GB2599718A

GB2599718A - Retrofittable roof vent

Info

Publication number: GB2599718A
Application number: GB2016090.9A
Authority: GB
Inventors: Neil Rowbotham Bryan
Original assignee: Individual
Current assignee: Individual
Priority date: 2020-10-09
Filing date: 2020-10-09
Publication date: 2022-04-13
Also published as: GB202016090D0

Abstract

The roof vent comprises upper and lower ends and side edges within which a planar grille is disposed, and a drainage outlet at the lower end. The vent also includes means to capture precipitation (e.g. rain) entering the grille and eject the same via the drainage outlet. Ideally, the vent is formed of two half-vent portions 2; an exterior portion having a venting area 4 to permit passage of air and an interior portion including the means to capture/eject precipitate. In one embodiment the capture/eject means comprises a plurality of interior members 5 offset from corresponding exterior members such that rain passing through outer openings 12 of the venting area 4 are caught by the interior members and channelled to the drainage outlet. In another embodiment the capture/eject means comprises a cowl chamber (29, figure 17). Walls (23, figure 12) and hooks (9, figure 11) may be included to fold and clamp felt about the vent during installation. The felt may also be clamped between half-vent portions.

Description

Ret rofittable roof vent The present invention relates to improvements in vents, in particular a retrofittable roof vent that is intended to be installed inside roof spaces under existing tilework of pitched roofs and as a replacement for a section of roof felt.

Vents are used in many scenarios to allow a fluid (gaseous or liquid) to pass into or out of a confined space such as a room, a building's facade or machinery housings.

One example of a use of vents is in the provision of controlled ventilation to loft spaces so as to reduce or prevent condensation and subsequent water damage. Vents may be retrofitted to an unsealed slated or tiled roof.

An important aspect of such a vent is to provide wind-load control to prevent wind uplift, and whilst air and moisture must be allowed to exit the vent, precipitation must be prevented from entering a roof-space through the vent. An example of a vent designed to address this issue is disclosed in GB2315856.

The present invention seeks to improve upon the prior art.

According to a first aspect of the present invention there is provided a retrofittable roof vent for fitting at a substantially planar aperture formed in an area of roof felt, the vent comprising: an upper end and a lower end and first and second side edges extending therebetween; at least one drainage outlet at the lower end of the vent; a substantially planar grille disposed between the upper and lower ends and the side edges; means to capture precipitation entering the grille and drain it from the drainage outlet when the vent is in use.

By providing a retrofittable roof vent made in accordance with the present invention a large weatherproof venting area may be created. This may be beneficially achieved by retaining the vent in a plane that is substantially parallel to the plane of the aperture such that the grille covers at least part of the aperture, preferably covers the aperture entirely or is the same size as the aperture. The vent of the present invention is retrofittable inside a roof cavity at an aperture formed in an area of roof felt beneath roof battens. Preferably when installed the vent preferably abuts an internal side of the roof battens.

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In some embodiments the vent comprises means for securing the vent to a component of the roof.

In some embodiments the vent comprises means to inhibit movement of roof felt overlapping a side member at each side of the vent.

In some embodiments a means to inhibit movement of a strip of roof felt is in the form of at least one upstanding member adjacent each side of the grille.

In some embodiments an upstanding member adjacent each side of the grille is a wall.

In some embodiments a means for securing the vent is provided by first and second side members at each side of the vent being capable of clamping roof felt therebetween.

In some embodiments a first side member comprises at least one projection configured to mate with a corresponding recess formed on the second side member.

Preferably a first side member comprises at plurality of projections configured to mate with corresponding recesses formed on the second side member.

In some embodiments the vent comprises a surround to the grille, with the surround comprising side members and being capable of clamping roof felt adjacent each side of the grille.

In some embodiments the vent comprises an upstanding lip adjacent its side edges.

In some embodiments the vent comprises at least one hook disposed towards the lower end of the vent to allow a user to hook the vent to a portion of roof felt to retain the grille in position.

In some embodiments the vent comprises a plurality of hooks to retain the grille in position.

In some embodiments vent comprises towards its upper end means to attach the vent to a retaining band of material to retain the grille in position.

In some embodiments the means to attach the vent to a retaining band of material is in the form of an aperture extending between the first and second side edges of the vent.

