GB2147381A

GB2147381A - Building ventilation

Info

Publication number: GB2147381A
Application number: GB08418064A
Authority: GB
Inventors: Eli Abt; Malcolm Robert Driver
Original assignee: Individual
Current assignee: Individual
Priority date: 1983-07-14
Filing date: 1984-07-16
Publication date: 1985-05-09
Also published as: GB8418064D0

Abstract

A ventilator for incorporation in the above ground foundation wall of a building includes a duct (10) arranged to open to the ambient above ground level a vertical section (34) and a lower duct (18) which opens below a suspended ground floor of a building such as a house. The parts are interconnected by couplings (12) and (16) and the vertical section (14) may be of varying length. In another embodiment the ventilator is constructed of two parts, the vertical section varying in length by a telescoping action (Fig. 6). <IMAGE>

Description

SPECIFICATION Ventilators for building structures This invention relates to ventilators for building structures, especially for voids beneath the suspended ground floors of dwellings.

The construction of private dwellings for sale in the United Kingdom is regulated by the National House Building Council (NHBC).

Where the oversite infill under the ground floors of such dwellings is over 600 millimetres deep because the site slopes, or because of the need for extensive excavation, or for other reasons, NHBC Practice Note 6 requires the use of a suspended floor in all cases.

Even where oversite infill is less than 600 mms deep, suspended construction is widely recognised and used as a simple but effective way of avoiding damage to ground floors.

Such damage can arise from unsatisfactory infill, failure to remove all vegetable and compressible matter, inadequate compaction, settlement or expansion of the infill, acid and/or sulphate attack, or a combination of these factors.

On firm shrinkable clays, such as are to be found over most of South East England, ground floor failures are liable to arise from shrinkage or swelling of the clay, particularly in proximity to trees, hedges and heavy scrub (whether removed or remaining), high water tables and/or changes in site drainage. The use of suspended ground floor construction helps avoid such failures.

With the growing scarcity of prime building land on which in situ concrete floor slab construction is safe and suitable, increasing use is being made of suspended ground floors on difficult sites for example those previously occupied by old buildings, those which are based on fill material and those which suffer from water problems. Suspended ground floors also offer significant advantages in the increasingly important refurbishment and rehabilitation of the country's existing building stock.

By virtue of its economy, flexibility, elimination of wet trades, thermal efficiency, speed and simplicity of application in both new and existing buildings, precast concrete beam and block construction for suspended ground floors has largely superseded the use of timber and reinforced concrete, and now constitutes about 25% of ground floors of all new private dwellings constructed in the United Kingdom.

NHBC requirements for precast concrete suspended ground floors for dwellings are set out in Practice Note 11 and now include the need to ventilate the subfloor void in all cases, irrespective of ground conditions, proximity of gas services or similar considerations. Since internal ground floor levels should conveniently be as near external ground levels as possible, there is usually insufficient room to insert a conventional straight ventilator under the suspended floor to terminate above external ground level. The purpose of this invention is to provide a ventilator which enables external air entry to be at one of several possible different levels in relation to the air ventilation passage opening into the subfloor void.

According to the present invention there is provided a cranked vent for incorporation in the wall of a building at a level enabling ventilation of a space below the ground floor of the building, the vent comprising a first hollow portion with at least a part extending horizontally and defining at one end an opening lying in a substantially vertical plane and defining at the other end a downwardly-facing opening lying in a substantially horizontal plane, a second hollow portion with at least a part extending horizontally and defining at one end an opening lying in a substantially vertical plane and defining at the other end an upwardly-facing opening lying in a substantially horizontal plane, and hollow extension means enabling the vertical spacing of the openings in substantially horizontal planes to be spaced by an adjustable distance from one another whereby, when installed, irrespective of local variation in soil level and/or the depth of the ground floor structure the opening in a vertical plane of the first hollow portion is above soil level and the opening in a vertical plane of the second hollow portion opens into said space below the ground floor.

Further according to the present invention there is provided a cranked vent for incorporation in the wall of a building at a level enabling ventilation of a space below the ground floor of the building, the vent comprising a first hollow portion with a part extending horizontally and defining at one end an opening lying in a substantially vertical plane, and with at the other end a vertically extending part defining at the lower end a downwardlyfacing opening lying in a substantially horizontal plane, and comprising a second hollow portion with a part extending horizontally and defining at one end an opening lying in a substantially vertical plane, and with at the other end a vertically extending part defining at the upper end an upwardly-facing opening lying in a substantially horizontal plane, the vertically extending parts together serving as hollow extension means enabling, in a telescopic manner, the vertical spacing of the openings in substantially horizontal planes to be spaced by an adjustable distance from one another, whereby, when installed, irrespective of local variation in soil level and/or the depth of the ground floor structure the opening in a vertical plane of the first hollow portion is above soil level and the opening in a vertical plane of the second hollow portion opens into said space below the ground floor.

