GB2548373A - Rafter fitting - Google Patents

Abstract

A rafter fitting for a pitched roof structure, the roof structure comprising a plurality of rafters (14, figure 1) that slope from a ridge to an end of the roof structure, a plurality of battens (16, figure 1) disposed on top of and extending perpendicular with respect to the rafters, and a membrane which extends across the roof structure between the rafters and the battens. Wherein top surfaces of the rafters define a rafter plane 34 and the rafter fitting comprises a rafter-facing surface configured to rest, in use, on the top surface of a rafter, and a membrane depressor 30 that is configured to depress the membrane below the rafter plane when the rafter fitting is in use. Also disclosed is a rafter fitting comprising at least one flow director 32 to direct water from a central region of the rafter fitting to an outer region of the rafter fitting.

Description

Rafter Fitting

TECHNiCAL FiELD

The invention relates to a rafter fitting for a pitched roof structure, which may in particular be a batten riser. The invention further relates to a pitched roof structure comprising a plurality of rafters and battens, a waterproof membrane and a rafter fitting.

BACKGROUND TO THE INVENTION

The primary function of a roof structure is to protect a lower space below the roof structure from external elements such as wind and precipitation. A typical pitched roof structure includes a plurality of parallel load-bearing rafters that slope from a ridge at the top of the roof structure to an eave at a lowermost edge of the roof structure, and a plurality of parallel battens disposed on top of, and extending orthogonally with respect to, the rafters. A pitch angle of the roof structure is defined between the rafters and a horizontal plane, which includes the eave.

Figure 1 illustrates a pitched roof structure 10 having a plurality of roof covering elements, such as tiles 12. The tiles 12 extend from an upper edge of the roof structure, described here as a ridge, but which may alternatively be a top abutment, to an eave at a lower edge of the roof structure. Figure 1 further illustrates an exposed section of the roof structure, illustrating the components of the structure that lie beneath the tiles 12. The roof structure can be seen to include a plurality of rafters 14 that extend from the ridge to the eave of the roof structure 10, and a plurality of parallel tile battens 16, which extend above and orthogonally with respect to the rafters 14. A waterproof membrane 18, or roof underlay, is provided between the rafters 14 and battens 16 and extends across the roof structure 10. With reference to Figure 2, the batten 16 is secured to each of the rafters 14 by means of a fastener 20, such as a nail, which has a shaft that passes through the batten 16 and the membrane 18, and then passes into the rafter 14 below.

As shown in Figure 1, the tiles 12 are affixed along the battens 16 in horizontally-extending rows or courses so as to provide a primary drainage system that is configured to direct a flow of precipitation down the tiles 12 towards a gutter (not shown), which is located at the roof eave. The waterproof membrane 18, the tile battens 16 and the tiles 12, together, define an enclosed volume 19 within the roof structure 10. The air that is trapped within this enclosed volume 19 is often stagnant such that when the outside air temperature drops, moisture is condensed on the underside of the tiles 12. Water may also enter the enclosed volume 19 due to strong winds that cause up-drafts, which can blow precipitation under the leading edge of the tiles 12. For this reason, the waterproof membrane 18 is provided to catch the water and to direct it to the roof eave, thereby forming a secondary drainage system of the pitched roof structure 10.

The inherent weight and rigidity of traditional waterproof membranes causes sections of the membrane to sag between the rafters, thereby forming a naturally parabolic shaped channel. The natural curve of the membrane acts to direct water away from the rafters and towards the nadir of the channel, from where it can safely be directed to the gutter below.

However, traditional waterproof membranes are expensive and heavy, which can make them difficult to install correctly. As a result, more lightweight membranes are increasingly being used as an alternative to the traditional membranes.

However, although cheaper than the traditional membranes, the reduced mass and increased flexibility of the lightweight membranes 18 makes it difficult to form a suitable channel between the rafters of the pitched roof structure. Consequently, the waterproof membrane is easily pulled tight across the rafters, thereby forming a substantially flat drainage surface, as is best illustrated in Figures 2 and 3. The trapped water is free to flow across the flat membrane, in a lateral direction, and tends to congregate towards the rafters where it may seep between the underside of the battens 16 and the membrane 18. Any water that leaches between the batten 16 and the membrane 18 is less likely to re-evaporate when the outside ambient temperature next increases.

The battens 16 may remain damp for prolonged periods, due to accumulation of water within the enclosed volume of the roof structure, which can eventually lead to a deterioration in the structural integrity of the battens 16. Furthermore, trapped water may also seep through the holes, made by the securing fasteners 20, and down into the internal roof space. This can lead to corrosion of the metal fasteners 20 and may even cause damage to the structural components of the roof.

In an attempt to alleviate this problem, a common solution is to provide an extra array of battens 22 between the membrane 18 and the tile battens 16 in order to elevate the tile battens 16 above the waterproof membrane 18. As is illustrated in Figure 4, these ‘counter battens’ 22 are arranged on top of the membrane and in parallel with the supporting rafters 14. The horizontal tile battens 16 are laid onto the “counter battens” 22 to form an air gap B between the membrane 18 and the underside of the tile battens 16. However, so called ‘counter battens’ 22 merely lift the tile battens 16 away from the waterproof membrane 18. They do not prevent moisture from seeping between the underside of the ‘counter battens’ 22 and the waterproof membrane 18, nor do they prevent moisture from entering the internal roof space through the holes made, by the securing fastener 20. Furthermore, by arranging the ‘counter battens’ 22 in parallel with the rafters, they are more likely to channel water across an upper surface of the membrane in the vicinity of the rafter 14, thereby increasing the likelihood that water will seep between the counter battens 22 and membrane 18, and further into the internal roof space below.

