WO2011073535A1

WO2011073535A1 - Building element and method for manufacturing building element

Info

Publication number: WO2011073535A1
Application number: PCT/FI2010/051062
Authority: WO
Inventors: Erkki NÄRHI; Pekka Roivio; Tarmo Mononen; Jyrki Kesti; Marko Moisio
Original assignee: Rautaruukki Oyj
Priority date: 2009-12-18
Filing date: 2010-12-20
Publication date: 2011-06-23

Abstract

The invention relates to a multilayer building element and a method for manufacturing the same. The building element (1) comprises a polymeric-based insulation material layer (2), a first surface layer (3) on the first side of the polymeric-based insulation material layer (2), and a second surface layer (4) on the second side of the polymeric- based insulation material layer (2). According to the invention, the first and the second surface layer (3, 4) are implemented as a nonstructural membrane-like surface layer (3) and the building element (2) comprises one or more elongated stiffening frame elements (5, 50) extending in at least one direction within an insulation material layer (2) in order to render structural load-bearing strength to the building element.

Description

Building element and method for manufacturing building element

The invention relates to a building element in accordance with the preamble of claim 1 capable of combining a load-bearing structure with thermal and moisture barrier insulation and, in particular, to a building element having a multilayer structure and comprising a polymeric-based insulation material layer as well as, on the first side of the polymeric-based insulation material layer, a first surface layer and on the second side of the polymeric-based insulation material layer, a second surface layer.

Additionally, the invention relates to a method in accordance with the preamble of claim 17 for manufacturing a building element.

Background of invention

Building elements such as those used as roof elements and wall elements are subjected to quite high loads due to various factors, e.g., snow accumulated on the roof, whereby the roof element is required to exhibit a sufficient mechanical strength. Snow loads may rest on roofs for several months during a year thus also making the time-related strength qualities such as creep strength of the elements crucial as to their performance. The weight and costs of the elements may not rise excessive while the tendency is to increase the size of elements in order to achieve shorter erection times. Respectively, among other qualities, a wall element is required to have strength under a wind load that subjects the wall element to a bending moment between support columns. Moreover, at the erection site, the wall areas shall be completed rapidly, which means need for a larger element size and, respectively, at the element factory, for shortest possible throughput times in production. As to the facade cladding material, the facade designer or architect aims to vary the facade cladding material individually for each project.

In the prior art are known metal-clad building elements (sandwich panel) in which a multilayer structure is comprised of cladding sheets such as surface sheet steels with a core insulation material placed therebetween such as mineral wool (MW) and/or expandable PUR/PIR/EPS insulation material. The behavior of the sandwich structure particularly under bending is based on the cooperation of the core material and the surface cladding sheets by virtue of a resin bond established therebetween. The load-bearing capability of these panels is conventionally improved by profiling the surface sheets, i.e., by contouring one or both of the surface sheets steels. However, this not always economically or technically possible due to specific requirements posed on building elements in a given application. Higher load-bearing capacity has been aimed at, among other solutions, by way of embedding stiffening frame elements in the sandwich structure as described in patent EP 1347111 B 1. This kind or arrangement, however, becomes problematic due to undesirable discontinuities caused by the stiffening frame elements in the resin bonds between the insulation material and the surface sheets, whereby the reinforcing elements must be provided with sharp crests to minimize bond discontinuities. Moreover, the stiffness of this kind of a sandwich structure is governed by the resin bond between the surface sheets and the insulation material as well as the long-time durability thereof.

Subsequent to the manufacture of sandwich elements on a continuous production line, variations on the facade surfaces of the elements cannot be implemented in a cost-effective way inasmuch as, after the elements leave the production line, variation is possible only by way of adding different facade surfaces onto the surface sheets. Accordingly, there is a need to provide a wall element with the possibility of having variation on its facade surface and/or interior surface.