Still further according to the present invention there is provided a cranked vent for incorporation in the wall of a building at a level enabling ventilation of a space below the ground floor of the building, the vent comprising a first hollow portion with at least a part extending horizontally and defining at one end an opening lying in a substantially vertical plane and defining at the other end a downwardly-facing opening lying in a substantially horizontal plane, and with a coupling member fitted in the downwardly-facing opening, a second hollow portion with at least a part extending horizontally and defining at one end an oening lying in a substantially vertical plane and defining at the other end an upwardly-facing opening lying in a substantially horizontal plane, and with a coupling member fitted in the upwardly-facing opening, and hollow extension means of selected different lengths co-operating with the coupling members of the first and second hollow portions thus enabling the vertical spacing of the openings in substantially horizontal planes to be spaced by an adjustable distance from one another whereby, when installed, irrespective of local variation in soil level and/or the depth of the ground floor structure the opening in a vertical plane of the first hollow portion is above the soil level and the opening in a vertical plane of the second hollow portion opens into said space below the ground floor.

Ventilators embodying the invention will now be described, by way of example only, with reference to the accompanying diagrammatic drawings, in which: Figure 1 is an exploded isometric view of a first embodiment of ventilator in accordance with the invention; Figure 2 is a fragmentary vertical section on the line 2-2 of Fig. 3 of a cavity wall construction incorporating a ventilator as illustrated in Figure 1; Figure 3 is a section on the line 3-3 of Figure 2; Figure 4 is a scrap view illustrating an alternative to a part of the construction of Figures 1, 2 and 3; Figure 5 is a vertical section on the line 5-5 of Figure 6, of a second embodiment of cranked ventilator; Figure 6 is a section on the line 6-6 of Figure 5.

Figure 7 is an elevation of a first part of a two-portion embodiment of vent; Figure 8 is a side elevation of the portion illustrated in Fig. 7; Figure 9 is a section on the line 9-9 of Fig 7; Figure 10 is an elevation of the second portion of the third embodiment; Figure 11 is a side elevation of the second portion; Figure 11A is a scrap section on the line 1 1A-1 1A of Figure 11; Figure 11 B is a scrap section on the line 11 B-1 1 B of Figure 9; Figure 12 is a section on the line 12-12 of Fig 10; Figure 13 is a composite section on the line 9-9 of Figure 7 and 12-12 of Fig 10 but showing a modification.

Figure 14 is an elevation of a first modification of an upper portion of the vent of the third embodiment: Figure 15 is a section on the line 15-15 of Figure 14; Figure 16 is an external side elevation of the duct or hollow portion illustrated in Figure 14; Figure 17 is an elevation of a second modification of an upper portion of the vent of the third embodiment; Figure 18 is a section on the line 18-18 of Figure 17; Figure 19 is an external side elevation of the duct or hollow portion illustrated in Figure 1 7; Figure 20 is a longitudinal second of the cranked vent of the second modification of the third embodiment as installed in a cavity wall.

Referring first to Figures 1 to 3, one cranked ventilator embodying the invention comprises a first hollow portion 10 defining an opening to the ambient above soil level, an upper coupling member 12, a hollow extension piece 14 which can be selected to have various lengths, normally multiples of the depth of a course of bricks, a lower coupling member 16 and a second hollow portion 18 defining an opening into the gap between a timber or precast concrete ground floor and the ground. As illustrated, all five components listed define a rectangular section passage, the hollow portions 10, 18 each having an opening lying, as installed, in substantially vertical planes and also each having openings lying in substantially horizontal planes. The coupling members 12, 16 and extension piece 14 together enabling the openings in horizontal planes to be spaced by considerable distances.

Considering now the details, the hollow portion 10 defining an opening to the ambient takes the form of a rectangular, horizontally-extending duct portion of plastics material and an inner end part which has a plurality of external ribs 20 integral with the material of the duct itself and these act, when installed as shown in Figure 2, as a water baffle so that any water which passes down the cavity will not automatically penetrate into the inner or outer skin of the brickwork but will trickle down the ribs and the channels defined between them thus minimising the risk of causing dampness. As best illustrated in Figure 2 serrations 24 preferably at Smm spacings are provided and these act both as a guide for cutting the duct to suit the selected external air brick 26 and also act as keys for the mortar layers surrounding the duct surface.

