GB2593974A - Cavity-wall weep device - Google Patents

Abstract

A cavity-wall weep device 10 for draining water from a cavity 100 of a cavity wall. The cavity-wall weep device 10 comprises a body 12 which defines a conduit 14 having an inlet 16 positionable at or adjacent to the interior of the outer wall and an outlet 18 positionable at or adjacent to the exterior of the outer wall. The conduit 14 narrows from the inlet to increase flow velocity from the inlet and widens towards the outlet to slow flow and prevent spouting. The conduit may have a stepped narrowing and the device may lack internal baffles which would inhibit the venturi effect provided by the narrowing and widening.

Description

Cavity-Wall Weep Device The present invention relates to a cavity-wall weep device, and particularly relates to a cavity-wall weep device for draining water from an interior to an exterior of an outer wall of a cavity wall. The invention further relates to a wall comprising a cavity-wall weep 5 device.

Cavity walls comprise interior and exterior walls which are spaced apart and define a cavity therebetween, the cavity providing an insulative effect on the building. The walls are typically formed from porous building materials and water, such as rain water, can permeate through the exterior wall and reside in the cavity. The water may be in the form of liquid water, such as that on a cavity tray, or water vapour. Such water can cause damp and other detrimental effects on the building.

To remove water from the cavity, holes in the exterior wall can be formed to allow for drainage of moisture, water vapour or liquid water. Such holes can typically be made by not filling a mortar joint between bricks. However, the hole may subsequently be filled in error by a worker assuming the hole was left unintentionally. Additionally, the hole can provide a path for vermin such as small mammals, birds or insects to enter and nest in the cavity. Furthermore, the hole can be unsightly and allow for wind-driven rain to enter the cavity.

Cavity-wall weep devices are known to be positioned in the wall during construction and these define a path for water drainage through the wall. However, such devices can either be large, and so create a negative visual impact on the wall, or are small and so restrict water flow from the building. Additionally, the openings of the devices can be obstructed by mortar during construction of the wall.

The present invention seeks to provide a solution to these problems According to a first aspect of the present invention, there is provided cavity-wall weep device for draining water from a cavity of a cavity wall, the cavity-wall weep device comprising: a body which defines a conduit having an inlet positionable at or adjacent to the cavity and an outlet positionable at or adjacent to an exterior of the cavity, the conduit having a waist with a cross-sectional area smaller than a cross-sectional area of the inlet and a cross-sectional area of the outlet, the waist being between the inlet and the outlet for increasing a rate of water flow from the inlet to the outlet and/or for decreasing a spouting effect.

A waist represents a narrowing and then a widening of the conduit. The narrowing increases water velocity and decreases pressure towards and at the waist due to the Venturi or pseudo-Venturi effect. This encourages a greater volume of water to enter the conduit by reducing water build-up at the inlet. A rate of volume of water drained from the cavity is thereby increased. The increased velocity and decreased pressure caused by the narrowing may have a suction effect on the water at the inlet so as to encourage a greater rate of fluid flowing through the device. The widening of the conduit increases a cross-sectional area of the conduit and increases a length of interface between conduit walls and a bore of the conduit. However, the increase in cross-sectional area is greater than the increase in length of interface. Therefore, the widening decreases the frictional force per volume of fluid between the fluid and the walls of the conduit. This reduces a force acting to prevent fluid flow and therefore a total rate of fluid flowing through the conduit can increase. The widening of the conduit additionally decreases turbulence of water in the conduit and therefore increases a total volume of water able to flow therethrough. Additionally, the widening creates a larger volume which draws in a greater volume of water entering the inlet.

Alternatively, a larger inlet may match a height of the brick to prevent occlusion by mortar whilst a smaller outlet may be required to provide a smaller visual impact. This therefore creates a narrowing of a conduit extending therebetween. Such a narrowing increases a velocity of fluid flowing therethrough due to the Venturi effect which may result in unacceptable spouting of the water from the outlet. A widening at or adjacent to the outlet may decrease a velocity of fluid flow at or adjacent to the outlet, via the Venturi effect and via turbulence due to the divergence of the conduit. Such a decrease in velocity prevents spouting and encourages water to drip or trickle out of the outlet, minimising visual impact. This narrowing and widening is manifested in a waisted conduit.

