GB2338497A

GB2338497A - Weep vent

Info

Publication number: GB2338497A
Application number: GB9819430A
Authority: GB
Inventors: George Molyneux
Original assignee: G Molyneux
Current assignee: G Molyneux
Priority date: 1998-06-18
Filing date: 1998-09-08
Publication date: 1999-12-22
Anticipated expiration: 2018-09-08
Also published as: GB9813098D0; GB2338497B; GB9819430D0

Abstract

The present invention provides a weepvent (212) comprising a duct (210) and a hood (200), which duct has a first (214) and second opening in fluid flow communication with one another, and which hood (200) has an opening in a side wall (202) thereof.

Description

2338497 1 WALL VENTILATION DEVICES The present invention relates to wall

ventilation devices, in particular, but not exclusively, to cavity wall ventilation devices.

Background of the Invention

A cavity wall is normally the perimeter wall of a building, and comprises two walls separated by a cavity that is bridged, for example, around window and door openings in the cavity wall. The wall forming the external surface of the building is commonly known as the outer wall leaf and the wall providing the internal is surface of the building is commonly known as the inner wall leaf. Both the inner and outer wall leaves may be masonry walls. Alternatively, the outer wall.leaf may be a masonry wall, whilst the inner wall leaf is a timber wall; this type of cavity wall is commonly referred to as a ',timber frame construction". A common cavity wall arrangement comprises an inner and outer wall leaf thickness of about loomm each and a cavity width of about somm.

A masonry wall usually consists of standard substantially rectangular shaped bricks or substantially square or rectangular stones held together with mortar.

Masonry walls generally comprise horizontal and perpendicular mortar joints. Horizontal mortar joints are generally of the order of lomm high. Vertical mortar joints are generally of the order of 1Omm wide.

Cavity walls generally further comprise a cavity tray damp proof course. A cavity tray damp proof course may be a strip of liquid impermeable material (usually in a 1 - 2 single piece) that is used to span a cavity to arrest the downward movement of water in the cavity and to guide the water towards the outer wall leaf. To achieve this, the continuous strip of liquid impermeable material commonly has one of its longitudinal edges sandwiched in a horizontal mortar joint in the inner wall leaf and the opposing longitudinal edge sandwiched in a horizontal mortar joint of the outer wall leaf. The horizontal mortar joint in the inner wall leaf is at least 15Omm higher up the wall than the horizontal wall joint in the outer wall leaf. Such an arrangement of the cavity tray damp proof course means that water in the cavity is guided away from the inner wall leaf towards the outer wall leaf. Furthermore, this arrangement of the cavity tray damp proof course provides a vertical damp proof barrier between the inner and outer wall leaves to prevent a damp cavity bridge occurring via any mortar droppings which fall onto the damp proof course during construction of the wall.

Recent UK Building Regulations require all cavity trays to have sealed stop ends to prevent water which has collected on the cavity tray discharging off the ends of the cavity tray into the cavity. Drainage holes are required in the outer wall leaf to direct water collecting on the cavity tray to the exterior of the cavity wall. These drainage holes are commonly known as weepholes.

Sometimes, a lintel used to span the top of an opening in a cavity wall, for example a window, may have a dual purpose as a lintel and as a cavity tray.

Cavity trays may be rigid or flexible. Flexible cavity trays are generally supported.

1 Current building regulations require that masonry cavity walls which are subject to external weather include weepholes. It is also a requirement in some cases, for example, in the provision of timber frame cavity walls, that provision is made for both ventilation and drainage of the cavity. It is a requirement of timber frame cavity walls that at least 500mirJ of ventilation outlet is provided per metre run of wall.

In the past, provision for liquid drainage was made by omitting most or all of the mortar from a perpendicular mortar joint of the outer wall of the cavity wall at the level of the cavity tray damp proof course. However, such a drainage means makes no provision for prevention of ingress of wind driven rain into the cavity. Also, such a gap in the mortar provides ready access for insects into the cavity. Furthermore, the opening frequently became blocked by mortar used to build the wall and other particulate materials.

