GB2140843A - Roof space ventilator - Google Patents

Abstract

The ventilator 1 comprises a sheet 20 having projections 21 upon a surface. The projections abut against a roofing material to space it from the sheet surface, providing an air passage therebetween the sheet and the proofing material. Flaps 23 may be pivotally connected to the sides of the ventilator, for connecting the ventilator to roof rafters. <IMAGE>

Description

SPECIFICATION Roof space ventilator This invention relates to a roof space ventilator.

Continuing awareness of the energy crisis related to the building industry has led to the increasing use of high levels of insulation. For example, it is not uncommon to find 1 50 mm of insulation in the roof space of modern low energy buildings. Such levels of insulation are highly cost effective and can achieve overall heat transfer coefficients as low as 0.2 Wm-2 K-'.

The installation of loft insulation can lead to problems with condensation which occurs when moisture laden air finds its way into the roof space of a roof structure through the building fabric. This problem is particularly prevalent when sarking felt has been employed below the roof finish; the sarking felt abuts against the high level of insulation at the periphery of the roof space thereby blocking airflow into and out of the roof space through the eaves and creating what is effectively a cold sealed void.

It is known to install a ventilating piece between the sarking felt and the insulation at the periphery of the roof space in order to provide a free passage of air into and out of the roof space through the eaves.

Many previous ventilators comprise a flat tray which serves to space the insulating material from the inside surface of the roof adjacent to the eaves. Ideally this should provide a space between the insulating material and the interior of the roof surface for the free passage of air. However, when sarking felt is employed below the roof surface it may sag and completely obstruct the air passageway.

Ventilators have been developed to cope with this problem, but these are usually of complicated construction and relatively expensive to manufacture.

It is an object of the present invention to provide a simple roof space ventilator which is capable of providing a free air passageway into and out of a roof space, and which has sufficient rigidity to withstand applied loadings from the sarking felt.

According to the present invention there is provided a roof space ventilator comprising a sheet having a plurality of projections upon at least one surface thereof, said projections being adapted to abut against a roofing material of a roof structure in order to space the roofing material from the or each surface of the sheet to provide an air passageway between the sheet and the roofing material.

Advantageously the projections comprise a plurality of discrete protrusions arranged over the or each surface of the sheet.

Preferably the discrete protrusions are arranged in a plurality of rows and desirably the protrusions of alternate rows are aligned with one another.

The ventilator in use is normally located between two adjacent roof rafters and preferably the ventilator is provided with two flaps one of which can be attached to one of the rafters, and the other of which can be attached to the other of the rafters.

Desirably each flap is pivotally connected to the ventilator so that each flap may be attached to either an upper surface or a side surface of each rafter.

Preferably each flap is provided with a hinge to enable an outermost part of the flap to bend relative to the part of the flap pivotally connected to the sheet.

It is preferable that the protrusions are generally spheroid, paraboloid or hyperboloid in shape. The protrusions may conveniently be arranged in a plurality of rows which, when the ventilator is located in the roof structure, run substantially transverse to the roof rafters. In addition, the protrusions of adjacent rows may be located at different positions along the sheet. It is preferable that the protrusions of alternate rows are located at the same position along the sheet.

It is desirable that the sheet is provided with corrugations which run substantially parallel to the rows of protrusions.

The ventilator may suitably be vacuum formed as a single sheet from a thermoplastics material.

Reference is now made to the accompanying drawings, in which: Figure 1 is a cross-sectional view showing a ventilator according to the invention in position in a roof space adjacent the eaves; Figure 2 is a perspective view of an embodiment of a roof space ventilator according to the invention; and Figures 3 and 4 show the roof space ventilator of Fig. 2 positioned between adjacent rafters.

In Fig. 1 a ventilator 1 is shown positioned in the roof space of a roof structure generally designated 2. The roof structure 2 is supported by roof rafters 3 and ceiling joists 4.

The ventilator 1 is situated above a wall plate 5 between an insulating material 6 and roof tiling 7; the roof tiling comprises battens on sarking felt.

The insulating material 6 rests upon floor 8 and extends over the wall plate 5 into a wall cavity between an internal wall 9 and an external wall 10. The wall cavity is shown filled with insulating material 11.

A soffite board 1 2 and a fascia board 1 3 are provided at the eaves of the roof structure 2 leaving a gap 14 through which air can flow in the direction indicated by arrows A.

The interposition of the ventilator 1 between the insulating material 6 and the roof tiling 7 provides a free passage of air into the roof space. The air circulates through the roof space then leaves through a ventilator located at a similar position at the opposite side (not shown) of the roof structure 3.

Referring to Fig. 2 the ventilator 1 comprises a plastics sheet 20 upon which a plurality of protrusions 21 are formed. The sheet 20 is provided with corrugations 22 which run transverse to the general direction of air flow across the ventilator in the direction indicated by arrows B.

Flaps 23 are provided along opposite edges of the ventilator 1 and the flaps facilitate the attachment of the ventilator to the rafters 3 of the roof structure 2. Each flap 23 is pivotally connected to the ventilator at a hinge 24.

Furthermore each flap 23 includes an additional hinge 25.

The purpose of the hinges 24 and 25 is to enable the ventilator 1 to be attached to the roof rafters 3 in different ways. Fig. 3 shows one way in which the ventilator 1 may be attached to the roof rafters 3; this form of attachment is most suitable when the ventilator 1 is to be incorporated in the roof structure during the construction of the roof structure. A portion 23a of each flap 23 is fixed to upper surface 3a of the roof rafters by nails 26a A portion 23b of each flap can be depressed below the level of surface 3a under the pressure of the sarking felt.

An alternative way of attaching the ventilator 1 to the roof rafters 3 is illustrated in Fig.

4; this form of attachment is most convenient when installing the ventilator into a fully constructed roof structure. The portion 23a of each flap 23 is fixed to a side surface 3b of the rafters 3 by nails 26b. The flap 23 pivots about hinge 24 only.

In use a lower surface 1 a of the ventilator abuts against the insulating material 6, while projections 21 abut against the sarking felt in order to space the upper surface 1 b of the sheet 20 from the sarking felt. The air flows between the sarking felt and the sheet 20 through the gaps between the protrusions 21.

In Figs. 3 and 4 the sarking felt and the insulating material 3 have been omitted for clarity.

If desired the projections can be provided on the lower surface 1 a of the ventilator so that the air flows between the lower surface 1 a and the insulating material 6.

Claims (9)

1. A roof space ventilator comprising a sheet having a plurality of projections upon at least one surface thereof, said projections being adapted to abut against a roofing material of a roof structure in order to space the roofing material from the or each surface of the sheet to provide an air passageway between the sheet and the roofing material.

2. A ventilator according to Claim 1, in which the projections comprise a plurality of discrete protrusions arranged over the or each surface of the sheet.

3. A ventilator according to Claim 1 or 2, in which the discrete protrusions are arranged in a plurality of rows.

4. A ventilator according to Claim 3, in which the protrusions of alternate rows are aligned with one another.

5. A ventilator according to any preceding claim, in which a flap is provided on each side of the ventilator, each flap being adapted to be connected to a roof rafter.

6. A ventilator according to Claim 5, in which each flap is pivotally connected to the ventilator.

7. A ventilator according to Claim 6, in which each flap is provided with a hinge to enable an outermost part of the flap to bend relative to the part of the flap pivotally connected to the sheet.

8. A ventilator according to any preceding claim, in which the projections are substantially spheroid, paraboloid or hyperboloid in shape.

9. A roof space ventilator substantially as herein described with reference to and as shown in the accompanying drawings.