Additionally, the waist may act as a baffle or barrier. This baffle or barrier may prevent or limit the entry of insects, birds, small animals or other vermin into the cavity.

Furthermore, the baffle or barrier may prevent or limit wind-driven rain from entering the cavity via the conduit The tapering of the body, corresponding to the conduit, may improve mortar adhesion and thereby prevent or limit removal of the device from the wall.

Preferably, the body may have walls and a wall thickness at or adjacent to the outlet may be less than a wall thickness of at least part of the body away from the outlet. A smaller wall thickness at the outlet provides a smaller visual impact whilst allowing for the wall thickness to be greater in other places to improve mechanical properties.

Advantageously, the wall thickness of the body may taper towards the outlet. A taper may 10 be easier to manufacture than an abrupt change in wall thickness.

Beneficially, the conduit may comprise an outlet-proximal portion which may extend between the waist and the outlet, and an inlet-proximal portion which may extend between the waist and the inlet.

Optionally, the outlet-proximal portion may have interior surfaces and at least a majority of a longitudinal extent of the outlet-proximal portion may have interior surfaces which diverge uniformly towards the outlet A long uniform widening, divergence or expansion, rather than a sharp widening, reduces turbulence in fluid flow and therefore increases a rate of fluid flow.

Additionally, the interior surfaces of the outlet-proximal portion may have a first divergence at or adjacent to the waist and a second divergence at or adjacent to the outlet, the first and second divergences being different. Two different widenings, divergences or expansions allows for different degrees of widening in different places. This can allow a more abrupt or extreme widening at or adjacent to the outlet where a generation of turbulence may not as significantly affect the fluid flow through the majority of the conduit.

Furthermore, the tapering of the wall may correspond to the second divergence. The tapering of the wall thickness causing the second widening results in more of the conduit having a uniform wall thickness and a uniform widening.

Preferably, the diameter of the waist may be between 2 mm and 6 mm. Advantageously, a diameter of the waist may be between 3.5 mm and 4.5 mm. Most preferably the diameter of the waist is 4 mm or substantially 4 mm. These range of values are optimum for preventing ingress of vermin and wind driven rain, whilst still allowing sufficient flow of fluid. The diameter is preferably the narrowest dimension of the waist and may be the width.

Beneficially, a height of the body matches or substantially matches a height of a brick, a length of the body matches of substantially matches a depth of the brick and a depth of the body matches or substantially matches a joint of a brick wall. The height of the body matching the height of the brick prevents or limits blockage by allowing for a larger inlet which may be less affected by debris. The length of the body matching the length of a brick enables the cavity-wall weep device to provide a path through the wall whilst minimising the body protruding from the wall. The depth of the body matching a joint allows the cavity-wall weep device to be contained within the a joint and so easily incorporated within a brick wall.

Additionally, the height of the body may be between 60 mm and 70 mm.

Furthermore, the inlet may have an area greater than an area of the outlet. A greater inlet diameter allows for more fluid to flow therethrough and reduce the impact of blockages. A smaller outlet diameter minimises the visual impact of the drainage device Preferably, the diameter of the inlet and outlet may otherwise be considered to be the greatest dimensions of the inlet and the outlet.

Optionally, the inlet may have a diameter which is at least three times greater than a diameter of the outlet. This ensures that the outlet is sufficiently large to minimise impact of blockages whilst also minimising the visual impact of the outlet.

In a preferable embodiment, the inlet may have a diameter which corresponds to at least a majority of the height of the body. This maximises the size of the inlet.

Preferably, the inlet proximal portion at least in part tapers cui-vately in a downstream direction. A curvate tapering may reduce turbulence of the fluid Advantageously, the inlet proximal portion may at least in part taper linearly in a 30 downstream direction A linear tapering may be easier to manufacture.