In an attempt to overcome the problems associated with providing drainage by omitting the mortar from a plurality of mortar joints along the length of the wall, many devices, generally in the form of a plastic moulding, have been,designed. These devices replace at least the majority of the mortar in a perpendicular mortar joint in the outer wall leaf. Such devices allow for both drainage and ventilation of the cavity and are commonly known as 11weepvents11.

Good building practice requires perpendicular mortar joints in a masonry wall to be only lomm wide. Therefore, the available space provided by a perpendicular mortar joint in a masonry wall is a significantly limiting factor - 4 to the amount of drainage and ventilation provided by such A plastic moulded weepvents.

Whilst, these aforesaid moulded weepvents can be designed to reduce ingress of wind driven rain and insects into the cavity, they are still susceptible to blockage by mortar.

It is a generally accepted feature of building construction, that the horizontal section of the cavity tray acts as an arresting platform for mortar dropping down the wall cavity when the wall above the cavity tray damp proof course is being built. This mortar which drops down the cavity is known as "mortar droppings". Mortar droppings are produced when a bricklayer presses a brick down onto a pre-laid wet mortar bed causing mortar to be squeezed out from below the brick being laid. The majority of this mortar is removed, by the bricklayer using his trowel. However, in some instances small discrete quantities of mortar fall down the cavity. Wire wall ties bridge all cavities, therefore, even if a larger quantity of mortar falls down the cavity there is a very high chance that it will be broken up by hitting the wire ties as it falls.

Although, the mortar droppings may only be in the form of small discrete droppings, the typical design of the cavity tray is such that it encourages mortar droppings to be directed towards the base of the prior mentioned weepvents. In this case, the mortar droppings are at the same level as the weepvent inlets and thus the weepvent inlets commonly become at least partially blocked (normally the base portion thereof) by the mortar droppings.

X - 5 It is an aim of preferred embodiments of the present invention to provide an improved weepvent.

Sunmary of the Inventio The present invention provides a vent comprising a duct and a hood wherein said duct comprises a first and second opening in fluid flow communication with one another and said hood has an opening in a side wall thereof.

Suitably, the duct has a substantially rectangular cross-section.

is Suitably, the hood is adjustably located of said duct and is moveable between an extended and a retracted position. Preferably, the hood is slideably moveable between the extended and retracted positions thereofSuitably, the hood is located at the upper face of the first opening of said duct, when said duct is in use. The hood may be located at the exterior or interior of the f irst opening. Suitably, the hood is coplanar with a wall of the duct. Furthermore, the hood suitably abuts that wall of the duct.

Suitably, when the vent is in use in a wall the first opening of the duct opens onto one f ace of the wall and the second opening of the duct opens onto the opposite face of the wall. Suitably, when the vent is in use in a cavity wall, the first opening of the duct opens into the cavity of the cavity wall and the second opening of the duct opens onto the exterior surface of the outer wall leaf of the cavity wall.

Suitably, the hood extends beyond the first opening when in the extended position. The hood may be arranged such that, it does not extend substantially beyond the first opening when in the retracted position. Suitably, the distance which the hood can extend beyond the first opening can be varied.

Suitably, the hood spans the full width of the duct.

Side walls of the hood, suitably extend along only a portion the full length of the hood. Suitably, the side wall (s) extends along no more than % of the length of the hood. Suitably, the side wall(s) extends along at least % of the length of the hood. Suitably, both side walls is comprise an opening. Suitably, the opening in the side wall(s) extends beyond the first opening of the duct when the hood is in the extended position. Suitably, there are no side walls on the part of the hood which extends beyond the f irst opening of the duct when the vent is in use.

Suitably, side walls of the hood do not extend beyond the surface of the wall in which a vent in accordance with the present invention is located.

