GB2088924A - Improved relating to the ventilation of roof spaces within pitched roofs - Google Patents

Abstract

An eaves closure piece 8 for fitting in the eaves within the roof space of a pitched roof comprising rafters 1 and ceiling joists 3 supporting a ceiling 4 is constructed to support the end of a strip of glass fibre insulating matting 7 laid between the ceiling joists to provide a ventilation passage between the eaves and the roof space through an eaves space 6. For this purpose the closure piece is formed from a sheet of plastics material having a fold line 11 which extends along it and divides the sheet into parts 9 and 10. The parts 9 and 10 are provided with flaps 12 at their ends and these flaps are nailed to the rafters 1 and the joists 3 in positions such that the part 9 extends partly across the eaves space 6 and the part 10 is held spaced from the roof felting 5 to maintain a passage from the eaves openings into the roof space. <IMAGE>

Description

SPECIFICATION Improvements relating to the ventilation of roof spaces within pitched roofs A very common form of pitched roof which is commonly used on houses, and also on other buildings as well, comprises sloping roof rafters which are arranged side by side with spaces between them and horizontal ceiling joists which are also arranged side by side and are fixed at their ends to the rafters. The ceiling joists support the ceilings of rooms below the roof space and at the edges of the ceilings between the junctions between the joists and the rafters eaves are formed at the tops of the walls which support the roof.

The eaves are formed in such a way that ventilation openings remain to allow air to flow upwards through the eaves into the roof space and this is important to ensure that the roof space remains well ventilated.

If the roof space is not satisfactorily ventilated, it tends to become damp and this may cause deterioration of the rafters and joists and it may also bring about corrosion of the fixings between the rafter, joists and other roof fixings and can in time lead to destruction of the roof.

In these days of energy conservation, it is essential that the roof spaces of such roofs should be thermally insulated to reduce the escape of heat through the roof and one common form of insulation consists in laying strips of glass fibre matting over the top surface of the ceiling between the joists. The strips of matting are such that they are a close fit between the joists.

For such insulation to be really effective, it is important that the matting should extend up to the edge of the ceiling between the ends of the joists at the eaves. However, when the glass fibre matting is laid right up to the ends of the joists in this way, there is a tendency for the ends of the strips of matting to sag over the edge of the ceiling between the joists into the eaves cavities.

This tends to block the ventilation from the eaves into the roof space with the undesirable consequences described above.

The object of the present invention is to provide an eaves closure piece for fitting in the eaves within the roof space of a pitched roof comprising rafters and ceiling joists supporting a ceiling, the closure piece being constructed so that it will support the ends of strips of glass fibre matting laid between the ceiling joists and yet still provide ventilation passages between the eaves and the roof space.

To this end, according to this invention, such an eaves closure piece comprises a sheet of plastics material having a fold line which extends along the sheet and divides the sheet into two parts, one of which, in use, is fitted between the ends of a pair of adjacent ceiling joists and the other of which fits between a corresponding pair of adjacent rafters, and means for holding the other part spaced from roof felting or sarking between the rafters so that, in use, a ventilation passage is maintained between the other part of the closure piece and the felting or sarking to maintain ventilation of the roof space from the eaves.

The present invention also consists, according to another of its aspects, in a method of partially closing the eaves within the roof space of a pitched roof comprising rafters and ceiling joists supporting a ceiling to prevent the ends of glass fibre insulating matting laid on the ceiling between the joists from sagging into the eaves to maintain ventilation through the eaves into the roof space, the method comprising fitting a closure piece in accordance with the invention described above between the ends of each pair of joists with the first part of each closure piece overlying the edge of the ceiling and the other part of each closure piece extending upwards and inwards at an inclination to the ceiling along roof felting or sarking between the rafters with spaces between the other parts and the felting or sarking to form ventilation passages from the eaves to the roof space.

With the closure pieces in accordance with the invention fitted in position, the one part of each closure piece extends beyond the edge of the ceiling across a part of the eaves space and this part is supported on the edge of the ceiling. Strips of glass fibre insulating matting can then be laid with their end portions extending over the first parts of the closure pieces and their ends abutting the upwardly extending second parts of the closure pieces. The end portions of the matting are thus prevented from sagging down into the eaves and their ends are prevented from extending right up to the felting or sarking by the second parts which maintain the ventilating passages.

In one example of a closure piece in accordance with the invention, the sheet of plastics material is rectangular and of a length equal to the clear space between adjacent ceiling joists, and adjacent rafters, which is usually sixteen inches, and the sheet has a fold line extending longitudinally adjacent its middle, the part on one side of the fold line forming the first part of the sheet and the part on the other side of the fold line forming the other part of the sheet. Two flexible flaps project from each end of the sheet, one on each side of the fold line and the two flaps on the other part of the sheet form the means for holding the other part of the sheet spaced from the roof felting or sarking.In use, when part of the sheet is laid on the edge of the ceiling between a pair of joists, its two flaps are bent upwards and are nailed to the adjacent side faces of the two joists between which the closure piece is fitted. The two flaps on the other part of the sheet are bent downwards and are nailed to the adjacent side faces of the two rafters between which the closure piece is fitted in positions such that there is a clearance space between the other part of the sheet and the felting or sarking of the roof between the rafters to which the flaps are nailed.