Fabrication of a large-size panel element with a sheet metal cladding is awkward inasmuch as sheet steel for example is generally delivered in about 1.5 m wide strips, whereby making an element having a width in excess of 2.5 m would need a butt, overlap or tongue-and-groove joint between adjacent sheet steel strips. Moreover, the element becomes heavy and quite costly due to its complicated structure. Prior art has been hampered in that conventional embodiments have been incapable of providing a building element suited for use a prefabricated load-bearing roof element, which could dispose with the need for stiffening element placed exterior to the roof element and offer structural stiffness even without surface sheets. Prior art is also disadvantaged by the heavy weight and low cost-effectiveness of known structures. Furthermore, prior-art constructions rely on the resin bond between the insulation material and the surface sheet layers or, alternatively, on the use of heavy surface sheets. In conclusion, prior art embodiments have been inferior in the fabrication of a large-size building element.

Insulated building elements are fabricated as individual elements or on a continuous production line. A problem in conventional fabrication techniques arises from the limitations in reliably achieving a sufficient insulation layer thickness inasmuch as the curing and homogeneous quality of the insulation material becomes uncontrollable at increased thickness of insulation material. Therefore, it has been problematic to embed reinforcing members of sufficient lateral height into the insulation material of roof elements.

Brief summary of the invention

Accordingly, it is a goal of the present invention to provide a building element and a method for manufacturing the same in such a fashion that the above- described problems are overcome. The goal of the invention is achieved by virtue of a multilayer roof building element in accordance with the specifications of claim 1, said roof element being characterized in that the first surface layer is implemented as a nonstructural membrane-like surface layer and that the building element comprises one or more elongated stiffening frame elements extending in at least one direction within an insulation material layer in order to render structural load-bearing strength to the building element. It is an object of the invention to provide a method suited for manufacturing a load-bearing roof element with an appreciably good thermal insulation capability. Another object of the invention is achieved by virtue of a method defined in the preamble of claim 17 characterized by performing the curing of the insulation material in a first and a second stage, whereby in the method the stiffening frame elements are located into the mold press prior to the application of the insulation material in the first or the second stage. Preferred embodiments of the invention are disclosed in the dependent claims.

The goal of the invention is achieved by virtue of rendering load-bearing qualities to the building element by virtue of internal stiffening frame elements embedded in an insulation material, whereby a nonstructural membrane-like surface layer or equivalent moisture barrier can be applied directly onto the insulation material. More precisely, surface sheet steels or at least one of them conventionally used in load-bearing roof elements is replaced by a membrane-like surface layer or a moisture barrier directly adhered onto the insulation material, thereby achieving an entirely novel type of construction. In other words, the load-bearing capability of a conventional sandwich element is attained by surface sheet steels and an insulation material as well as mutual bonding thereof. In the present invention the surface sheet steels are replaced by nonstructural membrane-like surface layers and the load- bearing capability of the building element is accomplished by means of stiffening frame elements embedded in the insulation material.

The method according to the invention for manufacturing a building element is based on adhering the membrane-like surface layer or moisture barrier layer directly to the core of the insulation material and thereupon curing the insulation material in two steps, whereby stiffening frame elements are embedded in the insulation material either the first or the second step.

In the invention it has been found unexpectedly that a load-bearing roof element can be implemented with the help of stiffening frame elements embedded in an insulation material, while simultaneously accomplishing direct adherence of the moisture barrier to the insulation material thus offering an entirely novel kind of method for manufacturing load-bearing building elements. The roof element according to the invention is excellent in enduring long- term loads caused, i.a., by heavy snow inasmuch as the load-bearing capability of the structure is based on stiffening frame elements embedded in the insulation material, not on a resin bond between the surface sheet steels and the insulation material. Moreover, the insulation material serves as padding for the stiffening frame elements thus preventing bulging thereof under stress. In the embodiment according to the invention, the stiffening frame elements also adhere to the insulation material during its curing step, which further improves their load-bearing capacity and prevents bulging. As the structure according to the invention does not have significant thermal bridges, it can readily meet the thermal insulation requirements that are expected to become more stringent in the future. Furthermore, the building element according to the invention can be fabricated as a relatively lightweight large-size element that is ready for mounting as a roof element onto roof support structures thus allowing rapid erection of finished roofing areas. Moreover, it is extremely easy to make different kinds of penetrations in the roof element by locating them between the stiffening frame elements inasmuch there are no metallic materials to be worked on.

