Abstract:
A generally flat structural panel includes a center foam core and opposed outer facings, or sheets, with a metal insert disposed about and attached to the edges of the core and at least one of the outer facings. The metal edge insert provides high strength for the insulated foam panel, eliminates the need for structural members such as studs which act as thermal conductors, and facilitates coupling between adjacent panels, ceilings and floors using various connection arrangements. The structural insulated panels also form the basis of a modular construction system that allows for the use of standard size inside and outside panels of the same size which form a grid in which the outside panels always enclose an area that is a multiple of the module. In one embodiment, a lateral surface of the foam core is provided with a linear array of recesses, or grooves, and a facing is attached to that surface in the field to permit electrical wire routing in the recesses, as required, at the construction site. In another embodiment, metal strips attached to the surface of the core and adapted for secure attachment to a facing such as of drywall provide a space between the foam core and drywall sheet for wire routing.

Description:
FIELD OF THE INVENTION 
     This invention relates generally to structural panels for buildings and is particularly directed to structural insulated panels having a foam core, opposed facings of common structural materials attached to the core, and a metal peripheral edge bonded to the edges of the core and facings. 
     BACKGROUND OF THE INVENTION 
     The traditional house is stick built, i.e., constructed of 2× dimensional structural lumber members and nails. This method of construction is slow and manpower intensive, requires a large supply of a limited commodity, and affords a limited number of structural shapes. 
     Another construction approach uses Structural Insulated Panels (SIPs). The basic structural unit in the SIP construction approach employs two rigid faces on either side of a light insulated foam core. This approach requires good adhesion of the faces to the core to form a structural I-beam. Panels of this type are also joined with lumber and nails. 
     A more recent approach uses steel studs rather than the 2× dimensional lumber approach. Substituting steel for lumber increases material and labor costs. In addition, steel is a good thermal conductor which gives rise to an increase in energy loss on the order of 50% over the conventional lumber construction approach if steel studs are installed between the inside and outside casings of the panels. Using steel and studs as a replacement for lumber also does not make optimum use of the positive structural characteristics of steel as a building material. In addition, SIPs are typically made with rather thick facings as compared to metal edging. SIP panel facings are typically on the order of 0.25&#34; to 0.75&#34; in thickness in the form of a flat sheet that is not readily formed. The junctures of such panels typically employ a lumber spline with nails and screws for joining. Building supply centers stock such building components pre-hung, pre-finished, and pre-assembled with the exception of the main structure of the house. This limits variation in house construction and design. 
     The present invention addresses the aforementioned limitations of the prior art by providing a structural insulated panel with metal edges disposed about and securely attached to a center foam core and outer opposed facings affixed to the center core. 
     OBJECTS AND SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide a structural insulated panel with improved strength which can be assembled in the field for custom applications. 
     It is another object of the present invention to provide a metal strip around the peripheral edge of a foam core, sandwich-type structural panel for substantially increasing the strength of the panel, facilitating panel connection to adjacent, similar panels, and other structural members, and reducing heat transfer between the surfaces of a wall formed of a plurality of such panels. 
     Yet another object of the present invention is to provide an open face structural panel having a foam core with a plurality of spaced fastening access grooves for accommodating wire runs within the panel. 
     A further object of the present invention is provide a modular building system using standard size structural panels and employing a grid wherein the outer panels enclose an area which is a multiple of the basic module and the inner and outer panels are of the same size. 
     This invention contemplates laminating a light gauge metal section on the edge of a bonded panel with thick facings. The metal may be on the inside or outside edge of the panel and does not extend through the panel so as to act as a conductor for heat loss. The metal edge portion may be on one or all of the edges of the panel, with the metal edge joined structurally at the corners in the latter case. The metal edge may be flat or contoured and is easily laminated into the structural insulated panel because the panel&#39;s plastic foam core is sufficiently compressible (without machining the foam) to allow for easy bonding. The panel&#39;s thick outer facings are generally comprised of a conventional building material such as plywood, oriented strand board, drywall, composite gypsum with recycled newsprint, or other rigid production boards from 1/4&#34; to 3/4&#34; thick. The metal edging is preferably galvanized steel, but may also be aluminum or painted steel or even a thin structural plastic. The panel&#39;s inner core may be expanded polystyrene, extruded polystyrene, urethane, polyisocyanurate or other conventional insulating material. Non-plastic insulating materials such as paper, egg crate, honey comb, and straw board may also be used. The metal edges may serve as self-aligning splines or recesses for screwing or bolting panels together. The metal edge may assume virtually any shape depending upon the use of the structural panels in the construction. For exterior wall panels, a spline system, a toe screw system, or an open channel bolt-together arrangement may be used. For roof panels, the spline system is preferred. For interior walls, a ship lap side panel junction allows for a four corner connection while still maintaining a module connection. When steel is used for the metal edging, a less costly facing material may be used because the steel carries much of the load. The edging need only be attached to one of the panel facings because it is a fully adhered component of the panel, with attachment to only one side of the panel substantially improving the panel&#39;s insulation value as the steel edging does not function as a through conductor. 
