GB2508281A

GB2508281A - A coping system for the top of a wall

Info

Publication number: GB2508281A
Application number: GB201317527A
Authority: GB
Inventors: Colin Eric Mason
Original assignee: CJM DEVELOPMENTS Ltd
Current assignee: CJM DEVELOPMENTS Ltd
Priority date: 2012-10-05
Filing date: 2013-10-03
Publication date: 2014-05-28
Also published as: EP2696022B1; EP2696022A1; GB201317527D0; GB201217886D0; GB2495225A

Abstract

A coping system for capping the top of a wall having an external face that is having insulation applied thereto, the coping system comprising a support 200 and a pair of extrusions 199, each extrusion having a length and a consistent cross section along the length, the cross section comprising an elongate arm 206 terminating in a hollow portion 207 and a distal end distal from the hollow portion 207, the support 200 being provided with a pair of sockets 205, each socket 205 receiving the distal end of one extrusion 199. The extrusions may be manufactured from uPVC. The elongate arm 206 may be provided with spaced apart weak points 208 to allow its length to be shortened. Each socket 205 may have ridges 209 which are complimentary to the weak points. The support 200 may have a fixing portion in the form a base 201 positioned on the flat top of the wall and a spacer 204 arranged to space the socket from the fixing portion. A sealing cap 220 may be provided on top of the support 200. Also disclosed is a window sill extension member.

Description

I

WINDOWSILL EXTENSIONS AND COPING SYSTEM

This invention relates to windowsill extensions, such as (non-exclusively) oversill or undersills typically but non-exclusively for use with external insulation cladding of a building around a typically previously existing window, and to a coping system for capping a wall.

It is known to clad existing buildings with thermal insulation; typically, this is done as a retrofit process in order to reduce thermal losses from and so improve the energy efficiency of existing buildings. Examples of the insulation used in such a process are phenolic insulation materials. The insulation materials used typically increase the width of the building's walls by of the order of 60 to 200 millimetres. This means that any existing windowsills are likely to be behind the front face of the insulation once it has been applied to the wall.

It is known to provide over-or undersills fabricated from aluminium. These comprise a bent, pre-painted aluminium sheet that is attached either over (an oversill or under (an undcrsill) an existing windowsill in order to extend the length of the existing oversill. However, we have appreciated that there are several problems with such windowsill extensions. Being formed of a metal material, they are conductive to heat, and therefore represent a cold bridge across the insulation. Furthermore, they are provided in lengths longer than the existing windowsill and cut to length on site. The cutting facilities for cutting aluminium on a common building site are minimal, which leads to the installer typically having to cut the aluminium with a hacksaw. This is hard work, and unless the installer is very skilled is likely to be inaccurate; it can result in damage to the prepainted aluminium adjacent to the cut.

Careless handling on site can result in dents and bending of the aluminium which is then scrap. Aluminium has a high scrap value and thus is liable to pilfering.

Whilst most installers would prefer for aesthetic reasons to use oversills rather than undersills, invariably they do not, because they not only would have to cut a rebate to form the sill overlap either side of the reveal, but they would have to cut along the length of the rear of the sill to adjust the width required, which may vary from one window to the next, even on the same property. To cut and adjust a fabricated sill on site is difficult, especially cutting down the length at the rear with the tools generally available on site, being time consuming and prone to error.

According to a first aspect of the invention, there is provided an external windowsill extension formed as an extrusion.

Thus, the windowsill extension can be more conveniently manufactured.

Typically, the extrusion will be of a plastic material. As such, the windowsill extension can be manufactured out of a material that is easy to cut to size on site.

Furthermore, plastic materials are generally less conductive to heat than the metal materials used to make prior art windowsill extensions. In an alternative, the extrusion can be formed of metal material, such as aluminium.

The extension will typically be for use in extending the width of an existing exterior windowsill in a building which is being clad with external insulation.