In some embodiments the grille comprises a plurality of channels disposed towards the inward-facing side with inner openings located between adjacent pairs of channels; a plurality of covers disposed towards the outward-facing side with outer openings located between adjacent pairs of covers; the inner openings, outer openings and a space between the covers and the channels allowing for fluid communication between the inward facing side and the outward facing side; the covers and channels being arranged such that the covers are aligned with the inner openings and the channels are aligned with the outer openings; the channels and covers extending between upper and lower ends of the grille.

In some embodiments the outer openings are substantially aligned within the middle third of the channels, or are substantially aligned with the centres of the channels and the inner openings are substantially aligned within the middle third of the covers, or are substantially aligned with the centres of the covers.

In some embodiments the drainage outlet is configured to drain liquid from the plurality of channels.

In some embodiments covers each comprise a base and a pair of side walls.

In some embodiments the walls of covers have external faces that are acutely angled to the base.

By providing walls that have external faces that are acutely angled to the base the distance between adjacent covers widens from the opening towards free ends of the walls. Thus a Venturi effect may be created so as to enhance airflow.

In some embodiments the walls of covers and/or the walls of channels have free ends that are rounded in cross-section.

In some embodiments a base of a cover has a depression on its outward-facing side.

By providing a base that has a depression on its outward-facing side liquid may drain from the outer side of the covers without entering the space between the covers and channels.

Preferably any such depression is substantially linear and extending substantially the full length of the cover.

In some embodiments the vent is formed of two identical half-vents.

In some embodiments channels are defined by a first half-vent and covers are defined by a second half-vent.

In some embodiments the vent comprises a first part having a grille and a second part forming a cowl with a chamber configured to cover the grille, with liquid in the chamber being drainable therefrom via the drainage outlet.

In some embodiments the chamber comprises a lower wall that is angled to the grille to drain liquid towards the drainage outlet and an upper wall having a downward-facing opening that is suitable to connect to the cowl to a pipe.

In accordance with a second aspect of the present invention there is provided a kit of parts containing a plurality of half-vents configured such that when two half-vents are attached together they create a vent made in accordance any preceding statement of invention.

In some embodiments the half-vents used to create a vent are substantially identical. In other embodiments a first half-vent may comprise a grille and second half-vent might comprise a cowl.

In accordance with a third aspect of the present invention there is provided a method of retrofitting a roof vent comprising the steps of: a) providing a retrofittable roof vent made in accordance with any previous

statement of invention;

b) forming an aperture in an area of roof felt; c) positioning the vent such that its grille is located at the aperture and the drainage outlet overlaps the roof felt.

In some embodiment the step of positioning the vent comprises the step of folding roof felt at either side of the vent such the felt abuts an upstanding member of the vent adjacent each side of the grille.

In some embodiments the step of positioning the vent comprises the step of clamping roof felt adjacent first and second parts of the vent adjacent each side of the grille.

Advantageously the vent of the present invention may be fitted from inside a roof space.

In order that the present invention may be more fully understood a specific embodiment of a roof vent will now be described by way of example with reference to the accompanying drawings, of which: Figure 1 is a plan view of the exterior face of a half-vent made in accordance with the present invention; Figure 2 is a plan view of the interior face of the half-vent of Figure 1 made in accordance with the present invention; Figure 3 is a perspective view of the exterior face of the half-vent of Figure 1; Figure 4 is a perspective view of the interior face of the half-vent of Figure 1; Figure 5 is a side view of two half vents attached together so as to form a vent in accordance with the present invention; Figure Lisa view of the drainage outlet of the vent of Figure 5; Figure 7 is a cross-section of the covers and channels of the vent of Figure 5 illustrating how ventilation occurs; Figure 8 is a cross-section of the covers and channels of the vent of Figure 5 illustrating how precipitation and condensation are managed; Figure 9 is a view of a roof wherein a section of roof felt has been removed as a first step towards installing the vent of Figure 5 Figure 10 illustrates how a retaining band may pass through an aperture in the vent of Figure 5; Figure 11 illustrates how the vent of Figure 5 is positioned over the aperture illustrated in Figure 9 by attaching the retaining band to rafters and hooking the vent to the roof felt; Figure 12 illustrates how roof felt is folded adjacent a side of the vent when installed; Figure 13 illustrates the vent beneath the tiles overlapping the roof felt; Figure 14 illustrates a second method of installing the vent of Figure 5 by clamping roof felt between two half-vents; Figure 15 illustrates a spacer for use with large vents made in accordance with the present invention; Figure 16 illustrates how the spacer of Figure 15 is positioned; Figure 17 is a perspective view of a cowl for use with the half-vent of Figure 1; and Figure 18 is a exploded perspective view of a vent made in accordance with a second embodiment of the present invention, the vent incorporating the cowling of Figure 17 and the half-vent of Figure 1 Referring to the drawings, a roof vent 1 in the form of a panel may be constructed from two identical half-vents 2.