Beneficially, the body may include a plurality of protrusions for increasing bonding with in use mortar. This helps to keep the wall-drainage device in position Additionally, the waist is formed as a step. In the instance that water does not fill the conduit, the step at the waist may encourage water which has collected on the interior 5 surface of the upper wall of the conduit to drip into the conduit. Alternatively, the step may assist with for manufacturing purposes.

Optionally, at least part of a top of the body at or adjacent to the inlet may be planar or substantially planar. A planar top provides a surface to which the mortar can bond and may be easier to handle. Additionally, it spaces the significant tapering of the conduit 10 from the inlet to prevent or limit the effect of blockages from mortar debris.

In a preferable embodiment, said top is sloped relative to a bottom of the body. A sloped top provides narrowing of the conduit.

Preferably, the waist in-use creates a Venturi effect on water flowing therethrough.

According to a second aspect of the present invention there is provided a wall including 15 a cavity-wall weep device according to a first aspect of the present invention.

Preferably the wall comprises bricks and a height of the body of the cavity-wall weep device matches or substantially matches a height of a brick, a length of the body matches of substantially matches a depth of the brick and a depth of the body matches or substantially matches a width of a joint of the wall.

Advantageously the outlet is flush or substantially flush with an exterior wall of the brick wall This minimises the visual impact of the outlet.

According to a third aspect of the present invention there is provided a method of manufacturing a cavity-wall weep device according to a first aspect of the present invention The invention will now be more particularly described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows a perspective view of an embodiment of a cavity-wall weep device in accordance with a first aspect of the present invention, with a brick of a cavity wall shown in dashed line; Figure 2 shows a cross-section of the cavity-wall weep device of Figure 1, with 5 an exterior wall of a cavity wall shown in dashed line; Figure 3 shows a front view of the cavity-wall weep device of Figure 1, with bricks of the exterior wall shown in dashed line; Figure 4 shows a perspective view of the cavity-wall weep device of Figure 1 with part of a wall cut away for clarity; Figure 5 shows a representation of a lateral cross-section of the cavity-wall weep device of Figure 1 with velocity of in use fluid flow therethrough indicated by coloured arrows; and Figure 6 shows the representation of Figure 5 with pressure of in use fluid flow therethrough indicated by coloured arrows.

Referring to Figures 1 to 4 there is shown a cavity-wall weep device 10, or cavity-wall wall-weep device, for draining water from a cavity 100 of a cavity wall to the exterior of the cavity 100, the exterior wall 102 preferably being formed from bricks. The cavity-wall weep device 10 comprises a body 12 which defines a conduit 14 having at least two openings; an inlet 16 and an outlet 18. The conduit 14 has a waist 20 or throat between the inlet 16 and the outlet 18 to increase a rate of water flow from the inlet 16 to the outlet 18. The waist 20 preferably generates a Venturi effect.

Throughout the specification, a downstream direction may be defined as being a direction from the inlet 16 to the outlet 18. An upstream direction may be defined as being a direction from the outlet 18 to the inlet 16.

The conduit 14 defines an enclosed passageway for fluid flow having an opening at each end, although it will be appreciated that the conduit may have more than two openings. The inlet 16 is preferably larger than the outlet 18, and therefore has a diameter which is larger than a diameter of the outlet 18 or, where a plurality is provided a cumulatively larger area. At least a majority, and here substantially all, of an inlet end of the body comprises the inlet 16. However, the inlet may alternatively occupy less than a majority of the inlet end of the body. The inlet 16 is elongate and is here rectangular or substantially rectangular, although the inlet may not necessarily be rectangular and may include any other shape, for example square, circular or elliptical. Similarly, the conduit 14 has a non-circular cross-section, and is here rectangular, although it will be appreciated that the conduit may have a circular cross-section.