     Several types of panel-to-panel junctures may be employed with the peripheral metal edging of the present invention. The junctures can be an open or closed system. The open system has an open recess at the panel edge and connection is made in the open slot. A closed system employs a solid panel with a minimum number of holes through the panel required for connection. Screws, wedges, or cam-lock connection devices can be used with a closed system. 
     The open or closed type of connection allows for precise connection between panels and also permits the panels to be disconnected and reconnected. Structural insulated panels in accordance with the present invention thus provide flexibility for changing panel configuration or building expansion without destruction of components. The connection in the open system can be made easily with nut and bolt combinations with the bolts acting as alignment pins so that panels can be easily and quickly assembled. The open system allows for a wiring chase in the fastening access groove, with additional wiring chases provided through the panel. Structural insulated panels in accordance with the present invention can be mass-produced in a variety of shapes and provided to local building centers where homes can be purchased as a series of pre-fabricated panels. The homes cannot only be erected using a bolt together system, but also can be changed without destroying the building structure components. 
     Another aspect of this invention contemplates a modular system that allows buildings to be constructed with panels of a standard size. The panels work off a grid in which the outside panels always enclose, or form the perimeter of, an area that is a multiple of the module. The inside panels work off of the same module using the same model and ship lap ends to allow for corner junctures. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The appended claims set forth those novel features which characterize the invention. However, the invention itself, as well as further objects and advantages thereof, will best be understood by reference to the following detailed description of a preferred embodiment taken in conjunction with the accompanying drawings, where like reference characters identify like elements throughout the various figures, in which: 
     FIG. 1 is a horizontal-sectional view of a modular arrangement for a building structure incorporating structural insulated panels in accordance with the present invention; 
     FIG. 2 is a generally vertical sectional view illustrating details of the manner in which a structural insulated panel in accordance with the present invention may be attached to roof, floor, ceiling and structural support members in accordance with the present invention; 
     FIGS. 3, 4, and 5 are front elevation, top plan, and lateral elevation views of a structural insulated panel in accordance with the present invention; 
     FIG. 6 is a partial sectional view illustrating the manner in which a pair of structural insulated panels as shown in FIGS. 3, 4 and 5 may be connected together; 
     FIG. 7 is a partial sectional view of a pair of structural insulated panels in accordance with another embodiment of the present invention; 
     FIG. 8 is a partial sectional view of another coupling arrangement for a plurality of structural insulated panels in accordance with another embodiment of the present invention incorporated as walls in a building structure; 
     FIG. 9 is a partial sectional view of an edge of one of the structural insulated panels shown coupled together in FIG. 8; 
     FIG. 10 is a side elevation view of another embodiment of a structural insulated panel in accordance with the present invention; 
     FIG. 11 is a plan view of an edge portion of the structural insulated panel of FIG. 10 illustrating details of its metal edge; 
     FIG. 12 is a partial sectional view showing a coupling arrangement for a pair of structural insulated panels as shown in FIGS. 10 and 11; 
     FIG. 13 is a partial sectional view showing another arrangement for coupling a structural insulated panel in accordance with the present invention to floor and roof members; 
     FIG. 14 is a partial sectional view showing details of the coupling between two structural insulated panels similar to the wall panel shown in FIG. 13; 
     FIGS. 15 and 16 are top plan views of two other embodiments of structural insulated panels in accordance with the present invention; 
     FIG. 17 is a partial sectional view showing the coupling between a pair of adjacent structural insulated panels as shown in FIG. 15; 
