Title:
PREFABRICATED WALL PANELS AND A METHOD FOR MANUFACTURING THE SAME
Kind Code:
A1


Abstract:
A multi-layer prefabricated wall panel for modular building and a method for manufacturing the same. The panel comprises a load-bearing and vapor barrier core layer; an interior insulating and utility installation layer bonded to the inner face of the core layer; an exterior sheet of a first rigid building material bonded to the interior insulating layer; and an interior sheet of a second building material bonded to the outer face of said core layer. The method for manufacturing the wall panel comprises the steps of forming a stack of the panel layers with adhesive coating between successive layers and bonding the layers to each other by uniform compressing forces.



Inventors:
Yogev, Yitzhak (Qiryat Tivon, IL)
Application Number:
11/754406
Publication Date:
12/04/2008
Filing Date:
05/29/2007
Primary Class:
Other Classes:
52/745.19
International Classes:
E04C2/36
View Patent Images:
Related US Applications:



Primary Examiner:
ADAMOS, THEODORE V
Attorney, Agent or Firm:
MARTIN D. MOYNIHAN d/b/a PRTSI, INC. (c/o Purrfect Patents LLC 11213 Piedmont Drive, Fredericksburg, VA, 22407, US)
Claims:
1. A multi-layer prefabricated wall panel, the panel having an interior and exterior planar surfaces and a thickness defined therebetween, the panel comprising: a load-bearing and vapor barrier core layer having an inner face and an opposite outer face; an interior insulating and utility installation layer bonded to the inner face of said core layer, the interior insulating and utility installation layer comprising a plurality of channels extending from top to bottom thereof for accommodating utility lines; an exterior sheet of a first rigid building material bonded to said interior insulating layer; and an interior sheet of a second building material bonded to the outer face of said core layer.

2. The wall panel of claim 1 wherein the core layer comprises at least two tubular metal members and one or more interior sandwich panels extending between said two metal members, the one or more sandwich panels and the metal members having substantially the same length and thickness so as to form in combination a solid layer with two opposite flat faces.

3. The wall panel of claim 2 wherein said one or more sandwich panels comprise thermal insulating material sandwiched between two flat metal skins.

4. The wall panel of claims 3 wherein said thermal insulating material is selected from the group consisting of mineral wool, polymer foam and timber.

5. The wall panel of claim 1 wherein said insulating and utility installation layer comprises a plurality of spaced apart elongated blocks of insulating material.

6. The wall panel of claim 1 wherein said insulating and utility installation layer comprises a mattress-like body made of insulating material provided with a plurality of channels extending the entire length of said mattress-like body having openings at top and bottom edges of the body.

7. The wall panel of claim 1 wherein said exterior sheet is selected from the group consisting of a cement board, a timber board, a metal sheet and a reinforced plastic sheet.

8. The wall panel of claim 1 wherein said interior sheet is selected from the group consisting of a gypsum board, a cement board and a timber board.

9. The wall panel of claim 1 wherein said thickness is in the range of 140 to 260 mm.

10. The wall panel of claim 2 further comprising a top frame member and a bottom frame member welded to said at least two metal tubular members for forming a frame around the panel.

11. A method for fabricating a building panel, the method comprising the steps of: forming a stack of horizontally placed building layers in a successive manner; coating the upper surface of each layer with an adhesive before the next layer is placed thereon; and subjecting said stack to uniform compression forces.

12. The method of claim 11 wherein said stack comprises a first sheet of a building material, a core layer, an insulating and utility installation layer and a second sheet of building material.

13. The method of claim 11 further comprising the step of incorporating a frame metal into said stack of building layers.

14. The method of claim 11 wherein said subjecting step is performed by means of a vacuum manifold.

15. The method of claim 11 wherein said subjecting step is performed by means of a compression plate.

16. The method of claim 11 wherein said compression forces are in the range of 0.2 to 0.6 Kg/cm2.

17. A building component comprising at least one prefabricated wall panel as defined in claim 1.

Description:

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to modular construction and more specifically to prefabricated wall panels for use in modular buildings, to a method for fabricating the panels and to building components including the same.