Half-vent is substantially planar 2 and is formed in one piece from a plastics material. In the present embodiment half-vent 2 is formed of 2mm thick recycled acrylonitrile butadiene styrene (ABS) plastic but in other embodiments any suitable material may be used such as other plastics materials, metal, or derivatives thereof.

Half-vent 2 comprises a substantially planar rectangular frame 3 and a substantially planar venting area 4.

Frame 3 has an upper end 3a, a lower end 3b a first side 3c and a second side 3d. The nomenclature 'upper' and 'lower' is employed to indicate the relative position of ends 3a, 3b when vent 1 is installed over an underlapping seam of roofing underfelt.

In the present embodiment the height of frame 3 (i.e. the distance from upper end 3a of frame 3 to the lower end 3b of frame 3) is 49cm.

The width of frame between first and second sides 3c, 3clof frame 31s 32cm.

The width of frame 3 is important as it must be compatible with standard rafter bay widths, which are normally in the range of 40cm to 60cm. Thus in most embodiments the width of vent is anticipated to be less than 60cm or less than SOcm, or less than 40cm, or less than 35cm, or commonly in the range of 30cm to 40cm.

Frame 3 comprises a plurality of projections 7 on one half of its interior face and also comprises a plurality of corresponding recesses Son the other half of its interior face. Thus, when two half-vents 2 are positioned with their interior faces in contact, the projections 7 on each half-vent 2 may mate with the recesses Son the other half-vent 2.

Projections 7 are in the form of impact studs.

As in the present embodiment recesses 8 are provided in the form of through-holes they are visible on both the internal and external faces of a half-vent.

Venting area 4 is formed of a plurality of substantially linear elongate members 5 that are substantially '[-shaped' in cross-section, with each member comprising a comprise a base 5a and side walls 513, Sc that are angled to base Sa. Side walls 5b, Sc have respective free ends 5d, 5e.

Between each pair of adjacent covers 5 is a substantially linear opening 6 that has a width of approximately 4mm.

Side walls 5a, 5b on a particular elongate members each have exterior faces that are at an acute angle to base Sa; thus walls 5b, Sc on a particular elongate member have exterior faces that are angled towards each other, as illustrated in Figure 6.

Thus on an adjacent pair of elongate members S the distance between free ends 5d, Se of side walls 5b, Sc is greater than the width of the outer opening 12 between the bases 5a of the adjacent pair of elongate members S. S The provision of non-parallel faces of adjacent elongate members S can enhance air flow in any one direction depending on prevailing pressures (good ventilation requires an inlet and an outlet). A venturi type effect can take place on either the negative or positive wind-load sides of a pitched roof, or through high thermal convection from within an internal roof void.

Free ends of 5d, Se of side walls 5b, Sc are rounded in cross-section to avoid water cohesion and to aerodynamically aid air flow.

Similarly the internal corners of elongate member 1 where side walls 5b, Sc meet base 5a are rounded to aerodynamically aid airflow, On the exterior face of half-vent 2 each of the elongate members comprises on its base Sa an elongate linear depression 5f such that the outer face of base 5a is concave in cross-section.

Two hooks 9 extend outwardly from the exterior face of half-vent 2 adjacent each side thereof. Hooks 9 are disposed between venting area 4 and the lower end of half-vent 2.

Adjacent the upper end of half-vent 2 on its interior face is located a linear recess 19 that extends between first and second sides of half-vent 2.

Adjacent the lower end of half-vent 2 and extending between the lower ends of elongate members Sand the lower edge 3b of half-vent 2 is a rectangular recess 14, that together with a corresponding recess 14 on a second half-vent defines a drainage outlet 15 when vent 1 is assembled as illustrated in Figure 6.