The plastic material may comprise or consist of a plastic such as poly vinyl chloride (PVC), typically unplasticised PVC (uPVC), or acrylonitrile butadienc styrcnc (ABS).

Of these, uPVC. is low cost, resilient and weathers well.

Typically, the extrusion will have a length and a consistent cross section along the length, the cross section comprising an elongate arm terminating in a hollow sill portion. Being hollow, the sill portion will provide rigidity. Typically, the hollow portion will be generally quadrilateral in outline, typically approximating a parallelogram, such as a rectangle. The hollow sill portion may provide a sill edge to be positioned distal from an original sill.

Typically, the extrusion may be provided with a fixing location for a flexible sheet arranged to provide a key for a render coating, the location being provided adjacent to an edge of the hollow portion furthest from the sill edge. As such, the cross section may comprise a recess, such as a part-circular recess, on the edge of the hollow portion furthest from the sill edge. The extension may be provided with a rod, such as a cylindrical rod, that fits within the recess, the rod being attached to the flexible sheet. Alternatively, the flexible sheet can be fixed to the extrusion by means of an adhesive. The flexible sheet may be formed as a mesh cloth, typically formed of glass fibre cloth.

This allows for a, typically, mesh cloth to be provided behind the new sill but at the leading edge of the new insulation, to provide a key for the render and so to ensure that the render attaches to the new sill, locking it in place and scaling the lop of the insulation system from the ingress of weather and insects and so on.

In addition, the cross section of the extrusion niay comprise a key for a render coating, extending away from the hollow portion from an edge furthest from the sill edge. The key may comprise a fiat surface having ridges or perforations thereon to provide the key.

Prior art sills fabricated from aluminium folded from a flat sheet generally terminate at the end of a return drip flange, and as such arc not bonded for the full length into render underneath the sill; as such, they have a cross section of a simple bent line.

This aesthetically is not ideal when viewed from below and also leaves the top of the insulation system under the sill open to the ingress of weather and insects, with the possibility of wind noise from or damage to the sill. The sill edge being unsupported from the rear may also result in mechanical damage/deformation from ladders etc. Thus, such an extrusion has advantages that apply to both nietal and plastic extrusions.

The elongate arm may be provided with spaced apart weak points, defining positions where the elongate arm may be more easily broken than elsewhere. The weak points may be formed as grooves along the length of the extrusion. This allows the length of the elongate arm (which will typically be perpendicular to the length of the extrusion) and so the width of the extension to be varied depending on the circumstances, particularly on the width of the existing windowsill and the thickness of the insulation to be installed, typically by snapping parts off thc length of the elongate arm at a

suitable weak point.

The extension may be provided with a seal, the seal acting to seal the windowsill extension against an existing windowsill or windowframe. As such, the seal may comprise a first part comprising a socket sized to receive the elongate arm and a second part comprising a flexible seal, which can press against the windowframe or windowsill. The socket may have parts complementary to the weak points, which may be ridges where the weak parts are grooves. As such, the weak parts may engage with the complementary parts to hold the elongate arm in the socket. The first part may be provided with adhesive, typically on an adhesive pad, by means of which it can be attached to the existing windowsill or windowframe. The use of this socketed seal provides fine adjustment of the required sill width and allows for circumstances where the existing window frame is not exactly parallel to the exterior wall surface.

The hollow portion may be formed with a recess arranged so as to encourage water to drip from an underside of the hollow portion. This may be formed as a concave recess in the underside of the hollow portion.

The extension may function as an oversill or an undersill. Whilst the elongate arm may be straight along its length (and so the width of the extension) for use as an ovcrsill, where the extension is an undersill, the elongate arm may havc at least one bend along its length. At least one bend niay correspond to a transition from contacting or being adjacent to the underside of the existing sill to being in contact with the wall.

There may be a single bend, which may be greater than 90 degrees from planar and which corresponds to the bend meeting the underside of the existing windowsill, but the remainder of the elongate arm that is not to be positioned against the wall and which is adjacent to the hollow portion extending away from the existing windowsill.