The body 12 defines an inlet-proximal portion 22, first conduit section or first chamber of the conduit 14. The inlet-proximal portion 22 extends between the inlet 16 and the waist 20. A lower wall 24a or bottom of the body 12 at this portion is planar or substantially planar. An inlet-adjacent portion 26a, first planar portion or top, of an upper wall 28a of the body 12 at inlet-proximal portion 22 and directly adjacent to the inlet 16 is also planar or substantially planar. Here the inlet-adjacent portion 26a of the upper wall 28a is sloped in a downstream direction and/or sloped towards the lower wall 24a; however, the inlet-adjacent portion may be parallel with the lower wall. Whilst the lower wall 24a and the inlet-adjacent portion 26a of the upper wall 28a is described and shown as being planar, it will be appreciated that either or both may in fact not be planar.

The upper wall 28a of the inlet-proximal portion 22 further comprises an in-use vertical or substantially vertical planar portion 30, or second planar portion Here the vertical planar portion 30 is directed downwards and is preferably parallel or substantially parallel to a plane of the opening of the inlet 16. However, the vertical planar portion 30 may be at an angle relative to the opening of the inlet and may, for example, be perpendicular to the inlet-adjacent portion and/or not vertical or substantially vertical.

At or adjacent to the vertical planar portion 30, the upper wall 28a further comprises a curvate portion 32. The curvate portion 32 here includes a concave curvature, although the curvature may be convex. The curvature of the curvate portion 32 is preferably a catenary curve, although it may also be a parabola, quadratic, sinusoidal, exponential curve or any other type of curve. The vertical planar portion 30 vertically spaces the curvate portion 32 from the inlet-adjacent portion 26a; however, the vertical planar portion of the upper wall may not be included and the curvate portion may extend directly from the inlet-adjacent portion.

At or adjacent to and downstream of the curvate portion 32 is a sloped planar portion 34, or third planar portion The sloped planar portion 34 preferably extends towards the lower wall 24a in a downstream direction and is planar or substantially planar. However, the sloped planar portion may not be planar or substantially planar and/or may be parallel with the lower wall.

The upper wall 28a being generally directed towards the lower 24a results in the narrowing of the conduit 14 and thus the reduction in cross-sectional area of the conduit 14.

The upper wall 28a and lower wall 24a are joined by lateral walls 36a which are planar or substantially planar and are at least in part orthogonal to the upper and lower walls 28a, 24a. At a transition 38 between the lateral walls 36a and the upper and lower walls 28a, 24a the walls are curvate and/or have a chamfered edge. The lateral walls 36a preferably extend towards each other in a downstream direction from the inlet 16 to the waist 20 so as to taper the conduit 14. However, the lateral walls may be parallel with each other and therefore may not act to taper the conduit.

The waist 20 is downstream and at or adjacent to the sloped planar portion 34; however, the sloped planar portion may not be included and the curvate portion may extend to, at or adjacent to the waist. At the waist 20 is a step 40 or abrupt narrowing of the conduit 14 and body 12. The step 40 is preferably at or on the inlet-proximal portion 22 and is at the upper and lateral walls 28a, 36a, although it may only be at the upper wall. Whilst a waist is described, it will be appreciated that a waist may not be included.

The waist 20 preferably has a diameter between 2 mm and 6 mm, more preferably a diameter of the waist 20 is between 3.5 mm and 4.5 mm and most preferably the diameter of the waist 20 is 4 mm or substantially 4 mm. Here the diameter is the width of the waist 20 and is preferably the narrowest dimension of the waist 20. For example, the height of the waist 20 may greater than the width and may be between 6 mm and 7 mm. The waist has a smaller cross-sectional area than the inlet and the outlet and preferably has the smallest cross-sectional area of the conduit 14. The waist 20 of the conduit 14 is preferably rectangular or substantially rectangular for example having chamfered edges.

However, the waist may have any other shape such as square, circular or elliptical.

The body 12 and the conduit 14 have an outlet-proximal portion 42 or second chamber or conduit section which is defined between and/or extends between the waist 20 and the outlet 18. The outlet-proximal portion 42 has an upper wall 28b, a lower wall 24b and lateral walls 36b. Preferably at least a majority of the outlet-proximal portion 42 uniformly widens, diverges, expands or enlarges in a downstream direction. More preferably the outlet-proximal portion 42 comprises a first widening 44, divergence or expansion in a downstream direction at or adjacent to the waist 20 and a second widening 46, divergence or expansion in a downstream direction at or adjacent to the outlet 18. The first divergence 44 is preferably uniform, straight, constant and/or linear.