In an assembled vent 1 an opening to the drainage outlet 15 is linear and extends along part of lower edge 3b.

Figure 5 illustrates an assembled vent 1 formed of two half-vents 2a, 2b, wherein the two half-vents 2a, 2b have been attached together by mating projections 7 with recesses 8.

It will be immediately appreciated from Figure S that vent 1 is substantially planar S throughout. Indeed, at its widest between the external faces of elongate members 5 of half-vent 2a and the external faces of elongate members 5 of half-vent 2b vent 1 is around 2cm.

Critically, under certain building regulations if a ventilated roof is being constructed, there is a requirement to have a SOmm fully ventilated air gap between insulation and roof felt, in order to avoid condensation. The vent of the present invention is capable of fitting into such a space. Thus in many embodiments it is anticipated that substantially planar vents made in accordance with the present invention will be (throughout) less than Scm in depth, less than 4cm in depth, less than 3cm in depth, around 2cm in depth or between 1.5cm and 2.5cm in depth.

Whilst vent 1 is rotationally symmetrical once immediately assembled, one side of the vent will be outward facing when vent 1 is installed as it will be positioned towards the exterior of a roof, and the other side of the vent may be considered to be inward-facing as it will be positioned towards the interior of a roof.

For the purposes of explanation the side of vent 1 provided by half-vent 2a may be considered to be an outward-facing side of vent land side of vent 1 provided by half-vent 2b may be considered to be an inward-facing side of vent 1.

Thus elongate members 5 of outward facing side 2a act as 'covers' for the vent and the elongate members 5 of inward facing side 2a act as liquid-conducting 'channels' for the vent.

Elongate members S of outward facing side 2a are located in a first plane and elongate members 5 of inward facing side 2b are located in a second plane that is substantially parallel to the first plane.

Elongate members S of half-vent 2a overlap the elongate members of half-vent 2b. That is to say that side walls 5b, Sc of the elongate members of half-vent 2a extend towards bases 5a of the elongate members 5 of half-vent 2b, and vice versa, as best illustrated in Figures 6 and 7.

A space 10 is defined between the plane of the bases Sa of the elongate members 5 of half-vent 2a and the plane of the bases 5a of the elongate members 5 of half-vent 2b. Thus side walls 5b, Sc of the elongate members 5 of half-vents 2a, 2b are all positioned within space 10.

Outer openings 12 are substantially aligned with the middle of elongate members 5 of half-vent 2b.

Similarly inner openings 13 are substantially aligned with the middle of elongate members 5 of half-vent 2a.

Thus, laterally (except at the edges of venting area 4) each elongate member 5 of half-vent 2a laterally overlaps a pair of elongate members of half-vent 2b and vice versa.

Elongate members 5 of half-vents 2a, 2b are positioned such that there is fluid communication from the outer openings 12, through space 10 to the inner openings 13.

This fluid communication allows for venting area 4 to act as an air vent as illustrated in Figure 5, wherein the arrows indicate possible airflow.

Linear recesses 19 together form a linear aperture 20 extending between the first and second side edges of vent 1.

Referring to Figure 7 it may be seen that the arrangement of elongate members 5 of vent 1 acts to prevent the ingress of precipitation 11 through vent 1 from an exterior of a building to an interior of a building.

Precipitation 11 reaching vent 1 contacts elongate members of outward-facing half-vent 2a and may either run directly off vent 1 through elongate depressions 5f formed in the outer surface of base 5a or may pass through outer openings 12 into space 10.

Precipitation 11 that does pass into space 10 is caught by elongate members.5 of half-vent 2b, which acting as channels direct precipitation 11 to drainage outlet 15 whereupon it flows out of vent 1 at its lower edge onto the weather side of the underfelt that underlaps vent 1.

Thus vent 1 is substantially weatherproof.

Similarly, any condensation that occurs in vent 1 is captured and drained from drainage outlet 15. Advantageously owing to the large surface areas of elongate member 5, vent 1 is able to condense a relatively large volume of water, all for release to the exterior of a property via drainage outlet 15.

The dimensions of elongate members Sand the spacing thereof may be important.

For example, some building regulations require that roof vents have apertures of 4mm at most in order to prevent the ingress of wildlife/insects to a building.

Thus, for many roof vents it may be preferable to have outer openings 12 between elongate channels of no greater than 4mm in width.

