1 INSULATING PANEL AND METHOD OF FORMING SAME This invention relates to an insulation panel and method of forming same. The invention has particular application to an insulating panel for sectional doors, more particularly, 5 sectional or articulated panel garage doors, and reference herein will be made to such application. However, the invention has application more generally to insulation panels which may be fitted between frame members of a door or wall panel. o Insulation of buildings has long been sought for the reduction of heating and cooling requirements and the consequential reduction in energy consumption for buildings in general and parking garages in particular. In domestic applications, the parking garage has for many years been 5 incorporated into the main building with the result that significant energy losses can occur through the non-insulation of the parking garage, a large proportion of which occurs through the garage door. Moreover, in the assessment of a building's energy rating, the integral garage is not included 0 in the calculation because even if the walls and ceiling are insulated, significant energy transmission occurs through the garage door or doors. As a result, the energy rating provided is often inaccurate. Additionally, the home owner has to put up with the garage being either too hot or too cold compared 25 to the remainder of the house. Garage doors are of several forms, but of relevance to the present invention, are of a form which includes one or more rigid panels which may be lifted, tilted, slid, hinged or pivoted between an open position and a closed position, known 30 by the generic term sectional garage doors, or by the registered trade mark "PANELIFT". The present invention aims to provide an insulation panel and method of forming same which alleviate one or more of the 2 shortcomings of the prior art and/or current building practice. Other aims and advantages of the invention may become apparent from the following description. With the foregoing in view, in one aspect the present 5 invention resides broadly in an insulation panel including: a body of expanded polystyrene foam material and having a front face; a binding layer adhered to the front face of the body by an adhesive and having an intermediate face remote from the 0 front face of the body; and a covering layer of polyvinyl material bonded to the intermediate face of the binding layer by a bonding agent. In another aspect, the present invention resides broadly in a method of forming an insulation panel including: 5 providing a body of expanded polystyrene foam material and having a front face; applying an adhesive to the front face of the body, the adhesive being suitable for adhesion between polystyrene foam and paper based material to provide an adhesive covered face 20 of the body; laying a binding layer of paper based material onto the adhesive covered front face of the body to provide a binding covered body having an intermediate face remote from the front face of the body and leaving the binding covered body for a 25 time sufficient for the adhesive to set; applying a bonding agent to the intermediate face of the binding layer to provide a bonding agent covered face; and laying a covering layer of polyvinyl material onto the bonding covered face of the binding layer to provide a 30 composite panel; and 3 applying pressure to the composite panel. Preferably, the binding layer is a paper based or cardboard material of a weight suited for the absorption of some of the adhesive on one side and some of the bonding agent 5 on the other side, whereby the binds the body to the covering layer. It will be seen that the binding mechanism is that the binding layer absorbs both the adhesive and the bonding agent, one into each face and at least part way into the thickness of the binding layer. 0 It has been found that a paper having a weight of 170 gsm performs adequately, but it will be appreciated that the invention is not limited to a specific weight of paper. Accordingly, a paper weight in the range of 100 gsm to 250 gsm would be particularly suited, but it is expected that 100 gsm 5 should be about the lower limit, otherwise the adhesive and bonding agent may have too little material to establish sufficient adhesion or bonding. Thicker paper or cardboard may be used, but will add to the weight of the finished product, and may weaken the binding of the covering layer to the body. 0 The material used for the body is preferably a polystyrene foam selected for its insulating properties. In a preferred form, the body is provided in block form, that is, in the form of a rectangular prism. In such form, the block has a thickness sufficient to provide the insulating property, 25 but is also convenient with respect to the physical size for ease of handling and installation. Moreover, the thickness is preferably selected to correspond to the width of the frame members of the door or wall panel to be insulated. In a preferred form, the body is formed of polystyrene 30 having a density in the range of 11.0 