It is an object of the present invention to provide a solution that allows moisture, which has been trapped in the internal volume, to exit the roof structure without causing damage to the roof components.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention, there is provided a rafter fitting for a pitched roof structure, the roof structure comprising a plurality of rafters that slope from a ridge to an eave of the roof structure, a plurality of battens disposed on top of and extending orthogonally with respect to the rafters, and a membrane which extends across the roof structure between the rafters and the battens, wherein top surfaces of the rafters define a rafter plane, and wherein the rafter fitting comprises a rafter-facing surface configured to rest, in use, on the top surface of a rafter, and a membrane depressor that is configured to depress the membrane below the rafter plane when the rafter fitting is in use.

Advantageously, the membrane depressor counteracts the tendency for the membrane to be pulled taut and depresses the membrane below the rafter plane, thereby displacing the membrane away from a lower surface of the batten, even if the membrane was pulled taut across adjacent rafters when it was laid. The depressed portion of the membrane defines a drainage channel that is configured by the membrane depressor to direct water below the rafter plane and in a substantially ridge to eave direction down the pitched roof structure. In this way, any water that lands on the membrane is directed into the drainage channel is conveniently and quickly channelled away from the structural components of the roof, such as the rafters, and towards a gutter at the eave of the roof.

Furthermore, by depressing the membrane below the roof plane, a portion of the membrane is necessarily spaced apart from the lower surface of the batten, thereby providing an pathway between the membrane and the batten, through which air can flow in a substantially ridge to eave direction. In this way, the rafter fitting improves ventilation within the roof structure, which enables the dissipation of moist air throughout the internal roof cavity and reduces the likelihood of condensation forming in any given region of the roof.

The membrane depressor may comprise at least one membrane-depressing member which may be configured to protrude downwardly with respect to the rafter-facing surface when the rafter fitting is in use. When the rafter-facing surface of the rafter fitting is received on the upper surface of a rafter of the roof structure, the at least one membrane-depressing member is advantageously configured to protrude below the upper surface of the rafter and hence protrude below the rafter plane, thereby providing a simple and effective means of depressing the membrane. The at least one membrane-depressing member is thereby arranged to contact with portions of the membrane located in the vicinity of the rafter and act to depress those portions of the membrane below the rafter plane to define the drainage channels in the membrane. Hence, the membrane is therefore depressed below the rafter plane even if the membrane was initially pulled taut when it was laid on the roof. The membrane-depressing member may protrude from the rafter-facing surface by approximately 5 mm.

The at least one membrane-depressing member may comprise a shank. A membrane-facing surface of the shank may comprise at least one substantially rounded edge. Providing a rounded edge in this way means that, in use, the edges of the membrane-depressing members do not puncture or tear at the membrane.

The rafter fitting may be configured to straddle the rafter when in use. The rafter fitting may comprise at least one pair of membrane-depressing members that are spaced apart slightly more than the width of a typical rafter. By straddling the rafter, the membrane-depressing members are advantageously configured to locate and align the rafter fitting on top of the rafter. In this way, the membrane depressor may advantageously secure the rafter fitting in place, so that, during construction of the roof structure, the rafter fitting may provide a stable base on which to mount a batten. The pair of membrane-depressing members may be spaced apart by approximately 45 mm, which is the width of a typical rafter.

The or each membrane-depressing member may be provided at a peripheral edge of the rafter-facing surface. For example, the at least one membrane-depressing member may be provided substantially at a comer of the rafter-facing surface. A membrane-depressing member may be arranged at each of the four corners of the rafter-facing surface. In this way, membrane depressing members may be spaced apart so as to dissipate the depressing force exerted on the membrane by the rafter fitting, when installed in the pitched roof structure.

The rafter-facing surface may have an aperture or opening through which a securing member can pass. When the rafter fitting is installed in the roof structure the securing member, or fastener, is able to pass sequentially through the batten, the aperture the membrane and then finally into the rafter below, thereby locking the rafter fitting into the roof structure.

The rafter fitting may comprise a batten support that is configured to support the batten of the pitched roof structure when the rafter fitting is in use. The batten support may comprise a first batten-supporting surface that is configured, in use, to support a base surface of the batten. The first batten-supporting surface of the batten support may be configured to be substantially parallel to the top surface of the rafter of the pitched roof structure when in use. Advantageously, the batten support may be received between a rafter and batten of the pitched roof structure such that the first batten-supporting surface provides a substantially stable base on which to lay the batten during construction of the roof. In this way, the rafter fitting provides a strong connection between the rafter and batten and thereby promotes a robust construction of the roof structure.

The batten support may also comprise a second batten-supporting surface for supporting an eave-facing surface of the batten when the rafter fitting is in use. The second battensupporting surface may be configured to provide support for a ridge-facing surface of the batten. The second batten-supporting surface may be substantially perpendicular to the first batten-supporting surface. Advantageously, the second batten-supporting surface may be configured to provide support for the batten in such a way as to maintain the position of the batten on the rafter fitting during construction of the roof.

When the rafter fitting is in use, the second batten-supporting surface may be arranged to be orthogonal to the rafter. The position of the rafter fitting can be maintained by membrane depressing members, as described above, which protrude from the underside of the batten support and are configured to straddle the upper surface of the rafter on which the rafter fitting is installed. In this way, the rafter fitting conveniently resists any movement of the batten away from its perpendicular alignment with respect to the rafter.