The lower wall 24b of the outlet-proximal portion 42 is preferably continuous, coplanar and integrally formed with the lower wall 24b of the inlet-proximal portion 22. The lower walls 24a, 24b being planar allow for the device 10 to be mounted onto and supported by a brick. All the walls 24a, 24b, 28a, 28b, 36a, 36b may be considered to be wall-mounting surfaces and preferably the device includes at least one planar wall-mounting surface.

A waist-adjacent portion 48a of the upper wall 28b of the outlet-proximal portion 42 is uniformly sloped so as to extend away in a downstream direction from the lower wall 24b, so as to widen the conduit 14. Similarly, a waist-adjacent portion 48b of the lateral walls 36b of the outlet-proximal portion 42 extend away from each other, so as to widen the conduit 14. In this way the waist-adjacent portions 48a, 48b of the upper wall 28b and lateral walls 36b define the first divergence 44 of the outlet-proximal portion 42. However, it will be appreciated that the first divergence may only be defined by the lateral walls extending away from each other, with the upper and lower walls being parallel to each other. Alternatively, the first divergence may only be defined by the upper wall extending away from the lower walls and the lateral walls may be parallel with each other.

Whilst the first divergence 44 is described as uniform and/or linear, and therefore the lateral and upper walls 36b, 28b extending uniformly and/or linearly away from a centre line of the conduit 14, the first divergence may in fact not be uniform, for example it may irregularly widen. Alternatively or additionally, the first divergence may curvately widen.

Preferably, a wall thickness of the body 12 at or adjacent to the outlet 18 is less than a 30 wall thickness of the body 12 away from the outlet 18. At least one of the walls 28b, 24b, 36b tapers at or adjacent to the outlet 18 and preferably all the walls 28b, 24b, 36b of the body 12 taper at or adjacent to the outlet 18. Such a tapering of the wall thickness is such that the conduit 14 widens and in this way the wall thickness tapers away from the centreline of the conduit 14. Thus, the tapering of the walls 28b, 24b, 36b at an end at the outlet 18 corresponds to the second divergence 46. The walls 28b, 24b, 36b preferably taper to a point, although the walls may in fact be blunted. The walls 28b, 24b, 36b at or adjacent to the outlet 18 may therefore have a bell mouth and/or be filleted.

The outlet 18 is preferably rectangular or substantially rectangular and may more preferably be square or substantially square. This may be with the exception that the corners are cui-vate. The outlet 18 preferably has a height of between 5 mm and 10 mm and more preferably is or is substantially 7.5 mm. The width of the outlet 18 is preferably the same as the height, although it will be appreciated that the width may be different.

The body 12 preferably includes a plurality of protrusions 50 or projections for increasing bonding with in use mortar. The protrusions 50 are planar and may be ridges or plates which extend outwardly from the body 12, preferably from the upper and lateral walls 28a, 28b, 36a, 36b. There are six ridges 50 and these are spaced uniformly along an axial extent of the body 12, although there may be any number of ridges 50. The ridges 50 extend further from the conduit 14 at the upper wall 28b than at the lateral walls 36b; however, the ridges may for example extend equally in all directions from the conduit or may extend further from the conduit at the lateral walls. At least one and preferably four of the ridges 50 are aligned with a vertical direction and or a plane of the opening of the outlet 18. At least one and preferably two of the ridges 50 are aligned at an angle to this plane and these are at or adjacent to the curved portion. Therefore, said ridges 50 may extend perpendicularly or substantially perpendicularly upwardly to a downstream direction at the conduit 14 where the ridges 50 are positioned.