The width of outer openings 12 thereby determines to an extent the volume of precipitation that the elongate members 5 when acting as channels for fluid must be able to disperse via drainage outlet 15 without overflowing.

It is considered that where an elongate member has a base Sa and sides walls Sb, Sc the width of base 5a between side walls 5b, Sc should preferably be at least 1.5 times the height of side walls, 5b, Sc or more preferably at least 2 times the height of side walls 5b, Sc.

Thus in the present embodiment the width of base Sa between side walls Sb, Sc is 20mm and the height of side walls 5b, Sc is 10mm.

It is considered that preferably the height of a an elongate member's side walls Sb, Sc should be at least 1.5 times the width of the outer opening 12 with which the elongate members is aligned, or more preferably at least 2 times the width of the outer opening 12 with which elongate members is aligned.

Thus in the present embodiment the width of outer opening 12 is 4mm and the height of walls 5b, Sc is lOmm.

Figures 9 to 13 illustrate a first method of installing vent 1.

A user first cuts a rectangular aperture 16 in a section of roof felt 17 located between two rafters 18 in an internal space under a roof. Aperture 16 is cut to roughly the same size as venting area 4. Aperture 16 is in a plane that is substantially parallel to the plane defined by rafters 18.

A user inserts a band of material 21 through linear aperture 20 and having located the lower end of vent 1 through aperture 16 such that vent 1 is retained on roof felt 17 at a lower edge of aperture 16 by hooks 9.

The user may then thread band of material 21 over rafters adjacent each side of vent land secure band of material 21 by any suitable means.

In another mode of installation a user may affix a batten between adjacent rafters such that the batten abuts an upper area of vent 1 so as to retain vent 1 in position.

If desired a user may apply an adhesive such as mastic to vent 1 so as to bond vent 1 to roof felt 17 around the perimeter of aperture 16.

If desired a user may snap hooks 9 off from outward facing side 2a of vent 1 so that those hooks 9 do not interfere with tiles or tile battens.

When vent 1 is installed in a pitched roof the upper end of vent 1 is disposed above its lower end with an outward face 2a of vent 1 positioned up against the felt surrounding aperture 16. In this position vent 1 is substantially parallel to sloping rafters 18 and has its venting area 4 substantially covering aperture 16.

As the drainage outlet 15 is positioned over an underlapping seam of felt any precipitation captured by the elongate members 5 of the venting area 4 is directed downwardly to drainage outlet 15.

Figure 12 illustrates that a user may install vent 1 by retaining folds 22 of roof felt 17 at each side of an aperture 16 so as to inhibit any ingress of water towards the sides of vent 1.

Such a fold 22 of roof felt may be inhibited from unfolding by provision of an upstanding wall 23 located adjacent either side of venting area 4.

Furthermore, a lip 24 located adjacent side edges 3c, 3d of vent 1 may be used to direct any precipitation that passes fold 22 downwardly to drain from the lower end of vent 1.

To aid understanding of the position of vent 1 Figure 13 illustrates vent 1 in position in a roof space with tiles that would normally be in position over vent 1 having been removed.

When installed vent 1 may have its elongate members in contact with timber battens 39 that form part of a normal pitched roof.

Beneficially elongate depressions 5f provide a channel for drainage of precipitation even if elongate members 5 are pressed tight against battens 39.

Thus, depression 5f minimizes the contact of elongate members 5 with timber battens by leaving a gap for water and airflow and lessens the likelihood of batten decay.

Turning to a second mode of installation, and Figure 14, a vent 1 formed of two half-vents 2a, 2b may clamp a portion of roof felt 25 between the two half-vents 2a, 2b. Projections 7 pass through roof felt 25 so as to secure vent 1 in position at an aperture 26.

Roof felt 25 is clamped between frames 3 of half-vents 2a, 2b.

Whilst in the present embodiment roof felt may be clamped adjacent each of four sides of a rectangular aperture in other embodiments roof felt may only be clamped adjacent either side of an aperture or may only be clamped adjacent a top of an aperture (with the bottom of the vent resting on hooks or being secured by other means).

Referring to Figures 15 and 16, in some embodiments and particularly those comprising elongate members of significant length it may be desirable to provide a substantially elongate spacer 27 that is shaped to fit within space 8 of vent 1 so as to maintain the alignment of elongate member Sand minimize the flexing thereof.