Thus, the first and second batten-supporting members of the batten support, in combination with membrane depressing members, may be advantageously configured to establish and maintain the perpendicular alignment of the batten with respect to the rafter

The rafter fitting may comprise a batten spacer that is configured to space the rafter-facing surface away from the batten support. The combination of the membrane depressor and the batten spacer of the rafter fitting advantageously forms an enlarged air gap between the membrane and the tiles of the pitched roof structure. This is achieved by raising the battens above the membrane whilst simultaneously depressing the membrane below the rafter plane. Further advantageously, by spacing the rafter-facing surface away from the batten support, the rafter fitting is configured to elevate the batten above the rafter on which the rafter fitting is installed, thereby preventing any water running along the upper surface of the rafter from making contact with the batten.

The batten spacer may comprise at least one flow director configured to direct a flow of water approaching the flow director in a direction from a leading edge to a trailing edge of the rafter fitting, in a lateral direction from a central region of the rafter fitting towards an outer region of the rafter fitting. In this way, water is advantageously directed away from the rafter fitting. When the rafter fitting is integrated into the roof, the flow director of the rafter fitting acts to direct water that approaches the rafter fitting, flowing in a substantially ridge to eave direction, laterally and away from the rafter on which the rafter fitting sits. In this way, the flow director ensures that the flow of water cannot seep between the membrane and the batten. Water is thereby prevented from reaching a position between the batten and the rafter, from which it may not easily evaporate.

The at least one flow director may project from the underside of the batten support of the rafter fitting. The batten spacer may define the at least one flow director. Advantageously, the rafter fitting may thereby provide a single structure configured to a) direct water away from the rafter fitting and b) space the batten support away from the rafter-facing surface of the rafter fitting.

At least part of the membrane depressor may be integrally formed with the at least one flow director. When installed in the pitched roof structure, water approaching the rafter fitting in a generally ridge to eave direction may be directly channelled by the at least one flow director into the channel formed by the at least part of the membrane depressor.

At least part of the at least one flow director may be disposed at an acute angie to a centre line of the rafter. Advantageously, the at least one flow director is configured to direct the fiow of water in a direction that is substantiaiiy away from the centre line of the rafter to a region outboard of the rafter.

At ieast one fiow director may be substantiaiiy V-shaped. The aperture may be arranged in a chevron shape to conveniently accommodate the V-shaped flow directors whilst also providing the iargest possibie aperture through which water may flow.

The at least one flow director may be configured, in use, to direct the flow of water away from the aperture. A first flow director may be configured to project from the underside of the batten-support at a position that is substantially upstream from the aperture. The hole in the membrane that is formed by the securing means or fastener, is a particuiar point of weakness in the membrane, and by arranging the first flow director upstream of the aperture, and hence upstream of the fastener, the rafter fitting is able to direct any water that approaches its leading edge away from the hole by means of the first flow director. A second flow director may be configured, in use, to project from the underside of the batten-support at a position that is substantiaiiy downstream from the aperture. The second flow director may be configured to direct water that passes through the aperture, away from the hoie in the membrane and towards the peripheral edges of the rafter fitting.

The rafter fitting may be formed from an injection-moulded plastics material. By virtue of being formed form an injection moulded plastic, the rafter fitting may be sufficiently strong to support a batten and rafter, yet sufficiently lightweight so as not to add excess mass to the pitched roof structure into which it is installed. The rafter fitting may also be easily and inexpensively manufactured.

The invention also extends to a pitched roof structure comprising a plurality of rafters that slope from a ridge to an eave of the roof structure, a plurality of battens that are disposed on top of and extend orthogonally with respect to the rafters, a membrane that extends across the pitched roof structure, between the rafters and the battens, and a rafter fitting, wherein the top surfaces of the rafters define a rafter plane, wherein the rafter fitting comprises a rafter-facing surface that rests on the top surface of a rafter, and wherein, in the vicinity of the rafter, the membrane is depressed below the rafter plane by a membrane depressor of the rafter fitting. A membrane portion extending between adjacent rafters may define a channel below the rafter plane which is configured to direct water in a substantially ndge to eave direction.

The rafter fitting may be at least partially disposed between a batten and a rafter of the roof structure. The membrane may be a waterproof underlay.

According to a second aspect of the present invention, there is provided a rafter fitting for a pitched roof structure, the roof structure comprising a plurality of rafters that slope from a ridge to an eave of the roof, a plurality of battens disposed on top of and extending orthogonally with respect to the rafters, and a membrane that extends across the roof between the rafters and the battens. The rafter fitting comprises a rafter-facing surface, a batten support and a batten spacer that is configured to space the rafter-facing surface away from the batten-support. The rafter fitting also comprises at least one flow director configured to direct water approaching the rafter fitting in a ridge-to eave direction, in a lateral direction from a central region of the rafter fitting towards an outer region of the rafter fitting.

The batten spacer of the rafter fitting advantageously forms an air gap between the membrane and the tiles of the pitched roof structure by raising the battens above the membrane. By spacing the rafter-facing surface away from the batten support, the rafter fitting is configured to elevate the batten above the rafter on which the rafter fitting is installed, thereby preventing any water running along the upper surface of the rafter from making contact with the batten. By virtue of the flow director, water is advantageously directed away from the rafter fitting. When the rafter fitting is integrated into the roof, the flow director of the rafter fitting acts to direct water that approaches the rafter fitting, flowing in a substantially ridge to eave direction, laterally and away from the rafter on which the rafter fitting sits. In this way, the flow director ensures that the flow of water cannot seep between the membrane and the batten. Water is thereby prevented from reaching a position between the batten and the rafter, from which it may not easily evaporate.

The batten spacer may be configured to provide a lateral air passage through the rafter fitting. The lateral air passage advantageously allows air to flow laterally through the air passage. The lateral air passage may define a continuous channel, or ventilation pathway, which allows air to flow laterally through the rafter fitting in the vicinity of the securing fastener. Advantageously, the pathway Increases the rate of evaporation in the vicinity of the rafter fitting. This ensures that any moisture that has been able to pool around the hole made in the membrane by the fastener can be dissipated before it causes damage to the structural components of the roof.

