Roof vent

Abstract

 A roof vent comprises a base (10) having front and rear edges (12 and 14), at least two walls (20) extending from the rear edge (14) to the front edge (12) of the base, a cover (16) mounted on the walls and a filter covering the opening at the rear edge between the base and the cover, the cover (16) extending from over the rear edge (14) of the base only part of the way to the front edge (12), and the walls (20) being of reduced height adjacent the front edge (12). The vent provides ventilation between the spaces above and below the underfelt without rending the underlay or impairing its effectiveness.

Description

[0001] This invention relates to roof vents for allowing ventilation of the loft and spaces between the various layers that exist in a modern roof, by way of the natural breaches in the roof's cladding and the underlay's horizontal overlap.

[0002] The details of the construction of a pitched roof vary from country to country and from one area of a country to another, but in general rafters support a waterproof underlay on which are laid battens to which the outer cladding of tiles, slates or the like is secured. One variation on this basic theme is that the rafters may be boarded, i.e. boards may be secured to the top of the rafters to block off the space between the rafters, and in this case counter-battens or false rafters are provided on top of the boards and beneath the underlay.

[0003] Roofs of this general character perform satisfactorily as their prime purpose is to control wind load and keep driven snow and rain out of the attic space, but they have the disadvantage that ventilation of the space between the bottom of the underlay, the underside of the outer cladding and the inner roof space is severely limited. In the context of increasing standards of heating this limited ventilation results in condensation with its attendant problems.

[0004] It is an object of the present invention to obviate or mitigate these problems of ventilation.

[0005] The present invention is a roof vent comprising a base having front and rear edges, at least two walls extending from the rear edge to the front edge of the base, a cover mounted on the walls and a filter covering the opening at the rear edge between the base and the cover, characterised in that the cover extends from over the rear edge of the base only part of the way to the front edge, and in that the walls are of reduced height adjacent the front edge.

[0006] Means may be provided on the base for securing the roof vent to a component of the roof.

[0007] The walls may be side walls and at least one bracing wall may be provided intermediate to the side walls and extending from the front to the rear edge of the base.

[0008] Preferably two intermediate bracing walls are provided.

[0009] The base may meet the cover at its sides and be curved away from the sides, the walls being bracing walls in-between the sides of the base and below the cover.

[0010] A flap can be mounted to be movable between a first position in which the opening is closed and a second position in which the opening is open.

[0011] The present invention provides a method of ventilating a roof characterised by locating roof vents as defined in any of the last six preceding paragraphs at the horizontal overlap between strips of underlay to provide communication between the spaces above and below the underlay and atmosphere.

[0012] Embodiments of the present invention will now be described, by way of example with reference to the accompanying drawings, in which:-

Fig. 1 is a plan view of a first embodiment of a vent acording to the present invention;

Figs. 2 and 3 are respectively front and side elevations of the vent shown in Fig. 1;

Figs. 4 and 5 are respectively bottom and top perspective views of the vent shown in Fig. 1; and

Figs. 6, 7 and 8 are respectively a plan view and front and side elevations of a second embodiment of a vent according to the present invention.

[0013] Referring now to Figs. 1 to 5, a roof vent according to the present invention has a base 10 with a front edge 12, a rear edge 14 and two side edges. The base 10 is curved between its sides, and towards its front edge its depth as measured from the plane of its sides is progressively reduced to zero at the front edge 12 to provide a wedge shape to the front.

[0014] At the rear of the base 10 is provided a cover 16 which extends between the sides of the base and defines with the base 10 an opening 18. The cover 16 extends from over the rear edge 14 only part of the way to the front edge 12, whereas two bracing walls 20 extend from the rear edge 14 to the front edge 12. At each rear corner of the base is provided means for securing the vent to a component of the roof, the means in this embodiment being a spring clip 22. A flap 24 is mounted on a hinge at the rear edge of the cover 16 to be movable between a first position in which it covers the opening 18 and a second position in which it is clear of the opening. A filter 26 is mounted in the opening 18.

[0015] To understand the use of the vent, it must first be understood that in an unboarded roof the underlay is laid on the rafters from the bottom of the roof in horizontal overlapping strips or runs which are allowed to droop between the rafters. Working from inside the loft space the vent of Figs. 1 to 5 is firstly located with its front edge 12 immediately above the top edge of a lower strip of underlay and with the cover 16 in contact with the surface of the upper strip of underlay. The vent is then moved into the upper strip of underlay to remove its droop and open up a passage between the upper and lower strips of underlay down into which the vent can pass with the curved
base 10 in contact with the drooping lower strip of underlay. The bracing walls 20 maintain a constant gap below the underside of the slate or tile battens.

[0016] The vent is secured in position when two clips 22 engage the top edge of the lower strip of underlay. The length of the cover 16 from its rear edge to its front edge is the same as the normal overlap of the underlay and the front 12 upper section of the base 10 is exposed to the space above.