     FIG. 18 is a partial sectional view showing the coupling between a pair of adjacent structural insulated panels as shown in FIG. 16; 
     FIGS. 19-23 are partial sectional views of various embodiments of structural insulated panels in accordance with the present invention, each having a different coupling arrangement for attachment to an adjacent, identical panel; 
     FIGS. 24 and 25 are partial plan and sectional views, respectively, of another embodiment of a structural insulated panel in accordance with the present invention and a coupling arrangement therefor; 
     FIGS. 26, 27 and 28 are respectively plan, side elevational and sectional views of an open face insulated structural panel in accordance with yet another embodiment of the present invention, where FIG. 28 is a sectional view of the panel taken along site line 28--28 in FIG. 26; and 
     FIGS. 29 and 30 are sectional views of the panel shown in FIGS. 26, 27 and 28 illustrating additional details thereof. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIG. 1, there is shown a horizontal sectional view of a modular system 10 including a plurality of insulated structural panels for use in building construction in accordance with one aspect of the present invention. The modular system 10 includes first, second, third, fourth, and fifth structural insulated panels 12, 14, 16, 18 and 20. Each of the structural insulated panels includes a foam core and opposed outer and inner facings. Thus, first panel 12 includes an inner foam core 12a and outer and inner facings 12b and 12c. The second panel 14 includes foam core 14a and outer and inner facings 14b and 14c. The third panel 16 includes foam core 16a and outer and inner facings 16b and 16a, respectively. Finally, the fourth and fifth panels 18 and 20 respectively include foam cores 18a and 20a, outer facings 18b and 20b and inner facings 18c and 20c. The modular system 10 further includes an outer corner 22 coupled to the first and second panels 12, 14 and an inner corner 26 coupled to the fourth and fifth panels 18, 20 as described below. 
     The first panel 12 includes a metal edge 42 which is inserted between the panel&#39;s inner foam core 12a and its inner facing 12c. An adhesive is applied to metal edge 42 for securely affixing it to the panel&#39;s foam core 12a and inner facing 12c. Metal edge 42 extends over the entire peripheral edge portion of the panel. Similarly, the second panel 14 includes a metal edge 44 extending around its peripheral edges which is coupled to the panel&#39;s inner foam core 14a and inner facing 14c by means of a conventional adhesive such as an epoxy cement or glue. Coupling arrangement 40 connects the first and second panels 12, 14 to the outside corner 22 by means of the combination of a metal channel connecting strip 46 and a plurality of screws 48, 50 and 52. Thus, screw 48 is inserted through the connecting strip 46 and metal edge 42, screw 50 is inserted through the connecting strip and the outside corner&#39;s inner metal facing 22a, and screw 52 is inserted through metal edge 44 and the connecting strip. Similarly, another portion of the metal edge in combination with a connecting angle 56, screw 57 and drywall screw 58 is used to securely couple the second panel 14 to the third panel 16. A similar coupling arrangement 68 attaches the opposing edge of the third panel 16 to the fourth panel using a metal edge 16d of the third panel 16. 
     Inner corner 26 includes an inner metal bracket 26a and an outer facing 26b on two sides thereof. Another coupling arrangement 30 connects the fourth panel 18 to the inside corner 26 along adjacent edges thereof in the following manner. The fourth panel 14 includes a metal edge 32 extending around the periphery thereof and securely attached to the panel&#39;s foam core 18a and inner facing 18c by means of an adhesive. Similarly, the inner metal bracket 26a of the inside corner 26 is affixed to the corner&#39;s foam core and outer facing 26b by means of an adhesive. A metal channel connecting strip 36 is disposed in contact with the fourth panel&#39;s metal edge 32 and the inside corner&#39;s inner metal bracket 26a and screws 38a and 38b are inserted through the connecting strip and metal edge 32 and screws 38c and 38d are inserted through metal channel connecting strip 36 and the inside corner&#39;s inner metal bracket 26a. First and fourth screws 38a and 38d draw the fourth panel 18 and the inner corner 26 together in tight fitting engagement when tightened. A similar coupling arrangement 54 connects the inside corner 26 to the fifth panel 20 as shown in FIG. 1. 
