EP2913454B1

EP2913454B1 - Building panel

Info

Publication number: EP2913454B1
Application number: EP15155217.1A
Authority: EP
Inventors: Jean Pierro Giovanni Antonio Malvicini
Original assignee: Individual
Current assignee: MALVICINI, JEAN PIERRO GIOVANNI ANTONIO
Priority date: 2014-02-17
Filing date: 2015-02-16
Publication date: 2023-11-08
Anticipated expiration: 2035-02-16
Also published as: EP2913454A1; EP2913454C0

Description

The present invention relates to a building panel according to the preamble of claim 1.
In the last years the attention to problems related to ecological sustainability and energy saving has been constantly increasing in the building field, and a higher and higher common sensibility is developing in paying attention to problems concerning sustainability and environmentally-friendly aspects in different fields of our everyday life.
Currently the market is giving more and more importance and interest to a building concept which is more oriented to environmental sustainability, to energy efficiency and to occupant comfort, which is identified by the term green building.
Green building aims at following criteria and concepts respectful of the environment and of the comfort of the human being, following a sensibility developed in the last 40 years towards a new manner of constructing the built environment, aiming at saving resources, at using renewable energy, at reducing gas emissions such as greenhouse gases.
Particularly the principles of green building are substantially a group of attitudes and rules that consider the construction of a building sensibly integrated with the environment wherein it is inserted.
The object of green building therefore is to build without damaging the environment, drastically reducing the impact of the new constructions on the environment and on people, looking for a harmony with what surrounds the building.
Unlike the concepts of the "conventional" building, the most important aspects guiding the design are parameters such as: orientation, choice of the materials and constructive strategies as a function of performances, availability and expedience.
The goal remains to optimize the integration between the environment and the building and to maximize the performances of the latter in favor of life quality, economic concern and environmental respect.
In this sense therefore all the advantages that can be given by the technological progress have to be considered as belonging to green building concern: new materials and innovation thereof, energy recovery systems, hybrid systems for using alternative energy sources, optimization of prefabrication, industrial standardization in the production and of control systems.
Finally it results that one of the most important aspects of the green building is prefabrication. Such aspect is considered only for the advantages offered by the constructional speed in the building yard; actually it is a key element in the whole process obtained by modern technology.
Many of the material choices, constructional solutions, possibilities of economic saving and quality control are around prefabrication. The prefabrication process has further transformed the conventional product into a product that can be offered on a larger scale and which is adaptable anyway.
A constructional practice that is used a lot in green building is that of prefabricated buildings made of wood, wherein prefabricated panels made of wood are used, both for the external perimetral walls of the building and for the internal partition walls.
Wood is a material having a lot of benefits, but it has also some drawbacks.
The two main drawbacks of the wood are the possibility of being subjected to modification in the shape over time, with subsequent undesired structural movements, and a thermal conductivity that in order to be lower than 0,20 W•m^-1•K^-1, that is in order to be within the category defined by the current standards as class A, has to form panels for perimetral walls with a thickness of at least 30 cm, which therefore have a very high weight.
The thermal conductivity, or thermal k, is defined as the ratio, under stationary conditions, of the flow of heat to the temperature gradient causing the heat passage.
Moreover there are prefabricated panels such as described hereinbefore, which have a metal load-bearing structure, insulating material internally placed, and structural plates coupled on the opposite faces of the load-bearing structure.
Document EP2397617 for example describes a panel composed of a metal structure composed of metal section bars with a "U" shaped cross-section and gypsum panels applied on the metal structure by means of screws.
The document US5592796 describes a similar panel, wherein in addition the section bars with "U" shaped cross section in the short sides have an inwardly-bent depression, such to have bearing ridges against which the structural plates may be affixed, such to form a kind of air space to increase heat insulation.
Document US2010223870 describes a system including a structural member for separating two environments that have different temperatures and a method of manufacturing the structural member. The system includes a barrier constructed with a plurality of the structural members. The structural member includes a core and a thermal barrier layer on at least a portion thereof.
Document WO2004009926 describes an insulation element made from mineral fibres, in the form of insulation strips, insulation boards, insulation felt or similar, for installation between two building components arranged at a separation from each other, namely profiles in single plank walls or pre-fabricated walls and/or facing sheets and for sound and thermal insulation of ceilings and walls and similar building components, comprising a mineral fibre body with two large surfaces, preferably arranged separate and parallel to each other and lateral surfaces connecting the above.