A vent in accordance with the present invention may be used in wall leaves of various thicknesses. If the wall leaf is of greater thickness than the length of the duct of the! vent, side walls of the hood may extend beyond the first opening of the duct and thereby extend the passageway through the wall leaf provided by the duct. In this case, the side walls of the hood prevent mortar of the mortar joint in which the vent is located from spreading into the passage formed by the duct.

7 Suitably, the side walls are not continuous along the full length of the hood. The hood may comprise no side walls. % The hood may comprise a central wall, which central wall projects from the surface of the hood and extends perpendicular to the surface of the hood. Suitably, the central wall extends along a major portion of the full length of the hood. Suitably, the central wall extends substantially parallel to any side wall(s) of the hood.

The duct may comprise one or more projecting guides to support the hood. Such projecting guides may be located on the interior or exterior surface of the duct.

An edge of the hood may be turned under to provide a channel, which channel co-operates with a projecting guide of the duct. Hence, a means of slideably mounting said hood of said duct is provided. Suitably, the channel and the corresponding guide extend along substantially the full length of the duct. Suitably, opposing edges of the hood are both turned under to provide a channel.

The hood may be provided with gripping means. The gripping means may comprise one or more of a projecting rib, a projecting flange or a hole in the hood.

A vent in accordance with the present invention may comprise a grill with relatively small grill apertures suitable to prevent ingress of rain driven wind, insects and small mammals or birds into the vent. Suitably the grill is located in the region of the second opening. When the vent is in use in a.wall, the grill is suitably aligned with the external face of the wall.

A 8 - Suitably, a vent in accordance with the present invention can be used for drainage and/or ventilation of a cavity wall.

1 Suitably, a vent in accordance with the present invention is adapted for use in a horizontal mortar joint of a wall, in particular in a horizontal mortar joint of an outer wall leaf of a cavity wall.

Suitably, the hood of a vent in accordance with the present invention can be adapted to extend across the full width of a cavity of a cavity wall in which the vent is located. when in use in a cavity wall, the hood of a vent in accordance with the present invention is suitably is arranged to reduce the likelihood of blockage of the first opening of the duct by mortar droppings. Suitably, when in use in a cavity wall, a vent in accordance with the present invention does not substantially impede the flow of water along the cavity tray damp proof course.

The outer surfaces of the duct and/or the hood may comprise, for example, raised ribs and/or recessed grooves to provide anchorage for mortar when the vent is embedded in a mortar joint of a wall.

The vent may comprise stop means to limit the movement of the hood relative to the duct.

1 The present invention further provides a cavity wall having an outer wall leaf, an inner wall leaf and a cavity in which a vent in accordance with the present invention is located, said vent being located in a mortar joint of said outer wall leaf.

9 The present invention yet further provides a method of ventilating and/or draining a cavity wall, wherein a vent in accordance with the present invention is located in a mortar joint of the outer wall leaf of said cavity wall.

Suitably, the vent is located in a horizontal mortar joint of the outer wall leaf of the cavity wall.

Brief Description--of the Drawings

The present invention will now be described, by way of example, with reference to the following drawings, in which.

is Figure 1 shows a perspective view of a vent in accordance with the present invention; Figure 2 shows a cross-section of the vent of Figure 20 1 along line X-X; Figure 3 shows a side view of the vent of Figures 1 and 2; Figure 4 shows the vent of Figures 1-3 in use in a cavity wall; Figure 5 shows a vent of Figures 1-3, in an alternative use in a cavity wall; Figure 6 shows a perspective view of an alternative hood of a vent in accordance with the present invention; Figure 7 shows a vent in accordance with the present invention incorporating the hood of Figure 6; 1 - 1 Figure 8 shows an alternative arrangement of the vent of Figure 7; Figure 9 shows areversed verson of the hood for use in a vent ' of the present invention; Figure 10 shows a vent in accordance with the present invention incorporating the hood of Figure 9; Figure 11 shows an alternative arrangement of the vent of Figure 10, and Figure 12 shows the vent of Figures 10 and 11 in use in a cavity wall.

