top of the cavity wall 3 with the respective side wings 27 resting on the inner leaf 6 and the respective side wings 28 resting on the outer leaf 8. The moisture barriers 1 are arranged in overlapping relationship to each other, so that each upper moisture barrier 1 overlaps its adjacent lower moisture barrier I with the lower end 35 of the overlapping moisture barrier 1 abutting the upper end 37 of the metal mesh 3 of the lower moisture barrier 1, as illustrated in Fig. 3.

Initially the lowermost moisture barrier 1 is secured to the inner and outer leaves 6 and 8 of the cavity wall 3 by masonry bolts (not shown) or nails (not shown) and washers (not shown) if required through the holes 30 in the side wings 27 and 28, and the remaining moisture barriers 1 are then sequentially secured to the cavity wall 3 by masonry bolts or nails (not shown) and washers if required. The felt 17 is then laid over the rafters and extends over the moisture barriers 1, and the laths 16 are then secured on the felt 17 to the rafters 12. The tiles 15 are secured to the to laths, and the felt 17 adjacent the edges 20 of the tiles 15 is folded over the tiles 15 to overlap the top surface of the tiles 15 adjacent the edges 20. Suitable formwork is then provided for facilitating casting of the barge element 5, and concrete is cast on top of the moisture barriers 1 in the formwork to form the barge element 5. The concrete is supported over the central channel 26 of the barrier plates 25 by the mesh sheets 33 until cured, and on curing the concrete is keyed to the moisture barriers I by the mesh sheets 33. After curing, the formwork is removed.

The advantages of the invention are many. The provision of the moisture barrier I comprising the barrier plates 25 prevents moisture which penetrates through the concrete of the barge element 5 reaching the inner leaf 8. Indeed, most of the moisture which penetrates through the barge element 5 is collected in the channels 26 of the barrier plates 25 and channelled downwardly to run down the inner side of the outer leaf of the front or rear wall of the building, neither of which are illustrated and then soaks away. Thus, the barrier plate 25 prevents the passage of moisture which would otherwise penetrate through the barge element 5 to the inner leaf 6 of I0 the cavity wall 3, and furthermore, prevents any such moisture running down the surface of the inner leaf 6 within the cavity 7, which would otherwise lead to damp patches on the inner leaf 6 being visible within the building, and/or deterioration of the internal plasterwork.

While the barrier plates have been described as being of galvanised sheet metal, the barrier plates may be of any other suitable material, for example, plastics material or the like. It is also envisaged in certain cases that the central channel 26 may be of any other suitable or desirable cross-section, and indeed, in certain cases, the central channel may be omitted.

It is also envisaged that instead of the moisture barrier being provided by a plurality of overlapping barrier plates, the moisture barrier may be provided by a single barrier plate which would extend from the apex of the cavity wall 3 to the front or rear wall of the building, as the case may be.

While the keying means has been described as being of galvanised expanded metal mesh, any other suitable keying means may be provided. Indeed, in certain cases, it is envisaged that the keying means may be provided by merely roughening the surface of the barrier plate or plates for keying the concrete of the barge element during casting.