2. Discussion of the Related Art

Industrialized building methods are becoming more popular over the last decades in the construction industry for both domestic and public buildings, Also referred to as large-panel construction, such methods utilize high degree of factory prefabrication in order to reduce site work and improve the quality and speed of construction. The large prefabricated panels are transported from the factory to the construction site where they are assembled in a modular manner to form walls, ceiling and/or floors. Optionally, the panels may be assembled, at least partially, at the factory site to form larger building components, where limitation to the size of pre-assembled components is mainly due to transportation possibilities. In either case, work and debris at the construction site is reduced significantly as compared with traditional and/or conventional construction methods.

Various prefabricated large panels for modular building are known in the art, including multi-layer sandwich panels. However, available building panels and the manufacturing methods for fabricating such panels still suffer from a number of drawbacks. In particular, fabrication of known large building panels involves mechanical fastening for joining the different components and/or layers of the panel to each other. Thus, not only the assembling of the panels to form larger building components walls requires manual work, but in many cases the fabrication of the panel themselves require manual work which slows down the manufacturing and increase costs. Furthermore, the panels so produced may suffer from uneven fastening and consequently from insufficient flatness and from weak points or seaming lines susceptible to instabilities. Moreover, many times known prefabricated panels do no provide all the properties required from building components in terms of stability, insulation, easiness of utility installation, etc.

Therefore there still exists a need for improved prefabricated building panels and for an improved process for manufacturing the same.

Accordingly, it is the object of the present invention to provide a building panel which is fabricated as one solid integral piece, which is structurally strong and dimensionally stable, which provides high level of thermal and acoustic insulation and is moisture and vapor resistant as well as fire resistant.

A further object of the invention is to provide a building panel having the above features which allows for easy installation of utility lines such as electricity wiring and plumbing and which provides flexibility at the planning and manufacturing stage so that it can be easily tailored to specific needs and allows for future changes.

An additional object of the invention is to provide prefabricated panels having the above features, which allow for joining individual panels to each other as well as to floor and ceiling by welding rather than by mechanical fasteners.

Yet, a further object of the invention is to provide a method for fabricating large-size and extra-large-size panels having the above features, which minimizes manual work at the fabrication site as well as reduces assembling and finishing work at the construction site.

Other advantages of the invention will be apparent from the following description.

SUMMARY OF THE PRESENT INVENTION

The present invention provides improved prefabricated wall panels for modular building and an improved method for fabricating the same.

One aspect of the present invention is a multi-layer prefabricated wall panel having an interior planar surface and an exterior planar surface. The panel comprises: a load-bearing and vapor barrier core layer having an inner face and an opposite outer face; an interior insulating and utility installation layer bonded to the inner face of the core layer; an exterior sheet of a first rigid building material bonded to the interior insulating layer; and an interior sheet of a second building material bonded to the outer face of the core layer.

The core layer preferably comprises at least two tubular metal members and one or more interior sandwich panels extending between the at least two metal members, wherein the one or more sandwich panels preferably comprise thermal insulating material, selected from the group consisting of mineral wool, polymer foam and timber, sandwiched between two flat metal skins. The wall panel further comprises a top frame member and a bottom frame member welded to the least two metal tubular member for forming a frame around the panel.

The interior insulating and utility installation layer comprises a plurality of channels extending from top to bottom thereof for accommodating utility lines. In accordance with one embodiment of the invention the interior insulating and utility installation layer comprises a plurality of spaced apart elongated blocks of insulating material. In accordance with another embodiment, the insulating and utility installation layer comprises a mattress-like body made of insulating material provided with a plurality of channels extending the entire length of the mattress-like body and having openings at the top and bottom edges of the body. The one or more sandwich panels and the metal members are having substantially the same length and thickness so as to form in combination a solid layer with two opposite flat faces. Preferably, the exterior sheet is selected from the group consisting of a cement board, a timber board, a metal sheet and a reinforced plastic sheet and the interior sheet is selected from the group consisting of a gypsum board, a cement board and a timber board. The thickness of the wall panel, defined as the distance between interior and exterior planar surfaces of the wall panels is preferably in the range of 140 to 260 mm.