Description of Preferred Embodiments h The vent 10 of Figure 1, comprises a duct 12 and a hood 14. The duct 12 has a generally rectangular crosssection and a first opening 16 to the rear of the duct 12 and a second opening 18 to the fore of the duct 12. The duct 12 further comprises a grill 20 having perforations 22, situated in the second opening 18. The grill 20 is arranged to deter ingress of rain driven wind, insects and small mammals into the duct 12. The perforations 22 of the grill 20 are suitably no larger than 7mm, preferably no larger than 6mm, more preferably no larger than 5m:m and especially no larger than 4mm wide. Alternative grills, comprise a' mesh or louvres, for example (not shown).

The duct 12 further comprises projections 24 along a substantial portion of the length of the duct 12.

The hood 14 has a substantially flat, planar configuration. opposing longitudinal edges 26 and 28 of the hood 14 are turned under to provide channels 30. The channels 30 cooperate with the projections 24 to provide a means of anchoring the hood 14 to the duct 12, wherein the hood 14 is in an abutting relationship with the upper wall of thh duct. The location of the hood 14 relative to the duct 12 can be varied by sliding the hood 14 between an extended position (as shown) and a retracted position (not shown) In the extended position the hood 14 extends beyond the first opening 16. The proportion of the hood 14 which extends beyond the opening 16 can be varied by sliding the hood 14 along the projections 24 of the duct 12.

Figure 2 illustrates the co-planar arrangement of the hood 14 and the upper wall of the duct 12. Figure 2 further illustrates the relative arrangement of the channels 3o of the hood 14 and the projections 24 of the duct 12.

Figure 3 illustrates the vent of Figure 1 and Figure 2 showing the hood 14 in an extended position.

Figures 1 and 3 further illustrate projections 32 on the surface of the hood 14. The projections 32 serve a dual purpose of providing anchorage means for the vent 10 when in use, and providing gripping means for the hood 14.

Figure 3 further illustrates the arrangement of the grill 20. ' As can be seen from Figures 1 and 3, the dimensions of the grill 20 are greater than the dimensions of the cross-section of the duct 12. The lower edge 34 of the grill 20 projects beyond the bottom face 36 of the duct 12 by a greater extent than the other edges of the grill project beyond the respective other faces of the duct 12. This over projection of the lower edge 34 of the grill 20 provides a means of directing droplets of liquid passing through the vent 10 and out of the opening 18, away from the wall surface (not shown) in which the vent 10 is located. Provision of a grill 20 with edges which project b(yond the surfaces of the duct 12 provides a means of preventing the duct 12 from being recessed into the mortar joint of a wall in which the vent 10 is located.

Figure 4 illustrates two vents 52 and 54 which are equivalent to vent 10 of Figures 1-3 in use in a cavity wall 40. Both vents are located in horizontal mortar Joints 42 of the outer wall leaf 44 of the cavity wall 40. An advantage of using a horizontal mortar joint rather is than a perpendicular mortar joint is that although the height of the vent is limited to lomm (in accordance with good building practices) the width of the vent is effectively unlimited. Furthermore, the likelihood. of ingress of wind driven rain into a narrower vertical opening is less.

The cavity wall 40 further comprises a cavity 48 and an inner wall leaf 46. The inner wall leaf 46 further comprises an insulated steel lintel 49 supporting the cavity wall 40 above a wall opening in which there is located a window frame 50.

For the purpose of illustration only, a first vent 52 and a secqnd vent 54 are illustrated, two such vents are not commonly used in such close proximity. The first vent 52 is located in the outer wall leaf 44 of the cavity wall 40 to provide ventilation means only. The vent 52 is arranged with the hood 14 located in its retracted position. In the retracted position, the hood 14 does not extend beyond the opening 16 of the duct 12. Furthermore, 1 - 13 the hood 14 in the retracted position does not extend beyond the inner surface 45 of the wall 44. The vent 52 is sandwiched between bricks 56 and 58 of the outer wall leaf 44. Bedding mortar for the brick 58 is laid on top of the brick 56 and either side of the vent 52.