A benefit of the method according to the invention is that the membrane-like surface layer or moisture barrier is adhered directly to the insulation material thus disposing with a separate securing step with the help of mechanical fixing means or a separate bonding step. The method according to the invention makes it possible to fabricate load-bearing building elements with a thickness even twice that of conventional building elements. Brief description of the drawings

Next some preferred exemplary embodiments of the invention are described in more detail by way of making reference to the appended drawings in which:

Fig. 1 shows a drawing of a building element according to the invention; Fig. 2 shows a partial cutout drawing of another embodiment of the building element according to the invention;

Fig. 3 shows a partial cutout drawing of another embodiment of the building/roof element according to the invention;

Fig. 4 shows a top view drawing of another embodiment of the building element according to the invention; Fig. 5 shows a side-elevation drawing of an embodiment of the building element according to the invention;

Fig. 6 shows a sectional drawing of the stiffening element frame of a building element according to the invention;

Fig. 7 shows a perspective drawing of the stiffening element frame of the construction of Fig. 6;

Fig. 8 shows a perspective drawing an embodiment of the building element according to the invention;

Fig. 9 shows a perspective drawing of an application of the building element according to the invention as a continuous-section element; and

Fig. 10 shows a conceptual drawing of an application of the building element according to the invention as an industrial building element.

Detailed description of the invention

In Fig. 1 is shown an embodiment of a building element according to the invention, wherein the element comprises an insulation material layer 2, a first surface layer 3 situated on the first side of the insulation material layer 2, a second surface layer 4 situated on the second side of the insulation material layer and elongated stiffening frame elements 5, 50 embedded in the insulation material.

A building element according to the invention uses a polymeric-based insulation material 2 such as polyurethane (PUR) or polyisocyanurate (PIR) capable of expanding and/or forming an adhesive bond to the surface against which it expands. In this context, the term polymeric-based insulation material refers to an insulation material, whose major component is polymeric. Insulation material 2 must also be lightweight to allow long spans of the building element and ease the handling of the building element also as a large-size element. During fabrication, insulation material 2 expands against surface layers 3, 4, whereupon it forms an adhesive bond therewith.

Onto the first and/or second layer of insulation material layer can be formed a membrane-like moisture barrier layer that serves as a surface layer 3, 4 of the building element 1. The moisture barrier may be any suitable water-impermeable barrier such a PVC moisture barrier film that is pliable and membrane-like. The moisture barrier layer protects the underlying insulation material layer 2 from moisture and other environmental stresses such as solar UV radiation. The underside of moisture barrier layer 3, 4 is advantageously made favorable to adhesive bonding like a felted surface or the underside is provided with a bond-promoting polyester or glass fiber matrix. This arrangement secures adhesive bonding of the moisture barrier layer 3 or other similar surface layer 3, 4 directly to the core material without mechanical fixing or separate bonding steps. The seams of the moisture barrier layer or also any equivalent surface layer 3, 4 may also be secured by heat- welding techniques, such as hot-air heat welding, applied to the seams between adjacent building elements and/or in a case where the surface layer 3, 4 of a given building element comprises more than one moisture barrier film. In an alternative

embodiment, the moisture barrier layer is a separate layer adhered to the first and/or the second surface layer 3, 4. The surface layer of insulation material layer 2 of the surface layers 3, 4 thereof can be selected to suit the intended application. The surface layer 3, 4 may be a polyester laminate if the roof element is desired to form a solid and finished internal ceiling surface, for instance. The surface layer 3, 4 may also comprise a thin- film foil. The surface layers 3 and 4 are advantageously selected such that surfaces of equal air permeability are formed on both sides of the building element, whereby the building element 1 has no risk of warping and the building element 1 becomes essentially planar. According to the invention, surface layers 3 and 4 are nonstructural, i.e., they do not substantially serve as a load-bearing member of the sandwich structure. In an embodiment, the first surface layer 3 of the building element 1 is implemented as a moisture-barrier layer while the second surface layer 4 is made of a polyester laminate, for instance. This kind of a building element is suited for use as a roof element.

