GB2383056A

GB2383056A - Roof construction for ventilation

Info

Publication number: GB2383056A
Application number: GB0224695A
Authority: GB
Inventors: John Louis Shillabeer
Original assignee: Cavity Trays Ltd
Current assignee: Cavity Trays Ltd
Priority date: 2001-12-13
Filing date: 2002-10-23
Publication date: 2003-06-18
Anticipated expiration: 2022-10-23
Also published as: GB0224695D0; GB0129854D0; GB2383056B

Abstract

A building component (100) to be mounted on roof timbers adjacent the eaves of a pitched roof has an upper support surface (102) for supporting roof felt and a front portion (104) shaped to engage the top of a fascia board (124). The front portion (104) is hinged (106) so that it can be angled to suit different roof pitches. Insulation (126) is held away from the underside of the support surface (102) by a tray-like ventilation member (116, 118). Thus a clear ventilation path is ensured beneath the felt from the eaves to behind the component (100).

Description

ROOF CONSTRUCTION The present invention relates to a method of constructing (or reconstructing/repairing) a roof, to a building assembly comprising a roof assembly, and to a component for use therein.

A conventional roof construction, e. g. for a house, involves roof timbers covered with a layer of underlay felt. In a pitched roof construction the felt slopes downwardly, and any rainwater that penetrates to the felt should run down and be discharged into an eaves gutter.

There is a tendency for the felt to sag, particularly adjacent the eaves, which can lead to pooling of water. To reduce or avoid this problem we have previously designed an anti-pooling device marketed under the name"Hardedge Strips. Fig 1 shows a length of this strip 10. It is a rigid polypropylene profile having a main planar body portion 12 that spans rafters 14 adjacent the eaves, and an angled front portion 16 shaped to engage the top of a fascia board 18. The angling and shaping of the front portion is intended to enable the strip to fit roofs of a range of pitches. In some cases the fit is rather imprecise.

Fig 1 also shows felt 20 (partly cut away). It can be seen that the strip 10 supports the felt 20 so that it

does not sag between the rafters 14, and also provides support to the weathering edge of the felt.

Fig 1 also shows fibrous insulation material 22.

This is applied from beneath and tends to get pushed up between the roof trusses where it is laid into the eaves, especially when more insulation is being applied to upgrade the level of insulation. The insulation material then approaches or even touches the underside of the felt 20. This seriously impairs the ventilation, which is important for the preservation of the timbers and is also required by building regulations.

It would be desirable to provide a felt support strip adapted to fit roofs of a range of pitches.

It would be desirable to provide a felt support strip which reduces the risk of impaired ventilation.

Preferred embodiments of the invention address at least one, and preferably both, of these issues.

In a first aspect the invention provides a building component comprising a support portion which defines a planar support surface for extending between roof timbers and supporting roofing felt; and a ventilation portion which extends beneath the support portion for contacting insulation material to hold it away from the support portion, and defining a ventilation path.

The ventilation portion may have the form of a tray with lateral edge portions and a base portion. The base portion may have ventilation apertures.

In a second aspect the invention provides a building component comprising a felt support having a planar support surface for extending between roof timbers and supporting roofing felt and a front portion hingedly connected thereto and shaped to engage an upper region of a fascia board.

Preferably a component embodies both aspects.

In another aspect the invention provides a building assembly comprising a wall; a roof construction traversing the top of the wall, the roof construction comprising spaced roof timbers and roofing felt spanning the timbers; and a building component according to the first aspect extending across the top of the wall and supporting the roofing felt.

The component may be supplied in a size to suit one spacing between trusses, or in a size to suit more than one spacing. For example, an embodiment may be 1200mm long, thus suiting two 600mm spaced trusses. In theory one could make the product any length, as long as one can handle it on site.

The under-section (ventilation portion) may be shaped and rigidly held in position, or alternatively it may fold flat or hinge (for ease of packing/ transporting), in which case it would preferably be proportioned so it is impossible to nail the product to the top of the truss, unless the under-section is hinged open.

The under-section may be proportioned to provide any amount of requisite airflow. For instance in roofs above 15 degrees, one normally requires the equivalent of a 10mm continuous gap. Below 15 degrees a 25mm continuous gap is desired. Currently we propose to produce a model offering the largest gap, on the basis it will suit all applications.