A second aspect of the invention is a method for fabricating a building panel, the method comprising the steps of: forming a stack of horizontally placed building layers in a successive manner; coating the upper surface of each layer with an adhesive before the next layer is placed thereon; and subjecting said stack to uniform compression forces. The method may further comprise the step of incorporating a frame metal into said stack of building layers. The step of subjecting the stack to uniform compression forces may be performed by means of a vacuum manifold or alternatively by means of a compression plate. The stack preferably comprises a first sheet of a building material, a core layer, an insulating and utility installation layer and a second sheet of building material.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood and appreciated more fully from the following detailed description taken in conjunction with the drawings in which:

FIGS. 1 and 2 are a partial isometric view and a partial frontal view, respectively, of a wall panel according to one embodiment of the present invention, illustrating the multi-layer structure of the panel;

FIG. 3 is a horizontal cut of the wall panel of FIGS. 1 and 2 taken along line 3-3 of FIG. 1;

FIG. 4 is a vertical cut of the panel of FIGS. 1 and 2 taken along line 4-4;

FIG. 5 is an isometric view of the metal frame in accordance with the embodiment of FIG. 1 showing the upper and lower framing and the vertical load-bearing metal members;

FIG. 6A and 6B illustrate two embodiments of the interior sandwich panels of the core layer;

FIG. 7 is a vertical cross sectional view of a building comprising the wall panel of FIG. 1, showing connections of the wall panel to floor and ceiling and a utility line running through the inner insulating layer;

FIG. 8 is a horizontal cut through a wall panel of the invention in accordance with a second embodiment;

FIG. 9 is a partial isometric view of the inner insulating layer in accordance with the second embodiment depicted FIG. 8;

FIG. 10 is a vertical cross sectional view through a building comprising of wall panels of FIG. 8;

FIGS. 11A and 11B are frontal and side cross-sectional views, respectively, illustrating the formation process of a panel in accordance with the novel method of the invention;

FIG. 12A is a frontal view of a wall panel of the invention comprising pre-designed a window opening;

FIG. 12B is a horizontal cross section through line B-B of FIG. 13A.

FIG. 13A is a horizontal cut through a wall in accordance with the invention, showing two adjacent panels joined together to form a wall;

FIG. 13B is a horizontal cut through a building corner in accordance with the invention, showing perpendicularly joined panels.

It will be realized that the drawings are not drawn to scale and that the aspect ratio of the elements illustrated, as well as the dimensional ratios between different elements, are distorted in order to better demonstrate various features of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention provides improved wall panels and improved methods for manufacturing the same. The panels of the invention comprise multiple layers, each designed to impart the panel a particular functionality and/or benefit, while the method of the invention for fabricating the multi-layer panel as one integral unit with no mechanical fasteners between elements, further imparts the panel structural stability and enhanced flatness and smoothness. In accordance with the novel method of the invention, the different layers of the panel are bonded to each other under pressure by one compression step rather than being fastened to each other by mechanical fasteners such as screws and bolts. Besides enhancing stability and appearance, this allows for manufacturing extra large panels which significantly reduces the number of joints and consequently reduces site work and cost as well as the amount of defects that might be introduced during joints assembling.

Referring to the FIGS. 1-4, there is shown a wall panel, generally designated 10, in accordance with one embodiment of the invention. Wall 10 comprises a core layer 20, an interior insulating and utility installation layer 30, an exterior sheet 40 and an interior sheet 50. Layers 20, 30, 40 and 50 are bonded to each other to form one integral panel having two opposite smooth planar surfaces defined by the outward faces of sheets 40 and 50. Panel 10 further comprises a top frame member 64 and a bottom frame member 62 which together with members 25 of core layer 20 form a peripheral metal frame 60 that encompasses panel 10 to enhance the panel structural stability and to allow weld-joining to adjacent panels as well as to ceiling and floor. Frame 60 is illustrated in FIG. 5.