The fire-resistance qualities of building element 1 may be enhanced by placing mineral wool 7 onto the first and/or second surface layer 3, 4 of the thermal insulation material 2 with a gypsum board 8 placed thereunder in order to form an air-tight element surface, i.e., a ceiling surface as shown in Fig. 3. When such additional layers 7, 8 are placed under the surface layer 3, 4, the surface layer 3, 4 may be made from paperboard, paper, thin-film foil or other suitable material. More precisely, the additional layers 7, 8 do not bond directly to the insulation material layer 2, but instead they are bonded to the surface layer 3, 4, which means the additional layers 7, 8 are adhered in a production step different from the actual curing of the insulation material along the production line. If desired, one or both of the surface layers 3, 4 may also be selected to act as a vapor barrier.

As shown in Fig. 4, the building element according to the invention comprises, aligned at least in the longitudinal direction of the building element 1 , a plurality of elongated stiffening frame elements 5 embedded in the insulation material layer 2. According to preferred embodiment, the internal and longitudinal stiffening frame elements 5 of building element 1 are also complemented with stiffening frame elements 50, 51 placed in each end of the building element 1 as shown in Fig. 4. Thereby the stiffening frame elements 50 and 51 placed at the ends of building element 1 form a stiff framework that at least partially rests on the support points of the building. Moreover, when the building element 1 is used in a form having 2 openings, a transverse stiffening frame element (not shown in drawings) is located at the intermediate support in order to improve the element strength at the support. Hereby the transverse stiffening frame element transmits the load to the intermediate support. Such transverse support frame elements secure the strength of the building element according to the invention under compressive stress at a support.

In one embodiment the longitudinal stiffening frame elements of the building element are bonded to each other by means of reinforcing strips (not shown in drawings) located orthogonal to the longitudinal direction of the frames. These reinforcing strips can be made, e.g., from sheet metal or plywood. This embodiment is particularly suited for improving the buckling behavior of the element web.

The number, shape and dimensions of the longitudinal stiffening frame elements 5 in the building element 1 are selected on the basis of load-bearing capability requirements and dimensions of the building element 1. Advantageously the stiffening frame elements 5 have the shape of stiffening frame element 5 shown in Fig. 6, i.e., C-shaped, whereby the stiffening frame elements 5 comprise an upright web portion 11 and transverse flange portions 9, 10 projecting from both edges of the web portion 11. Alternatively, the flange portions 9, 10 may be aligned in different direction (not shown in drawings), whereby the stiffening frame elements 5 are essentially Z-shaped. The first and the second flange portion 9, 10 may further be complemented with stiffness-enhancing bent edges 17 as shown in Fig. 6.

Moreover, the stiffening frame elements 5, 50 may be complemented with bumps 7 that elevate the surface of the flanges 9, 10 at a distance from the surface layer 3, 4 and the press mold surface, whereby the insulation material layer 2 fills the space between the flange portion 9, 10 and the surface layer 3, 4 at least partially. This embodiment offers improved thermal insulation qualities. In the light of the above description it is obvious that the stiffening frame elements are fabricated from sheet steel or other suitable metal. According to the invention the polymer-based insulation material supports the web portions of the support frames thus limiting buckling of the frame elements, whereby a supportive reaction force is created between the insulation material and the support frame element web with the result that in an overload situation, the web buckles only locally. As local buckling occurs at substantially higher loads, the load- bearing capability of the element is thus improved essentially.

Further according to the invention, an adhesive bond is established between the web/flange portions of the stiffening frame elements and the insulation material, which further contributes advantageously to the buckling behavior of the frame elements.

A stiffening frame with C- or Z-section elements is particularly suited for stiffening a building element according to the invention inasmuch as also the flange portions of the stiffening frame elements are adhesively bonded to the insulation material, whereby their bending upward is hampered by virtue of the adhesive bonding when the stiffening frame element is close to buckling.