Alternatively, there may be at least two bends, one bend corresponding to a transition of the elongate arm from contacting the wall to contacting the underside of the windowsill (which will typically be approximately 90 degrees) and a second bend which corresponds to a transition of the elongate arm from contacting the underside of the existing sill to extending away from the existing sill. The portion of the elongate arm in contact with the wall can be mechanically fixed to the wall.

Providing the elongate arms with the bend(s) discussed facilitates easier manufacture.

A single extrusion, using a single die, can be formed immediately after extrusion into either the straight-arm form discussed above for use as an oversill or the bent-arm form discussed above for use as an undersill.

The extension may be provided with end caps, sized so as to fit in and seal either end of the hollow portion. The end caps may be provided with a key for a render coating, which is perpendicular to the end of the hollow portion, and which will therefore be parallel to the length of the extrusion.

According to a second aspect of the invention, there is provided a method of cladding an external face of an external wall below a windowframe with insulation, the windowframe having an existing external windowsill, the method comprising fixing a windowsill extension according to the first aspect of the invention with respect to the existing windowsill and applying insulation to the wall, such that the windowsill extension provides a sill edge further from the wall than an outer edge of the insulation distal from the wall.

The method may comprise the step of cutting the windowsill extension to match the width of the windowframe.

Where the extension is provided with a key for a render coating, such as the flexible sheet or as part of the extrusion, the method may comprise the step of applying a render coating over the key.

The method may comprise the step of varying the width of the extension by snapping the elongate arm along a weak point.

Where the extension is an oversill, the step of fixing the windowsill extension relative to the windowframe may comprise the step of fixing the flexible seal relative to the windowframe and receiving the elongate arm within the socket.

Where the extension is an undersill, the step of fixing the windowsill extension may comprise mechanically fixing a portion of the elongate arm separated from the hollow portion by each bend. Typically, the mechanical fixing could comprise screws, bolts or nails into the wall.

The method may comprise the step of fitting the end caps into either end of the hollow portion. Where the end caps are provided with a key for a render coating, the method may comprise the application of the render coating over the key of the end caps.

According to a third aspect of the invention, there is provided a method of manufacturing an external windowsill extension, the method comprising extruding the extension.

Typically, the extrusion is formed of plastic material, which may comprise or consist of a plastic such as poly vinyl chloride (PVC), typically unplasticiscd PVC (uPVC).

This is low cost, resilient and weathers well.

The extension may be in accordance with the first aspect of the invention.

According to a fourth aspect of the invention, there is provided a coping system for capping the top of a wall having an external face that is having insulation applied thereto, the coping system comprising a support and a pair of extrusions, each extrusion having a length and a consistent cross section along the length, the cross section comprising an elongate arm terminating in a hollow portion and a distal end distal from the hollow portioii, the support being provided with a pair of sockets, each socket receiving the distal end of one extrusion.

As such, this provides a coping system that can make use of the extrusions defined abovc with respect to the preceding aspects of the invention. Again, a single extrusion and/or a single die can be used for niultiple purposes, which is exceedingly efficient.

Typically, the extrusion is formed of plastic material, which may comprise or consist of a plastic such as poly vinyl chloride (PVC), typically unplasticised PVC (uPVC).

This is low cost, resilient and weathers well.

Typically, the hollow portion will be generally quadrilateral in outline, typically approximating a parallelogram, such as a rectangle. The hollow sill portion may provide a sill edge distal from the elongate arm.

Typically, the extrusion may be provided with a fixing location for a flexible sheet arranged to provide a key for a render coating, the location being provided adjacent to an edge of the hollow portion closest to the elongate arm. As such, the cross section may comprise a recess, such as a part-circular recess, on the edge of the hollow portion closest to the elongate arm. The extension may be provided with a rod, such as a cylindrical rod, that fits within the recess, the rod being attached to the flexible sheet. The flexible sheet may be formed as a mesh cloth, typically formed of glass fibre cloth.