     Referring to FIG. 2, there is shown a sectional view of another arrangement incorporating structural insulated panels in accordance with the present invention. FIG. 2 shows a roof panel 60 coupled to and supported by first, second, and third wall panels 62, 64 and 66 which, in turn, are attached to and supported by a concrete foundation 68. Attached to an upper surface of the concrete foundation 68 is finished flooring 70. The third wall panel 66 includes an outer facing 66a, an inner facing 66b, and an insulating foam core 66c. Similarly, the first and second structural insulated panels 62 and 64 respectively include outer facings 62a and 64a, inner facings 62b and 64b, and insulating foam cores 62c and 64c, respectively. Roof panel 60 includes a lower panel 60a, a foam core 60b, and upper facing (which is not shown in the figure for simplicity). The first, second, and third wall panels 62, 64 and 66 each have a respective peripheral metal edge 62d, 64d and 66d disposed about the inner periphery thereof. The first panel&#39;s metal edge 62d is adhered to the panel&#39;s foam core 62c and inner facing 62b. Similarly, the peripheral metal edges 64d and 66d of the second and third panels 64, 66 are adhered to the foam cores 64c and 66c and inner facings 64b and 66b of these respective panels. 
     Disposed in the roof panel 60 is a metal coupling bracket 60c. The roof panel 60 is connected to the first panel&#39;s metal edge 62d by means of the combination of a coupling bracket 60d and a pair of screws 72a and 72b. Screw 72a is inserted through coupling bracket 60d and the first panel&#39;s metal edge 62d, while screw 72b is inserted through coupling brackets 60c and 60d. Peripheral metal edge 62d is also used for connecting the first panel 62 to the second panel 64 by means of a combination of coupling bracket 76, screws 74a and 74b, and the second panel&#39;s peripheral metal edge 64d. Disposed intermediate the first and second structural insulated panels 62 and 64 is a panel edge strip 62e. A similar coupling arrangement 78 is used to securely connect the second panel 64 to the third panel 66, with an edge strip 64f disposed intermediate the second and third panels. The second panel 64 is shorter than the first and third panels 62, 66 to accommodate the thickness of a second floor 82 described below. The lower edge of the third panel 66 is coupled by means of its peripheral metal edge 66d to the concrete foundation 68 by means of the combination of screws 81 and 82 and coupling angle 80. An outer peripheral metal edge 66e of the third panel 66 is affixed to the panel&#39;s foam core 66c and outer facing 66a and engages and rests upon the concrete foundation 68. 
     An interior wall panel 102 in accordance with the present invention includes first and second outer facings 102a and 102b and a foam core 102c disposed therebetween. A generally U-shaped peripheral metal edge 104 is disposed about the periphery of the panel&#39;s foam core 102c and is attached to peripheral edge portions of the two outer panels 102a, 102b. A lower edge of the structural insulated panel 102 is maintained in position on the foundation&#39;s flooring 70 by means of a combination of a U-shaped mounting bracket 106 and screw 108. The panel&#39;s peripheral metal edge 104 is inserted in U-shaped mounting bracket 106 and is securely maintained in fixed position on the concrete foundation 68. An upper portion of the panel&#39;s peripheral metal edge 104 is positioned within an upper U-shaped mounting bracket 98 which is attached to the ceiling 88 of the second floor 82 by means of screws 100. Channels formed in the upper edge of the interior wall panel 102 by its peripheral metal edge 104 receive the upper mounting bracket 98 and permit the wall panel to be raised, allowing its lower portion to be removed from the lower mounting bracket 106 for relocating or removing the wall panel. 
     Second floor 82 includes a plurality of spaced floor joists 86 connected to the second wall panel 64 by means of the combination of coupling bracket 76 and screws 74c and coupling arrangement 78. An end of floor joist 86 is disposed in contact with the second wall panel&#39;s inner facing 64b. Ceiling 88 is suspended from the floor joist 86 by means of a plurality of brackets such as brackets 92 and 94 attached to the floor joist 86 as well as to the ceiling 88 by means of a plurality of screws 96a, 96b and 96c. Disposed on the upper surface of the floor joist 86 is a floor surface 84 such as of carpet. 
     Referring to FIGS. 3, 4, and 5, there are respectively shown front elevation, top plan, and lateral elevation views of a structural insulated panel 114 in accordance with another embodiment of the present invention. Structural panel 114 includes an inner foam core 122 and first and second outer facings 116 and 118. Disposed along an edge of the structural panel 114 are first and second spaced metal strips 120a and 120b. Each of the first and second metal strips 120a, 120b is attached to an edge of the foam core 122 and two respective inner edge portions of the first and second panels 116, 118 by means of an adhesive. 
