CONSTRUCTIONAL ELEMENT

Abstract: A constructional element in the form of a roofing panel or board (10) has insulation material (15) such as foam in the interior thereof between oppositely facing first and second faces (11, 12). Retention means, for example channel-section bars (16), are held in position in the insulation material (15), for the reception, in use, of fixing screws (20) to fix a waterproof layer (19) to one of the faces (11, 12), each fastened screw terminating in the interior of the insulation material (15) so as not to extend through the other of the faces. The retention means are such as to distribute therethrough any load on the fixing screws attempting to release them.

Description: CONSTRUCTIONAL ELEMENT This invention relates to a constructional element, particularly in the form of a panel or board for use in the construction industry. In the construction industry roofing structures are known which comprise an inner roof deck at the outer side of which is disposed an insulation board. Commonly a vapour control layer is sandwiched between the roof deck and the insulation panel, the layer being fixed on site, and adhesively bonded at its respective opposite sides to said deck and said panel. With this form of roofing arrangement the insulation board is the outermost element of the construction, and to protect it against the weather, a waterproofing membrane is fixed to the outer side of the board. This is effected either by adhesive bonding, or by mechanical fixing through to the roof deck. As far as mechanical fixings are concerned, it can, in many cases, be uneconomic, impractical or undesirable to use such fixings, in that they are: i) specialised for the application, expensive and potentially/possibly of great length (the deck may be unsuitable). ii) time consuming to apply on site, e.g. into dense concrete. iii) only able to fix by puncturing the vapour control layer. An object of the invention is to provide a constructional element which enables mechanical fixings to be used to secure a member, such as a membrane, thereto in an efficient manner. According to the invention a constructional element comprises oppositely facing first and second faces, insulation material in fixed position between said first and second faces, and retention means between said first and second faces, being held in position by said insulation material, said retention means being for the reception and retention, in use, of fixing means to fix a member to a face of the element, with the retention means being such as to distribute therethrough any load/force attempting to release the fixing means. Preferably the retention means is an elongated bar, for example of channel-section, embedded in said insulation material. Conveniently the bar is metallic, for example steel, but it could be of plastics material. The invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a partly cut away, perspective view of a constructional element of the invention with a membrane shown fixed thereto, and Figure 2 is an enlarged view of the cut-away area of the element of Figure 1 , with a further portion of the element cut away, and the membrane not shown. Figure 1 shows one embodiment of a constructional element of the invention, in the form of a roof insulation board 10 of rectangular form. As with conventional boards of this type, the board has respective first and second oppositely directed faces 1 1 , 12 which are intended to form, in use, inner and outer sides of the board. Although the board illustrated is of composite form, with one of the faces being defined on a member which contributes considerable depth to the board, as will be described, its faces 1 1 , 12, can alternatively be formed by identical facing sheets or equivalent thin members. The composite board illustrated has its face 1 1 defined by a relatively thin inside material layer 13, whilst its face 12 is defined by a thicker outside material board 14. However the invention does not relate to the nature or number of the layers/boards which make up the composite board 10, but more to the interior construction between said members. As shown in the drawings, there is between the layers 13 and 14 a continuous layer 15 of foamed insulation material such as polyurethane foam. Although shown as a single 'block', this insulation layer 15 can be made up of a series of abutting elongate foamed inserts or blocks of square or rectangular cross-section extending, in the embodiment illustrated, parallel to the shorter sides of the board. Within the insulation layer 15 is embedded a number of mechanical fixing retention means. In the embodiment illustrated, the fixing means are in the form of steel bars, one of which is shown at 16 in the cutaway area of the board shown in Figures 1 and 2. The bars need not be steel and could thus be of any other suitable metallic construction. The use of wooden bars is also possible. In fact the retention means could be other than bars, and could, in some instances be of plastics material. Thus in addition to plastics material channel-sections, or other plastics material forms which are not fully flexible, it would be possible to use perforated metal sheet or plate. Fully flexible metal or plastics material forms which could be rolled up in the manner of a sheet would not be suitable, since, as will be explained, such forms would not, in use, satisfactorily distribute therethrough fixing means pull-out load, due to their lack of sufficient rigidity. In the board illustrated, a number of parallel, spaced, normally equi- spaced, such bars 16 can be provided, these extending parallel to either the longer or shorter sides of the board as required. As shown in the Figures, the bar 16 can be of inverted rectangular externally lipped- channel section, namely of top hat form, a lip being denoted by numeral 1 7. The bar is completely embedded in, and thus fixed in position by, the insulation material, which itself, firmly bonds with each