The outer end of the hollow duct portion 10 will accommodate the air brick 26 which may be a proprietory terracotta air brick as illustrated in Figure 4 or made of plastics as illustrated in Figure 2. Both forms of air brick have sloping leaves 28 which help to reduce the ingress of water.

The ribbed inner end part of the hollow portion 10 which, as installed, lies within the cavity 22 of the wall has a downwardly-facing opening which accommodates and is a tightfit in relation to the upper coupling member 12 which serves additionally to check the ingress of any water which may have penetrated through the air brick provided, of course, that the joint is sealed. The coupling member 12 has a circumferential rib 30, each vertical end surface of which has three small ribs 32 which when assembled align themselves with the three ribs 20 of the upper hollow portion 10.

The extension piece 14, which is engaged by a lower part of the upper coupling member 12 has a length dependent upon the number of courses of brickwork which it is intended that the ventilator should span in a vertical direction. As with the coupling member 12, the extension piece 14 also has ribs 34 which align with the ribs 20 of the upper duct 10. A further, identical coupling member 16 is engaged in the lower end of the extension piece 14 and in turn this engages in an upwardlyfacing opening 36 lying in a horizontal plane of the hollow portion 18 defining an opening lying in a vertical plane to the interior gap below the flooring.

The lower opening defining means or horizontal duct portion 18, termed a 'shoe', generally corresponds to the upper hollow portion 10 and has ribs 38 at the end faces which once again align with the ribs 20 of the upper duct portion. Any moisture will drip off the ends of these lower ribs or channels in preference to running into the adjacent brickwork. The ribs 38 are continued on the underface of the hollow portion 18. Again, as for the upper hollow portion 10, serrations 40 are provided on the upper and lower surfaces for precisely the same purpose. A grill 42 may be provided at the final opening into the gap below the flooring to prevent the passage of vermin and if chosen to be sufficiently fine will also prevent the passage of insect life.

It will be apparent that the cranked ventilator in accordance with this embodiment provides for flexibility in use both as to size and manner of installation.

Turning now to the embodiment illustrated in Figures 5 and 6 in which like parts are given the same reference numerals but with the addition of a prime, the upper horizontal duct or hollow portion 101 is provided with internal ribs 44 which act as a water check and a single extension piece 141 is provided of rectangular section which fits over a downwardly-extending, coupling part 48 of the upper duct portion. Similarly the lower duct horizontal portion 1 81 has an integral upwardly-extending connecting part 50 which receives on its outer surface the lower end of the extension piece 14'. As with the first embodiment, the extension piece 14' will be provided in different lengths.

The modified construction involves fewer components and therefore will be more economical to produce and moreover omits the ribs which act as water baffles. The latter, however, can be incorporated if desired.

Referring now to the crank-vent assembly illustrated in Figures 7-12 and embodying the invention, it will be immediately apparent that only two moulded components, preferably of polypropylene, are employed which substantially simplifies manufacture and reduces costs without sacrificing the adjustability provided by the first two embodiments. Broadly, the component illustrated in Figures 7 to 9 forms an upper portion 60 of the assembly and includes a duct or hollow part 62 extending horizontally and having an opening 64 in a vertical plane which, when installed, will lie adjacent to or be directly connected to an air brick (not shown). The air brick may be as illustrated in connection with the first or second embodiment.The component illustrated in Figures 10 to 12 forms the lower portion 80 of the assembly and includes a horizontally-extending duct or hollow part 82 terminating at an opening 84 lying in a vertical plane (as installed) and intended to communicate with space lying between the floor structure of a building and the ground.

In more detail, the upper portion 60 is of 'L' shape and includes the horizontally-extending duct or hollow part 62 and a verticallyextending duct or communicating part 66, the latter terminating at its lower end in an opening 68 lying in a horizontal plane. The two parts 62, 66 are at right angles to one another.

As in the first embodiment, external ribs 70 are provided which serve to reinforce the material of the moulding and also these ribs act as water barriers. On the horizontallyextending part 62, the ribs 72 are of lesser depth than those of the vertically-extending portion. These ribs serve to increase keying to the mortar of the brickwork. Internally at the junction between the horizontally-extending part 62 and the vertically-extending communicating part 66 there is an upstanding ridge 74 which serves as a barrier against ingress of water to the vertical part 66 of the upper portion of the vent.