Core layer 20 comprises at least two rectangular, preferably square, tubular metal members 25 extending about the full length L of panel 10 and one or more interior sandwich panels 22 extending between members 25 and in contact therewith to fill the space therebetween. Members 25 and panels 22 are of the same length and thickness so as to form a mattress-like layer having two opposite flat faces, a flat top edge and a flat bottom edge. The outward sides 26 of members 25 define the side edges of layer 20. Members 25 constitute the main load-bearing construction elements of panel 10 and therefore should be distributed at appropriate intervals. Thus, depending on the size of panel 10 and on the total construction requirements, one or more additional members 25 may be incorporated into layer 20 between panels 22. In practice, frame members 62 and 64 are welded to members 25 to form structural metal frame 60, which is incorporated into panel 10 at the manufacturing process as explained below.

Interior panels 22 are sandwich panels comprising an insulating core material 24 sandwiched between opposite skins 26 and 28. Preferably, skins 26 and 28 are metal sheets, preferably 0.2-0.8 mm thick steel sheets. Skins 26 and 28 serve as vapor barrier between the interior and exterior of panel 10. Insulating material 24 may be any insulating material and may be in the form of prefabricated blocks or as a bulk material. Possible materials for insulator 24 include mineral wool, expanded or extruded polymer foam or polymer fibers, timber blocks or wood fibers and the like. Preferably, insulator 24 is mineral wool of 100-140 kg/m3 density. However, insulator 24 may be selected in accordance to the thermal and acoustic insulation requirements at the particular location where the building is to be built. Thus, for rough weather conditions where thermal insulation is crucial, insulator 24 is preferably polyurethane or polystyrene foam while under milder weather conditions insulator 24 is preferably mineral wool, being a better acoustic insulator. Sandwich panels 22 may be prefabricated off-the-shelf panels or may be especially fabricated to suit particular insulation and dimensional requirements. Alternatively, when insulating material 24 is in the form of blocks, panels 22 may be formed during the manufacturing process of panel 10. The width (horizontal dimension) of panels 22 can vary and is mainly determined by the width of available metal sheets. When layer 20 comprises more than one panel 22, panels 22 are abutted against each other to form continuous insulating layer between the two metal skins. FIGS. 6A and 6B illustrate two possible embodiments for abutting and joining sandwich panels 22 to each other to form a continuous layer. According to the embodiment illustrated in FIG. 6A, the exterior skins 26 and 28 of panel 22a extend to some extent 26a and 28a, respectively, beyond insulator 24 so that when the panels are abutted against each other, portion 26a overlap skin 26 of adjacent panel and portion 28a overlap skin 28 of adjacent panel, in a slate-like manner. According to the embodiment illustrated in FIG. 6B, additional skins 23 are placed against both skins 28 and 26 along the seam line between adjacent panels 22b. In accordance with both embodiments, the continuous overlapping exterior contact between adjacent panels reinforces layer 20 and enhances its structural stability. It will be realized that since the metal skins of panels 22 are only a fraction of a millimeter thick, the double-skin overlapping areas at the vicinity of seam lines do not affect the face smoothness of layer 20 to any significant extent.

Next to core layer 20 toward the interior face of panel 10, is insulating and utility installation layer 30. In accordance with the embodiment illustrated in FIGS. 1-7, the interior insulating layer 30 comprises a plurality of spaced-apart elongated insulating blocks 32, preferably of a rectangular cross section, disposed between core layer 20 and interior sheet 40. Blocks 32 are preferably made of a water-proof closed-cell polymer foam such as expanded polystyrene. However, at areas where additional strength is required, such as for example where cupboards are to be suspended from the wall, polymer blocks may be replaced by structured wood blocks in metal profiles for enhancing anchoring force of cupboard to wall. Elongated blocks 32 of length Li extend longitudinally between bottom frame member 62 and horizontal beam 67 of top frame member 64. Length Li corresponds to the interior height of the building. Blocks 32, preferably about 40 to 100 mm thick and about 100 to 300 mm wide, are equally spaced, leaving elongated channels 33 therebetween. Channels 33 are of preferably narrower dimensions than that of blocks 32 so that layer 30 comprises of about 75% solid and about 25% space. Channels 33 allow for installation of utility lines such as electrical wiring, plumbing pipes, communication lines etc., as best seen in FIG. 7. A plurality of openings 65a and 65b provided at bottom frame 62 and beam 67, respectively, in alignment with channels 33 allow for threading the utility lines through the frame for connection to utility hubs installed under floor and/or above ceiling.