to 32.0, and having a thermal conductivity between 0.03 and 0.05 kWm K'. The polystyrene is also preferred to include fire retardant material. Insecticide and/or other pesticide may also be 4 added, but it will be appreciated that common fire retardant materials also can have a pesticidal quality. The covering layer is preferably polyvinyl chloride film, plasticised or unplasticised. However, it will be appreciated 5 that the covering layer is selected from plastics materials that may be bonded by a bonding agent and therefore have a room-temperature solvent. In this specification, the term polyvinyl material is to be taken to encompass plastics materials, whether thermosetting or thermoplastic, which have 0 a room-temperature solvent whereby chemical bonding by a bonding agent may be effected, unless the context indicates otherwise. In this specification, the term bonding agent is to be taken to mean that the mechanism by which adhesion takes place includes solvent bonding or solvent welding onto at 5 least one of the materials being bonded, unless the context indicates otherwise. The covering layer is preferably of the order of 0.1 to 0.8 mm thickness, and may include a pattern and/or ornamentation on or in the surface. For example, the covering 0 layer may be coloured and/or include colouring, colour coating and/or texturing on or to one or both surfaces. The covering layer is preferably pressed onto the bonding agent covered face of the binding covered body by passing between a pair of pinch rollers. 25 The adhesive is preferably a polyvinyl acetate or polyvinyl alcohol, aqueous based glue or such like. In particular, the adhesive is selected for its ability to bond to the cellulosic, sizing or other material in the binding layer. The bonding agent is preferably a solvent or aqueous 30 based adhesive which provides at least some chemical bonding to the covering layer. A preferred form of bonding agent is ethylene vinyl acetate. It will be appreciated that if a non aqueous, solvent-based adhesive is selected, the solvent must 5 not adversely affect the structure of the polystyrene or other polymeric materials forming the panel. The sizing of the insulation panel according to the invention may be, for example, from 300 mm to 1200 mm wide, 5 from 500 mm to 5000 mm long and 30 mm to 150 mm thick. Additionally, two or more panels may be installed in edge-to edge abutting relationship to each other. However it is preferred that the panels are separated by joiner strips having two opposed channels. The sides of the channels form 0 flanges separated by a web, the width of the web being commensurate with the thickness of the panel, but so as to provide a grip on the panel, the edge of which is inserted into each channel. In similar fashion, an edge strip is provided, but with one channel to form a protective edging for 5 the panel. The joining and edge strips may be formed from metal or plastics. In another aspect, the present invention resides broadly in insulated sectional door having a plurality of panels connected to one another in edge-to-edge hinged relationship, 0 at least one of said panels being insulted by an insulation panel according the invention. In order that the invention may be more readily understood and put into practical effect, an exemplary embodiment of the present invention will now be described with 25 reference to the following drawings, and wherein: Fig. 1 is a diagrammatic pictorial view of an insulating panel according to the invention installed on or in a panel of a sectional door; Fig. 2 is a diagrammatic pictorial view of a joining 30 strip for interposition between two adjoining insulating panels; Fig. 3 is a diagrammatic pictorial view of an edge strip f n-r r-n Ur1 nc s- ;n -xWnn(-)cq - H c n E s- f ;n I n qii 11 1 I n r- ns: n -I 6 Fig. 4 is a diagrammatic sectional view of the insulating panel of Fig. 1 illustrating details of its layers; Fig. 5 is an end view of the joining strip of Fig. 2; Fig. 6 is an end view of the edge strip of Fig. 3; and 5 Figs. 6 and 7 are end views of an alternative joining and edge strip to those of Fogs. 5 and 6 respectively. The insulating panel 10 illustrated in Fig. 1 has a body 11 of polystyrene foam and a covering layer 12 of polyvinyl chloride adhered to the front face of the panel in accordance 0 with the method of the invention. The insulating panel is shown as installed in a typical panel of a sectional door 13, referred to hereinafter as a door-panel. The door-panel has a main web 14 which extends between a lower flange 15 and an upper flange 17. A lower lip extends along the distal edge of 5 the lower flange 16 and an upper lip 18 extends along the distil edge of the upper flange. A further lip 19 extends along the distal edges of each lip. The main web also has a central rib 29 extending substantially parallel to the flanges. The insulating panel is sized to fit neatly or with 0 slight interference between the further lips and the central rib, but it will be seen that the panel also sits on the lower flange. The front