Document EP2180107 describes a wall comprising a first panel and a second panel defining the surfaces of the wall and extending in planes substantially parallel to each other and a sheet of sound and/or thermal insulating material located between the panels, an elongate fixing element formed of metal positioned between the first and second panels, and having first and second side surfaces arranged in a plane substantially parallel to the planes of the first and second panels, wherein the first panel is attached to the first side surface, the second panel is attached to the second side surface, and wherein a mat comprising from 20 to 95 weight % aerogel is positioned between the first panel and the first side surface of the fixing element.
Document GB2389127 describes a wall stud having two sidewalls interconnected by a spanning web that comprises first and second portions connected to respective sidewalls and being connected themselves by a curved member. The curved member also has at least one row of longitudinal slots formed along its length. Sound insulating material may be packed within the stud.
Document DE19934310 describes a stand profile having two profile legs which run at a distance from one another in the longitudinal direction of the profile and are connected to one another by a profile web. The profile web is equipped with at least one spring section running in the longitudinal direction of the profile and having a low transverse spring hardness, which is formed out of the plane spanned by the profile web and provides a flexible connection of the profile legs.
Document WO2004009927 describes an insulating layer consisting of mineral fibres, and a building wall comprising a supporting framework consisting of at least two interspaced, preferably perpendicularly oriented posts, especially in the form of C, U, W or ohm-shaped profiled metal parts, a lining on at least one side, preferably in the form of gypsum plasterboard and/or gypsum fibreboard, and heat and/or sound insulation consisting of an insulating layer.All such documents, however describe a division or partition element for rooms, resting on the basement and on an existing floor. The structural elements of steel U-section bars therefore have the only aim to support the gypsum elements, or other material, in order to form a compartimental room divider.
Therefore currently there is the unsatisfied need for a panel having optimal acoustic and thermal insulation performances, that can be prefabricated, and contemporaneously that can be a structural element and a load-bearing element both for the floor above and for the upper storeys of the building, similar to all intents and purposes to a load-bearing brickwork.
The present invention aims at overcoming the above drawbacks of the currently known panels by providing a building panel, such as described hereinbefore, which further comprises the features of the characterizing portion of claim 1.
Gypsum fibre is a slurry of natural baked gypsum and cellulose fibres, preferably obtained from selected and chopped recycled paper. These two components are mixed in water, preferably without any other binders, since the gypsum mixed in water penetrates into the cellulose fibres by a calcination process. Once a homogeneous mixture is obtained, the plate is formed with the desired thickness by being compressed, dried, smoothed on the opposite faces and possibly treated with a waterproofer.
By the presence of fibres, the gypsum fibre plates have a high stability, an optimal mechanical strength and optimal fire resistance characteristics.
Cement fibre plates are composed of a mixture of cement and fibres with a high tensile strength, particularly organic, natural and synthetic strands.
Therefore the panel is composed of a metal structure, which takes such mechanical properties, thanks to the intimate coupling with structural plates of gypsum fibres or cement fibres, to have the stiffness and load-bearing property of a load bearing wall or brickwork, hence being a structural and constructional element with the purpose of the construction of buildings. Therefore, it is important to point out that structural plates are not a simple finishing as in the currently known panels, but on the contrary, they contribute in reaching the desired mechanical properties. The head section bars act as load distributors, the load section bars are load-bearing elements intended to transmit and share static actions to the plates of gypsum fibre or cement fibre and to physically connect them thus creating a single structural element.
It is only because of the integral connection of the elements (head section bars, load section bars and structural plates) that the panel as a whole is able to perform its load-bearing properties. It is necessary for all the described elements to be mechanically integral and to have dimensions sufficient for the distribution of the static and dynamic loads transmitted through the panel. Therefore it is clear that the metal section bars distribute and transmit the load forces to the structural plates, which necessarily have to take part in the static strength of the structure. Therefore the panel is not a passive partition element, but it is an element bearing the multi-level building structure.
Gypsum fibre allows optimal performances to be provided guaranteeing the applicability of the material in a seismic area, since they allow the panel to react well to horizontal stress. The tensile strength value of the material evaluated parallel to the plane of the plate is about of 2.4 N/mm².