     Additional details of the structural insulated panel of FIGS. 3, 4 and 5 as well as details of the coupling between adjacent similar panels is shown in the sectional view of FIG. 6. In FIG. 6, a first structural insulated panel 124 is attached to a second, identical structural insulated panel 126. The first structural insulated panel includes first and second outer facings 124a, 124b and an inner foam core 124c. Similarly, the second structural insulated panel 126 includes first and second outer facings 126a and 126b and an inner foam core 126c. Disposed along an edge of the first structural insulated panel 124 are first and second metal edge strips 128a and 128b. Disposed along an opposing edge of the first panel 124 is a recessed portion as shown in the second structural insulated panel 126 which is adapted for receiving the first and second metal edge strips 128a and 128b as shown in the figure. First and second screws 130a and 130b inserted through the first and second outer facings 126a,  126b as well as through the metal edge strips 128a, 128b securely maintain the first and second panels 124, 126 connected together in a tongue and groove arrangement. The extended portion 124d of the first panels foam core 124c is positioned in abutting contact with the recessed edge 126d of the second panel&#39;s foam core 126c. 
     Referring to FIG. 7, there is shown a sectional view of a pair of panels 125 and 132 in accordance with another embodiment of the present invention. The first panel 125 includes first and second outer facings 125a, 125b, a foam core 125c, and first and second metal edge strips 129a and 129b. The second panel 132 includes first and second outer facings 132a and 132b as well as an inner foam core 132c. In the recessed end portion of the second panel are disposed first and second metal edge strips 134a and 134b. The extended lateral edge of the foam core 125c and first and second metal edge strips 129a, 129b of the first panel 125 are adapted for insertion in the recessed edge portion of the second panel 132. With the respective edge portions of the first and second panels 125, 132 disposed in abutting contact, first and second screws 136a and 136b are inserted through the metal edge strips 134a, 134b of the second panel 132 and the metal edge strips 129a, 129b of the first panel 125 for securely coupling the two panels along their respective abutting edges. 
     Referring to FIG. 8, there is shown a generally horizontal sectional view of a panel coupling arrangement 140 employing metal edge strips in accordance with another aspect of the present invention. The panel coupling arrangement 140 couples first, second, third and fourth interior insulated panels 142, 144, 146 and 148 together. The panel coupling arrangement 140 of FIG. 8 also securely couples first and second exterior panels 156 and 158 together as well as to the fourth interior insulated panel 148. As in the previously described embodiments, all of the panels shown in FIG. 8 include first and second outer facings and an inner foam core. The insulated interior panels 142, 144, 146 and 148 respectively include metal edge strips 142a, 144a, 146a and 148a. Each of the metal edge strips is securely bonded to the outer facing and inner core of its associated panel structure. Each of the metal edge strips 142a, 144a, 146a and 148a includes an angled distal portion having a respective aperture therein allowing the four metal edge strips to be securely joined as shown in the figure. With the four metal edge strips arranged as shown in FIG. 8, self-tapping screws 154b and 154d are respectively inserted through metal edge strips 142a, 144a and 146a, 148a. The access provided by the coupling arrangement 140 shown in FIG. 8 allows screws 154b and 154d to be driven in by a power drive such as a power screw driver rather than by a hand-operated ratchet tool. Self-tapping screws 154a  and 154c may also be respectively inserted through metal edge strips 142a, 148a and 144a, 146a for increasing the strength of the panel coupling arrangement 140 shown in FIG. 8. 
     Metal edge strip 160 attached to the opposing edge of the fourth insulated interior panel 148 also includes a pointed distal end portion having an aperture therethrough. Metal edge strip 160 is attached to the first and second exterior panels 156 and 158 by means of the combination of screws 164a and 164b, connecting bracket 162, and metal edge connecting strips 156a and 158a disposed respectively in the first and second exterior panels 156, 158. Screw 164a is inserted through aligned apertures in metal edge connecting strip 160 and connecting bracket 162. Similarly, screw 164b is inserted through aligned apertures in connecting bracket 162 and the metal edge connecting strips 156a, 158a of the first and second exterior panels 156, 158. 