The interior faces of blocks 32, opposite the faces in contact with panels 22, are covered by interior sheet 50 of length Li. Interior sheet 50 may be of any building material suitable as interior wall including a gypsum board, a cement board, a timber board and the like. Preferably sheet 50 is an off-the-shelf gypsum board of 9 to 32 mm thickness. It will be appreciated that panel 10 requires no further finishing on the interior side of the building as it is well known in the art to cover inner surfaces with gypsum boards. Exterior sheet 40, of length L, bonded on the outward surface of core layer 20 may be of any durable building material suitable for withstanding the climate conditions where the building is to be located, including cement, timber, metal, reinforces polymer sheets and the like. Preferably, sheet 40 is a cement board of 7.5 to 20 mm thick. It will be appreciated that although not necessary, any type of cladding (i.e. siding, stucco, EIFS, brick, stone) may be applied to the interior and/or exterior faces of the panel similar to traditional construction methods. The cladding may be applied at the manufacturing site or may be applied later at the construction site after the building is erected. It will be appreciated that the structure of wall 10 is designed such that there is minimum continuous metal thermal conductive path from one face of the wall to opposite face. It will be further appreciated that the interior sandwich panel of the core layer serve as vapor barrier between inside and outside.

Referring to FIG. 5, there is illustrated metal frame 60 that encompasses the peripheral edges of layers 20 and 30 of panel 10. Layers 40 and 50 are bonded to the opposite outermost surfaces of frame 60 as best seen in FIGS. 4 and 7. Frame 60 comprises a bottom frame member 62, an upper frame member 64 and two vertical load-bearing members 25. Frame members 62 and 64 extend the full width of panel 10 and are each having a profile comprising of vertical and horizontal sections configured to receive the layers of panel 10 and to allow metal welding to corresponding metal frames in floor and ceiling. Thus, top member 64 comprises upper and lower L-shaped profile sections 66 and 67, respectively, directed at opposite directions and connected by vertical section 61. Similarly, bottom frame member 62 comprises two L-shaped profile sections 63 and 68 connected by vertical section 69. Core layer 20 of length L is accommodated between the horizontal sections of sections 66 and 63 while blocks 32 of layer 30, having length Li, are inserted between L-shaped sections 67 and 68 and are positioned between openings 65a and 65b to provide openings into the channels 33 that are formed between the blocks as best seen in FIG. 1.

The overall combined thickness T of panel 10 is preferably in the range of 120 to 300 mm, where the core layer 20 is about 80-140 mm thick, the interior insulating layer 30 is about 40-100 mm thick, the interior sheet 50 is about 9-32 mm thick and the exterior sheet is about 7.5 to 20 mm thick. The vertical dimensions of panel 10, L and Li, correspond to the exterior and interior heights of the building, respectively, and are determined according to construction plan. Preferably, L is in the range of 3 to 4 m, while Li is 20 to 60 cm shorter. The horizontal dimension of panel 10 can be of up to 15 m, meaning that for some buildings, depending on the building size, a complete wall can be prefabricated as one integral piece having continuous smooth flat surfaces. It will be appreciated that the possibility to provide an extra-large multi-layer wall panel significantly reduces assembling work and cost. It will be also appreciated that as no mechanical fasteners are required for joining the multiple layers to each other or for joining adjacent portions of the same layer in order to form a larger component, the structural integrity and stability of the panel as well as surface flatness and smoothness, are significantly enhanced compared with prior art panels. Furthermore, the unique multi-later structure of panel 10 provides high level of thermal and acoustic insulation, vapor barrier properties, easiness of installation of utility lines and enhanced flexibility in tailoring the wall panels to fit specific construction requirements.