In use spacer 27 is positioned substantially perpendicularly to the longitudinal axes of elongate members 5.

A spacer may be held in a substantially fixed position in a variety of ways. For example a spacer may be adhered to the covers and/or channels or may snap fit to covers and/or channels. A spacer may be fixed at each of its ends to frame 3.

In other embodiments other forms of spacer may be employed. For example, struts may be provided to attach adjacent channels and/or covers. A plurality of spacers may be employed within a single vent.

Turning to Figures 17 and 18 and a second type of vent 38 that is made in accordance with a second embodiment of the present invention, there is provided cowl 28 that is suitable for use with a half-vent 2.

Cowl 28 comprises a chamber 29 and a substantially rectangular frame 30 surrounding chamber 29.

Cowl frame 30 has an upper end 30a, a lower end 30b a first side 30c and a second side 30d. The nomenclature 'upper' and 'lower' is employed to indicate the relative position of ends 30a, 30b when cowl 28 is attached to vent 1.

Frame 30 is substantially identical in size and formation to frame Sand comprises a plurality of projections 31 and recesses 32 that are configured to mate with projections 7 and recesses 8 located on half-vent 7.

Frame 30 similarly comprises a linear recess 33 (to part define an aperture for retaining a band of material) adjacent its upper end and a rectangular recess 34 (to part-define a drainage outlet) adjacent its lower end, and hooks 35.

However, cowl 28 does not comprise a plurality of elongate members, but instead has chamber 29, which is sealed except for an circular inlet 36 located at the upper end of a cylindrical conduit 37 extending from chamber 29 adjacent the upper end 30a of frame 30.

When cowl 28 is attached to frame 3 of half-vent 2 chamber 29 covers the entirety of venting area 4.

Thus when cowl 28 is attached to half-vent 2 and installed in a pitched roof with half-vent 2 and cowl 28 positioned over an underlapping seam of roofing underfelt liquid from chamber 29 is able to drain via the drainage outlet formed between lower end 30b of frame 30 and lower end 3b of frame 3 Chamber 29 comprises side walls 29a, 29b and a lower wall 29c. Side walls 29a, 29b are substantially orthogonal the plane of frame 30. Lower wall 29c is angled to the plane of frame 30 at an acute angle of approximately 45 degrees so as to guide liquid in chamber 29 to the drainage outlet at the bottom of vent 38.

The angle of lower wall 29c should preferably be at least 10 degrees to the horizontal when vent 38 is installed such that liquid readily drains from chamber 29.

Thus as most pitched roofs are angled at between 15 degrees and 60 degrees it is considered that in many embodiments of cowls suitable for use with vents in pitched roofs a lower wall may be angled at up to 50 degrees to cowl frame 30. Any arrangement suitable for liquid to drain from a chamber may be employed.

Formed at the top of chamber 29 is substantially circular inlet 36 that is configured to be attached to a ventilation duct that may be connected to, for example, an extractor fan in a bathroom In the present embodiments the vent comprises three different means to secure the vent to a component of the roof so as to retain the vent in position at an aperture; the ability to clamp roof felt, the linear aperture adjacent its upper end and the hooks adjacent its lower end.

In some embodiments, however, only a single means may be provided. For example, a vent might be provided with only the ability to clamp roof felt. Alternatively a vent might be provided only with hooks adjacent its lower end, with a user employing a batten or other means to retain the upper end of the vent in position.

In other embodiments a vent might have one or more projections on a face of the vent, the projections being suitable to be wedged against or hook over a batten.

Although in the present embodiment the elongate members, outer openings and inner openings are elongate and substantially linear in other embodiments different shapes and patterns may be employed.

In this specification an apparatus/method/product "comprising" certain features is intended to be interpreted as meaning that it includes those features, but that it does not exclude the presence of other features.

In this specification the terms 'upper end' and 'lower end' of the vent are intended to mean that the upper end is configured to be positioned higher than the lower end when the roof vent is in use, such that liquid can drain towards the drainage outlet at the lower end of the vent.

Many variations are possible without departing from the scope of the present invention as defined in the appended claims.