     Referring to FIG. 9, there is shown additional details of the metal edge strip 148a of the fourth insulated interior panel 148. The distal angled portion 150 of the metal edge strip 148a facilitates secure connection of the interior insulated panel 148 to one or more similar panels by means of screws (not shown) inserted through apertures 152a and 152b in the distal end portion of the metal edge strip. Metal edge strip 148a is attached to the outer panels 148b, 148c and the foam core 148d of the interior insulated panel 148 by conventional means such as an adhesive. 
     Referring to FIG. 10, there is shown another embodiment of a metal edged insulated panel 170 in accordance with the present invention. Panel 170 includes exterior and interior facings 174 and 176 attached to an inner foam insulating core 172. Disposed about the inner periphery of panel 170 and attached to the panel&#39;s inner core 172 and interior facing 176 is a contoured metal edge strip 178. A corner portion of the metal edge strip 178 disposed about the panel&#39;s interior facing 176 is shown in the plan view of FIG. 11 of a portion of the panel. The metal edge strip 178 of the panel 170 is provided with a plurality of pre-punched apertures 178a for connection to adjacent panels as shown in the partial sectional view of first and second panels 180 and 182 of FIG. 12. The first panel 180 includes interior and exterior facings 180a and 180c and an inner foam core 180b. Similarly, the second panel 182 includes interior and exterior facings 182a and 182c and an inner foam insulating core 182b. The apertures in the metal edge strips 180d and 182d of the first and second structural insulated panels 180, 182 are aligned with corresponding apertures in a metal channel connecting strip 184. Screws 186a, 186b, 186c and 186d are inserted through aligned apertures in the metal channel connecting strip 184 and metal edge strips 180d and 182d for securely coupling the first and second structural insulated panels 180, 182. The first and second panels 180, 182 are drawn together when screws 186a and 186d are tightened. A filler interior facing 220 shown in dotted line form in the figure may be provided to cover and conceal the connection hardware. 
     Referring to FIG. 13, there is shown a vertical sectional view of another arrangement for connecting an exterior insulated wall panel 192 to a roof panel 190 and a concrete foundation 196. Insulated panel 192 includes exterior and interior facings 192a and 192c and an insulating foam core 192b. Disposed about the interior edge portion of panel 192 is a metal strip 192e. A lower portion of the metal edge strip 192e is affixed to the concrete foundation 196 by means of an anchor bolt and nut combination 194. An upper portion of the metal edge strip 192e is securely attached to the roof panel 190 by means of the combination of a roof panel connecting plate 190c, an angle roof attachment plate 200, screws 198a and 198b, and a nut and bolt combination 202. Roof connecting plate 190c is attached to an interior surface of the roof panel&#39;s interior facing 190b and is disposed in its inner foam core 190a. 
     Referring to FIG. 14, there is shown the manner in which a pair of insulated wall panels similar to the wall panel 192 shown in FIG. 13 may be securely coupled together. In FIG. 14, a first wall panel 204 includes inner and outer facings 204a and 204b and a foam core 204c. Similarly, a second wall panel 206 includes inner and outer facings 206a and 206b and a foam core 206c. The first wall panel 204 further includes metal edge strip 204d bonded to the panel&#39;s inner facing 204a and its foam core 204c. Similarly, the second wall panel 206 includes a metal edge strip 206d attached to the panel&#39;s inner facing 206a and its foam core 206c by conventional means such as an adhesive. Each of the metal edge strips 204d and 206d extends around the entire peripheral portion of its associated panel and includes a respective aperture for receiving a nut and bolt combination 208 for coupling the peripheral metal edge strips of adjacent panels 204 and 206 as shown in FIG. 14. An interior panel strip 210 may be placed over the metal edge strips 204d and 206d and maintained in position by an adhesive to conceal the panel coupling hardware. First and second sealant strips 212a and 212b may also be positioned intermediate the first and second panels 204 and 206 to provide a watertight seal between the panels. 