of the layers 13 and 14 and thus is also itself firmly fixed in position. However as explained, the insulation could be formed by abutting lengths of insulation material, but here these would still tightly engage and encompass each bar, with material sandwiching the lips 17 therebetween and normally extending into the channel-section. It will be appreciated that various other forms of cross-section could be provided for the bars, such as a non-lipped channel section, and additionally, as will be described, instead of the retention means being continuous, a number of separate, discrete spaced elements could be embedded in the same manner, along a line parallel to either the longer or shorter sides of the board as described. The retention means would normally lie centrally within the board, i.e. mid-way between the faces 1 1 , 12, or mid-way between opposite faces of the foam layer of the board. The retention means would normally be accurately positioned. Markings 18, to be described, show the disposition of the retention means. One object of providing the retention means within the roof insulation board is to enable convenient fixing of a waterproofing element 19, i.e. a felt sheet, at the outer face 12 of the board in the manner of the prior art referred to. However by providing mechanical fixing retention means within the insulation board, it will be appreciated that it is no longer necessary for the mechanical fixings to extend into the roof deck. This has several advantages. Firstly it is unlikely that the mechanical fixing means will now need to be specialised for each particular application. Secondly the fixing means can now be shorter in that they do not have to penetrate down into the deck. Thirdly the fixing means will take less time to apply, particularly in that they do now not have to penetrate into concrete or equivalent. Finally as the fixing means/fixings do not pass out of the insulation board, there is no puncturing of the vapour control layer which, with prior art constructions, leads to destruction of the vapour control for which the layer is actually provided. The mechanical fixings would normally be conventional headed screws 20, the screw head, for example, engaging a fixing plate 21 or washer on the waterproof layer 19 to hold the layer tightly down onto the surface 1 1 or 12 of the board. The plate/washer 21 may however be optional. The fixing could alternatively comprise a conventionally screwed shank together with an integral extension part, for example to retain something other than a sheet, such as a pipe or the like. Figure 1 shows, in phantom, markings 18 in the form of lines on the outer surface 12 of the board, which lines correspond to the sides of the channel defined by each bar, so that a user can readily ascertain where the retention means are located within the boards and can thus, in use, fix the waterproofing layer 19 to this outer side surface 12 by means of mechanical fixing elements, e.g. said screws 20, passing through the outside board 14 and into the base of the inverted channel-section provided by the bar 16. Normally the fixing elements would be such that they would have their respective ends received into the bar 16 as a tight secure fit thereby retaining the fully tightened fixing element in position so as securely to fix the waterproofing membrane to the outer side surface 12, with each fixing element having its end terminating inside the composite board 10, so as not to pass therethrough and puncture the vapour control layer. Of course the lines 18 could also or instead be provided on surface 1 1 , and the board 10 used with fixings passing into it initially through the layer 13. As described, it will be appreciated that the fixings can be inserted into the board at any position along the length of the bar as indicated by the markings 18. However, as described, the bar or equivalent retention means could be discontinuous, and the discrete retention means could be other than linearly aligned. Appropriate markings could still however be provided, or alternatively the spacings of the retention means could be determined and known for each board so that it would be relatively straightforward to calculate where a waterproofing membrane or the like should be fixed. Instead of a plain retention surface being provided to engage each fixing element, pre-formed fixing positions could be provided along the length of a bar, or in each separate spaced discrete retention means provided in a line across the board. Again, however, it may be desirable/necessary to provide indications on the face of the board as to where said pre-formed fixing positions are disposed. These markings can be in addition to those showing the retention means themselves. Although as shown, the uppermost base of the bar is substantially flush with the inner surface of the board 14, this is only the arrangement for this illustrated embodiment, and in an alternative embodiment, even if the outer side is provided by a board rather than a layer such as 13, the upper surface of the bar could be covered with foam material. However it will be appreciated that what is required is that the retention means is fixed sufficiently securely in position between the inner and outer sides of the composite board 10 by means of the foam material, even though this may not encompass, enclose or surround all parts of the retention means in question. It will, for example, be appreciated, from Figure 2, that sufficient securement of the retention means might well be provided purely by the side lips 1 7 respectively being tightly embedded in the foamed material, with no foam extending into the channel-section, or being engaged against the outer surface of the base of the channel- section. The advantage of the retention means of the present invention is its ability to spread, and thus distribute through the retention means, any force/load which may be applied to inserted fixing means to try to release and/or remove