This allows for a, typically, mesh cloth to be provided behind the ncw sill provided by the coping system but at the leading edge of the new insulation, to provide a key for the render and so to ensure that the render attaches to the new sill.

In addition, the cross section of the extrusion may comprise a key for a render coating, cxtcnding away from the hollow portion from an edge furthest from the sill cdge. The key may comprise a flat surface having ridges or perforations thereon to provide the key.

The elongate arm may be provided with spaced apart weak points, defining positions where the elongate arm may be more easily broken than elsewhere. The weak points may be formed as grooves along the length of the extrusion. This allows the length of the elongate arm (which will typically be perpendicular to the length of the extrusion) and so the width of the extension to be varied depending on thc circumstances, particularly on the width of the wall and the thickness of the insulation to be installed, typically by snapping parts off the length of the elongate ann at a suitable weak point.

Each socket may have parts complementary to the weak points, which may be ridges where the weak parts are grooves. As such, the weak parts may engage with the complementary parts to hold the elongate arm in the socket.

The support may comprise an extruded body, typically also of plastic material, and possibly of the same plastic material as the extrusions. The support may comprise a fixing portion, which can be positioned on a flat top surface of the wall (for mechanical fixing thereto) and a spacer body arranged to space, typically vertically the sockets from the fixing portion.

Both of the extrusions and the support may be provided in lengths, perpendicular to the cross section. The coping system may comprise a jointing member, arranged to join successive lengths of the extrusion. The jointing member may comprise a pair of back-to-back sockets, each arranged to receive an edge of the elongate member. The coping system may also comprise a joining cap, which joins successive lengths of the support by engaging a protrusion on each length of the support.

According to a fifth aspect of the invention, there is provided a method of manufacturing external windowsill extensions, comprising: * using a die to form lengths of extrusion having a profile, the extrusion being of a plastic material heated to a temperature where it is malleable; * bending at least some of the lengths whilst the extrusion is still sufficiently hot to be flexible; and * allowing the extrusions to cool so as to no longer be malleable; the method comprising generating a plurality of sets of cooled extrusions using the same die, the sets differing in the bends that have been applied to the extrusion.

As such, this allows for sonic of the sets to have different shapes whilst still using the same die. This is useful, as extrusion dies are a relatively expensive component to provide, and being able to utilise the same die for differently-shaped windowsill extensions would be particularly efficient.

One of the sets niay have no bends applied to it. This allows for a base form that has not been bent during manufacture.

Typically, the extrusion will have a length and a consistent cross section along the length, the cross section comprising an elongate arm terminating in a hollow sill portion. The bends will typically be applied to the elongate arm.

As such, one of the sets will have no bends applied to it and as such may comprise an oversill, whereas at least one of the sets will have at least one bend applied to it, and comprise an undersill or an oversill.

There may be a plurality of bent sets each having at least one bend in the elongate arm. One bent set may have a single bend, which may be greater than 90 degrees from planar and which corresponds to the bend meeting the underside of the existing windowsill, but the remainder of the elongate arm that is not to be positioned against the wall and which is adjacent to the hollow portion extending away from the existing windowsill. Another bent set may have at least two bends, one bend corresponding to a transition of the elongate arm from contacting the wall to contacting the underside of the windowsill (which will typically bc approximately 90 dcgrccs) and a sccond bend which corresponds to a transition of the elongate arm from contacting the undcrsidc of thc cxisting sill to extcnding away from thc cxisting sill. A furthcr bcnt set may comprise a single bend of less than 90 degrees from planar, the single bend representing a transition of the elongate arm from running down a wall above an existing windowsill to running down the windowsill, for use as an oversill.

Thus, we have described several different windowsill extensions that can be manufactured with a single die.

The sets may comprise the extrusions of the windowsill extension of the first aspect of the invention or the coping system of the fourth aspect of the invention.