1 is Vent 54 is located in the wall for the purpose of both drainage and ventilation of the cavity 48. The lintel 49 of the cavity wall 40 performs dual roles of wall support and provision of a cavity tray damp proof course. In order to provide drainage of the cavity wall 48, a vent 54 is required to be located at the lowest part of the cavity tray/lintel 49 in the outer wall leaf 44 of the cavity wall 40. The vent 54 is arranged such that the hood 14 extends beyond the opening 16 of the duct 12. In this instance, the hood 14 extends across the full width of the cavity 48 to abut the lintel 49. The vent 54 is sandwiched between the lintel 49 and the brick 60 and is again held in place by bedding mortar at either side of the vent 54. The hood 14 is arranged in the extended position before the brick 60 is placed on top of the vent 54. The hood 14 retains mortar droppings 62 which fall down the cavity when the wall above the vent is being built, and thus reduces the likelihood of blockage of the opening 16 of the duct 12 by the mortar droppings 62.

Figure 5 illustrates a vent 10 located in an outer wall leaf 72 of a cavity wall 70. The cavity wall 70 of Figure 5 is a timber frame cavity wall comprising a timber framed inner wall leaf 78 and cavity 80. Figure 5 further illustrates the location of the internal ground floor 82 in the inner wall leaf 78. The internal ground floor 82 is supported by a masonry foundation wall 84. The masonry foundation wall 84 comprises a concrete block inner wall leaf 86, a concrete block outer wall leaf 88 separated by 1 a wall cavity 90, which wall cavity 90 has been f illed with a concrete infill 76. The vent 10 is on a level with the top surface 74 of the cavity concrete infill 76 of the cavity wall 70.

The vent 10 is installed in the outer wall leaf 72 of the cavit wall as per the vent 54 of Figure 4. However, in this case, the hood 14 extends further beyond the opening 16 of the duct 12 to span the full width of the cavity 80. Again, the vent 10 of Figure 5, provides both drainage and ventilation of the cavity 80.

is Figure 6 illustrates a hood 100 for a vent in accordance with the present invention, which hood has a substantially flat, planar configuration. The hood 100 comprises side walls 102, which side walls extend along a proportion of the length of the hood 100. The hood 100 further comprises a central wall 104, extending along a substantial proportion of the length of the hood 100. The side walls 102 suitably extend along between 'A and % of the length of the hood 100. The central wall 104 is substantially parallel to and midway between the side walls 102. The hood 100 further comprises tabs 106 and 108 at opposed ends of the hood 100. Tabs 106 and 108 provide gripping means for the hood 100. Alternatively, a semi-circular cutout may be provided.

Figure 7 illustrates the hood 100 of Figure 6 located in a duct 110 to provide a vent 112 in accordance with the present invention.

The hood 100 of Figure 7 is located within the duct of the vent 112. The hood 100 is inserted into the duct 110 through the first opening 114 of the duct 110.

A grill 116 is located in the second opening 118 of the 1 1-- - is duct 110. The side walls 102 of the hood 100 extend beyond the opening 114 of the duct 110 when the hood 100 is in the extended position as shown.

Arrangement of the hood 100 as shown in Figure 7, provides a means of extending the length of the duct 110 of vent 112. The vent 112 can therefore, be used in walls of varying thicknesses.

Figure 8 illustrates the vent of Figure 7. Figure 8 illustrates the hood 100 of the vent 112 in a further extended position. Figures 7 and 8 illustrate that the effective length of the duct can be varied by varying the degree of extension of the hood 100 beyond the opening 114. In use, the vent as illustrated in Figures 7 and 8 should be arranged such that the hood 100 in the extended position does not extend beyond the inner surface of the wall in which the vent is located.. The vent as shown in Figures 7 and 8, is arranged mainly for the provision of ventilation means. However, such an arrangement could also provide drainage means.