The batten spacer may comprise a first batten spacer part arranged towards the leading edge of the batten riser and a second batten spacer part arranged towards the trailing edge of the batten riser. A spacing between the first and second batten spacers may define the lateral air passage. A ventilation aperture may be defined by the openings formed between the first and second batten spacer, along each flank of the rafter fitting.

The at least one flow director may project from the underside of the batten-support of the rafter fitting. The batten spacer may define the at least one flow director. At least part of the at least one flow director may be disposed at an acute angle to a centre line of the rafter. The at least one flow director may be substantially V-shaped.

The rafter-facing surface may have ah aperture or opening through which a securing member can pass, wherein the at least one flow director may be configured to direct the flow of water away from the aperture when the rafter fitting is in use. A first flow director may be configured to project from the underside of the batten-support at a position that is substantially upstream from the aperture. A second flow director may be configured, in use, to project from the underside of the batten-supporting surface at a position that is substantially downstream from the aperture. Advantageously, the first and second flow directors may be configured to direct water flowing in a substantially ridge to eave direction away from the aperture, which thereby prevents water from seeping through the aperture and into the internal roof space.

The invention also extends to a pitched roof structure comprising a plurality of rafters that slope from a ridge to an eave of the roof structure, a plurality of battens that are disposed on top of and extend orthogonally with respect to the rafters, a membrane that extends across the roof between the rafters and the battens, and a rafter fitting arranged between a rafter and a batten. The rafter fitting comprises a rafter-facing surface that rests on the rafter, a batten support that supports the batten and a batten spacer configured to provide a spacing between the rafter and the batten, and wherein the spacer comprises a flow director configured to direct water approaching the flow director in an ridge-to eave direction, in a lateral direction from a central region of the rafter fitting towards an outer region of the rafter fitting.

The batten spacer may be configured to provide a space between the batten and the membrane. The flow director may be configured to direct water away from the rafter of the pitched roof structure. The leading and trailing edges of the rafter fitting may face the ridge and eave of the pitched roof structure, respectively.

It will be appreciated that preferred and/or optional features of the first aspect of the invention may be incorporated alone or in appropriate combination within the second aspect of the invention also.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1, which has already been described, shows a perspective view of a tiled pitched roof structure according to an embodiment of the invention;

Figure 2 shows a partial cross-sectional view, along line A-A, of the roof structure of Figure 1, and Figure 3 shows an enlarged view of a portion of the pitched roof structure shown in

Figure 2; and

Figure 4 shows a partial cross-sectional view of a known pitched roof structure.

Preferred embodiments of the present invention will now be described, by way of example only, with reference to the remainder of the accompanying drawings in which:

Figure 5 shows a perspective view of a rafter fitting according to an embodiment of the invention:

Figure 6 shows a perspective view of the underside of the rafter fitting of Figure 5;

Figure 7 shows a top view of the rafter fitting of Figure 5;

Figure 8 shows a bottom view of the rafter fitting of Figure 5;

Figure 9 shows an end view of the rafter fitting of Figure 5;

Figure 10 shows a side view of the rafter fitting of Figure 5;

Figure 11 shows a partial cross-sectional view of a pitched roof structure according to an embodiment of the invention, and Figure 12 shows an enlarged view of a portion of the pitched roof structure shown in Figure 11; and.

Figures 13a and 13b show a perspective view of the rafter fitting of Figure 5, provided between a batten and rafter of a pitched roof structure according to an embodiment of the invention.

Throughout this specification, terms such as ‘upper’ and ‘lower;’ are used with reference to the orientation of a roof structure and to the orientation of a rafter fitting in situ within such a roof structure, as shown in Figures 1 to 13 of the accompanying drawings.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Referring to Figures 5 to 10, a rafter fitting in the form of a batten riser 24 is provided with a downward facing rafter-facing surface 26, an upward-facing batten support 28, a membrane depressor 30 and a flow director 32, which also acts as a batten spacer. The batten riser 24 is configured for use in a pitched roof structure 10 as shown in Figure 1. A leading edge 25 of the batten riser 24 is arranged so that, in use, it is orientated to face the ridge of the pitched roof structure 10, and a trailing edge 27 of the batten riser 24 is arranged so that, in use, it faces the eave of the pitched roof structure 10.

An upper portion of the batten riser 24 defines the batten support 28, which is configured to receive and support a batten 16 when the batten riser 24 is installed in the pitched roof structure 10. The batten support 28 is defined by first and second orthogonal plates 33, 35. The first plate 33 has an aperture 40 at the centre that takes up a major part of the first plate 33.

The flow director 32 comprises first and second flow directors 42, 44 that are each arranged to project downwardly from the batten support 28. Each flow director 42, 44 comprises a generally V-shaped ridge. The first flow director 42 is arranged towards the leading edge 25 of the batten riser 24, above the aperture 40. The second flow director 44 is arranged towards the trailing edge 27, below the aperture 40. The first and second flow directors 42, 44 are spaced apart such that openings are defined at the sides of the flow director 32.

The rafter-facing surface 26 is defined by base surfaces of the flow directors 42, 44 and is configured to be arranged on a top surface of a rafter 14 of the pitched roof structure 10 when the batten riser is in use.

The first and second flow directors 42, 44 also act as spacers that act to space the rafterfacing surface 26 away from the batten support 28.

The membrane depressor 30 is defined by four membrane-depressing members 38, which are each arranged to protrude downwardly from a peripheral edge of the underside of the batten support 28.