There now follows, by way of example only, description of embodiments of the invention, in which: Figure 1 shows a cross section vertically through a region around a window to which has been fitted a windowsill extension according to a first embodiment of the invention; Figure 2 shows an end cap for use with the windowsill extension of Figure 1; Figure 3 shows a cross section horizontally through the region of Figure I; Figure 4 shows a cross section vertically through a region around a window to which has been fitted a windowsill extension according to a second embodiment of the invention; Figure 5 shows a cross section vertically through a region around a window to which has been fitted a windowsill extension according to a third embodiment of the invention; Figure 6 shows a cross section vertically through a region around a window to which has been fitted a windowsill extension according to a fourth embodiment of the invention; Figure 7 shows a cross section through a region around the top of a parapet wall to which has been fitted a coping system according to a fifth embodiment of the invention; Figure 8 shows a joining cap for use with the coping system of Figure 7; Figure 9 shows a scaling strip for usc with the coping system of Figure 7; and Figure 10 shows ajoining plug for use with the coping system of Figure 7.

Figures 1 to 3 of the accompanying drawings show a windowsill extension in accordance with a first embodiment of the invention. The extension allows an external wall I of a building to be clad with insulation 2. Without the extension, the existing window sill 3 would not extend past the external surface 4 of the insulation 2; the extension serves as an extension to the original windowsill 3.

The extension 5 is formed as an extrusion of, in this embodiment, unplasticised poly vinyl chloride (uPVC). It has a length in direction L (into the page in Figure 1) and a width extending in direction W (horizontally in Figure 1). It has a constant cross section as shown in Figure I. The cross section comprises an elongate arm 6 and a hollow sill portion 7 at one end of the elongate arm 6. Given that, in this embodiment, the elongate arm 6 lies along the top edge of the existing sill 3, the windowsill extension 5 forms an oversill.

The hollow sill portion 7 is generally of the form of a parallelogram, which serves to provide rigidity. The edge of the hollow portion 7 distal from the elongate arm forms a replacement sill edge 8. A concave recess 21 encourages rainwater falling on the hollow sill portion 7 to fall, rather than running along the underside of the hollow sill portion 7.

The elongate arm 6 is provided with a plurality of weak points 9 of the form of ridges along the length of the extrusion. The elongate arm 6 can be snapped at any of these points to change the length of the elongate arm 6. This allows use of the same extrusion with multiple different widths of wall and insulation (dimension D).

The extrusion is also provided with a part-circular recess 10 along the length, where the elongate arm 6 joins the hollow sill portion 7. This houses a cylindrical uPVC rod 11, to which is attached a glass fibre mesh cloth 12. The mesh cloth 12 falls down the back of the hollow sill portion 7, and extends downwards therefrom. The hollow sill portion 7 is also provided with a key portion 13 extending from the back surface (that is, the far surface from the sill edge 8) of the hollow sill portion 7. The key portion 13 has protrusions 14 that serve as a key for a render coating, although perforations could equally well be used alternatively or additionally.

A seal 16 is also provided. This comprises a socket portion 17, comprising a U-shapcd extrusion in which the end of the elongate arm 6 distal from the hollow sill portion 7 is received. The socket portion 17 has ridges within the socket which engage the weak point grooves 9 and so restrict movement of the elongate arm 6 once inserted into the socket portion 18. The seal 16 also comprises a flexible seal web 19.

As such, when it is desired to clad the wall 1, the desired thickness of insulation 2 is laid onto the wall 1. A suitable length of the extrusion is cut to fit the window opening and windowsill, and the length of the elongate arm 6 snapped to length along the appropriate groove 9. A rebate 27 is cut in either end of the extrusion to fit into the window opening; this is significantly easier to do so in uPVC rather than, say, aluminium. The seal 16 is attached to the windowsill, typically by use of an adhesive pad 20, and the end of the elongate arm 6 received within the socket portion 17. The flexible web seal abuts the window frame 22, so that water cannot penetrate below the extension. Further liquid adhesive can be used to bond the elongate arm 6 to the original windowsill 3.

