GB2135360A - Roof ventilation - Google Patents

Abstract

A roof ventilation device in the form of an elongate unit (11) defines a ventilation slot such that a row of such units, mutually aligned and secured along the eaves of a roof structure can provide for the passage of ventilation air into the roof space to minimise the risk of condensation. Each unit has upper and lower web members (2, 3) spaced apart to define the slot and means, such as a row of vertical fins (15), to subdivide the ventilation slot into a multiplicity of ventilation apertures through which the ventilating air must pass. The grill-like structure prevents birds and small animals entering the roof space. A gauze strip (7) may be provided across the rear face of the unit. The row of ventilating units can be fixed on top of a facts board (14) or the upper course of bricks supporting the edge tiles. The upper web member (2) of each unit preferably projects forwardly of the corresponding edge of the lower member in order to prevent the outer strip portion (18a) of roof lining felt (18), which projects over the units, from sagging so as to shut off the ventilation apertures. <IMAGE>

Description

SPECIFICATION Roof ventilation unit, system and method This invention relates to the ventilation of roof spaces in new and existing buildings.

More particularly the invention concerns a ventilation unitwhich can form part of a ventilation system to be provided at the eaves of a roof structure to allow ventilating airto flow into the roof space so as to inhibit condensation. Such condensation tends to occur particularly where the roof space is well insulated from the remainder of the building beneath.

Such roof space ventilation is now required by building regulations, and although there have been various proposals to meet these regulations, they have all presented certain disadvantages and problemswhich have yet to be overcome. For example, it is known to provideventilating aperturesinthe horizon talsoffitewhich extends laterally from the depending facia board beneath the edge of a tiled roof to the adjacent wall. However, in orderto prevent small birds and other animals from gaining entryto the roof space, these apertures have commonly been covered by gauze netting or other openwork material.Howev or, this gauze tends to be difficult to handle and install properly, and it has been found that in time dust and other mattertendsto accumulate on the gauze to reduce and possibly even stop completelythe required ventilation.

Accordingly, in its broadest aspect the invention provides a ventilator device for use in ventilating roof spaces in buildings, the device comprising an elongate unit for installation in a generally horizontal position at the eaves of a roof and having upper and lower rigid elongate generally parallel members defining therebetween an elongate slot for the transverse passage of air through the unit, and spacer means supporting said upper and lower members in their spaced-apart condition, means being provided to extend along and across said slot to provide a multiplicity of discrete ventilating apertures for conveying into the space air flowing into said elongate slot.

Such a device is easily handled and can readily be installedwhere required atthe eaves of a roof byfixing to an appropriate horizontally extending component of a roof structure. The upper and lower members are preferably web members spaced apart bythe spacer means in a generally parallel mutual disposition, the arrangement being such that when the unit is disposed with the lower elongate web member generallyhorizontal,theforwardedgeofthe upper web member projectsforwardly of, orover-hangs,the corresponding forward edge of the lower web member.

This configuration allows the unit to be fixed along the edge of a tiled roofbeneaththeoutermosttiles with a generally flexible sheet member, commonly referred to a roofing felt, held againstthe upper web member bytheweightofthe outermost tiles without fear ofthe outer edge strip of the felt closing the elongate ventilating aperture between these two web mem bers. This is because the over-hang ensures that as the felt ages and sags at its outer edge under its own weight, total closure of the gap between the corresponding outer edges of the two web members is prevented.

The unit is preferably provided with a plurality of strengthening ribs spaced longitudinally ofthe unit and spanning the gap between the two web members.

Some of these strengthening ribs may be provided in pairs at positions where the unit is otherwise adapted to be fixed to a suitable component of the roof structure. For example, at the positions of the paired ribs, the unit may be formed with fixing apertures in the upper and lowerwebmembersverticallyaligned so as to allow fixing elements such as nails, screws etc., to pass vertically through the unit into such component.

The outer surface of the upperweb member is preferably provided with an elongate groove providing a narrow strip portion ofthe upper web member with a reduced thickness into which fixing pins or other elements employed forfixing other components required at the edge ofthe roof may be driven. These other components may, for example, be tile infill members having segmental infill portions to fill the gaps formed beneath the edge tiles by the fluted, or corrugated tile profile, these infills projecting upwardliy from a generally horizontal fixing flange to be fixed relative to the ventilating unit by the aforesaid fixing pins.