[0017] When secured in position and tiled or slated over, the vent allows air to pass from the loft space through the opening 18 into the vent and thence into the space above the underlay and into the atmosphere, and vice versa, thus providing ventilation to prevent condensation. The number of vents that are spaced over the inner roof surface depends upon the size and construction of the roof and the rafters and architectural specifications. The filter prevents the passage of insects and the like through the vent, while the flap adjusts the flow of air into the roof space.

[0018] It should be noted that the vent can be placed in position in an underfelted roof that may be many years old without structural alterations.

[0019] Referring now to Figs. 6 to 8, a second embodiment of a vent according to the present invention has a base 40 with a front edge 42 and a rear edge 44. A cover 46 is similarly located relative to the rear edge 44 of the base but as both the base and the cover are in this embodiment planar a pair of side walls 47 are provided to support the cover on the base and define with the cover and the base an opening 48 in which is located a filter. A pair of bracing walls 50 extend substantially the length of the base between the side walls. The front ends of the walls 47 and 50 are reduced in height to curve upwardly with the front of the base 40 as seen in Fig. 8 to provide a smoothly curved nose at the front of the vent. In front of the cover 46 is a boundary wall or flange 52 surrounding an opening into the interior of the vent. The flange 52 comprises the fixing means in this embodiment.

[0020] The vent of Figs. 6 to 8 is for use in a roof with boarded rafters and is placed in position from above the boards as the underlay is being laid. In a boarded roof false rafters or counter-battens are secured to the top surface of the boards, the counter-battens running up and down the roof parallel to the rafters. When a lower run of underlay is in position then a vent as shown in Figs 6 to 8 is inverted, so that the cover 46 lies on the underlay between a pair of false rafters, with the top edge of the underlay at the front edge of the cover and the flange 52 placed into a previously cut hole in the boards or sarking to secure the vent in position.

[0021] In this embodiment also a flap may be provided to open or close the opening surrounded by the flange 52.

[0022] The next run of underlay is then placed in position over the vent with its bottom edge on the rear edge of the cover 46. In this way the space above the vent between the underlay, the counter battens and the boards is in communication with the loft space beneath the boards, through the vent and with the space above the underlay.

[0023] The present invention provides ventilation of a roof by locating ventilators at the overlap between the various strips or lays of underlay to provide atmospheric communication between the spaces above and below the underlay.

[0024] The embodiment of Fig. 1 may be modified to minimise any risk of an unacceptable wind uplift factor by providing extensions of the cover 16 which are flexible and can move downwards into the three spaces between the walls 20 on to the base 10, thus closing down the the air flow in the event of positive or negative wind loading. In a further modification of Fig. 1 opposing baffles or diffusers are provided beneath the three extension flaps of cover 16 to keep the flow of air through the vent within acceptable limits.

Claims

1. A roof vent comprising a base having front and rear edges, at least two walls extending from the rear edge to the front edge of the base, a cover mounted on the walls and a filter covering the opening at the rear edge between the base and the cover, characterised in that the cover (16,46) extends from over the rear edge (14,44) of the base only part of the way to the front edge (12,42), and in that the walls (20,47) are of reduced height adjacent the front edge (12,42).

2. A roof vent as claimed in claim 1, characterised in that means (22,52) are provided for securing the roof vent to a component of the roof.

3. A roof vent as claimed in claim 1 or claim 2, characterised in that the walls are side walls (47) and at least one bracing wall (50) is provided intermediate the side walls (47) and extends from the front to the rear edge of the base.

4. A roof vent as claimed in claim 3, characterised in that two intermediate bracing walls (50) are provided.

5. A roof vent as claimed in claim 1 or claim 2, characterised in that the base (10) meets the cover (16) at its sides and is curved away from the cover between its sides, the walls (20) being bracing walls intermediate the sides of the base.

6. A roof vent as claimed in any preceding claim, characterised in that a flap (24) is mounted to be movable between a first position in which the opening (18) is closed and a second position in which the opening is open.

7. A vent as claimed in any preceding claim, characterised in that a flexible extension of the cover is provided for each space between adjacent walls, and opposing baffles or diffusers are provided beneath the flexible extensions.

8. A vent as claimed in claim 2 or any of claims 3 to 8 when dependent on claim 2, chracterised in that the means for securing the vent comprises clips (22) at the rear edge of the base.

9. A vent as claimed in any of claims 1 to 4, characterised in that a boundary wall (52) is provided in front of the cover (46) and surrounding an opening into the interior of the vent, the boundary wall comprising fixing means for the vent.

10. A method of ventilating a roof, characterised by locating roof vents as claimed in any preceding claim at the horizontal overlap between strips of underlay to provide communication between the spaces above and below the underlay.

Drawing