The hollow sill portion 7 now extends past the front surface 4 of the insulation, such that the sill edge replaces that of the existing windowsill 3. Because the extension 5 is acting as an oversill, a smooth top surface is presented to someone looking at the installed extension.

As such, the back surface 15 of the hollow sill portion 7 is now resting against the insulation 2. The mesh cloth 12 is laying against the front surface 4 of the insulation 2. The key portion 13 extends a short way over the top of the mesh cloth 12. A layer of render 23 can then be applied over the top of the insulation 2, mesh cloth 12 and key portion 13, fixing the extension 5 relative to the insulation 2; because of the texture of the mesh cloth 12 and the protrusions 14 on the key portion 13, the render 23 coating will be keyed into those members, increasing the stability of the fixing.

Holes can be provided through the key portion 13, so that a mechanical fixing of the extension S relative to the insulation can be implemented to increase stability.

Figure 2 shows an end cap 24 that can be used with the extension 5. The end caps fit in either end of the hollow sill portion 7, and so have a corresponding cross section, acting to seal the hollow sill portion 7 against, in particular, moisture ingress. The end caps each have their own key portion 25, having protrusions 26 to act as a key for the render coating 23. These key portions will protrude horizontally from thc edge of the extension, and so allow the render coating 23 to stabilise the extension in a further dime us ion.

Figure 4 of the accompanying drawings shows a windowsill extension in accordance with a second en-ibodiment of the invention. Equivalent integers to those of the first embodiment of the invention have been given the same reference numerals, raised by 50.

In this embodiment, rather than providing an oversill, the extension 55 provides an undersill, in that it is provided underneath the original sill 53. Whilst this does not provide the aesthetically pleasing smooth top surface of the oversill of Figures 1 to 3, undersills can be preferrcd for ease of installation.

The extension 55 is formed of the same extrusion as the extension of the preceding embodiment, except that the elongate arm 56 has been the subject of a bend 80 along the length of the extrusion. This bend can be introduced using a former immediately subsequent to extrusion, where the extruded uPVC plastic material is still sufficiently hot to be malleable. This allows the same extrusion die to be used for the extensions of Figures 1 and 4. As undersills do not require the width to be adjusted on site, the snap off grooves can be omitted from the extrusion by a minor adjustment to the die, together with a further adjustment to provide the width of elongate arm required.

Furthermore, as will become apparent below, the extension can be provided in a plurality of widths corresponding to dimension B (the thickness of the insulation 52); because the insulation 52 generally comes in a recognised discrete set of thicknesses, only a limited number of different bend positions need be provided, which can all be generated from the same extrusion die by bending the elongate arm 56 in different places. The bend leaves the elongate arm 56 in two portions: a first portion 81 distal from the hollow sill portion 57 and a second portion 82 between the first portion 81 and the hollow sill portion 58.

In use, the first portion 81 is mechanically fixed to the wall 51. The bend 80 is greater than 90 degrees from planar, such that, with the first portion held against the vertical wall 51, and the bend 80 abutting the horizontal underside 83 of the existing sill 53, the second portion 82 and the hollow sill portion 57 extend downwards at a gentle angle as they extend away from the wall 51.

The insulation 52 can be placed between the first portion and the back surface 65 of the hollow sill portion 57. As previously, this will leave the mesh cloth 62 overlaying the front surface 54 of the insulation 52, with the key portion 63 on top of a portion of the mesh cloth 62. A render coating 73 can then be applied over the mesh cloth 62 and key portion 63, being keyed to those portions as before. The same end caps as used with the first embodiment can also be used with this embodiment.

A windowsill extension in accordance with a third embodiment of the invention is shown in Figure 5 of the accompanying drawings. This embodiment is similar to the second embodiment, and corresponding integers have been given the same reference numerals, raised by 50 with respect to the embodiment of Figure 4.