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Claims

Claims: 1. A retrofittable roof vent for fitting at a substantially planar aperture formed in an area of roof felt, the vent comprising: an upper end and a lower end and first and second side edges extending therebetween; at least one drainage outlet at the lower end of the vent; a substantially planar grille disposed between the upper and lower ends and the side edges; means to capture precipitation entering the grille and drain it from the drainage outlet when the vent is in use.
2. The vent of claim 1 comprising means for securing the vent to a component of the roof.
3. The vent of claim 1 or 2 comprising means to inhibit movement of roof felt overlapping a side member at each side of the vent.
4. The vent of claim 3 wherein means to inhibit movement of roof felt is in the form of at least one upstanding member adjacent each side of the grille.
5. The vent of claim 4 wherein an upstanding member adjacent each side of the grille is a wall.
6. The vent of any preceding claim wherein a means securing the vent is provided by first and second side members at each side of the vent being capable of clamping roof felt therebetween.
7. The vent of claim 6 wherein a first side member comprises at least one projection configured to mate with a corresponding recess formed on the second side member.
8. The vent of any preceding claim comprising a surround to the grille, with the surround comprising side members and being capable of clamping roof felt adjacent each side of the grille.
9. The vent of any preceding claim comprising an upstanding lip adjacent its side edges.
10. The vent of any preceding claim comprising at least one hook disposed towards the lower end of the vent to allow a user to hook the vent to a portion of roof felt to retain the grille in position.S
11. The vent of any preceding claim comprising a plurality of hooks to retain the grille in position.
12. The vent of any preceding claim comprising towards its upper end means to attach the vent to a retaining band of material to retain the grille in position.
13. The vent of claim 12 wherein the means to attach the vent to a retaining band of material is in the form of an aperture extending between the first and second side edges of the vent.
14. The vent of any preceding claim wherein the grille comprises a plurality of channels disposed towards the inward-facing side with inner openings located between adjacent pairs of channels; a plurality of covers disposed towards the outward-facing side with outer openings located between adjacent pairs of covers; the inner openings, outer openings and a space between the covers and the channels allowing for fluid communication between the inward facing side and the outward facing side; the covers and channels being arranged such that the covers are aligned with the inner openings and the channels are aligned with the outer openings; the channels and covers extending between upper and lower ends of the grille.
15. The vent of claim 14 wherein the outer openings are substantially aligned within the middle third of the channels, or are substantially aligned with the centres of the channels and the inner openings are substantially aligned within the middle third of the covers, or are substantially aligned with the centres of the covers.
16. The vent of claim 14 or 15 wherein the drainage outlet is configured to drain liquid from the plurality of channels.
17. The vent of any of claims 14 to 16 wherein covers each comprise a base and a pair of side walls.
18. The vent of claim 17 wherein the walls of covers have external faces that are acutely angled to the base.
19. The vent of claim 17 or 18 wherein the walls of covers and/or the walls of channels have free ends that are rounded in cross-section.
20. The vent of any of claims 17 to 19 wherein base of a cover has a depression on its outward-facing side.
21. The vent of any preceding claim wherein the vent is formed of two identical half-vents.
22. The vent of claim 21 when dependent upon any of claims 14 to 20 wherein channels are defined by a first half-vent and covers are defined by a second half-vent.
23. The vent of any of claims 1 to 13 comprising a first part having a grille and a second part forming a cowl with a chamber configured to cover the grille, with liquid in the chamber being drainable therefrom via the drainage outlet.
24. The vent of claim 23 wherein the chamber comprises a lower wall that is angled to the grille to drain liquid towards the drainage outlet and an upper wall having a downward-facing opening that is suitable to connect to the cowl to a pipe.
25. A kit of parts containing a plurality of half-vents configured such that when two half-vents are attached together they create a vent made in accordance with any preceding claim.
26. The kit of claim 25 wherein the half-vents used to create a vent are substantially identical or a first half-vent comprises a grille and a second half-vent comprises a cowl.
27. A method of retrofitting a roof vent comprising the steps of: providing a retrofittable roof vent made in accordance with any of claims 1 to 23; forming an aperture in an area of roof felt; positioning the vent such that its grille is located at the aperture and the drainage outlet overlaps the roof felt.
28. The method of claim 27 wherein the step of positioning the vent comprises the step of folding roof felt at either side of the vent such the felt abuts an upstanding member of the vent adjacent each side of the grille.
29. The method of claim 27 wherein the step of positioning the vent comprises the step of clamping roof felt adjacent first and second parts of the vent adjacent each side of the grille.20 25 30