The body 12 is preferably formed from plastics, such as thermoplastics, and is preferably formed via an injection moulding process. However, the body 12 may alternatively be formed from metal, such as steel or aluminium, or ceramics. Additionally, the body 12 may be formed from any other manufacturing technique such as stamping, machining, extrusion or blow moulding. The height of the body 12 matches or substantially matches a height of a brick, for example preferably being between 60 mm and 70 mm and more preferably 65 mm. A length of the body 12 matches or substantially matches a length of a brick, for example preferably being between 100 mm and 120 mm and more preferably being 102.5 mm. A width of the body 12 matches, substantially matches or is less than a width of a joint between bricks. For example, the width of the body 12 is less than or equal to a dimension within the range 5 mm and 15 mm and more preferably being less than or equal to 10 mm. However, it will be appreciated that the body 12 may instead match or substantially match the dimensions of other sized bricks.

In use, a cavity wall of a building may be constructed and during construction of an exterior wall 102 of the cavity wall the cavity-wall weep device 10 is positioned in the exterior wall 102. This positioning is so that an inlet 16 is at, adjacent to or directly fluidly communicative with a cavity 100 of the cavity wall, and the outlet 18 is at, adjacent to or directly fluidly communicative with the exterior of the cavity wall. The outlet 18 or end of the outlet 18 is preferably flush with the exterior face of the wall. The cavity-wail weep device 10 may be positioned so that it is directly above window and/or door lintels, for example, so that it may drain water which accumulates on the lintel. Alternatively, the cavity-wall weep device 10 may be positioned at a cavity tray of the cavity 100, for example so that the cavity-wall weep device 10 may drain water which accumulates on the cavity tray. However, the cavity-wall weep device 10 may be positioned anywhere within the wall, for example to drain water vapour or humidity in air or to provide other ventilation to the wall cavity.

The exterior wall 102 is preferably a brick wall and the cavity-wall weep device 10 is preferably positioned within the brick wall so that it is at a joint between two bricks. More preferably the joint is a head joint and the cavity-wall weep device 10 matches or substantially matches the height, width and length of the head joint. The cavity-wall weep device 10 may therefore be positioned between two bricks and mortar filled around it, or the cavity-wall weep device 10 may be pushed into mortar on a first brick and a second brick placed at another side of the cavity-wall weep device 10.

Once the building has been constructed with the cavity-wall weep device 10 in place, water may permeate through the exterior wall 102 into the cavity 100. If the cavity-wall weep device 10 has been positioned at a surface on which water accumulates, such as a lintel or a cavity tray, liquid water may enter the inlet 16 and flow towards the outlet 18. The narrowing of the conduit 14 in the inlet-proximal portion 22 increases water velocity towards and at the waist 20 due to the Venturi effect, as shown in Figure 5. This encourages a greater volume of water to enter the conduit 14 by reducing water build-up at the inlet 16. A rate of volume of water drained from the cavity 100 is thereby increased. The increase in water flow rate at the waist 20 results in a decrease in pressure due to the 5 Venturi effect, as shown in Figure 6. The increased velocity and decreased pressure caused by the narrowing may therefore have a suction effect on the water at the inlet 16 so as to encourage a greater rate of fluid flowing through the device. In the instance that water does not fill the conduit 14, the step 40 at the waist 20 may encourage water which has collected on the interior surface of the upper wall 28b of the conduit 14 to drip into 10 the conduit 14. This may increase a flow of water from the inlet 16 to the outlet 18.

The first divergence 44 of the conduit 14 increases a cross-sectional area of the conduit 14 and increases a length of interface between conduit 14 wails and a bore of the conduit 14. However, the increase in cross-sectional area is greater than the increase in length of interface. Therefore, the first divergence 44 decreases the frictional force per volume of fluid between the fluid and the walls 28b, 24b, 36b of the conduit 14. This reduces a force acting to prevent fluid flow and therefore a total rate of fluid flowing through the conduit 14 can increase. The divergence of the conduit 14 additionally decreases turbulence of water in the conduit 14 and therefore increases a total volume of water able to flow therethrough. Additionally, the first divergence 44 creates a larger volume which draws in a greater volume of water entering the inlet 16.