The component may be manufactured from heavy-duty polypropylene. It can thus be easily nailed to the upper surface of the trusses prior to the laying of the felt, and can provide a wide protected support area. The external edge (front portion), if hinged, accommodates a range of angles of roof and tilting fillet, and ensures the roofing felt may consistently project forward of the fascia. The inboard support area may extend approximately 400mm up the roof slope, covering a greater area than conventional support materials. This depth is used to advantage, preferably incorporating an integral

eaves ventilator. The extent and depth of any insulation laid in the roof space can be optimised because of the extended depth of the component. It permits the insulation to extend over the top of the internal skin, thus promoting maximum thermal compliance. Accidental eaves airflow restriction of insulation laid in the roof space is prevented, and at all times the integral airflow route is maintained.

The component may be supplied in 1200mm lengths, for speedy fixing across 600mm spaced trusses. The overall size may then be about 1200mm x 400mm x 29mm depth. The airflow rating is desirably not less than 25, 000mm per metre, fitted in continuous run.

An embodiment will now be described by way of example with reference to the accompanying drawings as listed below.

Fig 1 is a view of part of a roof construction adjacent the eaves incorporating a known felt-supporting strip.

Fig 2 is a front isometric view of a ventilating felt support embodying the invention; Fig 3 is a view similar to Fig 2 but showing the support upside down.

Figs 4,5 and 6 are front, side and rear elevations of the support.

Fig 7 is a schematic sectional view of the eaves region of a building incorporating the support shown in Figs 2-6.

The illustrated ventilating support 100 is intended to be mounted to roof timbers adjacent the eaves, so as to straddle three roof trusses. Thus if the truss centre spacing is 600mm, the support has a width of 1200mm so that it can be centred on one roof truss and extend onto, and be fixed to, the adjacent truss at each side.

The support 100 has a main felt-supporting planar panel 102 which, in this example, is 1200mm wide and 400mm deep. This is deeper than the conventional felt support-e. g. our hardedge strip has a depth of 250mm.

At the front (long) edge it is integrally formed with a stepped profile strip 104. The panel and strip join at a thinned line 106 which constitutes a living hinge so that the strip 104 can hinge relative to the panel 102.

A ventilation body portion 108 is provided beneath the main panel 102 over most of its area. As seen most clearly in Fig 3 this has the form of two trays 110,112 with a central spacing 114 to accommodate a roof truss.

At each side, the panel 102 projects slightly beyond the respective tray to provide a mounting strip 103 for overlying a roof truss. Each tray defines, with the panel, a ventilation space. Each tray has a base 116 and

side walls 118. At the front and rear each tray has a depending flange 120,122. Each tray is open at the front and rear and so defines a ventilation conduit. In the illustrated support 100 there are openings 123 in the base 116. These are provided to assist in manufacture but may also provide further ventilation paths.

In use, the ventilating support 100 is mounted on roof trusses at the eaves region. Its profile strip 104 engages the top of the fascia board 124. The support extends upwardly and rearwardly. Its length is such that it projects beyond a region where insulation material 126 presses up towards the felt 128.

Claims

1. A building component comprising a support portion which defines a planar support surface for extending between roof timbers and supporting roofing felt; and a ventilation portion which extends beneath the support portion and defines a contact surface spaced from the support surface for contacting insulation material to hold it away from the support portion, whereby a ventilation path is provided between said surfaces.

2. A building component according to claim 1 wherein the ventilation portion has the form of a tray with lateral edge portions and a base portion which provides said contact surface.

3. A building component according to claim 2 wherein said base portion has ventilation apertures.

4. A building component according to any preceding claim wherein the support portion includes a front portion hingedly connected to it and adapted to engage an upper section of a fascia board.

5. A building component comprising a felt support having a planar support surface for extending between roof timbers and supporting roofing felt and a front portion hingedly connected thereto and shaped to engage an upper region of a fascia board.

6. A building component substantially as herein described with reference to and as illustrated in Figs 2-7 of the accompanying drawings.

7. A building assembly comprising a wall; a roof construction traversing the top of the wall, the roof construction comprising spaced roof timbers and roofing felt spanning the timbers; and a building component according to any preceding claim extending across the top of the wall and supporting the roofing felt.

8. A method of building a pitched roof including locating spaced-apart roof timbers sloping down to an eaves region, securing a building component according to any of claims 1 to 6 so that it spans two or more roof timbers adjacent the eaves, and applying roof felt so that it overlies the support surface.

9. A method according to claim 8 wherein a fascia board is provided at the eaves, and the support portion of the building component has a front portion hingedly connected to it which is hinged to engage an upper region of the fascia board.