     Referring to FIGS. 15 and 16, there are shown two additional embodiments of structural insulated panels in accordance with the present invention. A first structural insulated panel 222 is shown in FIG. 15, with the manner in which two such panels may be coupled together shown in the sectional view of FIG. 17. Structural insulated panel 222 includes first and second outer facings 222a, 222b and an inner foam core 222c. Disposed on opposing lateral edge portions of panel 222 are a first pair of identical metal edge strips 224a and 224b. A second pair of identical metal edge strips 226a and 226b are also disposed on opposing lateral edges of panel 222. In addition, first and second edge slots 228a and 228b are disposed in opposing lateral edges of panel 222. The manner in which a pair of structural insulated panels 230 and 232 identical to the panel 222 shown in FIG. 15 may be coupled together is shown in FIG. 17. The first panel 230 includes first and second metal edge strips 230a and 230c as well as a first edge slot 230b.  The second panel 232 similarly includes first and second metal edge strips 232a and 232c as well as an edge slot 232b. Metal edge strips 230a and 232c and metal edge strips 230c and 232a are arranged in abutting contact when the first and second panels 230, 232 are arranged edge-to-edge. Self tapping screws 234a and 234b are inserted respectively through metal edge strips 230a, 232c and 230c, 232a for securely coupling the first and second panels 230, 232 together. 
     Referring to FIG. 16, there is shown another embodiment of a structural insulated panel 238 in accordance with the present invention. Panel 238 includes first and second outer facings 238a, 238b and a foam insulating core 238c. Disposed on a first lateral edge of panel 238 are first and second metal edge strips 240a and 240b. Also disposed in the first lateral edge of panel 238 are first and second edge slots 242a and 242b. Disposed on the second, opposing edge of panel 238 are third and fourth metal edge strips 244a and 244b. The manner in which a pair of panels as shown in FIG. 16 may be coupled together is shown in the sectional view of FIG. 18. In FIG. 18, first and second panels 246 and 248 are shown coupled together by means of self-tapping screws 250a and 250b respectively inserted through metal edge strips 246a, 248a and 246b, 248b. In the structural insulated panels shown in FIGS. 15 and 16, each of the metal edge strips is bonded to the panel&#39;s inner foam core and an adjacent outer facing by means of an adhesive as in the previous embodiments. 
     Referring to FIGS. 19, 20, 21, 22, and 23, there are shown various structural panel arrangements in accordance with the present invention. The structural insulated panel 252 shown in FIG. 19 includes first and second metal edge strips 252a and 252b and provides a tongue and groove connection between adjacent panels. Structural insulated panel 254 shown in FIG. 20 includes metal edge strips 254a and 254b on a first edge of the panel and metal edge strips 254c and 254d on a second, opposed edge of the panel. Additional details of structural panel 254 are shown in FIGS. 16 and 18. A pair of structural panels 254 as shown in FIG. 20 are connected together by means of a toe screw arrangement as previously described. The structural insulated panel 256 shown in FIG. 21 includes first and second metal edge strips 256a and 256b on opposed lateral edges thereof which provide a bolt together exterior coupling arrangement between adjacent panels. The structural insulated panel 258 shown in FIG. 22 includes first and second metal edge strips 258a and 258b which when coupled to adjacent, similar panels provides a bolt together interior modular coupling arrangement. 
     Referring to FIG. 23, there is shown yet another embodiment of a structural insulated panel 260 providing a tongue and groove with a catch type of coupling arrangement. Structural insulated panel 260 includes first and second outer facings 260a and 260b and a foam core 260c disposed therebetween. On one edge of panel 260 are disposed first and second metal edges 262a and 262b which are bonded to the foam core 260c as well as to first and second outer facings 260a and 260b, respectively. The opposed edge of panel 260 is provided with a pair of notches, or recesses, 266a and 266b respectively disposed on the inner surfaces of the first and second outer facings 260a and 260b. Notches 266a, 266b are adapted for receiving a respective tooth 264a, 264b on the distal end of one of the metal edges 262a or 262b of an adjacent panel. Thus, when a pair of panels 260 are positioned in abutting, edge to edge contact, teeth 264a and 264b respectively engage notches 266a and 266b for securely attaching the two panels. The tongue and groove with catch coupling arrangement provided by structural insulated panel 260 thus provides a locking feature for adjacent coupled panels. 
     Referring to FIGS. 24 and 25, there are respectively shown partial plan and sectional views of a pair of structural insulated panels 270 and 272 in accordance with yet another embodiment of the present invention. A first structural panel 270 includes first and second outer facings 270a and 270b as well as an inner foam core 270c. Similarly, the second structural insulated panel 272 includes first and second outer facings 272a and 272b as well as an inner foam core 272c. The first panel 270 further includes a metal edge strip 274, while the second panel 272 also includes first and second metal edge strips 276a and 276b. With the first and second panels 270, 272 positioned in edge abutting contact, adjacent portions of metal edges 274 and 276a are arranged in an overlapping manner permitting a self-threading screw 278a to be inserted through the two metal strips. A second self-threading screw 278b is inserted through the second outer facing 270b of the first panel 270 and the second metal edge strip 276b of the second panel 272. A notch 280 in the first outer facing 270a of the first panel provides access to the overlapped arrangement of metal edge strips 274 and 276a to permit installation of screw 278a for maintaining the first and second panels 270, 272 in secure coupling. 