This is valid, although to a smaller extent, also for the cement fibre that has a strength value of about 0.7 N/mm².
Moreover the empty sections of the panel, thus made, are used as housing for insulating material, that therefore guarantees optimal performances as regards the thermal and acoustic insulation.
The panel is not subjected to changes in the shape as the wood, it can be prefabricated with predetermined dimensions as required or according to the needs before being applied and it has a weight considerably reduced with respect to wood, particularly it is about one third of the weight of wood panels having the same insulation performances.
Structural plates can be mechanically connected to the load-bearing structure by connection elements such as riveting, nails, screws or pins such to guarantee an integral connection and to transmit the strains between the different internal elements (steel) and the external elements (gypsum fibre, cement fibre).
In a particularly advantageous embodiment, the structural plates can be coupled to the metal structure by means of glue. Unlike what occurs with the connection elements mentioned above, which operate a transmit of strengths in a point-like mode (point-like anchoring zones), this allows to operate a continuous distribution all along the gluing zone, i.e. all along the side of the section bars. This allows a better subdivision of the transmitted loads and cancel the tensional peek values detectable in the point-like contact zones (plate-section bar) in the case of mechanical coupling of the elements (riveting, nails, screws or pins), in connection with lower costs. Preferably, water resins are used as glues, for example of the type used in aeronautics. A predetermined amount of glue is placed on the part of the section bars intended to contact the structural plates, such to guarantee the bonding once the panel is assembled and a specific gluing pressure is exerted on the opposite faces of the panel.
In one embodiment the section bars are composed of elongated plate-like elements, arranged on planes perpendicular to the median plane of the panel.
The section bars therefore are placed edge-wise to the plane of the panel, and since they have a specific width they form cells that can be completely filled with insulating material.
According to one improvement said section bars have a C cross-section, the longitudinal edges being bent perpendicularly to the body of the section bar.
This gives a great stiffness to each section bar, and consequently to the whole panel.
This characteristic further allows the metal section bars to be easily joined to form the load-bearing structure, and contemporaneously it allows the structural plates to be easily fastened to the metal structure.
The load section bars are placed at a distance from each other or pitch that can be variable or regular, and of any value, preferably ranging from 20 cm to 1 m, and particularly corresponding to 40 cm.
The grid formed by the metal section bars can be irregular for the need of creating apertures for windows and doors. At said apertures there are provided transverse section bars that are placed perpendicular to the load section bars and fastened to two or more load section bars.
Moreover in proximity of the windows and doors it is possible to provide stiffening section bars, parallel to the load section bars, which join the transverse section bars with each other or with the head section bars.
This guarantees a good stiffness of the panel also at the apertures necessary for windows and doors.
In a preferred embodiment said section bars have a thickness lower than 10 mm, preferably ranging from 1 to 7 mm, particularly corresponding to 2 mm for one floor or two floors building, or corresponding to 5 mm for buldings up to 6 floors. Studies demonstrated that an increase in thickness of the section bars within the above range does not affect the thermic transmittance.
The preferred thickness of the section bars preferably corresponds to 2 mm both in order to keep low the thermal dispersion of the panel through the metal load-bearing structure and in order to guarantee a satisfying mechanical strength for reaching aseismic performances meeting the standards.
In one embodiment said section bars have a width in the direction perpendicular to their longitudinal axis ranging from 100 to 300 mm, particularly corresponding to 250 mm.
Said section bars are provided with through apertures, placed in the liner of the section bar itself.
Thus several advantages are contemporaneously achieved.
A first advantage is the reduction in the weight of the section bar and therefore of the whole panel; a second advantage is a reduction in the thermal conductivity; a third advantage is the possibility for the air to transmigrate and dehumidify the panel. As regards the reduction of the thermal conductivity, the presence of apertures acts as thermal break for the section bar, that is for preventing or drastically limiting the heat transfer from one end of the metal section bar to the other end. Apertures allow the heat flow to be reduced between the two parallel faces of the panel both by elongating the heat path, and by reducing the surface for the transfer of heat. Thermal break characteristics of the section bar allow such a dew point to be provided to prevent condensate from forming into the panel, which condensate may cause the panel to be rapidly deteriorated over time.