In this embodiment, rather than the single bend, the elongate arm 106 has two bends 130, 140, dividing the elongate arm into three sections: a first section 131 which can be mechanically fixed to wall 101, a second section 141 adjacent to the first portion and a third section 132 joining the second section 141 to the hollow sill portion 107. This therefore still makes use of the same extrusion, with two bends bcing applied by a former whilst the extrusion is still nrnlleable. The same extrusion die can therefore be used.

The first bend 130 is a right angle, so that with the first portion against the vertical wall 101, the second portion 141 will lay against the underside 133 of the existing windowsill 103. The second bcnd 140 controls the gentle angle at which the third portion 132 and the hollow sill portion 107 extend vertically downwards away from the windowsil 1103.

As such, this embodiment functions in an entirely similar way to that of Figure 4, except that, because of the bends 130, 140 in the elongate arm, there is less space that is not filled by the cuboid blocks of insulation (assuming the same gentle angle of descent away from thc windowsill). Some installers also prcfer having the elongate arm of a windowsill extension abutting against the underside of the existing windowsill 103, and some may prefer the aesthetics of this embodiment. Again, different positions of the bends 130, 140, can allow for differing widths of insulation 102 and of the existing windowsill 103.

It can therefore be seen that the same extrusion can be put to multiple uses.

A fourth embodiment of the invention is shown in Figure 6 of the accompanying drawings. This embodiment is similar to that of the first embodiment of the invention, and corresponding integers have been provided with corresponding reference numerals, raised by 300 with respect to the first embodiment.

Again, the same extrusion is used. However, rather than the downwards bend of the elongate arm, the elongate arm 306 has a single upwards bend 330. This means that the extension 305 can be used as an oversill, placed over an existing sill 303.

The elongate arm 306 is again divided into two portions: a first portion 301 running (town the windowframe 350 and a second portion 332 descending gently downwards along the top surface of the existing sill 303. A seal 316 is provided, which functions in the same manner as the seal of the first embodiment, except that it is attached to a vertical part of the windowframe 350 rather than the existing sill as in the first embodiment.

In the same manner as the first embodiment of the invention, a rod can be held within a recess 351 at the outer side of the junction of the key portion 315 with the hollow sill portion 307, the rod supporting the mesh cloth on the outside of the key portion 315. This external recess 351 can be part of the extrusion of any of the present embodiments, such that a user has a choice whether to use the mesh cloth 316 over the key portion (using external recess 351), under the key portion (using the recess discussed above, and shown in Figure 6 at 310) or not at all.

The same extrusion 199 is again used in the fifth embodiment of the invention, shown in Figures 7 to 10 of the accompanying drawings. Rather than a windowsill extension, the extrusion is used in a coping system, for capping the top of a wall, such as a parapet wall, that is being externally clad with insulation. No bends in the extrusion are required in this ease, such that the extrusion used is the same as that used in the first embodiment of the invention.

The coping system comprises an extruded support 200, having a length into the page of Figure 7, and with a consistent cross section as shown in that Figure. The support comprises a base 201 mechanically fixed (bolts or screws, typically) to the top surface 203 of the wall 202. The support also comprises a spacer portion 204 and a pair of sockets 205, the sockets being spaced vertically from the base by the spacer portion 204. The sockets face towards opposing faces of the wall 202, each projecting downwards by approximately 16 degrees below horizontal.

Two sets of lengths of the extrusion 199 are used, the sets extending towards opposing faces of the wall 202. The elongate arm 206 of each length of extrusion 199 is received within one of the sockets 205. The socket have ridges 209 corresponding to the grooved weak points 208 in the elongate arms 106, the ridges 209 acting to hold the elongate arms 206 in the sockets.

The elongate arms 206 are sized by snapping off the appropriate amount of the elongate arms 206 at the weak points, such that the horizontal component of the length of the elongate arms, plus the horizontal distance between the ends of the elongate arms 206, corresponds to the conibined width of the wall 202 and the external insulation 210. It is to be noted that the support 200 is provided halfway between the outer face 211 of the insulation and the inner non-insulated face 212 of the wall 202, and as such is not symmetrically located on the wall 202. In other applications both sides of the wall may be insulated.