Considering now the components in more detail and turning again to the batten support 28 of the batten riser 24, as is shown in Figures 5 to 10, the first plate 33 has an upwardly-facing surface, which defines a first batten-supporting surface 34 of the batten riser 24. The second plate 35 extends upwardly from the trailing edge 27 of the batten riser 24 and is thereby arranged orthogonally with respect to the first plate 33. An inward-facing surface of the second plate 35 defines a second batten-supporting surface 36 of the batten support 28, such that the second batten-supporting surface 36 is arranged to face the leading edge 25 of the batten riser 24.

The first-batten supporting surface 34 is substantially planar so that, when in use, it is configured to receive a base of the batten 16. The second batten-supporting surface 36 is arranged orthogonally with respect to the first batten-supporting surface 34 and is thereby configured, in use, to lie against and support an eave-facing surface of the batten 16.

An aperture 40 is provided in the centre of the first batten-supporting surface 34. The aperture allows a securing fastener such as a nail of screw to pass through the batten riser 24, in order to fasten it to a rafter of the roof structure 10.

Turning now to the flow director 32 of the batten riser 24, as can be appreciated from the Figures 5 to 8, the first flow director 42 is defined by a ridge arranged in a V formation. The ridge comprises first and second portions, each of which are disposed at an acute angle to a centre line of the batten riser 24. The first and second portions meet at a vertex.

The first V-shaped flow director 42 is arranged so that the vertex of the V points towards the leading edge of the batten riser 24. Thus, the first flow director 42 is configured to direct a flow of water that approaches the batten riser 24 in a direction in a lateral direction from a central region towards an outer region of the batten riser 24. The lateral direction need not be precisely horizontal, but can be any direction that has a component across the roof, rather than purely down the roof in leading-to-trailing edge direction. Because the first flow director 42 is located at a position on the batten riser 24 that is substantially upstream from the aperture 40, the first flow director 42 is configured to direct the flow of water away from the aperture 40 when the batten riser 24 is in use.

The second V-shaped flow director 44 is arranged in alignment with the first flow director 42. Because the second flow director 44 is located at a position downstream from the aperture 40, any water flowing through the aperture 40 will flow onto the second flow director 44 and will be directed away from the aperture 40 and towards the peripheral edges of the batten riser 24.

The aperture 40 is substantially chevron shaped to accommodate the V shapes of the first 42 and second 44 flow directors. The size of the aperture 40 is maximised whilst still maintaining sufficient structural integrity of the batten support. This minimises the volume of the first plate 33 to minimise the weight of the batten riser and hence minimise the material costs associated with the manufacture of the batten riser 24.

Considering now the membrane depressor 30, as shown in Figures 5 and 6, the four membrane-depressing members 38 of the membrane depressor 30 are shanks that are integrally formed with the flow director 32. Each membrane-depressing member 38 protrudes downwardly from the rafter-facing surface 26 of each batten spacer. In the embodiment shown, the membrane-depressing members 38 protrude downwardly by approximately 5 mm.

The four membrane-depressing members 38 are located at the ends of the first and second flow deflectors 42, 44 such that they are provided at the four comers of the batten riser 24. Put another way, the four membrane-depressing members 38 are arranged in two pairs. A leading-edge pair of membrane-depressing members 38 are integrally arranged with the peripheral ends of the first batten spacer, and a trailing-edge pair of membrane-depressing members 38 are integrally arranged with the peripheral ends of the second batten spacer.

Each membrane-depressing member 38 protrudes from the rafter-facing surface 26 of each batten spacer by approximately 5 mm. Within each pair of membrane-depressing members 38, the shanks are spaced apart by a distance that is slightly greater than the width of a typical rafter. In this embodiment, the membrane-depressing members 38 within each pair are spaced apart by approximately 45 mm.

In this embodiment, the batten riser 24 is made of a single piece of injection-moulded plastic. However, the batten riser 24 may be made from any suitable material and by any suitable method, for example by machining a suitable plastics material

The integration of the batten spacer into the pitched roof structure will now be described in detail. Turning first to the pitched-roof structure 10 in which the batten riser 24 may be installed, with reference to Figure 1, the pitched-roof structure 10 includes a plurality of parallel rafters 14, a plurality of parallel tile battens 16, and a plurality of tiles 12 fixed to the battens. The rafters 14 extend from the ridge to the eave of the roof, the battens 16 extend above and orthogonally with respect to the rafters 14 and the tiles 12 are affixed along the battens 16 in horizontally-extending rows. A roof underlay in the form of a waterproof membrane, is provided between the rafters 14 and the battens 16 and extends across the roof structure.

The top surfaces 15 of each of the rafters 14 together define a rafter plane of the pitched-roof structure 10. That is to say, each rafter 14 has at least one top surface 15 and each of the top rafter surfaces 15 together define a plane that extends from the ridge to the eave, and across the width, of the pitched-roof structure 10.

With reference to Figures 11 and 12, the batten riser 24 is configured to be installed between a batten 16 and a rafter 14 of the pitched-roof structure 10. In particular, the batten riser 24 is fitted to the rafter 14, above the membrane 18 and below the batten 16 at a point where the batten 18 intersects with the rafter 14.

To assemble the roof structure, the plurality of load-bearing rafters 14 are first disposed from the ridge to the eave of the roof. The waterproof membrane 18 is then draped across the rafters 14. A batten riser 24 is placed at a designated intersection point between a rafter 14 and a batten 16. The rafter-facing surface of the batten riser 24 is arranged to rest on top of the rafter 14. In particular, the rafter-facing surface of the batten riser 24 is arranged to make contact with a portion of the membrane 18 that sits on top the top surface of the rafter 14.