C-section elements in stiffening frame 5 creates the stiffness of a building element, such as a roof or wall element, as the insulation material layer 2 fills the space between flanges 9 and 10 of stiffening frame 5. Stiffening frames 50 and 51 at the ends of the building element 1 are advantageously oriented so that their flange portions 9, 10 are essentially directed toward the center of the building element 1 as shown in Fig. 1. Then, also the stiffening frames 50, 51 at the ends of building element 1 become filled with the insulation material 2, whereby the stiffness of element 1 is increased. In Fig. 5 the building element according to the invention is shown in a longitudinal side elevation view. As shown in the drawing, the web portion of stiffening frame 5, 50, 51 may be provided with perforation 6 to reduce thermal flow in the stiffening frame. Perforation 6 may be implemented as a continuous or discontinuous pattern.

In the present context, the term large-size building element refers to a building element suited for rapid erection of roof or wall panels, for instance. To this end, the width of a large-size building element must be at least 2.5 meters and length at least 5 meters. Advantageously, a large-size building element is a building element having a width not less than 2.8 meters and, moreover, most preferably having an element length not less than 7 meters or, when resting on an intermediate support, not less than 10 meters, whereby the element spans over two openings. After,

installation, the interelement seams are sealed with an expandable insulation material such as polyurethane.

In Fig. 2 is shown an embodiment of the invention, wherein the thickness of the insulation material layer T is greater than the height of H of the stiffening frame elements in the thickness direction of the insulation material layer 2, whereby the thermal insulation capability of the building element 1 is improved. Most advantageously, the stiffening frame elements 5, 50, 51 are located in the insulation material layer in such a manner that their second flanges 10 are spaced at a distance from the surface layer 3 to increase the thermal resistivity. This kind of structure can give the roof element a thermal conductance factor (U-value) smaller than 0.09 W/K m that is attained by selecting, e.g., the insulation material thickness to be T = 350 mm and the stiffening frame element height to be H = 275 mm when the stiffening frame element height is advantageously chosen to be in the range of 250-300 mm. The thickness of the insulation material layer 2 is advantageously selected to be in the range of 200-400 mm and most advantageously in the range of 275-350 mm. In other words, to improve the thermal resistivity of the element, the parameters are selected such that the thickness T of insulation material layer 2 is made larger than the height H of the stiffening frame elements 5, 50, 51 in the direction of thickness T of insulation material layer 2, whereby the elongated stiffening frame elements 5, 50, 51 comprise a first flange 9 and a second flange 10 as well as a web 11 between a first and a second flange 8, 9, and that, to improve the thermal insulation capability of the element, the elongated stiffening frame elements 5, 50, 51 are embedded in the insulation material layer 2 so that their first flanges 9 abut the surface layer 3, 4 and the second flanges 10 are spaced at a distance from the opposite surface layer 3, 4.

In Fig. 7 is shown an embodiment of the stiffening frame element 5, 50, 51 of the building element 1 such as a wall element, wherein the web 11 of the stiffening frame element is at least partially made from expanded diamond mesh. This arrangement provides an extremely lightweight and material-efficient stiffening frame element 5 of the building element 1, which allows a further lightweighted and more material-efficient structure of the stiffening frame element 1. The expanded diamond mesh of the stiffening frame element 5 is fabricated by conventional expanded mesh techniques, e.g., by cutting slits in the stiffening frame element and thereupon stretching its material laterally, whereby openings are created with a diamond shape, for instance. The openings 6 in turn serve to cut down thermal bridges. Alternatively, the web portion 11 may be provided with a conventional thermal-bridge-reducing perforation that reduces thermal leaks via the stiffening frame element. The perforations/openings 6 may be implemented as a continuous or discontinuous pattern. Obviously, the stiffening frame element and, in particular, its web 11 can left as such without perforations or other punched openings.