Owing to the fold in the sheet, the closure piece can readily be accommodated to roofs of different slopes.

In another example, the sheet of plastics material is again rectangular and has a fold line extending longitudinally at or adjacent its middle.

in this example the sheet is preferably of filled polypropylene. The sheet may be formed flat with a fold line about which it is subsequently folded or it may be formed with the two parts of the sheet on the two sides of the fold line at an inclination to each other. In the latter case, the two parts of the sheet must still be bendable relative to each other about the fold line to accommodate the closure piece to roofs of different pitches. In the second example, the other part of the sheet is formed with corrugations, the crests and troughs of which extend in a direction transverse to the fold line of the sheet. The corrugations then form the means for holding the other part of the sheet spaced from the roof felting or sarking.

With the second example, it is not necessary to nail the closure piece to the joists and rafters since it will wedge itself in position and the corrugations prevent the second part of the sheet from coming into contact with the roof felting or sarking along the whole length of the closure piece so that ventilation passages are always maintained Since it is not necessary to nail the closure piece in position, the end flaps are not required and in consequence the closure piece may be formed in long lengths and may then be cut into lengths to fit in between joists and rafters of any spacing. The fold line between the two parts of the sheet and the corrugations are preferably made by vacuum forming of the sheeting.

In a third example, the sheet of plastics material is divided in a direction transverse to the fold line into two sections which overlap each other and are connected to each other in such a way that the width of the overlap is adjustable to enable the overall length of the sheet to be adjusted so that it can be fitted between adjacent ceiling joists and rafters at different spacings.

Three examples of closure pieces and of methods in accordance with the invention are illustrated in the accompanying drawings in which Figure 1 is a perspective view of several closure pieces in accordance with a first example fitted in a roof space; Figure 2 is a perspective view to a larger scale of a second example; and Figure 3 is a perspective view of a third example.

Referring to Figure 1, a roof, only a small section at one side of which is shown, comprises a series of rafters 1 fixed at their bottom ends by plates 2 to ceiling joists 3 which support a ceiling 4 of a room below the roof. Felting 5 extends over the rafters 1 in the usual way. Eaves spaces 6 are provided between the edge of the ceiling 4 and the felting 5 and these eaves spaces communicate with openings in the eaves of the roof to allow ventilation of the roof space.

The ceiling 4 is thermally insulated to reduce the escape of heat through it by strips of glass fibre matting 7 which fit between the joists 3 and the ends of which extend almost up to the underside of the felting 5.

To prevent the ends of the glass fibre matting strips 7 from sagging into the eaves spaces 6 and so blocking the eaves openings and preventing ventilation of the roof space, a first example 8 of a closure piece is fitted between each adjacent pair of rafters 1 and joists 3.

Each of the closure pieces 8 comprises a rectangular sheet of cellular plastics material which is divided into two parts 9 and 10 by a fold line 11 which forms a hinge connecting the parts 9 and 10 together. Each of the parts 9 and 10 is provided with a flap 12 at each end (the flaps at only one end being shown in Figure 1) and each of the flaps 12 is hinged to one of the parts 9 or 10 along a further fold line 13.

The part 9 of each closure piece lies on the edge portion of the ceiling 4 and projects partly over the eaves space 6. The part 10 of each closure piece extends upwards substantially parallel to the felting 5. The parts 9 and 10 are both held firmly in position by nailing their flaps 12 to the adjacent faces of the joists 3 and the rafters 1. The flaps 12 are nailed in positions such that there is a small space along the whole length of each closure piece between the upper face of the part 10 and the underside of the felting 5 to allow air to flow from the openings in the eaves into the roof space. The ends of the strips of glass fibre matting 7 abut the parts 10 of the closure pieces and the parts 9 of the closure pieces prevent the ends from sagging into the eave spaces 6.

The second example 28 of the closure piece shown in Figure 3 is vacuum formed from a rectangular sheet of filled polypropylene. This example comprises two parts 29 and 30 with a fold line 31 between them. In this example the parts 29 and 30 are not provided with any flaps at their ends, but instead the part 28 is corrugated with corrugations having crests 32 and troughs 33.