The first divergence 44 or expansion of the conduit 14 in the outlet-proximal portion 42 decreases water velocity flowing therethrough due to the Venturi effect. The second divergence 46 adjacent to the outlet 18 further similarly decreases the velocity of water. This therefore reduces the chance of spouting of water from the outlet 18.

This effect on water flowing through the conduit 14 similarly applies to air, such as air having a high moisture content and therefore the narrowing and the widening of the conduit 14 increases a flow rate of air through the conduit 14. This increases a flow rate of water via water vapour through the present cavity-wall weep device 10 as compared to known cavity-wall weep devices. The device 10 may be used with any fluid. Preferably the device may prevent or limit back flow of fluid into the cavity 100.

Whilst the cavity-wall weep device 10 is described as being positioned in the wall during construction of the wall, it will be appreciated that the cavity-wall weep device 10 may be retrofitted to an existing wall. Additionally, while a brick wall is described, it will be appreciated that the cavity-wall weep device 10 may be used with walls made from any other masonry or material, such as concrete, breeze blocks or timber.

Whilst the inlet 16 is shown as extending the height of the body 12, this may not necessarily be the case. For example, the inlet may be smaller than the height of the body and the body may effectively have a spacer between the top of the body and the top of the inlet. This would allow for a smaller inlet whilst limiting mortar ingress into the conduit.

Additionally or alternatively, the inlet and the outlet may be similarly sized and the conduit may be cylindrical or substantially cylindrical. In this instance, the waist may or may not be between the inlet and the outlet. However, the wall thickness at the outlet is preferably tapered.

Whilst described as a cavity-wall weep device, it will be appreciated that the device may 15 be used in other wall drainage scenarios. For example, the cavity-wall weep device may be used to drain moisture from the earth on one side of a retaining wall to the exterior of the wall.

Whilst only one inlet and outlet are described and shown, there may be a plurality of inlets and an equal number of outlets, each inlet and outlet pair being joined by a conduit. 20 Alternatively, there may be multiple inlets fluidly communicative with fewer or a single outlet.

It is therefore possible to provide a cavity-wall weep device having an inlet, an outlet and a conduit therebetween. The conduit has a waist which generates a Venturi effect to increase a total rate of fluid flow from the inlet to the outlet. It is also possible to provide a cavity-wall weep device with a reduced visual impact by having a tapering wall thickness at the end of the body with the outlet. It is also possible to provide a cavity-wall weep device having a reduced impact from debris by having an inlet with a greater diameter than the outlet.

The words 'comprises/comprising' and the words 'having/including' when used herein with reference to the present invention are used to specify the presence of stated features, integers, steps or components, but do not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.

The embodiments described above are provided by way of examples only, and various other modifications will be apparent to persons skilled in the field without departing from the scope of the invention as defined herein. The following clauses outline features of interest. 3. 4

A cavity-wall weep device for draining water from a cavity of a cavity wall, the cavity-wall weep device comprising: a body which defines a conduit having an inlet positionable at or adjacent to the cavity and an outlet positionable at or adjacent to an exterior of the cavity; the conduit having a waist with a cross-sectional area smaller than a cross-sectional area of the inlet and a cross-sectional area of the outlet, the waist being between the inlet and the outlet for increasing a rate of water flow from the inlet to the outlet.

A cavity-wall weep device as in clause 1, wherein the body has walls and a wall thickness at or adjacent to the outlet is less than a wall thickness of at least part of the body away from the outlet.

A cavity-wall weep device as in clause 2, wherein the wall thickness of the body tapers towards the outlet.

A cavity-wall weep device as in any one of the preceding clauses, wherein the conduit comprises an outlet-proximal portion which extends between the waist and the outlet, and an inlet-proximal portion which extends between the waist and the inlet A cavity-wall weep device as in clause 4, wherein the outlet-proximal portion has interior surfaces and at least a majority of a longitudinal extent of the outlet-proximal portion has interior surfaces which diverge uniformly towards the outlet.