The construction of the units described herein according tothe invention can allowthemto be used in a roofstructure either with or without facia board and soffite. Where a facia board and soffite are used, the units can be fixed to the upper edge ofthefacia board to support the outer tiles and to allow entry of ventilating air into the roof space over the facia board.

In an open eaves structure without facia board and soffite the ventilator unit can be mounted on the outer edge ofthe upper course of bricks in the outer skin of a cavitywall structure,the outertiles again resting on the ventilator unit so mounted, which allows entry of ventilating air over the upper bricks into the roof space.

Preferred embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which: Figure lisa front perspective view of one embodiment of a ventilating unit according to the present invention; Figure 2 is a persepctive view,from above and behind,ofa partofthe Figure 1 unit; Figure 3 is a view, from the front and underneath, of part ofthe Figure 1 unit; Figure 4 is a front elevational view of part ofthe Figure 1 unit; Figure 5 is a rear elevational view of part of the Figure 1 unit; Figure 6 is a perspective view from above and behind a second embodiment of the ventilator unit according to the present invention;; Figure 7 is a front elevational view of a third embodiment of a ventilator unit according to the present invention; Figure 8 is a cross-sectional view of the ventilator unit shown in Figure 7taken on the line VIII-VIII; Figure 9 is a perspective view from above and behind the ventilator unit of Figure 7; Figure 10 is a sectional view of an eaves part of a roof support structure incorpoarting a ventilator unit ofthethird embodiment; Figure 11 is a sectional view an eaves part of another roofsupportstructure incorporating a ventilating unit according to the third embodiment; and Figure 12 is a sectional view of an eaves part of a horizontal roof support structu re incorporating a ventilator unit according to thethird embodiment.

With referencefirstto Figures 1 to 5, the illustrated ventilator device according to the first embodiment is an elongate unit 1 comprising upper and lower elongate rigid webs 2,3 extending generally parallel to one anotheroneabovethe other, and vertically spaced apart by end spacers 4 and a plurality of intermediate, longitudinally spaced spacers 5. This structure defines a longitudinally sub-divided elongate ventilating slot 6 for the passage of ventilating air into a roof structure, as will be described morefully with reference to the laterfigu res. Across the rearface ofthe unit is provided a strip of gauze 7 further sub-dividingtheventilating slot into a multiplicity of ventilation apertures.

As can be seen best in Figures 2 and 3,the upper web member projects at itsfront edge forwardly ofthe correpsonding front edge of the lowerweb member.

In this embodimentthis front edge of the lowerweb member is spaced rearwardly of the lowerfrontcorner ofthe end and intermediate spacers 4 and 5.

The unit is formed of tough plastics material and typically the dimensions are as follows:- For a pitched roof, Length (L)-600 mm width (W)-25mm depth (D)-15 mm For a flat roof, Length (L)-600 mm width (W)-25 mm depth (D)-30 mm The gauge if the gauze should be such astotrap most insects. The overhang of the upper web member relative to the lower member may be approximately 5 mm so asto shield the unit of possible closure by roofing felt, as is described later herein, or any other extraneous matter falling into the unitthereby blocking the airway.

The second embodiment shown in Figure 6 is a modified version ofthe first embodiment and is provided with a multiplicity of vertical webs, or fins 8 spanning the divided ventilating slot. These webs 8 replace the gauze 7 ofthefirst embodiment. These fins define a multiplicity of vertical slit-aperturesforthe passage of the ventilating air. Again, there is an over-hang 9atthefrontedge portionoftheupperweb member 2. Fixing apertures 10 are provided in the upperweb member 2 and corresponding fixing apertures (notvisible) are provided in the lowerweb member 3. Once again, there are a plurality of rigid spaced stiffening members 5.