     Referring to FIGS. 26 and 27, there are respectively shown plan and lateral elevation views of an open face panel 292 in accordance with another embodiment of the present invention. Open face panel 292 includes an interior facing 302 which is omitted from FIG. 26 for simplicity. FIG. 28 is a sectional view of the open face panel 292 shown in FIG. 26 taken along site line 28--28 therein. In addition to its interior facing 302, open face panel 292 includes a foam core 294 having a matrix array of recesses, or channels, 298 disposed in a surface thereof. The linear array of recesses 298 provides a wire run, or chase, for installing electrical wiring in the open face panel. Disposed on the same surface of the foam core 294 as the recesses 298 are a plurality of spaced, linear metal strips 296. Metal strips 296 are generally U-shaped and are affixed to the surface of the foam core 294 by means of an adhesive and are further attached to the panel&#39;s interior facing 302 by means of a plurality of screws 300 as shown in the sectional view of FIG. 29. The inner metal strips 296 provide a gap, or airspace, 306 between the panel&#39;s foam core 296 and interior facing 302. This gap 306 may also be used for wire runs within the open face panel 292. 
     FIG. 30 is a sectional view showing the manner in which two open face panels 308 and 310 are coupled together by means of first and second brackets 312 and 314 and first and second screws 316 and 318. The open face panel 292 shown in FIGS. 26, 27 and 28 is typically shipped to a job site with the metal strips 296 exposed allowing wire runs to be routed within the panel&#39;s recesses 298, followed by attachment of the panel&#39;s interior facing 302. The open face panel 292 provides easy access to the interior of the panel for electrical wiring, is easily assembled on site, is lighter than conventional panels, and requires minimal accessory hardware for electrical wiring. Providing the inner metal strips 296 with sufficient surface adhering to the panel&#39;s inner foam core 294 permits the open face panel 292 to be used as a structural panel. 
     There has thus been shown a structural insulated panel with metal edges which provides a lightweight, high strength structural member. The inventive structural insulated panel is particularly adapted for use with gypsum and cement-type panel faces which are brittle and weak in tension. The metal edge strip disposed either around the panel&#39;s entire periphery or along one edge thereof reinforces the gypsum, or cement faces, spreading the concentrated load of the panel fastening screws. Current building codes typically require 1/2 of gypsum drywall (or equivalent) as a fire barrier on the inside of all residential structures. Most prior art structural panels use a composite wood panel for the inside face. This wood inside face must be covered with gypsum to meet these building codes. If the original inside face is gypsum, it eliminates the need for an entire facing of wood. By adhering the metal edge strip to the panel&#39;s periphery, the tensile strength of the gypsum panel is substantially increased, allowing the panel to be used as a structural panel. The lamination of the metal edge strip to the edge of a structural insulated panel in accordance with the present invention is a simple and inexpensive means for making a new building system for economical housing. The metal edge strip is bonded in shear to an external face of the panel as well as to its foam inner core to substantially increase the panel&#39;s structural strength. In effect, the metal edge strip becomes an extension of the facing. Using a high quality adhesive, the structural strength of the panel&#39;s facing may be continued through to the metal edge strip with only a short overlap. An overlap of four to eight times the thickness of the panel&#39;s facing is generally sufficient for full strength continuation of the structural strength of the panel&#39;s facing. Another advantage of the coupling arrangement made possible by the panel&#39;s metal edge strip is in the use of power drive systems rather than a hand-powered ratchet wrench for attaching the panels. The coupling arrangements described above thus provide improved access to the coupling screws or nut and bolt combinations for joining and mounting the structural insulated panels. 
     While particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects. Therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of the invention. The matter set forth in the foregoing description and accompanying drawings is offered by way of illustration only and not as a limitation. The actual scope of the invention is intended to be defined in the following claims when viewed in their proper perspective based on the prior art.