With reference to Figures 13a and 13b, the batten riser 24 is arranged to straddle the rafter 14, with the membrane-depressing members 38 outboard of the rafter 14. The membranedepressing members 38 protrude below the upper surface 15 of the rafter 14 and hence protrude below the rafter plane. The membrane-depressing members 38 are thereby arranged to contact with portions of the membrane 18 located on each side of the rafter 14 and act to depress those portions of the membrane 18 below the rafter plane. The membrane 18 is therefore depressed below the rafter plane even if the membrane was initially pulled taut when it was laid on the roof.

Depression of the membrane 18 by successive batten riser 24 on adjacent rafters causes the membrane 18 to be depressed away from the battens 16 in the regions between the rafters, such that the membrane 18 forms a drainage channel between adjacent rafters 14 of the pitched-roof structure 10, as is shown in Figures 11 and 12. Thus, the membrane depressors counteract the tendency for the membrane to be pulled taut and flat by creating channels that extend down the roof in a ridge-to eave direction without the need to create sagging in the membrane 18 as the membrane 18 is laid.

By straddling the rafter 14, the four membrane-depressing members 38 are also advantageously configured to locate the batten riser 24 on top of the rafter 14. In this way, the membrane depressor 30 advantageously secures the batten riser’s position so that, during construction of the roof structure 10, the batten riser 24 provides a stable base on which to mount a batten 16. Advantageously, a membrane-facing surface of each membrane-depressing member 38 is substantially rounded so that, in use, the edges of the membrane-depressing members 38 do not puncture or tear at the membrane 18.

With the batten risers 24 in place, the batten 16 is then laid over the batten riser 24 so that the first batten-supporting surface 34 of the batten support 28 is configured to be parallel with the top surface of the rafter 31. The batten 16 is arranged such that the eave-facing surface of the batten 16 lies against the second batten-supporting surface 36 of the batten riser 24.

The first and second batten-supporting surfaces 34, 36 of the batten riser 24 provide a stable base on which to position and align the batten 16 when constructing the roof structure 10. Furthermore, the first 34 and second 36 batten-supporting surfaces are configured to align a central portion of the batten 16 with the aperture 40 of the batten support 28 so that the fastener 20 may safely pass through the batten riser 24 during construction of the roof structure 10.

The batten 16 and batten riser 24 are then secured to the rafter 14 by a securing fastener 20 such as a nail or screw. With reference to Figures 13a and 13b, the batten riser 24 is configured to receive the securing fastener 20 through the aperture 40 that is formed in the batten support 28. In this way, the fastener is aiiowed to pass sequentially through the batten 16, the aperture 40 the membrane 18 and then finally into the rafter 14 below so that the fastener 20 locks the batten riser 24 into the roof structure 10. Finally, tiles 12 are secured to the battens 16 in horizontal courses.

In the finished roof, the batten riser 24 acts in several ways to minimise moisture damage caused by moisture between the membrane 18 and the tiles 12.

Referring to Figures 11 and 12, the drainage channels formed by the membrane depressors are arranged to direct water below the rafter plane and in a substantially ridge to eave direction, in this way, any water that falls on the membrane is directed into the drainage channel where it is conveniently and quickly channelled away from the structural components of the roof, such as the rafters 14, and towards the gutter at the eave of the roof 10. These channels are formed even if the roof underlay was initially pulled taut when it was laid on the roof.

As is also clear in Figures 11 and 12, the first and second batten elevate the tile batten 16 above the rafter 14, and hence above waterproof membrane 18. Advantageously, by separating the batten 16 from the membrane 18, an air gap is formed between the batten 16 and the membrane 18 of the pitched roof structure 10, thereby creating an air flowpath that extends across the entire roof without interruptions.

By contrast, in a conventional roof structure, such as that depicted in Figure 1, air is substantially trapped within a series of horizontal chambers, which are defined by the battens 16, the tiles 12 and the membrane 18. Due to the flat profile of the membrane 18, the trapped air is unable to flow beneath the battens 16 from the ridge to the eave of the roof.

Thus, the batten spacer of the batten riser provides a pathway between the membrane 18 and the batten 16, through which air can flow in a substantially ridge to eave direction, allowing better ventilation and encouraging easy evaporation of water that is on the roof membrane 18.

This effect is enhanced even further by the presence of the membrane depressors. With reference to Figures 11 and 12, it is clear that by combining the membrane depressor 30 and the batten spacer of the batten riser 24, an enlarged air gap is formed between the membrane 18 and the tiles 12 of the pitched roof structure 10, which extends beneath the battens as well as above the battens. This enlarged airgap is achieved by raising the battens 16 above the membrane 18 whilst simultaneously depressing the membrane 18 below the rafter plane.

Thus, the installation of batten risers 24 throughout the roof structure has the effect of forming an enlarged and continuous internal roof cavity, which extends from the ridge to the eave of the roof structure 10 above and below the battens. In this way, the batten riser 24 improves ventilation within the roof structure 10, which enables the dissipation of moist air throughout the internal roof cavity and reduces the likelihood of condensation forming in any given region of the roof.

Surprisingly, a further advantage is realised during windy conditions, wherein an updraft of wind may typically cause a sudden reduction in the air pressure underneath the tiles 12. By increasing the flow of air across the roof structure within the internal roof cavity any localised pressure variations are effectively equalised thereby counteracting the uplift force inflicted on the tile.

Figure 13a reveals that when the batten riser 24 is installed in the roof a ventilation aperture 46 is defined along each flank of the batten riser 24, between the first and second flow directors. In this way, the first and second flow directors define sidewalls of a continuous channel, in the form of a lateral air passage, which runs from a left side of the batten riser 24 to a right side of the batten riser 24 between the ventilation apertures. An upper surface and a base surface of the lateral air passage is defined by the underside of the batten support 28 and the upper surface 15 of the rafter, respectively.