In the third embodiment illustrated in Figures 7 to 9 there are again a multiplicity ofvertical fins 8 subdividing the ventilating slot. Afso, there are a pluralityof upright, longitudinally spaced strengthen- ing ribs 5 as before; in-this embodiment, however, these ribs are provided in pairs at the longitudinal positions F of the fixing apertures 10in the upper and lower web members. This pairing ofthe strengthen- ing ribs provides additional resistance to breakageQ the unitwhen being nailed through these apertures to a member atthe eaves of the roof supportstructure.

The upperweb member is formed with an elongate groove 12in its uppersurface extending through the positions of the fixing apertures 10. This groove provides a strip portion along the upperweb member of reduced thickness. It is found thatfixing pins, nails orscrewsforfixing additional elongate elements of the roof structure to the unit can be driven into this strip portion with less likelihood of cracking the upper web member, bearing in mind thatthe unit is preferably made from a plastics material.

In this embodiment, the end spacer members4 are generallytrapezoidal in shape and have a slanting forward edge 13 extending from the forwardly projecting front edge ofthe upperweb membertothe corresponding front edge of the lower web member.

With reference to Figure 9, the preferred dimen sionsforthe unitofthisthird embodiment are as follows: length (L)-200 mm width (W)-25 mm depth (D)-23 mm Different examples of the manner in which a ventilator unit according to the present invention can be incorporated in a roofing structureforventilation of a roofing space will now be described with reference to Figures 1 Oto 12. Although these figures are illustrated with reference to the third embodiment, it is to be understood that any ofthe described embodiments, or any other structure in accordance with the invention, may be used.

Figure 10 illustrates the use of the ventilating unit with a roofing structure incorporating a vertically disposed, horizontally extending facia board 14 and a horizontal soffite 15. The facia board 14 is disposed outwardlyofthe outer building wall and the soffite 15 closesthegap between the facia board 14andthe outer wall. The facia board 14 is fixed to the outer faces ofthe outwardly projecting sloping rafters 16andthe outer edge of the soffite 15 is accommodated in an elongate rebate 17 inthefacia board, in a known manner.

Ventilator units according to the present invention are fixed end-to-end to form a row along the upper edgeofthefacia board 14byfixing members such as gavanised nails 17driventhroughthefixing apertures in the upper and lower web members 2 and 3 ofthe ventilating units.A bituminous sheetmember 18 lining the inside ofthe roofing tile structure is laid on the rafters 16 and projects forwardly over the top edge ofthe ventilator unit, as shown.Thetiles 26 are laid on top ofthis bituminous lining, orfelt, and the row of lower, outertiles is supported on the row of ventilator unitswith the felt held between the lower faces of the tiles and the front edges ofthe upperweb members of the ventilating units.

As shown, the outer edge strip 1 8a of the felt is unfixed andtendsto drop orsag awayfromthe underside of the tiles. However, because of the over-hang atthefrontedgeofthe upperweb members of the ventilating units, the felt cannot totallyshutthe opening to the ventilating slots of the ventilating units.

Figure 11 illustrates the use of ventilator units according to the third embodiment with an open eaves roof structure with no facia board and soffite.

Here, the units are mounted along the outer edge of the upper course of brickwork in the outer brickwork skin 25 by means of a layer of mortar 18 spread on this upper course. The units are disposed longitudinally in the gaps between the sloping rafters 16 passing obliquely overthis upper course of bricks. Again, the outer row of tiles 26 is supported on the ventilator units with the lining felt trapped between the lower faces ofthe tiles and the front edges ofthe upper web members of the ventilator units.

In the Figure 11 roof structure, the ventilator units have fixing members such as screws driven into the fixing apertures in the lowerweb member3, and when the units are pushed onto the still wet mortar 18 these screws become embedded so that when the mortar sets, the ventilator units are firmly fixed. The fixing screws 19 may not be necessary since the wet mortar may ooze through the fixing apertures 1 Oto provide a sufficient key when set.

In the arrangementshown in Figure 12,a row of ventilator units fills the gap 20 between the outerface of the upper course of brickwork and the innerface of a facia board 21 fixed to the outer edge of a roof boarding structure 22 in a horizontal, flat roofing arrangement. Here the ventilating units are fixed in the facia board by suitable fixing members, in this case screws 23 before the facia board is fixed to the roof boarding. Battens 24 are then fixed to the upper outer edge of the facia board and the felt roofing 27 laid across the roof boarding to project downwardly over the edge of the battens 24.