Therefore such apertures are not designed with the aim of allowing the passage between the load section bars of pipes and plants inside the wall, but they are designed in order to provide the above technical effects.
Said through apertures are shaped like segments adjacent with each other and parallel to the longitudinal axis of the panel.
According to a further improvement said apertures are only in a central part of the section bar with respect to the width of the section bar in the direction perpendicular to its own longitudinal axis.
The shape of the through apertures, their orientation and their arrangement in the section bars contribute in giving a higher resistance against torsional movements.
However it is possible to use solid metal section bars, that is imperforate ones, such to guarantee a high stability.
According to a preferred embodiment said section bars are made of galvanized steel.
The perforation of the section bars composed of said apertures therefore is particularly advantageous for the dehumidification, due to the moisture absorption characteristic of the galvanized steel.
Therefore the section bars do not create cold bridges and allow the insulation to freely breathe through the framework. Moreover they do not change shape and do not rot and this makes the quality of the section bars similar to that of the concrete panels, moreover they being much more light than wooden panels.
The properties of the section bars make almost impossible for cracks to appear in the finished wall panels. Moreover there are no cold bridges, heat dispersions or draughts, guaranteeing a constant temperature and clean air inside the living environments.
In one embodiment said thermally and acoustically insulating material comprises cellulose fibre. Cellulose fibre has good thermal and acoustic insulation properties and has the advantage of being completely recyclable. It is possible to use non-compacted recycled paper, but it is preferred to use panels of cellulose fibre.
In one variant embodiment said thermally and acoustically insulating material comprises polyester. Polyester has the advantage of being completely recyclable too.
In a further variant said thermally and acoustically insulating material comprises stone wool.
Stone wool is an optimal material for thermal and acoustic insulation, and it has reduced prices. In comparison with wall panels built on wood frame, the stone wool guarantees better insulating properties.
According to an embodiment said insulating material is composed of at least two panels of thermally and acoustically insulating material superimposed on each other.
According to an improvement said at least two panels of thermally and acoustically insulating panels have different thicknesses.
In combination or as an alternative said at least two panels of thermally and acoustically insulating material have different densities.
Experimental tests have shown that two insulating panels superimposed on each other guarantee a better insulation than one single panel with a thickness equal to the sum of the thicknesses of the two panels. This is true particularly when the two superimposed panels have a different thickness one with respect to the other. A further improvement is obtained by using panels of insulating materials having a different density with respect to each other. The use of different masses has an improving impact both on thermal and acoustic insulation. This effect is maximized when the two superimposed panels of insulating materials have both different thicknesses and different densities with respect to each other.
The total thickness of the insulating material in the panel corresponds to the width of the metal section bars.
Thus in the panel described up to now the insulating material is the 98% by weight of the load-bearing structure provided with insulating material.
Therefore the panel has a very low weight while having very high thermal and acoustic insulation performances.
Particularly the thermal k is lower than 0.18 W•m^-1•K^-1, particularly lower than 0.174 W•m^-1•K^-1. By means of separators in proximity of the section bars, it is possible to obtain a thermal k lower than 0.15 W•m^-1•K^-1; these separators can be for example ribbons of elastomeric material, or similar elements with mechanical connections such to soften the lateral strengths.
The very low weight strongly affects the costs and the speed for the installation, since a lower weight corresponds to a reduced excavation for the foundation and to a lower use of concrete and iron.
The described panel is completely load-bearing for one-floor buildings, that is it does not need piers made of concrete or wood and it acts as a load-bearing wall.
With the same metal structure it is also possible to build buildings up to five floors out of ground without using any other wood supports.
In one embodiment at least to one structural plate a vapor barrier film is coupled, interposed between the metal structure and the structural plate. If the insulating material is composed of polyester, it is possible to omit the vapour barrier film, since polyester is inert to moisture absorption.
According to one improvement at least one structural plate is treated such to be water-resistant.
In a further embodiment at least one structural plate comprises a wind resistant film interposed between the metal structure and the structural plate.
The panel is used preferably for external walls, but it can be used also for inner walls and for constructions intended to support loads.
For building partition walls preferably a panel with a metal structure with a thickness of 150 or 154 mm is used.
The panel can also be used for constructing floors, as a valid alternative to wood rafters, since it has a lower weight and therefore it can give lightness to the floor.