This positioning means that the rear faces 213 of the hollow sill portions 214 of each cxtrusion 199 will abut either the outer face 211 of the insulation or thc inner face 212 of the wall 202. In this embodiment, rather than having the mesh cloth underneath the key portion, the key portion 215 directly abuts the outer face 211 of the insulation or the inner face 212 of the wall 202, with the mesh cloth 216 being provided over the key portion 215. A mechanical fixing 217 can be provided to fix the key portion 215 to the outer face 211 of the insulation or the inner face 212 of the wall 202. A render coating 218 is then provided over the mesh cloth 216, the key portion 215 and the outer facc 211 of the insulation or the inner face 212 of the wall 202.

In order to join the lcngths of extrusion 199 and the lengths of the extruded support 200 together, jointing members are provided. A sealing cap 220, having a length S of approximately 25 millimetres, is provided, having a part circular recess 221 which engages a corresponding protrusion 222 on the support 200. The sealing cap therefore bridges the gap between successive lengths of the support. Its width T is such that it ovcrflies the abutting end of the sealing strip 223 discussed below.

In order to bridge the gaps between successive lengths of the extrusion 199, a sealing strip is provided. This has the same length as the elongate arm 206, and so can be cut to length. It is H-shaped in cross section (as shown in Figure 9 of the accompanying drawings), with socket portions 224 each receiving the elongate arm 206 of one length of extrusion 206. For the same purpose, joining plugs 225 are provided, which comprise a flange 226 separating two back-to-back plug sections 227 of corresponding cross section to the hollow sill portion 214, the plug sections 226 being received within the hollow sill sections 214 of successive lengths of the extrusion 199.

The end plugs of Figure 2 can be used to cap the extreme ends of the terminal extrusions 199.

Thus, the coping system described above provides a waterproof cap to the parapet waIl 202, whilst using the common extrusion 202, providing a further use for the same extrusion die. The hollow sill portions 214 form sill edges protruding over thc outer face 211 of the insulation or the inner face 212 of the wall 202

Claims

CL Al NI S 1. A coping system for capping the top of a wall having an external face that is having insulation applied thereto, the coping system comprising a support and a pair of extrusions, each extrusion having a length and a consistent cross section along the length, the cross section comprising an elongate arm terminating in a hollow portion and a distal end distal from the hollow portion, the support being provided with a pair of sockets, each socket receiving the distal end of one extrusion.
2. The coping system of claim 1, in which the extrusions are formed of plastic material, typically comprising or consisting of unplasticised PVC (uPYC).
3. The coping system of claim I or claim 2, in which the hollow portion provides a sill edge distal from the elongate arm.
4. The coping system of any preceding claim, iii which the elongate arm is provided with spaced apart weak points, defining positions where the elongate arm can be more easily broken than elsewhere.
5. The coping system of claim 4, in which each socket has parts complementary to the weak points.
6. The coping system of any preceding claim, in which the support comprises an extruded body.
7. The coping system of any preceding claim, in which the support comprises a fixing portion, which can be positioned on a flat top surface of the wall and a spacer body arranged to space the sockets from the fixing por ion.
8. The coping system of any preceding claim, in which the extrusions and the support are provided in lengths, perpendicular to the cross section, the coping system comprising a jointing member, arranged to join successive lengths of the extrusion.
9. The coping system of claim 8, in which the jointing member comprises a pair of back-to-back sockets, each arranged to receive an edge of the elongate member.
10. The coping system of claim 8 or claim 9, in which the coping system comprises a joinilig cal), which joins successive lengths of the support by engaging a protrusion on each length of the support.

I I. A coping system substantially as described herein with reference to and as illustrated in Figures 7 to 10 of the accompanying drawings.