Further advantages arise from this lateral channel. In particular, the continuous lateral channel forms a ventilation pathway that allows air to flow laterally through the batten riser 24 in the vicinity of the securing fastener 20. Advantageously, airflow through the channel increases the rate of evaporation in the vicinity of the batten riser 24. This ensures that any moisture that has been able to pool around the hole made in the membrane 18 by the fastener 20 can be dissipated before it causes damage to the structural components of the roof.

When the batten riser 24 is integrated into the roof, the flow director 32 of the batten riser 24 acts to direct water away from the rafter on which the batten riser 24 sits and towards the channels in the membrane 18.

The hole in the membrane 18 that is formed by the fastener 20 passing through the membrane to the rafter underneath is a particular point of weakness in the secondary drainage system of the roof, since it could allow moisture to penetrate beneath the membrane the rafter below. The first and second flow directors 42, 44 are configured in particular to guide water away from the hole in the membrane to guard against water seeping through the hole.

By arranging the first flow director 42 above the aperture 40 and hence above the fastener 20 the first flow director 42 is able to direct any water that approaches its leading edge 25 away from the hole in the membrane 18. Water that approaches the batten riser 24 in a substantially ridge-to-eave direction meets the first flow director 42 where it is directed laterally away from the centre line of the rafter 14 to a region outboard of the rafter 14 and hence towards the channels defined by the membrane. The first flow director 42 therefore guards against water entering into the region between the rafter and the batten, where it might othenA/ise seep between the membrane 18 and the batten 16 via the nail hole.

Any water that falls through the aperture 40 in the batten riser 24 will tend to hit the surface of the rafter where it is directed down the rafter in a ridge-to-eave direction by gravity. As it is directed down the rafter it quickly meets the second flow director 44. The second flow director 44 directs the flow of water in a lateral direction that is substantially away from the centre line of the rafter 14 to a region outboard of the rafter 14. Thus, the second flow director 44 directs water quickly away from the region between the rafter and the batten and hence away from the nail hole.

The features of the batten riser 24 increase the airflow paths across the roof which results in improved ventilation of the roof structure. Furthermore, the batten riser 24 creates flow directors and channels in the batten riser 24 itself and in the roof membrane 18 to direct water away from the most vulnerable parts of the roof structure and towards the eave of the roof where the water can be collected in guttering to be carried away from the roof. The result is a roof structure that is more resistant to leakage and water damage, particularly in the region of overlap between the rafters and battens of the roof.

It is expressly intended that the membrane depressor and flow director described above could be used independently from each other in different rafter fittings. In embodiments where the flow director is absent and the membrane depressor is present, the rafter fitting need not act as a batten spacer, and need not be fitted between a rafter and a batten but may be fitted to other parts of the rafter as desired.

Although in the embodiments described the batten spacer is defined by the flow director, embodiments are also envisaged in which the flow director and the spacer are defined by different parts of the batten riser.

In an alternative arrangement of the batten support, the second plate may extend upwardly from the leading edge of the batten riser rather than the trailing edge such that the second batten-supporting surface is arranged to face the trailing edge of the batten riser.

It will be appreciated by a person skilled in the art that the invention could be modified to take many alternative forms without deviating from the scope of the appended claims.

Claims (46)

1. A rafter fitting for a pitched roof structure, the roof structure comprising a plurality of rafters that slope from a ridge to an eave of the roof structure, a plurality of battens disposed on top of and extending orthogonally with respect to the rafters, and a membrane which extends across the roof structure between the rafters and the battens, wherein top surfaces of the rafters define a rafter plane, and wherein the rafter fitting comprises a rafter-facing surface configured to rest, in use, on the top surface of a rafter, and a membrane depressor that is configured to depress the membrane below the rafter plane when the rafter fitting is in use.

2. The rafter fitting of Claim 1, wherein the membrane depressor comprises a membrane-depressing member which is configured to protrude downwardly with respect to the rafter-facing surface when the rafter fitting is in use.

3. The rafter fitting of Claim 2, wherein the membrane-depressing member protrudes downwardly with respect to the rafter-facing surface by approximately 5 mm.

4. The rafter fitting of Claim 2 or Claim 3, wherein the membrane-depressing member comprises a shank.

5. The rafter fitting of Claim 4, wherein a membrane-facing surface of the shank comprises a substantially rounded edge.

6. The rafter fitting of any preceding claim, wherein the rafter fitting is configured to straddle the rafter when the rafter fitting is in use.

7. The rafter fitting of Claim 6, wherein the rafter fitting comprises at least one pair of membrane-depressing members that are spaced apart slightly more than the width of a typical rafter.

8. The rafter fitting of Claim 7, wherein the pair of membrane-depressing members are spaced apart by approximately 45 mm.

9. The rafter fitting of any preceding claim, wherein the or each membrane-depressing member is provided at a peripheral edge of the rafter-facing surface.

10. The rafter fitting of any preceding claim, wherein the or each membrane-depressing member is provided substantially at a corner of the rafter-facing surface.

11. The rafter fitting of any preceding claim, wherein the rafter-facing surface has an aperture or opening through which a securing member can pass.

12. The rafter fitting of any preceding claim, wherein the rafter fitting comprises a batten support that is configured to support a batten of the pitched roof structure when the rafter fitting is in use.

13. The rafter fitting of Claim 12, wherein the batten support comprises a first battensupporting surface that is configured to support a base surface of the batten when the rafter fitting is in use.

14. The rafter fitting of Claim 12 or Claim 13, wherein the batten support comprises a second batten-supporting surface for supporting an eave-facing surface of the batten.

15. The rafter fitting of Claim 14, wherein the second batten-supporting surface is substantially perpendicular to the first batten-supporting surface.

16. The rafter fitting of any of claims 11 to 14, wherein the rafter fitting comprises a batten spacer that is configured to space the rafter-facing surface away from the batten-support.