It will be seen that in all of the structures of Figures 10 to 12, the arrangement of ventilator units according to the invention are positioned to allowthe passage of ventilating air into the roof space in the direction of the arrows shown. This passage of air occurs by natural convection and air movement in the region of the eaves of the roof structure and reduces the risk of condensation occurring in the roof space.

The ventilator units of the above described embodiments, and in particularthose of Figure 6, and Figures 7to 9 can be readily made by moulding from plastics material. The embodiments of Figures 6 and 7 to 9 can in this way be integ rally formed with the ribs or fins 8.

The shape ofthe unit may be adapted so as to facilitate removal of the unitfromthe mold. For example, itwill be seen from Figures 8 and 9 thatthe upper and lower web members 2 and 3 may beformed with a thickness which reducesslightlyfrom the rearto the front edge; also,the upperface of the upper web member and the lowerface ofthe lower web member may converge slightly, again from the rear edges to the front edges.

These adaptations would facilitate the removal ofthe unitfrom a mould inthedirectionAasshown in Figure 8.

Although the primary intended use forthe ventilator is, as described above, to ventiiate roof spaces, it is envisaged thatthey can be used in otherwaysto provide ventilation. For example, a number of the units could be stacked one on top of anotherto provide a ventilatorfor a larger rectangular aperture of the type where an air brick would normally be used.

Also, a rowofthe units could be provided at the base ofthe outer cladding of the walls of a building built in accordancewiththe modern "timber-frame" method of construction. It has been found that in this type of construction condensation tends to occur within the timber frame units, which are lined on the outside with impervious plastics sheeting, and thatthis condensation causes rotting of the timber. A row ofthe ventilator units according to the present invention built into the outer cladding atthe base of a wall adjacent a horizontal elongate slot cut in the outer sheet lining of the timberframewould inhibit th is condensation by providing forairflowthroughthe cladding and intothetimberframe units.

The material from which the units are constructed is preferably a flame retardant polypropylene.

The comparatively short length ofthe above described ventilator units confers positive adavantages in that it avoids problems of overall expansion, and it facilitates easy handling for installation.

Claims (33)

1. A ventilator device for use in ventilating roof spaces in buildings, the device comprising an elongate unitfor installation in a generally horizontal position atthe eaves of a roof and having upper and lower rigid elongate generally parallel members defining therebetween an elongate slotforthetransverse passage of airthrough the unit, and spacer means supporting said upper and lower members in their spaced-apart condition, means being provided to extend along and across said slot to provide a multiplicity of discrete ventilating apertures for conveying into the spaceairflowing into said elongate slot.

2. Aventilator unit according to claim 1 wherein said upperand lower members comprise respective elongate web members spaced apart in a generally parallel mutual dispostion by said spacer means.

3. Aventilator unit according to claim 1 or claim 2 wherein said upper and lower members each have corresponding forward and rear elongate parallel edges and wherein the arrangement is such that with the unit disposed with the lower member in a generally horizontal plane, the forward edge of the upper member projects forwardly ofthe corresponding forward edge of the lower member.

4. A ventilator unit according to any preceding claim wherein the unit is formed with respective end spacer members extending between the upper and lowermembersto definetheendsoftheventilating slot.

5. Aventilating unit according to claim 4wherein a forward edge portion of the upper member projects forwardly beyond the point at each end of the unit were a generally upright forward edge ofthe respective end member adjoint the upper member.

6. Aventilator unitaccording to claim 4wherein at each end of the unit the end member has a forward inclined edge extending between the corresponding ends oftheforward edges ofthe upper and lower members.

7. Aventilatorunitaccordingto any preceding claim wherein said multiplicity of apertures are formed by an elongate gauze strip extending across said slot.

8. Aventilator unit according to claim 7wherein said gauze strip is fixed across the rear face ofthe unit.

9. Aventilator unit according to any of claims 1 to 6 wherein there are provided a multiplicity of parallel spacer elements extending across said aperture between the upper and lower members, said spacer elements being substantially regularly spaced along the unit to define a multiplicity of slit-like said apertures.

10. Aventilator unit according to any preceding claim wherein the lower member is adapted to be fixed to a ventilator support component.