Referring to FIG. 7, there is depicted a vertical cut through a building having walls made of panels 10, showing panel 10 joined to floor 80 and roof 90. As can be seen bottom profile 62 of panel 10 is welded to foundation frame 82, which also supports the floor reinforcing beams 84. At its upper end, panel 10 is welded to reinforcing roof beams 92. A utility line, designated 70, running through channel 33 of layer 30, may connect to a central utility line 71 that runs under the flooring 86 through opening 65b in frame 60 and/or to utility line 72 running above ceiling 96 through opening 65a. Utility line 70 may be an electrical wiring, a water or a heating pipe, a communication line such as an optic fiber or a telephone line, etc. It will be appreciated that panel structure allows for easy installation of such utility lines to be connected to central utility hubs under floor or above ceiling, by providing prefabricated infrastructure channels at a relatively high density. Layer 30 further facilitates guiding the utility lines and keeping them separated from each other.

An alternative embodiment of panel 10, generally designated 110, is illustrated in FIGS. 8-10. In accordance with this embodiment, the insulating utility-installation layer 30 of panel 10 is replaced by layer 130. Layer 130 comprises a solid body 131 of insulating material provided with a plurality of prefabricated utility channels 132 that run the full length of body 131 between top and bottom edges, extending between top openings 135 and bottom openings (not shown). Layer 130 is preferably made of expanded polystyrene. Channels 132 are preferably of oval cross section and are located closer to the inner face of layer 130. The other layers of panel 110 are similar to layers 20, 40 and 50 described above in association with FIGS. 1-6. However, in accordance with this embodiment, upper and lower frame members 164 and 162 are simpler in shape than frame members 62 and 64 of panel 10 and do not include openings. Referring to FIG. 10, unlike frame members 62 and 64, frame members 162 and 164 end toward the interior face of the panel with horizontal sections 161 and 163, respectively, and do not include a vertical section. Sections 161 and 163 extend up to openings 135 in layer 130 so as not to cover the openings. It will be realized that since layer 130 comprises one integral piece, there is no need to provide further vertical elements in frames 162 and 164. Embodiment 110 has the advantage of reducing panel assembling time as compared with panel 10 since layer 130 is placed as one piece instead of placing a plurality of separated blocks. Layer 130 also has the advantage of continuous and larger contact surfaces with adjacent layer, thus increasing the panel structural stability. Furthermore, in accordance with the structure of panel 110, sheet 50 is supported by layer 30 only and is not in contact with metal frame 60, such that there is no metal continuity between outer and inner sheets 40 and 50. This prevents any thermal conductivity between interior and exterior faces and provides higher level of thermal isolation.

Turning now to FIGS. 11, the present invention provides a novel method for fabricating multi-layer building panels by forming a horizontal stack of the multiple layers with intermediate layers of adhesive therebetween, and subjecting the stack to pressure, thereby bonding the layers to each other in a single operation. Compression may be applied either mechanically by a compression plate or by means of a vacuum device. In either case, the panels are uniformly pressurized. FIGS. 11 demonstrate the fabrication process of a panel in accordance with embodiment 10. It will be easily realized that the fabrication of a modified panel, such as panel 110, is performed in a similar manner. In accordance with the panel fabrication method of the invention, the multiple layers are orderly placed horizontally on a working table 200 comprising a horizontal working plate 205 supported on legs 204. The layers are placed one above the other wherein the yet-free upper surface of each layer is sprayed to be covered by a layer of adhesive before the next layer is placed over it. The steel frame, consisting of the two tubular columns and the top and bottom frame members, is incorporated into the panel at the appropriate stage in accordance with the specific structure of the panel in hand. Thus, referring to FIGS. 11, demonstrating fabrication of panel 10, the first layer to be placed on working surface 205 is interior sheet 50. The sheet is sprayed with adhesive layer and frame 60 is placed over its periphery. Two vertical supporting beams 208 and 210 configured to conform with the dimensions and with the upper and lower profiles of the multi-layer panel, are mounted along opposite sides of table 200 to support the panel during fabrication process and to facilitate alignment of the layers. Beams 208 and 210 are preferably removably mounted to plate 205 such as to allow the selection of beams in accordance with the panel in hand. After frame 60 is appropriately placed over sheet 50, supported on beams 208 and 210, the plurality of insulating blocks 32 are placed over sheet 50 to form insulating layer 30. Blocks 32 are inserted between sections 68 and 67 of frame 60 which guide appropriate placing and help to align the blocks. Next, blocks 32 are sprayed by adhesive and core layer 20 is placed over layer 30 and over sections 61 and 69 of frame 60. The upper surface of layer 30 is then sprayed to be coated by an additional adhesive layer and exterior sheet 40 is placed over layer 20, peripherally supported on and in alignment with the outermost surface of frame 60. A pressure P is then uniformly applied on the multiple layers until the adhesive is cured for reinforcing bonding between layers, forming one integral piece. Preferably the pressure applied is in the range of 0.2 to 0.6 Kg/cm2. It will be easily realized that a panel of structure 110 is similarly fabricated with the exception of mounting frame 160 onto layer 30 after the later is already placed over sheet 50. It will be also realized that layers 20, 40 and 50, as well as layer 130 in case of embodiment 110, may consist of one piece or may consist of a number of portions abutted against each other to form a continuous layer when placed over table 200. It will be appreciated that the dimensions of such portions is mainly determined by market availability. The adhesive used to bond the layers to each other is preferably sprayable one-component or tow-component polyurethane adhesive such as polyurethane adhesives distributed by Sika AG.