The lower portion 80 of the vent of the third embodiment is generally similar to the upper portion and as will be understood the vertically-extending communicating part 86 is of slightly smaller external dimensions than the internal dimensions of the vertically-extending communicating part 66 of the upper portion. This enables telescopic action and in order to ensure smooth sliding, in a modification the contacting surfaces may be reduced by providing an internal rib and groove in corresponding side walls of the vertically-extending parts 66, 68 of each portion. This modification is not illustrated.

The lower portion also has the duct or hollow part 82 extending horizontally which is approximately twice the length of the corresponding part of the upper portion because it will not normally co-operate with an air-brick or similar component. In order further to prevent the ingress of water to the space below the ground floor of the building an internal ridge 88 is provided at the junction between the vertically and horizontally extending parts 82,86, and as for the upper portion comparatively deep ribs 90 are provided on the external surface of the vertical communicating part and comparatively shallow ribs 92 are provided on the horizontally-extending hollow part. The latter serve only to assist keying to the mortar of the brickwork of the building structure.To assist in the initial assembly of the two portions the vertically-extending part 86 is chamfered at its upper edge as shown at 94.

In order to limit the telescopic action of the two portions, as shown in Figures 11A and 11 B, a recess 89 is provided in the outer surface of each side wall of the vertical part of the lower portion.

Just below the recess 89 a transverse groove 93 is provided and this co-operates at the maximum extension of the vent with a ridge 95 at the lowermost internal end edge of the vertical part of the upper portion. The recess 89 is located just below the upper, chamfered edge 94 of the lower portion of the vent and at its lower end the recess is itself chamfered at 97, whereas at the upper end it is sharply defined. It will be readily apparent that interengagement of the recess 89 and of the groove 93 and the ridge 95 will ensure that total disengagement of the portions is impossible, and two distinct locations are predetermined.

Referring now to Figure 13, the modification illustrated is applicable to all three embodiments and is intended to take into account the fact that during the building of a cavity wall, an appreciable amount of mortar is dropped by bricklayers and when it has accumulated on the upper surface of the horizontal part of the vent, the mortar will form a cold and moisture bridge. The modification avoids this problem by incorporating a haunch or inverted V section ridge 96. Aortar droppings will accumulate on either side but the haunch itself, being of impermeable plastics, will prevent the transmission of moisture and heat/cold. If a large quantity of mortar is expected the apex of the haunch can be extended by a vertically-extending strip 98 (broken lines).

Referring now to Figures 14 to 16, only the upper portion is illustrated of a first modification of the third embodiment. The general arrangement is identical to the upper portion as illustrated in Figures 7,8 and 9 and like parts have been given the same reference numerals. The objective of this modification is the same as for the modification illustrated in Figure 13 and also to facilitate engagement of the upper horizontal part 62 with an air brick 26. The upper horizontal part 62 has an inclined rib 100 and this forms a junction with an extension 102 of one wall of the vertical part 66. The rib 100 and extension 102 together minimize the risk of bridging the cavity with mortar droppings which inevitably arise during building.

To facilitate engagement with the air brick 26, the horizontal part 62 is prolonged at its upper wall by an extension 104 of the upper wall which forms a step 106 against which one edge of an air-brick can engage. The side walls of the horizontal part are also provided with extensions 108 also defining steps 110 and extensions 108 terminate at inclined edges 112. The extensions 104 and 108 together ensure accurate location of an air brick. The inclined edges 112 preferably lie at 25 to the vertical and the steps 106,110 have sufficient depth to ensure that an air brick can properly engage and be accurately located when in situ. Although the details differ, the assembled arrangement of this modification is apparent from Figure 20.

In Figures 17 to 19, the extensions which aid location of an airbrick 26 remain the same as in Figures 14 to 16 and will not be further described. In this modification, mortar droppings are accommodated by a V-section recess 114 in conjunction with a vertical extension 11 6 of one vertical wall of the part 66.

The incorporation of this modification in a cavity wall is apparent from Figure 20.

Claims

1. A cranked vent for incorporation in the wall of a building at a level enabling ventilation of a space below the ground floor of the building, the vent comprising a first hollow portion with at least a part extending horizontally and defining at one end an opening lying in a substantially vertical plane and defining at the other end a downwardly-facing opening lying in a substantially horizontal plane, a second hollow portion with at least a part extending horizontally and defining at one end an opening lying in a substantially vertical plane and defining at the other end an upwardly-facing opening lying in a substantiallV horizontal plane, and hollow extension means enabling the vertical spacing of the openings in substantially horizontal planes to be spaced by an adjustable distance from one another, whereby, when installed, irrespective of local variation in soil level and/or the depth of the ground floor structure the opening in a vertical plane of the first hollow portion is above soil level and the opening in a vertical plane of the second hollow portion opens into said space below the ground floor.