11. Aventilator unit according to claim 10 wherein said lower member is formed with a plurality of longitudinatlyspaced apertures in which fixing members may be secured.

12. Aventilator unit according to claim 11 wherein the uppermember isformed with fixing apertures corresponding to and vertically registered with the fixing apertures ofthe lowermemberso asto permit the unit to be fixed to the support component by elongate fixing members passing through the respective pairs of apertures.

13. Aventilator unit according to claim 12 wherein atthe longitudinal positions of a said corresponding pair of apertures in said upper and lower members, strengthening ribs, constituting said spacer means, are provided in pairs, one on either side of the position of said fixing members, for increased strength.

14. Aventilator unit according to any preceding claim wherein the upper member is formed with an elongate groove extending along the unit and forming a strip portion of said upper member with reduced thickness for accommodating fixing elements driven into said uppermemberforfixing another component tothe unit.

15. Aventilatorunitaccording to any preceding claim integrally molded from flame retardant polypropylene.

16. Aventilator unit according to any preceding claim wherein the length ofthe unit is approximately 200 mm.

17. Aventilator unit according to any of claims 1 to 15 wherein the length of the unit is approximately 600 mm.

18. Aventilator unit according to claim 16 or claim 17 wherein the width of the unit is approximately 25 mm.

19. Asystemforventilating a roof space, the system comprising a row of elongate ventilator units fixed and mutually aligned at the eaves ofthe roof, each unit defining an elongate ventilating slotforthe passage of air into the roof space via the eaves, and having means extending across the slot and providing a multiplicity of ventilating apertures th rough which the ventilating air passing into the slotwill flow.

20. Asystemaccordingtoclaim 19forventilating the roof space in a tiled, pitched roof, wherein the row of ventilator units are mounted on a support component, and themselves support an outer row of roof tiles, the ventilating slots together constituting a composite slot between said support component and said course of tiles forthe flow of air into the roof space.

21. Asystem according to claim 20 wherein said support component is an elongate, horizontally extending, vertically disposed facia board spaced outwardly of an outerwall surface beneath the roof structure, a horizontally disposed soffite extending, at a level beneath the level of said ventilator unit, between said facia board and said outer wall surface.

22. Aventilating system according to claim 20 wherein said supporting component is the upper edge of an outerwall overwhichthe roof projects.

23. Aventilating system according to claim 22 wherein said ventilator units arefixed to said upper edge by a layer of cementitious material, and an outer course of tiles is supported by said unit.

24. Asystem according to claim 20 or claim 23 wherein the outer edge portion of roof sheet material extends overthe row of ventilator units and is held in place by the weight of the tiles.

25. A system accordingtoclaim 24 wherein each unit comprises an upper and a lower generally horizontal web member, the forward edge ofthe upper member projecting outwardly over the corresponding edgeofthe lowermembersoasto prevent the part of the roof lining disposed outwardly of said row of units from fully shutting said ventilation slots.

26. A method of ventilating a roof space in a building comprising at the eaves ofthe roof structure a row of aligned, elongate ventilator units each providing a ventilation slotforthethrough flow of ventilating air into the roof space via the roof eaves, each unit being provided with means extending across its ventilating slot to define a multiplicity of ventilating apertures through which the ventilating air must pass so as to exclude entry of birds and animals into the roof space.

27. A roofventilatorsubstantially as herein before described with reference to Figures 1 to 5 ofthe accompanying drawings.

28. A roof ventilator substantially as herein before described with reference to Figure 6 of the accompanying drawings.

29. A roof ventilator substantially as hereinbefore described with reference to Figures 7 to 9 of the accompanying drawings.

30. A roof ventilator used in a ventilation system substantially as hereinbefore described with refer -ence to Figure 10 ofthe accompanying drawings.

31. A roof ventilator used in a ventilating system substantially as hereinbefore described with referenceto Figure 11 ofthe accompanying drawings.

32. A roof ventilator used in a ventilation system substantially as hereinbefore described with refer ence to Figure 12 of the accompanying drawings.

33. Aventilator device substantially as hereinbefore described with reference to Figure 13 ofthe accompanying drawings.