In this case the metal structure has a frame which is more or less spaced apart on the basis of the load bearing property. This operation allows the panel to have the necessary stiffness and load-bearing property and it allows not only weight but also the section to be reduced, since the frame composed of the metal structure acts as a real beam. In case of use as floor, the panel can have, on one or both its sides, a multilayer wood plate to absorb moisture, to avoid movements and to increase the weight bearing properties. The multilayer wood plate leans on the wall and contributes to thermally and acoustically insulate the floors between themselves. The gap of the floor, created by two panels spaced apart, can be filled with insulating material.
The amount of joints reduced at a minimum guarantees a rapid installation of the panel within a couple of hours, and a rapid installation is important since the constructions need to remain dry.
In one embodiment the panel is provided with an inner wall lining comprising, successively superimposing the first structural plate, a first plasterboard plate, a second insulating material, a second plasterboard plate, the second plasterboard plate being fastened to the first plasterboard plate by spacing elements.
The inner wall lining has two functions: it contributes in increasing the insulation of the whole wall assembly and it creates a housing for the plants, without them interfering with the structure.
According to an improvement a third plasterboard plate is superimposed on the second plasterboard plate. This allows a sufficient thickness of the outer plasterboard to be provided, that is the one facing the inner room. As an alternative it is possible to use only the second plasterboard plate, provided that it has the desired final thickness.
Preferably the second and third plasterboard plates are made of high-density plasterboard (HD). The presence of a double high-density plasterboard plate enhances both sound performances and thermal performances, the latter particularly with reference to the thermal capacity and dynamic behavior. As regards acoustic aspect this choice enhances the sound-proofing properties of the wall at low frequencies, while as regards thermal aspect the increase in the mass on the inner side results in an increase in the inner areal thermal capacity Ki. This value is the capacity of the wall of absorbing the internal loads, that is the possibility of controlling the variation of the temperature in the inner room stimulated by dynamic loads (the intermittent presence of people, on and off cycles of the plant). Particularly the higher this value is, the more the inner temperature variation will decrease during the operating phase, while increasing the internal comfort condition and improving the efficiency of the building/plant system.
According to a further improvement the spacing elements are metal section bars.
According to a further improvement the second insulating material is mineral wool.
In one embodiment the panel is provided with an external wall lining comprising an external plate made of cement fibre fastened to the second structural plate by spacing crosspieces, there being provided in the air space formed between the second structural plate and the outer plate of cement fibre a third insulating material.
The external wall lining acts for reducing the thermal bridges that can generate in the points of connection between the several panels, moreover it provides a finishing surface different from the structural one. The cement fibre plate provides an optimal water and humidity resistance.
While the cement fibre plates, due to the nature of the material, have a good resistance against weathering agents (rain), on the contrary the gypsum fibre plates lose their resistance capacities under the action of the rain. This causes in the structure a loss in the performance that may result in a deterioration thereof during the building step.
Therefore it is important to provide in the assembling step the gypsum plate to be suitably covered, such that during the temporary construction period they do not contact water and therefore they do not lose their structural properties. A further possibility may be to perform on the finishing surface of the plate, directly in the factory, a treatment (external wall lining, coupled cement plate, etc.) such to prevent the gypsum surface from directly contacting the outside.
According to an improvement the crosspieces are made of wood and treated by autoclave.
According to an improvement the third insulating material is wood fibre.
The selection of the materials depends also on other two aspects: the fire resistance and the recyclability of the components. The fact of using a series of plasterboard plates on one side and fibre cement on the other side of the structural assembly allows it to be suitably insulated while guaranteeing a fire resistance level compatible with the type of building made. The choice of using plates and insulating materials obtained from natural materials or from recycled materials, makes the panel environmentally friendly. Moreover the use of connections that can be easily removed, facilitates disposal operations for the several components of the assembly. The use of a material like steel for the structural section bars, increases the percentage of recyclable material present in the panel.
The structural behavior of the building composed of panels according to the present invention is given by orthogonal walls intersecting with each other giving stiffness to the whole system. For closing the wall assembly, on the upper side and lower side, there is the floor structure, frame members that take a real function of "covers" such to hold the structure together (structural concept of a box).