In Fig. 8 is shown an embodiment of a building element 1 implemented as a wall element 1 comprising an insulation material layer 2, a membrane-like surface layer 3 adhered to a first side of the insulation material layer, a membrane-like surface layer 4 adhered to a second side of the insulation material layer and elongated stiffening frame elements 5, 50 embedded in the insulation material. On the exterior side of the wall element 1 is formed a membrane-like surface layer 3 that serves as the exterior sheathing of the wall element 1. The term exterior side herein particularly refers to the exterior side of the wall element 1 that is sheathed in desired manner in order to provide a desired kind of a facade. The surface layer 3 can be selected to meet the needs of the facade cladding type to be placed onto the wall element 1 ; e.g., when a sheet steel cladding will be installed, the outer layer of the wall element may be complemented with a woven-cloth type of wind barrier that also serves as moisture barrier during building erection. The side of the surface layer 3 of insulation material 2 is advantageously made favorable to adhesive bonding such as a felted surface or, alternatively, the surface layer underside is provided with a bond- promoting polyester or glass fiber matrix. This arrangement secures adhesive bonding of the surface layer 3 to the insulation material 2 without mechanical fixing. Advantageously, this first surface layer 3 is made from a cloth-type material such as Tyvek fabric. Onto the interior side of the wall element 1 is formed a second surface layer 4, that is, an interior sheathing layer that may be, e.g., an aluminum foil serving as a vapor barrier and rain barrier during building erection. The interior sheathing layer may also be formed by a polyester laminate when the wall element is desired to provide an impervious and finished interior wall surface.

In the present invention, the surface layers 3 and 4 of the building element 1 are nonstructural, which means that they do not serve as strengthening surface layers of the sandwich structure, but rather, their function is to provide required barriers such as an air barrier, wind barrier or vapor barrier. Hence, the adhesive bond between the surface layers 3, 4 and the insulation material layer 2 does not appreciably contribute to the load-bearing capacity of the wall element. According to a preferred embodiment of the invention, the surface layers 3, 4 are directly bonded to the core material of the insulation material layer 2, which means that the surface layers 3, 4 are adhered immediately to the insulation material during the curing thereof without the need for separate bonding steps. Most advantageously this is accomplished on a continuous production line in order to implement cost-effective production. The surface layers 3 and 4 are advantageously selected such that their permeability to air is equal on both sides of the building element to avoid warping of the element and to produce an essentially planar element.

As shown in Fig. 8, the building element 1 such as a wall element or a roof element comprises elongated stiffening frame elements 5 that are placed at least in the longitudinal direction of the building element and are embedded in the insulation material 2. The stiffening frame elements 5 are located between the surface layers 3, 4 during the fabrication of the building element, e.g., on a continuous production line, whereupon the insulation material 2 can be injected. The stiffening frame elements 5, 50, 51 may be rollformed in conjunction with the continuous building element production line, whereby the rollformed, continuous-section stiffening frame element is fed in a continuous fashion to the continuous building element production line at the end of which a building element 1 of desired length is trimmed by a circular saw from the continuous building element stream.

The building element 1 may be installed in a fashion required by the construction of a building, but advantageously the building element 1 such as a wall element is preferably installed according to Fig. 9 or 10 so that the longitudinal axis of the element is aligned horizontal, whereby also the stiffening frame elements are horizontal. This embodiment suited for an elongated continuous or industrial building element. Figs. 9 and 10 show an advantageous placement of the wall elements in the facade of a building, where they may be clad either after their installation in the building or, alternatively, be provided with a ready- finished, desired-type of cladding prior to hauling the element to the erection site.

Additionally, the horizontal seams between adjacent wall elements may be provided with tongue-and-groove profiles, e.g., with the help of sheet metal T&G strips integrated with the insulation material (not shown in diagrams) or, alternatively, having the production line mold technically equipped for providing the element horizontal edges with T&G jointing means (not shown in drawings). The vertical seams between adjacent wall elements are sealed after erection with an expandable sealing material such as polyurethane foam.

It must be noted that the building element construction according to the invention can also be fabricated as individual elements with the same benefits of the present wall element construction such as freedom of variations and good stiffness, among others. According to one embodiment of the invention, the fabrication of the building element takes place in a mold press. According to one embodiment of the invention, the insulation material layer 2 comprises two or more portions fabricated in separate production steps. This kind of embodiment can be readily implemented in production.