them. As explained, an important application of a constructional element of the invention is at a roof deck, where a waterproof layer is fixed to the outer face of the board. Should any wind find its way underneath the waterproof layer it will tend to lift the layer, and thus a pull-out force/load will be exerted upon the fixing means i.e. the screws 20. With prior art arrangements fixing means have been used which merely have barbs to engage through mesh nets within a foamed insulation board. However such fixings can be regarded either as only temporary or as being unable permanently to resist wind forces or other pull-out loads. Even if screws are used with such mesh net constructions, resistance to pull-out loads is low. With the present invention the retention means are sufficiently inflexible so as spread/distribute any pull- out load/force applied to the fixing means engaged therewith. With plain bars, sheets and plates the screws cut a thread therein to provide a secure fixing, in contrast to the use of barbs. Where the bar, sheet or plate has a preformed fixing position therein, the screw would still tightly engage thereat, and with a perforated sheet the arrangement would be the same. Thus in all cases with the present invention the engagement of the fixing means is greatly improved over that of the prior art, so that with a suitably calculated spacing of fixing elements along the retention means, such as in Figure 1 , the layer 19 is held firmly in place and resists any wind load attempting to displace it. Additionally the fixing is unaffected by foot traffic on the board forming the roof. As with the arrangement described in relation to the prior art, the board would normally, in use, be adhesively secured at its face 1 1 to a vapour control layer, which itself, at its opposite side, would be adhesively secured to a roof deck or equivalent. However in some instances such a vapour control layer could be omitted. However even here the board would still be advantageous in providing for the use of fixing means which do not have to extend through and be engaged with the roof deck. Where a vapour control layer is to be provided, the inner side 1 1 would be adhesively compatible. With a board in general, a fixing could be made at each face 1 1 , 12, the fixing means at the respective opposite faces extending into the same or different retention means in the board. In addition to the fixing of a waterproof layer 19, a longer screw or other fixing could be used to fix another member on top of the layer 19, such as a second insulation board without such retention means therein. Thus the screw or other fixing would pass from the outer surface of the second board, through the second board, through the layer 19 and into the retention means in the first (inner) board 10. If necessary, dependent upon the type of mechanical fixings to be used, the bars 16 or equivalent may need to be positioned at pre-determined heights in the foam. The material forming the outer side surface 12 of the board can be rigid or flexible, for example plywood, rockfibre, aluminium foil or bituminous glassfibre tissue. Opposite interlocking sides of the board respectively can be provided, in a conventional manner, with tongues and grooves thereby ensuring a level joint between adjacent boards. At a roof, a row of such boards can be interlocked to provide a continuous line of fixing bars 16 by way of the markings 18 on the outer sides of the board faces, with, for example, the boards being staggered in adjacent rows. Although the retention means have been described as extending linearly, and parallel to one of the pairs of parallel sides of the board, it will be appreciated that the invention is also applicable to board shapes other than rectangular and that in addition the positioning of retention means could be more arbitrary and thus need not be in linear arrangements. However as mentioned above, it is clearly desirable for some marking of the position of each retention means to be provided. Although as shown in Figure 2, the bar 16 terminates short of the side edge of the board, the bar could instead terminate flush therewith and could thus be visible at at least one edge of the board. The advantage of terminating the bar short of said edge, is that the tongue and groove arrangement described can be provided with each board. It will be appreciated that provided that each retention means is fixed in or by foam between the upper and lower faces of the board, various parts of the board between fixing means, or away from a sole fixing means, need not be provided with insulation material. As used herein, the term 'insulation' includes insulation in relation to heat and also sound. The constructional element could take the form of a panel or equivalent instead of a board. The boards/panels can be produced by either a non-continuous or a continuous process. In an embodiment of one production method a foam block has one of its faces slotted and one or more inverted channel- section bars are engaged onto the one face with the arms of the channel received in the slots. A further foam block is then placed onto and secured to said face to form a composite foamed board. Required opposite outer facings can then be adhered to the two exterior faces of the board. In another embodiment the lipped channel section of the drawings is fitted between two foam blocks adhered together, the engaged faces of the blocks having respective projection and recess formations to be received in and receive the channel section, the channel lips 1 7 being tightly received between the engaged faces. In a continuous process, upper and lower board facings could be fed continuously at a required spacing apart to a location where two foam guns supply foam to the respective facing (inner) surfaces of said facings. Centrally between the facings is continuously fed the retention means, which is thus accurately positioned and secured in place as the foam hardens.