Figure 9 illustrates an alternative hood 200 having a substantially flat and planar configuration. The hood 200 has side walls 202 extending along a proportion of the length of the hood 200. Furthermore, the hood 200 comprises a central wall 204 extending along a substantial proportion of the length of the hood 200. The central wall 204 is substantially parallel to and midway between the side walls 202. The hood 200 further comprises tabs 206 at opposing ends of the hood. The tabs 206 provide gripping means for the hood 200.

Figure 10 illustrates the hood 200 of Figure 9 in combination with a duct 210 to provide a vent 212 in A accordance with the present invention. The hood 200 is located within the duct 210, and is inserted into the duct 210 through a first opening 214 of the duct 210. Figure 10 illustrates the hood 200 in an extended position, wherein the hood 200 extends beyond the opening 214 of the duct of the duct 210. In this extended position, the side walls 202 of the hood 200 do not extend beyond the opening 214 of the duct 210.

The central wall 204 of the hood 200 provides support for the hood 200. The central wall 204 further provides a means of dividing the opening 214 of the duct 210. Therefore, should a very wet or particularly large mortar dropping fall immediately adjacent one of the sides of the weep vent, the central wall 204 prevents mortar from splashing across the full width- of the opening 214. Suitably, the central wall 204 does not extend along the full length of the hood 200. Suitably, the central wall 204 stops short of the end 216 of the hood 200.

Figure 11 illustrates the vent 212 of Figure 10 with the hood 200 in a further extended position. In this further extended position, a proportion of the side walls 202 of the hood 200 extend beyond the opening 214 of the duct 210. The side walls 202 as arranged to extend beyond the opening 214 effectively extend the length of the duct 210. Suitably the side walls 202 do not extend beyond the inner face of the wall (not shown) in which the vent 212 is located.

Figure 12 illustrates the vent of Figures 10 and 11 in use in a cavity wall 140. The vent 112 is located in the outer wall leaf 142 of the cavity wall 140. The cavity further comprises an inner block wall leaf 144 and a cavity 146. Partial cavity insulation 148 is attached A A - 17 to the cavity face 150 of the inner wall leaf 144. The base of the cavity 146 is filled with a concrete infill 152. Strips of damp proof membrane 154 are provided on each cavity wall leaf 142 and 144. The damp proof membranes 154 indicate the cavity wall has reached the internal ground floor level. Weep vent 112 is located in a horizontal mortar joint 156 of the outer wall leaf 142 of the cavity wall 140.

is The hood 200 of the vent 112 is arranged in the extended position to extend across the full width of the cavity 146. The end 216 of the hood 200 abuts the cavity insulation 148. The vent as illustrated provides both ventilation and drainage means for the cavity 146. Arrangement of the central wall 204 to stop short of the end 216 of the hood 200,. provides. for substantially unhindered flow of water along the cavity base.

A veAt in accordance with the present invention can be provided in a variety of colours. The grill used to reduce the likelihood of ingress of rain and insects is generally visible from the outside of a wall in which a vent in accordance with the present invention is located. Generally, the grill is the only part of the vent which is visible from the outside of the wall.

In order to avoid providing the whole of the vent in a variety of colours, separate "clip on,' grills can be provided. The separate grills can be provided in a 30 variety of colours.

A vent in accordance with the present invention may be provided as a two part unit or a single part unit. The hood of a vent in accordance with the present invention 35 could be fixedly secured to the duct thereof.

1 - 18 The reader's attention is directed to all papers and documents which are f iled concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

is Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly. stated otherwise,' each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment (s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

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Claims

1. A vent comprising a duct and a hood wherein said duct comprises a first and second opening in fluid flow communication with one another and said hood has an opening in a side wall thereof.

2. A vent in accordance with Claim 1, in which said duct has a substantially rectangular cross-section.

3. A vent in accordance with Claim 1 or 2, in which said hood is adjustably located of said duct.

4. A vent in accordance with any of the preceding is Claims, in which said hood is moveable.between an extended and a retracted position.