The second example is used in very much the same way as the first example except that it is merely pushed into position between adjacent joists 3 and adjacent rafters 1 and no nailing is necessary. The polypropylene sheeting is vacuum formed so that the angle between the parts 29 and 30 is greater than the steepest angle of any pitched roofing. Accordingly as the closure piece is pushed into position, the crests 32 come into contact with the felting 5 and as the closure piece is pushed further across the space 6, the part 30 is bent slightly more towards the part 29 and the closure piece is jammed frictionally in position. It is then held in this position by the pressure against it of the end of the strip of matting 7. With the closure piece held in this way, passages for the flow of air from the eaves openings into the roof space are maintained between the felting 5 and the troughs 33 of the corrugations as indicated by arrows 34.

Instead of being corrugated as shown in Figure 2, the part 28 may have a series of recesses vacuum formed in it. These recesses form projections on the face of the part 30 which is directed towards the felting 5 and the projections perform exactly the same function as the crests 32 of the corrugations.

A third example 38 shown in Figure 3 of the drawings is the same as the first example except that it is divided in a direction perpendicular to a fold line 41 into two sections so that each of the parts of the sheet on the two sides of the fold line 41 are divided into two sections 39, 39' and 40, 40'. The parts 39 and 39' and the parts 40 and 40' overlap each other and the overlapping parts are connected to each other by fasteners 44 which fit through holes in the parts 39 and 40 and through slots 45 in the parts 39' and 40'. This allows a limited amount of longitudinal sliding movement between the parts 39, 40 on the one hand and the parts 39', 40' on the other hand to allow the overall length of the closure piece to be adjusted to fit between joists and rafters at different spacings. In this example flaps 42 are connected to the parts 39, 40 and 39',140' along hinge lines 43 and these flaps perform exactly the same function as the flaps 12 in the first example.

Claims (10)

1. An eaves closure piece for fitting in the eaves within the roof space of a pitched roof comprising rafters and ceiling joists supporting a ceiling, the closure piece being constructed to support the end of a strip of glass fibre matting laid between the ceiling joists and to provide a ventilation passage between the eaves and the roof space, and the closure piece comprising a sheet of plastics material having a fold line which extends along the sheet and divides the sheet into two parts, one of which, in use, is fitted between the ends of a pair of adjacent ceiling joists and the other of which fits between a corresponding pair of adjacent rafters, and means for holding the other part spaced from roof felting or sarking between the rafters so that, in use, a ventilation passage is maintained between the other part of the closure piece and the felting or sarking to maintain ventilation of the roof space from the eaves.

2. An eaves closure piece according to Claim 1, in which the sheet of plastics material is rectangular and has a fold line extending longitudinally at or adjacent its middle.

3. An eaves closure piece according to Claim 2, in which two flexible flaps project from each end of the sheet, one on each side of the fold line, the two flaps on the part of the sheet on one side of the fold line which forms the other part of the sheet, forming the means for holding the other part spaced from roof felting or sarking.

4. An eaves closure piece according to Claim 2, in which the means for holding the other part of the sheets spaced from the roof felting or sarking consists of corrugations formed in the other part of the sheet, crests and troughs of the corrugations extending in a direction transverse to the fold line of the sheet.

5. An eaves closure piece according to Claim 2, in which the means for holding the other part of the sheet spaced from the roof felting or sarking consists of recesses formed in the other part of the sheet, the bottoms of the recesses, in use, engaging with the felting or sarking.

6. An eaves closure piece according to any one of Claims 1 to 3, in which the sheet of plastics material is divided in a direction transverse to the fold line into two sections which overlap each other and are connected to each other in such a way that the width of the overlap is adjustable to enable the overall width of the sheet to be adjusted so that it can be fitted between adjacent ceiling joists and rafters at different spacings.

7. A method of partially closing the eaves within the roof space of a pitched roof comprising rafters and ceiling joists supporting a ceiling to prevent the ends of glass fibre insulating matting laid on the ceiling between the joists from sagging into the eaves to maintain ventilation through the eaves into the roof space, the method comprising fitting a closure piece in accordance with any of the preceding Claims between the ends of each pair of joists with the first part of each closure piece overlying the edge of the ceiling and the other part of each closure piece extending upwards and inwards at an inclination to the ceiling along roof felting or sarking between the rafters with spaces between the other parts and the felting or sarking to form ventilation passages from the eaves to the roof space.

8. A method according to Claim 7 in which the closure piece is in accordance with Claim 3 or Claim 6, and in which the two flaps on the one part of the sheet are bent upwards and are nailed to the adjacent side faces of the two joists between which the closure piece is fitted and the two flaps on the other part of the sheet are bent downwards and are nailed to the adjacent side faces of the two rafters between which the closure piece is fitted in positions such that there is a clearance space between the other part of the sheet and felting or sarking of the roof between the two rafters to which the flaps are nailed.

9. An eaves closure piece according to Claim 1, substantially as described with reference to any one of the Figures of the accompanying drawings.

10. A method according to Claim 7, substantially as described with reference to any one of the Figures of the accompanying drawings.