The task of the horizontal elements is to transfer to the vertical walls the horizontal shear stresses triggered in the floor level, and at the load-bearing walls also the vertical loads, enclosing them and making the response of the structure as homogeneous.
Therefore the system can be compared to a box whose faces have a behavior, if evaluated as the cooperation of vertical parts (walls) and horizontal parts (floors) that can guarantee a system able to suitably withstand wind and seismic stresses.
A lot of the stress exerted on the box during an excitation due to a horizontal force, will be related to the positioning of the structural centre of rigidity. It is desirable that it has a certain correspondence with the centre of mass, such to avoid torsional movements of the structure. The box-like behavior will be guaranteed only if the connections between the several plates, therefore the orthogonal walls one with the other and the floors, will be effective. More precise information is necessary on such aspect. The box-like structure with an integral behavior, if subjected to a force in one of the two main directions, will have the shear forces acting in the floors transferred to the load-bearing walls that will have to be calculated by shear, as provided by seismic standards and needs. The connection node between two superimposed walls and the floor therefore will have to be considered as a rigid element and able to transfer the shear coming from the structures above to the base wall, receiving also the shear stress of the floor at the same level. This has to be guaranteed also for structures transverse to the one just described.
Therefore it is necessary to guarantee a certain edge continuity, that for example can be expressed by a beam, preferably made of wood, travelling laterally all the floor structure, whose task is to transfer the horizontal transverse loads of the floor to the wall below. The beams of the floors and the guide of the lower and upper panels will be constrained to the edge beam, such to guarantee a rigid box-like behavior to the whole structure.
The beam allows also the floor and wall to have a better thermal insulation.
A building of this type can have up to five levels with no need for piers of reinforced concrete or wood.
In the metal structure it is possible to provide spacing section bars placed as a connection between two adjacent load section bars.
This allows a metal structure to be generated that comprises an outer frame and an inner frame, composed of load section bars and spacing section bars, placed perpendicular to one another such to form a grid of section bars.
The result is a panel with a great stiffness, since the spacing section bars prevent relative movements between adjacent load section bars, such as for example bowing or bending due to compression or weight.
The spacing section bars are placed at a distance from each other that can be variable or regular and of any value, preferably ranging from 20 cm to 1 m.
Experimental tests have however shown that the use only of load section bars and horizontal section bars placed only at the windows and doors for creating the proper openings, is enough to guarantee the necessary mechanical stability.
These and other characteristics and advantages of the present invention will be more clear from the following description of some embodiments shown in the annexed drawings wherein:

Fig.1 is a detail of the main components of the panel;
Figs.2 and 3 are the sectional diagram of two embodiments of the panel;
Fig.4 is a general example of the load-bearing structure;
Fig.5 is a particular example of the load-bearing structure;
Fig.6 and 7 are embodiments of a part of the panel;
Figs.8 and 9 are two embodiments of connection of the panel with the floor;
Fig.10 is a sectional view of a rolling shutter box integrated in the panel.

The building panel shown in its components in figures 1, 2 and 3 comprises a plurality of metal section bars 1 interconnected with each other such to form a load-bearing structure, thermally and acoustically insulating material 2 and a first and second structural plates 6 and 3 made of gypsum fibre or cement fibre coupled on the opposite faces of the load-bearing structure.
For the coupling it is possible to use connection elements such as nails, rivets, screws or pins, or glues.
The section bars 1 are composed of plate-like elongated elements made of galvanized steel, placed on planes perpendicular to the median plane of the panel.
Therefore the steel is produced with a zinc structural and it is accurately cut as non-combustible.
The section bars 1 are arranged edgewise with respect to the plane of the panel, and since they have a specific width they form a thickness intended to be completely filled with the insulating material.
The section bars 1 have a C cross-section, the longitudinal edges being bent perpendicularly to the body of the section bar 1.
In the examples of the figure the section bars 1 have a further bending of 90°C at the end of the edge in the direction of the median plane of the panel such to form a channel section in the side regions of the section bar 1.
The C or U shape allows several metal section bars 1 to be joined together to form the load-bearing structure, and contemporaneously it allows structural plates to be fastened to the metal structure.
The section bars 1 have a thickness ranging from 1 to 3 mm, preferably corresponding to 2 mm.