2. A cranked vent for incorporation in the wall of a building at a level enabling ventilation of a space below the ground floor of the building, the vent comprising a first hollow portion with a part extending horizontally and defining at one end an opening lying in a substantially vertical plane, and with at the other end a vertically extending part defining at the lower end a downwardly-facing opening lying in a substantially horizontal plane, and comprising a second hollow portion with a part extending horizontally and defining at one end an opening lying in a substantially vertical plane and with at the other end a vertically extending part defining at the upper end an upwardly-facing opening lying in a substantially horizontal plane, the vertically extending parts together serving as hollow extension means enabling, in a telescopic manner, the vertical spacing of the openings in substantially horizontal planes to be spaced by an adjustable distance from one another, whereby, when installed, irrespective of local variation in soil level and/or the depth of the ground floor structure the opening in a vertical plane of the first hollow portion is above soil level and the opening in a vertical plane of the second hollow portion opens into said space below the ground floor.

3. A cranked vent for incorporation in the wall of a building at a level enabling ventilation of a space below the ground floor of the building, the vent comprising a first hollow portion with a part extending horizontally and defining at one end an opening lying in a substantially vertical plane and defining at the other end a downwardly-facing opening lying in a substantially horizontal plane, and with a coupling member fitted in the downwardlyfacing opening, a second hollow portion with at least a part extending horizontally and defining at the other end an upwardly-facing opening lying in a substantially horizontal plane, and with a coupling member fitted in the upwardly-facing opening and hollow extension means of selected different lengths cooperating with the coupling members of the first and second hollow portions thus enabling the vertical spacing of the openings in substantially horizontal planes to be spaced by an adjustable distance from one another whereby, when installed, irrespective of local variation in soil level and/or the depth of the ground floor structure the opening in a vertical plane of the first hollow portion is above soil level and the opening in a vertical plane of the second hollow portion opens into said space below the ground floor.

4. A cranked vent according to any one of claims 1 to 3 wherein vertically-extending ribs are provided externally of the said horizontal portions and said hollow extension means, the ribs being intended to prevent passage of water across the vent.

5. A cranked vent according to any one of claims 1 to 4, wherein each horizontal part and the hollow extension means are of rectangular section.

6. A cranked vent according to claim 2 wherein each horizontal part has ribs which serve to assist keying to mortar when installed.

7. A cranked vent according to any one of claims 1 to 6 wherein at least one internal ridge is provided within the vent to prevent flow of incoming water to the interior of a building.

8. A cranked vent according to any one of claims 1 to 7 wherein the components are of moulded plastics.

9. A cranked vent according to claim 2 wherein the vertically-extending part and the horizontally-extending part of the first hollow portion lie at right angles to one another and the vertically-extending part and the horizontally-extending part of the second hollow portion lie at right-angles to one another.

10. A cranked vent according to any one of the preceding claims, further comprising on said horizontally-extending part of the first hollow portion, a deflector capable of forming a barrier, when installed to the transmission of moisture through any mortar which may accumulate on the upper surface of said part during building.

11. A cranked vent according to any one of claims 2 to 10, comprising means on the vertically-extending parts of the two portions which serve to limit the telescopic action whereby to prevent the two portions becoming disassembled.

12. A cranked vent according to claim 10 or claim 11 wherein the barrier comprises an inclined rib extending from the uppermost wall of the horizontal part of the upper portion and an extension of one vertical wall of the vertical part of the upper portion.

13. A cranked vent according to claim 10 wherein the barrier comprises a recess of Vsection in the uppermost wall of the horizontal part and an extension of one vertical wall of the vertical part of the upper portion.

14. A cranked vent according to any one of the preceding claims comprising location means on the upper horizontal part of the upper portion of the vent.

15. A cranked vent according to claim 14, wherein the location means comprises extensions of three walls of the horizontal part of the upper portion, two of the extensions being from side walls of the horizontal part and having edges inclined to the vertical and the third extension being from the upper wall of the horizontal part.

16. A cranked vent substantially as hereinbefore described with reference to Figures 1 to 4, Figures 5 and 6 or Figures 7 to 12 of the accompanying drawings.