Claims: CLAIMS 1. A constructional element comprising oppositely facing first and second faces, insulation material in fixed position between said first and second faces, and retention means between said first and second faces, being held in position by said insulation material, said retention means being for the reception and retention, in use, of fixing means to fix a member to a face of the element, with the retention means being such as to distribute therethrough any load/force attempting to release the fixing means. 2. An element as claimed in Claim 1 , wherein the retention means has a plain surface with which it is intended that fixing means in the form of screws are received and retained by their cutting of a thread therein. 3. An element as claimed in Claim 1 , wherein the retention means has pre-formed fixing positions defined therein. 4. An element as claimed in any one of Claims 1 to 3, wherein at least one of said first and second faces carries markings to indicate the position within the element of the retention means and/or pre-formed fixing positions defined thereby. 5. An element as claimed in any one of the preceding claims, wherein the retention means is held in position between separate sections of said insulation material which engages said means. 6. An element as claimed in Claim 5, wherein the separate sections are respective blocks of foamed material. 7. An element as claimed in any one of Claims 1 to 4, wherein the retention means is held in position within an integral section of said insulation material. 8. An element as claimed in any one of the preceding claims, wherein the retention means is positioned mid-way or substantially midway between said first and second faces. 9. An element as claimed in any one of the preceding claims, wherein the retention means is a bar. 10. An element as claimed in Claim 9, wherein the bar is of channel-section. 1 1. An element as claimed in Claim 10, wherein the bar is of externally lipped channel-section. 12. An element as claimed in any one of Claims 9 to 12, wherein the bar is of metal. 13. An element as claimed in any of Claims 9 to 12, wherein the bar is of plastics material. 14. An element as claimed in any one of Claims 1 to 8, wherein the retention means is a sheet/plate. 15. An element as claimed in Claim 14, wherein the sheet/plate is perforated. 16. An element as claimed in Claim 15, wherein the sheet/plate is of metal. 1 7. An element as claimed in Claim 15, wherein the sheet/plate is of plastics material. 18. An element as claimed in any one of Claims 1 to 3, wherein the retention means extend continuously from one side or substantially from one side to an opposite side or substantially to an opposite side of the element. 19. An element as claimed in any one of Claims 1 to 13, wherein between opposite sides of the element a series of discrete, spaced retention means extend. 20. An element as claimed in Claim 19, wherein the series of retention means are arranged linearly. 21. An element as claimed in any one of the preceding claims when used with fixing means to fix said member to said face of the element. 22. An element as claimed in Claim 21 , wherein the or each fixing means extends through one only of said first and second faces. 23. An element as claimed in Claim 21 or Claim 22, wherein the or each fixing means is a screw. 24. An element as claimed in any one of Claims 1 to 8 or Claims 18, 19 and 21 when dependent upon any one of Claims 1 to 8, comprising metallic retention means. 25. An element as claimed in any one of Claims 1 to 8 or Claims 18, 19 and 21 when dependent upon any one of Claims 1 to 8, comprising retention means of plastics material. 26. An element as claimed in any one of Claims 1 to 1 1 , or Claims 14 and 15, or Claim 18, 19 and 21 when dependent upon any one of Claims 1 to 1 1 , comprising wooden retention means.

Inventors: NALBORCZYK STEFAN MARTIN, TURNER MICHAEL JAMES PAUL, NALBORCZYK, STEFAN, MARTIN, TURNER, MICHAEL, JAMES, PAUL
Applicants: GRADIENT INSULATIONS UK LTD, NALBORCZYK STEFAN MARTIN, TURNER MICHAEL JAMES PAUL, GRADIENT INSULATIONS (UK) LIMITED, NALBORCZYK, STEFAN, MARTIN, TURNER, MICHAEL, JAMES, PAUL
Application year: 1997
Main classification: E04B1
IPC codes: E04B1, E04B7