In one method according to the invention, the building element is fabricated individually in a horizontal bed. During fabrication, the building element may in the same position it will be when erected onto a roof (embodiment 1) or, alternatively, it may be during fabrication turned into a position having the water barrier layer on the bottom (embodiment 2). This method for manufacturing a building element is carried out in a mold press wherein the compression height is adjustable. This arrangement allows the insulation material 2 to be formed in two steps. Next, some alternative embodiments of implementing the method are described.

According to the first embodiment, the method for manufacturing a building element is commenced by producing a second surface layer 4 onto the mold bottom. Next, into the press mold are inserted stiffening frame elements 5, 50, 51 that are placed either as separate frame elements or, advantageously, they are inserted as a single assembly ready for insertion into the press, whereby the individual frame elements 5, 50, 51 are attached to each other by suitable fixing means such as mechanical fixtures, welding or adhesive bonding. Subsequently, into the mold is injected a first portion of an expandable insulation material and the press is closed to a height substantially equal to the height H of the stiffening frame element assembly 5, 50, 51. Alternatively, prior to closing the press, the stiffening frame element assembly 5, 50, 51 is covered by a first surface layer 3 as shown in Fig. 1. After a sufficient curing time, the press is opened, whereupon fabrication can proceed by injection of a second portion of the insulation material onto the first, already cured layer of insulation material, either as an expandable insulation material or, e.g., as a ready-cured sheet of insulation, whose surface layers have an adhesive material applied thereto in order to accomplish insulation material layer 2. Onto the second portion of insulation is applied a first surface layer 3, whereupon the press is closed to a height T that corresponds to the final thickness of the building element 2. After a sufficient curing time, the press is opened and the element is removed from the press. The curing time, which is determined by the curing rate of the polymeric-based insulation material as well as by the size of the building element, can be set according to rules known in the art. If necessary, the building element can be transferred to post-processing thermal treatment.

According to a second embodiment of the invention, the method for manufacturing a building element is commenced by forming onto the bottom of the press mold a first surface layer 3 such as a water barrier layer and then injecting a first portion of an expandable polymeric-based insulation material onto the water barrier layer 3, whereupon the press is closed to a height T-H. After a sufficient curing time, the press is opened. The first portion of the expandable insulation material need not be cured to full hardness, but instead, it may suffice to have its surface cured enough to bear the weight of stiffening frame elements 5, 50, 51 in which stage the material is at least partially hardened. Alternatively, injection of the first portion of expandable insulation material may be replaced by having a ready- cured insulation slab placed onto the press bottom and securing the same by adhesive means. Next, into the press mold are inserted stiffening frame elements 5, 50, 51 that are placed either as separate frame elements or, advantageously, as a single assembly. Subsequently, into the mold is injected a second portion of an expandable insulation material, whereupon a required surface layer 4 is formed above the stiffening frame elements and the press is closed to a height T. After a sufficient curing time, the press is opened and the element is removed from the press.

According to one embodiment of the invention, the insulation material 2 is formed by two parts comprising an upper high-density insulation material layer and a lower low-density insulation material layer. This arrangement provides a harder outer surface layer, improved insulation or stiffer structure for conditions requiring one or more of these qualities.

To a person skilled in the art it is obvious that the spirit of the invention may be implemented in a plurality of different ways. Hence, the invention and its implementations are not limited by the above-described exemplary embodiments, but rather may be varied within the inventive spirit and scope of the appended claims.

Claims

What is claimed is:

1. A building element (1) of a multilayer structure comprising:

- a polymeric-based insulation material layer (2);

- a first surface layer (3) on the first side of the polymeric-based insulation material layer (2); and

- a second surface layer (4) on the second side of the polymeric-based insulation material layer (2),

characterized in that the first and the second surface layer (3, 4) have been implemented as a nonstructural membrane-like surface layer (3) and that the building element (2) comprises one or more elongated stiffening frame elements (5, 50) extending in at least one direction within an insulation material layer (2) in order to render structural load-bearing strength to the building element.