In the preferred embodiment shown in the figures, regarding panels intended to be peripheral walls, the section bars have a width in the direction perpendicular to their longitudinal axis corresponding to 250 mm.
The edges bent for providing the C cross-section each one has a width, that is a distance between the end portion and the end connecting to the main body of the section bar equal to 50 mm.
In the embodiment that provides the presence of the further bending of the edges of the section bar in the direction of the median plane of the panel, such lip has a width equal to 20 mm.
As regards partitions on the contrary a panel with an internal structure of 150 mm is used.
The thermally and acoustically insulating material is cellulose fibre, polyester or stone wool, particularly a panel of insulating material with a thickness corresponding to the width of the section bars 1, that is equal to 250 mm in the example of figure 1, or a plurality of panels of insulating materials superimposed on each other such to form a thickness corresponding to the width of the section bars 1.
Since the section bars 1 are arranged interconnected with each other to form a load-bearing structure, the panels of insulating material each one occupies one cell surrounded by section bars 1.
In the example of figure 1, the panel is used as a perimetral wall with the external environment on the left and the internal environment on the right. The first and second structural plates arranged on the opposite faces of the panel can be different, or can be identical to each other, above all in the case shown in figure 3, wherein the different behaviors of the panel with respect to the internal environment and external environment are guaranteed by the internal wall lining 31 and by the external wall lining 30 respectively.
The first structural plate 6 is intended to face the internal environment, and has a thickness ranging from 8 to 20 mm, preferably corresponding to 18 mm.
The structural plate of gypsum fiber with a thickness of 18 mm guarantees a capacity load for expansion bolts of at least 8 Kg/cm².
As an alternative or in combination the first structural plate can comprise a thin steel sheet, a plate of gypsum and wood fiber, hardboard, plywood plate, a plate of semi-hard wood fiber.
The panel can comprise a vapor barrier film 5, that is composed of cellulose.
In one variant embodiment the vapor barrier film 5 is composed of polyolefins, particularly low density polyethylene (LDPE).
The vapor barrier film 5 has a thickness ranging from 0.1 to 0.5 mm, particularly corresponding to 0.2 mm.
In the case of a vapor barrier film 5 made of LDPE of 0.2 mm the vapor permeability is of 0.002 *10^-9 Kg/m²sPa and the vapor diffusion resistance is 500*10⁹ m²sPa/Kg.
The second structural plate 3, intended to face the external environment, can be advantageously water-resistant and it can be coupled to a wind resistant film 4 interposed between the metal structure and the second structural plate 3.
The second structural plate 3 has a thickness ranging from 8 to 20 mm, preferably corresponding to 18 mm.
The wind resistant film 4 is preferably composed of cellulose.
As an alternative or in combination the second structural plate can comprise a structural of porous wood fiber, plywood, bitulite, resin bonded particle plates.
As it can be clearly seen in figure 2, the section bars are provided with through apertures shaped as segments adjacent with each other and parallel to the longitudinal axis of the section bar.
According to the preferred embodiment shown in the figure, the apertures are aligned on several rows parallel to each other.
The apertures 10 can be for example 75 mm long and 3 mm wide. Two successive apertures in the same row can be spaced by 25 mm, while two adjacent rows can be spaced by 9 mm.
As it can be seen in figure 2, the apertures 10 are only in a central part of the section bar with respect to the width of the section bar in a direction perpendicular to its own longitudinal axis. In the example in the figure, the central part has a width that is substantially one half of the entire width of the section bar 1.
As it can be seen in figure 2, on the second structural plate, intended to be faced towards the external environment, it is possible to fasten a finishing 8, which gives the external aesthetic appearance of the panel and therefore of the building.
Preferably the finishing layer 8 is fastened to the second structural plate 3, in a spaced apart manner, such to form a vent channel 7 with a thickness ranging from 10 to 30 mm, preferably of 20 mm. The vent channel is provided only in the case a finishing layer 8 is present.
For the fastening of the finishing layer 8 such to form the vent channel 7 it is possible to use for example purlins.
Preferably such purlins used for the external ventilation of the panel are wood elements suitably treated by autoclave such to make them free of any modifications of external temperatures or moisture.
The finishing layer 8 can comprise for example steel or other metals, wood, glass, a structural of natural stone, bricks, fired bricks, ceramic tiles etc.