6 A cavity-wall weep device as in clause 4 or clause 5, wherein the interior surfaces of the outlet-proximal portion have a first divergence at or adjacent to the waist and a second divergence at or adjacent to the outlet, the first and second divergences being different 7. A cavity-wall weep device as in clause 6 when dependent on claim 3, wherein the taper of the wall corresponds to the second divergence.

8. A cavity-wall weep device as in any one of clauses 4 to 7, wherein the inlet proximal portion at least in part tapers curvately in a downstream direction.

9. A cavity-wall weep device as in any one of clauses 4 to 8, wherein the inlet proximal portion at least in part tapers linearly in a downstream direction.

10. A cavity-wall weep device as in any one of the preceding clauses, wherein a diameter of the waist is between 2 mm and 6 mm.

11. A cavity-wall weep device as in clause 10, wherein a diameter of the waist is between 3.5 mm and 4.5 mm.

12. A cavity-wall weep device as in any one of the preceding clauses, wherein a height of the body matches or substantially matches a height of a brick, a length of the body matches of substantially matches a depth of the brick and a depth of the body matches or substantially matches a joint of a brick wall.

13. A cavity-wall weep device as in any one of the preceding clauses, wherein the height of the body is between 60 mm and 70 mm 14. A cavity-wall weep device as in any one of the preceding clauses, wherein the inlet has a greater area than an area of the outlet A cavity-wall weep device as in clause 14, wherein the inlet has a diameter which is at least three times greater than a diameter of the outlet 16. A cavity-wall weep device as in any one of the preceding clauses, wherein the inlet has a diameter which corresponds to at least a majority of the height of the body.

17. A cavity-wall weep device as in any one of the preceding clauses, wherein the body includes a plurality of protrusions for increasing bonding with in use mortar.

18. A cavity-wall weep device as in any one of the preceding clauses, wherein the waist is formed as a step.

19. A cavity-wall weep device as in any one of the preceding clauses, wherein at least part of a top of the body at or adjacent to the inlet is planar or substantially planar.

20 A cavity-wall weep device as in any one of the preceding clauses, wherein said top is sloped relative to a bottom of the body.

21. A cavity-wall weep device as in any one of the preceding clauses, wherein the waist creates a Venturi effect on water flowing therethrough.

22. A wall including a cavity-wall weep device as in any one of the preceding clauses.

23 A wall as in clause 22, further comprising bricks and a height of the body of the cavity-wall weep device matches or substantially matches a height of a brick, a length of the body matches of substantially matches a depth of the brick and a depth of the body matches or substantially matches a width of a joint of the wall.

24. A wall as in clause 22 or clause 23, wherein the outlet is flush or substantially flush with an exterior wall of the brick wall 25. A method of manufacturing a cavity-wall weep device as in any one of the preceding clauses

Claims (7)

1. Claims 1 A cavity-wall weep device for draining water from a cavity of a cavity wall, the cavity-wall weep device comprising: a body which defines a conduit having an inlet positionable at or adjacent to the cavity and an outlet positionable at or adjacent to an exterior of the cavity; the conduit having a narrowing for generating a Venturi effect that increases a velocity of fluid flowing through the conduit from the inlet. 2 3.C\I 15CO 4. 5
2. The cavity-wall weep device of claim 1, further including a widening toward the outlet for decreasing a velocity of fluid flow at the outlet.
3. The cavity-wall weep device of claim 1 or 2, wherein a cross-sectional area of the inlet is greater than a cross-sectional area of the outlet, and both respective inlet and outlet cross-sectional areas are greater than a cross-sectional area at the narrowing.
4. The cavity-wall weep device as in any one of the preceding claims, wherein the narrowing is formed as a step.
5. The cavity-wall weep device as in any one of the preceding claims, being substantially unobstructed by any structure protruding into the conduit that inhibits generation of the Venturi effect and increasing velocity of fluid flowing through the conduit from the inlet.
6. 6. A wall including a cavity-wall weep device as in any one of the preceding claims.
7. 7. The wall of claim 6, comprising bricks, wherein a height of the body of the cavity-wall weep device matches a height of a brick, a length of the body matches a depth of the brick and a width of the body matches a width of a joint between bricks