face rests against or is slightly embedded into the front face of the insulating panel and the central rib rests against or is slightly embedded into the rear face 25 of the insulating panel, and/or the insulating panel may bend slightly with its front face being slightly convex. The joining strip 20 illustrated in Figs. 2, 5 and 7 has a web 21 extending between a rear flange 22 and a front flange 23, each of which extend substantially at 90' from each side 30 the web 21. That is, the web 21 is substantially central between the respective side edges of the flanges. A rear gripping ridge 24 extends along the inside of each edge of the rear flange of the alternative joining strip of Fig. 7. The 7 insulating panel is sized to fit snugly between the flanges 22 and 23. In the case of the alternative form, at least part of the gripping ridge 24 may become embedded into the rear face of each of the two insulating panels which may be inserted 5 into the channels formed by the flanges 22 and 23 and the web 21. In similar fashion, a front gripping ridge 25 extends along the inside of each edge of each front flange. The edge strip 30 illustrated in Figs. 3, 6 and 8 has a web 31 extending between a rear flange 32 and a front flange 0 33, each of which extend substantially at 90' to the web 31. A gripping ridge 34 extends along the inside of the edge of the rear flange of the alternative edge strip of Fig. 8. The insulating panel is sized to fit snugly between the flanges 32 and 33. In the case of the alternative edge strip, at least 5 part of the gripping ridge 34 may become embedded into the rear face of the insulating panel. In similar fashion, a front gripping ridge 35 extends along the inside of each edge of each front flange. The edge strip is in substantial conformity with either half of the joining strip extending away from the 0 web 21. For joining strips and edge strips formed of metal, the front gripping ridge may form a corresponding crease in the covering layer, binding layer and body, but joining strips formed of plastics may not provide sufficient force to do so. 25 In either case, the front and, where provided, the rear gripping ridges, serve to hold the insulating panel in the channel. The rear flanges are wider than the front flanges to permit a fastener to be inserted through the rear flange and into a corresponding part of the sectional door whereby the 30 joining and edge strips may be fastened to the sectional door. The insulating panels may then be inserted, the fasteners being hidden from view thereby to provide an aesthetically pleasing finish to the installed panels. Additionally, the outer face of the front flanges may be coloured and/or 8 textured to match or contrast with the colour and/or pattern of the covering layer. The detail of the insulating panel illustrated diagrammatically in Fig. 4 includes the body 11 and covering 5 layer 12 as previously described with reference to Fig. 1, and it will be seen that between the covering layer and the body are the additional layers which permit the fixing of the protective covering to the polystyrene foam, the polystyrene foam possessing good insulating properties, but being somewhat 0 prone to mechanical damage. The body of polystyrene is typically of a density of 11 to 32 kg/m. The body is coated with PVA adhesive, at 41 and a 170 gsm paper layer 42 laid flat over the glue covered polystyrene. The papered body is put into a flat press under minimum pressure for two minutes, 5 after which the glue is allowed to dry or set and the paper trimmed to the size of the body. The lamination with the PVC is dome by first covering the paper layer with an even coating of EVA adhesive 43 as bonding agent. This enables the use of various overlays as the 0 covering layer, such as 0.1 mm standard vinyl range, 0.15 mm laminating foil known by the trade mark "InnoClad" and LG brand 0.4 to 0.7 mm Deco foil range. The covering layer is bonded to the paper covered polystyrene by passing through a nip roller system, then block stacking to permit the bonding 25 agent to set. The insulating panels according to the invention may be used to insulate existing sectional doors, the size of the panel being selected to fit between the frame members of typical sectional doors for parking garages. If the insulating 30 panel is to be installed between frame members of fixed walls, the spacing of the frame members may be greater than the with or length of the insulating panels. In such circumstances, the adjacent insulating panels are joined to and separated from one another by the appropriate length of the joining strips 9 hereinbefore described. It a break or an opening is required in the insulating panels, the edges may be terminated with the appropriate length of the edging strip. Although the invention has been described with reference 5 to a specific example, it will be appreciated by persons skilled in the art that the invention may be embodied in other forms within the broad scope and ambit of the invention as herein set forth and defined by the following claim.