As mentioned above, pressure P may be applied by a compression plate 125 pressed from above, as illustrated in FIG. 11, or alternatively may be applied by means of a vacuum manifold (not shown) coupled to table 200. In the later case, the vacuum manifold may be coupled to peripheral channels that circumferences plate 205 and open inwardly. A flexible air-impermeable cover is then used for entirely covering the table, including the table channels and the pre-assembled layers laying on the table, in an air-tight manner. As the vacuum manifold is activated, the cover is evacuated to form sub- atmospheric pressure under the cover to apply uniform pressure on the pre-assembled panel.

It will be appreciated that the method of the invention allows for enhanced flexibility in designing a wall panel in terms of the panel dimensions and the panel specific structure, to be tailored to specific requirements depending on location of the building and the location of the specific panel in relation to the building. It will be further realized that the fact that during assembling, the layers of the panel are horizontally displayed one following the other, enhances the easiness by which different materials may be selected for specific zones within the same panel in order to optimize the panel functionality. For example, when knowing in advance where cupboards are to be installed, the insulator material of interior insulating layer 30 (or 130) at the known locations may be specifically selected as wood blocks, instead of the polystyrene foam, for enhancing connection strength between cupboard and wall. Further, threading of utility lines may be performed while the panel is still in horizontal position or even before completion of the assembling process.

FIG. 13 illustrates a wall panel provided with a prefabricated opening adapted to receive a window frame. Panel 310 is a composite panel of substantially the same multi-layered structure as of panel 10 or panel 110 described above. Portions of core layer 20 and insulating layer 30 (or 130) are cut-out to form an opening 350. Two vertical metal studs 328 extending the full length of the panel are added to metal frame 360 for reinforcing the panel around the opening. It will be realized that the portions of layers 20 and 30 need not actually being cut out but instead layers portions of appropriate size may be placed above and below the opening during fabrication. A window frame 352 is already incorporated into the panel. In order to protect frame 352 during transportation, inner and outer sheets 50 and 40 fully cover the panel when fabricated. After installation of the panels at the construction site, portions 41 and 51 (shown in broken lines in FIG. 13B) are cut out to expose the opening and for mounting the window on window frame 352. It will be easily realized that the particular size and location of the window opening may varied and that a door opening may be similarly pre-prepared.

FIGS. 13A and 13B are horizontal cuts through a wall and a wall corner, respectively, of a building made of the panels of the invention, showing the joints between panels. Panels 10a and 110b and 110b are joined to each other by welding tubular members 25a and 25b of adjacent panels either in a parallel for forming a continuous wall or perpendicularly for forming a corner. During fabrication, core layer 20 at the vicinity of tubular members 25 as well as members 25 themselves, is left exposed, namely it is not covered by the other layers, in order to allow accessibility of the welding device to members 25 during weld-joining. After the panels are joined, complementary layer pieces 38, 48, and 58 for a continuous wall joint and pairs 34, 44 and 54 for a corner joint, are added for covering the joints.

It will be appreciated by persons skilled in the art that the present invention is not limited to what has been particularly shown and described hereinabove. Rather the scope of the present invention is defined only by the claims which follow.