2. The building element (1) of claim 1 , characterized in that the first or the second surface layer (3, 4) or, alternatively, the first and the second surface layer (3, 4) are implemented as a water barrier layer.

3. The building element (1) of claim 1, characterized in that over the first or the second surface layer (3, 4) or, alternatively, over the first and the second surface layer (3, 4) is placed a water barrier layer.

4. The building element (1) of any one of claims 1 - 3, characterized in that the first or the second surface layer (3, 4) or, alternatively, the first and the second surface layer (3, 4) has been induced to adhere adhesively directly to the core material of the insulation material layer (2).

5. The building element (1) of any one of claims 1 - 4, characterized in that the first or the second surface layer (3, 4) or, alternatively, the first and the second surface layer (3, 4) are made from a polyester laminate.

6. The building element (1) of any one of claims 1 - 4, characterized in that the first or the second surface layer (3, 4) or, alternatively, the first and the second surface layer (3, 4) are made from a cloth-type material such as Tyvek fabric.

7. The building element (1) of any one of claims 1 - 6, characterized in that the thickness (T) of the insulation material layer (2) is greater than the height of (H) of the stiffening frame elements (5, 50) in the thickness direction (T) of the insulation material layer (2) in order to achieve improved thermal insulation capability.

8. The building element (1) of any one of claims 1 - 7, characterized in that the elongated stiffening frame elements (5, 50) comprise a first flange (9) and a second flange (10) as well as a web portion (11) connecting the first and second flange (8,

9)· 9. The building element (1) of claim 8, characterized in that the elongated stiffening frame elements (5, 50) are embedded in the insulation material layer (2) so that their first flanges (9) abut the surface layer (3, 4) and the second flanges (10) are spaced at a distance from the opposite surface layer (3, 4) in order to achieve improved thermal insulation capability.

10. The building element (1) of claim 9, characterized in that the stiffening frame elements (5, 50) are complemented with bumps (7) in order to elevate the surface of the flanges (9, 10) at a distance from the surface layer (3, 4).

11. The building element (1) of any one of claims 1 - 10, characterized in that the stiffening frame elements (5, 50, 51) are C-shaped, whereby the stiffening frame elements comprise an upright web portion (11) and transverse flange portions (9, 10) projecting from both edges of the web portion (11).

12. The building element (1) of any one of claims 1 - 11, characterized in that the stiffening frame elements (50, 51) are placed in each end of the building element (1) in order to provide a stiff framework.

13. The building element (1) of any one of claims 1 - 12, characterized in that the stiffening frame elements (5, 50, 51 are at least partially made from expanded diamond mesh.

14. The building element (1) of any one of claims 1 - 13, characterized in that the insulation material layer (2) comprises two or more portions.

15. The building element (1) of any one of claims 1 - 14, characterized in that the building element (1) is a wall element or a roof element.

16. The building element (1) of claim 15, characterized in that the building element

(1) is a large-size element.

17. A method for manufacturing a building element, in which building element (1 ) its surface layers (3, 4) are adhesively bonded directly to an insulation material layer

(2) , i.e., to the first or the second side of the insulation material layer (2) comprising an expandable insulation material, characterized in that the curing of the insulation material is carried out in a first and a second step, whereby the method incorporates the placement of stiffening frame elements (5, 50) in the press prior to the injection of the first-step or second-step insulation material (2).

18. The method of claim 17, characterized in that the method comprises the steps of:

- forming onto the bottom of a mold press a first nonstructural surface layer

(3) ;

- injecting the first portion of the insulation material onto the first

nonstructional surface layer (3);

- closing the press at a height T-H, where T is the thickness of the insulation material layer (2) of the finished building element (1) and H is the lateral height of the stiffening frame elements (5, 50) in the thickness direction T of the insulation material layer (2), whereupon the portion of the first insulation material layer is cured at least partially;

- opening the press and placing stiffening frame elements (5, 50) in the press;

- injecting the second portion of the insulation material; and

- forming a second surface layer (4) as necessary and closing the press to a height T.