Claims

II

Claims 1. A moisture barrier for minimising passage of moisture from a concrete roof barge element to an inner leaf of a gable end cavity wall of a building on which the roof barge element is located, the moisture barrier comprising a barrier plate of moisture impervious material for placing on the cavity wall adjacent the top thereof and extending across a cavity of the cavity wall from the inner leaf thereof to the outer leaf, the barrier plate being adapted for securing to at least one of the inner and outer leaves of the cavity wall, and a keying means being provided for keying the roof barge element to the barrier plate. I0
2. A moisture barrier as claimed in Claim I in which the keying means is a passive keying means, and is adapted for integration into the concrete of the barge element as the concrete is being poured.
3. A moisture barrier as claimed in Claim 1 or 2 in which the keying means comprises expanded metal mesh.
4. A moisture barrier as claimed in any preceding claim in which the barrier plate is of inverted top hat cross-section, having a longitudinally extending central channel and at least one side wing extending sidewardly outwardly from a corresponding side wall of the centre channel.
5. A moisture barrier as claimed in Claim 4 in which a pair of side wings extend sidewardly outwardly from respective opposite side walls of the central channel.
6. A moisture barrier as claimed in Claim 4 or 5 in which each side wing extends along the corresponding side wall of the central channel.
7. A moisture barrier as claimed in any of Claims 4 to 6 in which the respective side wings are adapted for engaging the top of the inner and outer leaves of the cavity wall.
8. A moisture barrier as claimed in any of Claims 4 to 7 in which the central channel is adapted for locating within the cavity of the cavity wall between the inner and outer leaves thereof.
9. A moisture barrier as claimed in any of Claims 4 to 8 in which the central channel is of width substantially corresponding to the width of the cavity of the cavity wall.
10. A moisture barrier as claimed in any of Claims 4 to 9 in which the side wing which is adapted for engaging the top of the inner leaf of the cavity wall is of width sufficient to span the width of the inner leaf at the top thereof.
11. A moisture barrier as claimed in any of Claims 4 to 10 in which the side wing which is adapted to engage the top of the outer leaf of the cavity wall is of width sufficient to span the width of the outer leaf at the top thereof.
12. A moisture barrier as claimed in any of Claims 4 to 11 in which the side wings are of width substantially corresponding to the width of the corresponding ones of the inner and outer leaves of the cavity wall.
13. A moisture barrier as claimed in any of Claims 4 to 12 in which the keying means extends across an open mouth defined by the central channel.
14. A moisture barrier as claimed in any of Claims 4 to 13 in which the keying means overlaps the respective side wings of the barrier plate adjacent the open mouth defined by the channel.
15. A moisture barrier as claimed in any of Claims 4 to 14 in which the keying means extends across the respective side wings.
16. A moisture barrier as claimed in any preceding claim in which the barrier plate is of metal.
17. A moisture barrier as claimed in any preceding claim in which the barrier plate is of sheet metal.
18. A moisture barrier as claimed in any preceding claim in which the barrier plate is of galvanised sheet metal.
19. A moisture barrier as claimed in any preceding claim in which the barrier plate is formed by bending.
20. A moisture barrier as claimed in any preceding claim in which the barrier plate is of thickness of the order of 0.7mm approximately.
21. A moisture barrier as claimed in any preceding claim in which the barrier plate is adapted to co-operate with an adjacent barrier plate on the top of the cavity wall, with one end of the barrier plate overlapping an adjacent end of an adjacent lower barrier plate.
22. A moisture barrier as claimed in Claim 21 in which the keying means extends from one end of the barrier plate and terminates short of the other end thereof for accommodating an overlapping adjacent barrier plate.
23. A moisture barrier for minimising passage of moisture from a concrete roof barge element to an inner leaf of a gable end cavity wall of a building on which the roof barge element is located, the moisture barrier being substantially as described herein with reference to and as illustrated in the accompanying drawings.
24. A method for minimising the passage of moisture from a concrete roof barge element to an inner leaf of a cavity wall of a building on which the roof barge element is located, the method comprising prior to casting the concrete roof barge element on the top of the cavity wall placing a moisture impervious barrier plate extending across the cavity of the cavity wall from the inner leaf thereof to an outer leaf thereof and providing a keying means on the barrier plate for keying the barge element to the barrier plate.
25. A method as claimed in Claim 24 in which the keying means is provided as a passive keying means, and is integrated into the concrete of the barge element as the concrete is being poured
26. A method as claimed in Claim 24 or 25 in which the keying means comprises expanded metal mesh.
27. A method as claimed in any of Claims 24 to 26 in which the barrier plate is of inverted top hat cross-section, having a longitudinally extending central channel and at least one side wing extending sidewardly outwardly from a corresponding side wall of the centre channel.
28. A method as claimed in Claim 27 in which a pair of side wings are provided to extend sidewardly outwardly from respective opposite side walls of the central channel.
29. A method as claimed in Claim 27 or 28 in which each side wing extends along the corresponding side wall of the central channel.
30. A method as claimed in any of Claims 27 to 29 in which the side wings engage the top of the inner and outer leaves of the cavity wall.
31. A method as claimed in any of Claims 27 to 30 in which the central channel is located within the cavity wall between the inner and outer leaves thereof.
32. A method as claimed in any of Claims 27 to 31 in which the channel is of width substantially corresponding to the width of the cavity of the cavity wall.
33 A method as claimed in any of Claims 27 to 32 in which the side wing which engages the top of the inner leaf of the cavity wall is of width sufficient to span the width of the inner leaf at the top thereof.
34. A method as claimed in any of Claims 27 to 33 in which the side wing which engages the top of the outer leaf of the cavity wall is of width sufficient to span the width of the outer leaf at the top thereof. I0
35. A method as claimed in any of Claims 27 to 34 in which the side wings are of width substantially corresponding to the width of the corresponding ones of the inner and outer leaves of the cavity wall.
36. A method as claimed in any of Claims 27 to 35 in which the keying means extends across an open mouth defined by the central channel.
37. A method as claimed in any of Claims 27 to 36 in which the keying means overlaps the respective side wings of the barrier plate adjacent the open mouth defined by the channel.
38. A method as claimed in any of Claims 27 to 37 in which the keying means extends across the respective side wings.
39. A method as claimed in any of Claims 24 to 38 in which the barrier plate is of metal.
40. A method as claimed in any of Claims 24 to 39 in which the barrier plate is of sheet metal.
41. A method as claimed in any of Claims 24 to 40 in which the barrier plate is of galvanised sheet metal.
42. A method as claimed in any of Claims 24 to 41 in which the barrier plate is formed by bending.
43. A method as claimed in any of Claims 24 to 42 in which the barrier plate is of thickness of the order of 0.7mm approximately.

is
44. A method as claimed in any of Claims 24 to 43 in which the method comprises casting the roof barge element of concrete over the barrier plate.
45. A method as claimed in any of Claims 24 to 44 in which the barrier plate co-operates with an adjacent barrier plate on the top of the cavity wall, with one end of the barrier plate overlapping an adjacent end of an adjacent lower barrier plate.
46. A method as claimed in Claim 45 in which the keying means extends from one end of the barrier plate and terminates short of the other end thereof for accommodating an overlapping adjacent barrier plate.
47. A method as claimed in any of Claims 24 to 46 in which at least two barrier plates are located on the top of the cavity wall longitudinally aligned with each other in end-to-end relationship with an end of one of the barrier plates overlapping an adjacent end of an adjacent lower one of the barrier plates.
48. A method as claimed in Claim 47 in which the keying means of one of the barrier plates terminates adjacent an end of the keying means of the adjacent overlapping barrier plate.
49. A method as claimed in Claim 47 in which the roof barge element is cast of concrete over the overlapping barrier plates on the top of the cavity wall.
50. A method for minimising the passage of moisture from a concrete roof barge element to an inner leaf of a cavity wall of a building, the method being substantially as described herein with reference to and as illustrated in the accompanying drawings.