17. The rafter fitting of Claim 16, wherein the batten spacer comprises at least one flow director configured to direct a flow of water approaching the flow director in a direction from a leading edge to a trailing edge of the rafter fitting, in a lateral direction from a central region of the rafter fitting towards an outer region of the rafter fitting.

18. The rafter fitting of Claim 17, wherein the at least one flow director projects from the underside of the batten support of the rafter fitting.

19. The rafter fitting of Claim 18, wherein the batten spacer defines the at least one flow director.

20. The rafter fitting of Claim 19, wherein at least part of the or each membrane depressor is integrally formed with the at least one flow director.

21. The rafter fitting of any of claims 17 to 20, wherein at least a part of the at least one flow director is disposed at an acute angle to a centre line of the rafter.

22. The rafter fitting of Claim 21, wherein the at least one flow director is substantially V shaped.

23. The rafter fitting of Claim 22, when dependent on Claim 11, wherein the at least one flow director is configured, in use, to direct the flow of water away from the aperture.

24. The rafter fitting of Claim 23, wherein a first flow director is configured to project from the underside of the batten-support at a position that is substantially upstream from the aperture when the rafter fitting is in use.

25. The rafter fitting of Claim 24, wherein a second flow director is configured to project from the underside of the batten-support at a position that is substantially downstream from the aperture when the rafter fitting is in use.

26. The rafter fitting of any preceding claim, wherein the rafter fitting is formed from an injection moulded plastics material.

27. A pitched roof structure comprising a plurality of rafters that slope from a ridge to an eave of the roof structure, a plurality of battens that are disposed on top of and extend orthogonally with respect to the rafters, a membrane that extends across the pitched roof structure between the rafters and the battens, and a rafter fitting, wherein the top surfaces of the rafters define a rafter plane, wherein the rafter fitting comprises a rafter-facing surface that rests on the top surface of a rafter, and wherein, in the vicinity of the rafter, the membrane is depressed below the rafter plane by a membrane depressor of the rafter fitting.

28. The pitched roof structure of Claim 27, wherein a membrane portion extending between adjacent rafters defines a channel below the rafter plane which is configured to direct water in a substantially ridge to eave direction.

29. The pitched roof structure of Claim 27 or Claim 28, wherein the rafter fitting is at least partially disposed between a batten and a rafter of the roof structure.

30. The pitched roof structure of any of claims 27 to 29, wherein the membrane is a waterproof underlay.

31. A rafter fitting for a pitched roof structure, the roof structure comprising a plurality of rafters that slope from a ridge to an eave of the roof, a plurality of battens disposed on top of and extending orthogonally with respect to the rafters, and a membrane that extends across the roof between the rafters and the battens; wherein the rafter fitting comprises a rafter-facing surface, a batten support and a batten spacer that is configured to space the rafter-facing surface away from the batten-support, and wherein the rafter fitting comprises at least one flow director configured to direct water approaching the rafter fitting in a ridge-to eave direction, in a lateral direction from a central region of the rafter fitting towards an outer region of the rafter fitting.

32. The rafter fitting of Claim 31, wherein the batten spacer is configured to provide a lateral air passage through the rafter fitting.

33. The rafter fitting of Claim 32, wherein the batten spacer comprises a first batten spacer part arranged towards the leading edge of the batten riser and a second batten spacer part arranged towards the trailing edge of the batten riser, and wherein a spacing beween the first and second batten spacers defines the lateral air passage.

34. The rafter fitting of any of claims 31 to 32, wherein the at least one flow director projects from the underside of the batten-support of the rafter fitting.

35. The rafter fitting of Claim 34 wherein the batten spacer defines the at least one flow director.

36. The rafter fitting of any of claims 31 to 35, wherein at least part of the at least one flow director is disposed at an acute angle to a centre line of the rafter.

37. The rafter fitting of Claim 36, wherein the at least one flow director is substantially V shaped.

38. The rafter fitting of Claim 37, wherein the rafter-facing surface has an aperture or opening through which a securing member can pass, wherein the at least one flow director is configured to direct the flow of water away from the aperture when the rafter fitting is in use.

39. The rafter fitting of Claim 38, wherein a first flow director is configured to project from the underside of the batten-support at a position that is substantially upstream from the aperture.

40. The rafter fitting of Claim 39, wherein a second flow director is configured, in use, to project from the underside of the batten-supporting surface at a position that is substantially downstream from the aperture.

41. A pitched roof structure comprising a plurality of rafters that slope from a ridge to an eave of the roof structure, a plurality of battens that are disposed on top of and extend orthogonally with respect to the rafters, a membrane that extends across the roof between the rafters and the battens, and a rafter fitting arranged between a rafter and a batten; wherein the rafter fitting comprises a rafter-facing surface that rests on the rafter, a batten support that supports the batten and a batten spacer configured to provide a spacing between the rafter and the batten; and wherein the spacer comprises a flow director configured to direct water approaching the flow director in an ridge-to-eave direction, in a lateral direction from a central region of the rafter fitting towards an outer region of the rafter fitting.

42. The pitched roof structure of Claim 41, wherein the batten spacer is configured to provide a space between the batten and the membrane.

43. The pitched roof structure of Claim 41 or Claim 42, wherein the flow director is configured to direct water away from the rafter of the pitched roof structure.

44. The pitched roof structure of any of Claims 27 to 30 or Claims 41 to 43, wherein the pitched roof structure is a tiled roof.

45. A rafter fitting substantially as hereinbefore described with reference to any of Figures 1 to 13 of the accompanying drawings.

46. A pitched roof structure substantially as hereinbefore described with reference to any of Figures 1 to 13 of the accompanying drawings.