5. A vent in accordance with Claim 5, in which said hood is slideably moveable between said extended and said retracted positions thereof.

6. A vent in accordance with any of the preceding Claims, in which said hood extends beyond said first opening of said duct when in said extended position.

7. A vent in accordance with any of the preceding Claims, in which said hood does not extend substantially beyond the first opening of the duct when in the retracted position.

8. A vent in accordance with Claim 1 or 2, in which said hood is fixedly secured of said duct.

9. A vent in accordance with any of the preceding Claims, in which said hood is located at an upper surface 1 of said first opening of said duct, when said duct is in use.

10. A vent in accordance with Claim 9, in which said hood 5 is located at the exterior of said upper surface.

11. A vent in accordance with Claim 9, in which said hood is located at the interior of said upper face.

12. A vent in accordance with any of the preceding in which said hood is co-planar with a surface of said duct-

13. A vent in accordance with any of the preceding Claims, in which said hood abuts a surface of said duct.

is

14. A vent in accordance with any of thepreceding Claims, wherein, in use, said first opening of said duct opens onto one face of a wall and said second opening of said duct opens onto the opposite face of a wall when said. %

15. A vent in accordance with any of the preceding claims, in which, in use in a cavity wall, said f irst opening of said duct opens into the cavity of said cavity wall and said second opening of said duct opens into the exterior face of an outer wall of said cavity wall.

16. A vent in accordance with any of the preceding Claims, in which said hood spans the full width of said 30 duct.

17. A vent in accordance with any of the preceding Claims, in which a side wall of said hood extends along only a proportion of the length of said hood.

1 - 21

18. A vent in accordance with any of the preceding Claims, in which said side wall extends along no more than % of the length of said hood.

19. A vent in accordance with any of the preceding Claims, in which said side wall extends along at least % of the length of said hood.

20. A vet in accordance with any of the preceding 10 Claims, in which both side walls comprise an opening.

21. A vent in accordance with any of the preceding Claims, in which said opening in the side wall extends beyond said first opening of said duct when said hood is in the extended position.

22. A vent in accordance with Claim 1, in which a side wall is not continuous along the full length of the hood.

23. A vent in accordance with Claim 1, in which said hood comprises no side walls.

24. A vent in accordance with any of the preceding Claims, in which said hood comprises a central wall.

25. A vent in accordance with Claim 24, in which said central wall projects from a surface of said hood and extends perpendicular of said surface.

26. A vent in accordance with Claim 24 or Claim 25, in which said central wall extends along substantially the full length of said hood.

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27. A vent in accordance with Claim 24 to Claim 26, in which said central wall extends substantially parallel to any side walls of said hood.

28. A vent in accordance with any preceding Claim, in which an edge of said hood is turned under to provide a channel.

29. A vent in accordance with Claim 28, in which said 10 channel cooperates with a projecting guide of said duct.

30. A vent in accordance with Claim 28 and claim 29, in which said channel and said corresponding guide extend along substantially the full length of said duct.

is

31. A vent in accordance with Claim 28 to Claim 30, in which opposing edges of said hood are both turned under to provide a channel.

32. A vent in accordance with any of the preceding claims, which vent is adapted to be used in a horizontal mortar joint of a wall.

33. A cavity wall having an outer wall leaf, an inner wall leaf and a cavity, in which a vent in accordance with the present invention is located, said vent being located in a mortar joint of said outer wall leaf.

34. A cavity wall in accordance with Claim 33, in which 30 said vent is located in a horizontal mortar joint of said outer wall leaf.

35. A method of ventilating and/or draining a cavity wall, wherein a vent in accordance with any of Claims 1 to 1 31 is located in a mortar joint of the outer wall leaf of said cavity wall.

36. A method in accordance with Claim 35, wherein said vent is located in a horizontal mortar joint of said outer wall leaf.

37. A vent substantially as described herein and with. reference to Figures 1 to 5 of the drawings hereof.

38. A vent substantially as described herein and with reference to Figures 6 to 12 of the drawings hereof.

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