Figure 3 shows the preferred embodiment of the panel of the present invention. The panel is provided with an internal wall lining 31 and an external wall lining 30.
The internal wall lining 31 comprises, successively superimposing the first structural plate 6, a first plasterboard plate 310, a second insulating material 311, preferably mineral wool, a second plasterboard plate 312. The second plasterboard plate 312 is fastened to the first plasterboard plate 310 by spacing elements 314. A third plasterboard plate 313 is superimposed on the second plasterboard plate 312. Between the first plasterboard plate 310 and the first structural plate 6 there is provided the vapour barrier film 5 described above, that prevents condensate from forming into the layers. As an alternative it is possible to provide the vapour barrier film 5 between the second and third plasterboard plates, or between the second plasterboard plate 312 and the second insulating material 311.
The vapour barrier film 5 has a thickness of 0.20 mm; the plasterboard plates 310, 312, 313 have a thickness of 12.5 mm; the second insulating material 311 has a thickness of 50 mm. The metal section bars 314 are preferably made of steel, have a C section and a size of 50x50x2 mm, 2 mm being the thickness of the section bar.
The external wall lining 30 comprises an external plate 300 of cement fibre fastened to the second structural plate 3 by means of spacing crosspieces 302, a third insulating material 301, preferably wood fibre, being provided in the air space formed between the second structural plate 3 and the external plate 300 of cement fibre.
The cement fibre plate 300 preferably has a thickness of 12.5 mm, while the third insulating material 301 made of wood fibre preferably has a thickness of 50 mm. The wood crosspieces 302 therefore preferably have sectional dimensions of 50x50 mm.
Figure 4 shows an example of the metal load-bearing structure, according to a general outline.
The structure is composed of two head section bars 1' placed at two opposite ends of the panel, particularly the head side and the base, and two or more load section bars 1" parallel to each other and perpendicular to the head section bars 1' and fastened thereto.
It is possible to further provide spacing section bars 1‴ placed as a connection between two adjacent load section bars 1".
Thus the metal structure comprises an outer framework, composed of the two opposite head section bars 1' placed horizontally and of the more external load section bars 1" placed vertically, and an inner frame, composed of the load section bars 1" and spacing section bars 1‴, placed perpendicularly with each other to form a grid of section bars.
In the example of figure 4 the vertical load section bars 1" are placed at such a distance from each other of 40 cm and the horizontal spacing section bars 1‴ are placed at a distance from each other of 80 cm.
Such as shown in figure 5, the grid formed of the metal section bars can be irregular for the need of creating apertures for windows and doors 11.
In the proximity of the apertures for windows and doors 11 there are provided stiffening section bars 1^IV, parallel to the load section bars, which connect the spacing section bars 1‴ with each other or with the head section bars 1'.
The distances between the section bars 1 therefore are preferably variable in order to obtain a load-bearing structure that exactly meets the panel needs.
Figure 6 shows a further embodiment of the panel, in the low part in contact with the ground or the foundation. The metal structure is visible by its head base section bar 1' and a load section bar 1".
The panel is fastened to the foundation by means of plates 90, particularly by means of L-shaped plates, which are screwed to the foundation and to the panel, particularly to the bent edges of the head base section bar 1'.
Figure 7 shows a further example wherein several head section bars are placed in succession one to the other and are joined such to form a single head section bar 1' placed at the base of the panel, by means of C-shaped plates 91, placed inside the head section bars, astride of the adjacent ends thereof.
The C-shaped plates 91 are fastened to the section bars 1 by means of screws.
Even the other section bars 1 of the structure can be composed of several elements connected with each other by C-shaped plates 91.
Figure 8 shows a first embodiment of connection of the panel with the floor. A wooden joist 328 mounts the lower wall panel. The joist 328 is coupled to the lower panel by means of self-tapping screws 323. An edge bean is provided on the joist 328 to connect the floor and the upper and lower panels. The edge beam 329 is attached to the joist 328 and to the lower panel by means of screws 324. The floor is constituted by a U-section beam 326 which leans on the wooden joist 328, and is attached thereto by means of anchoring screws 325. The floor beam 326 is coupled to the edge beam 329 by means of a L-shaped plate 327. A floor plate 320 made of multilayered wood leans on the floor beam 326 and on the edge beam 329. The upper panel leans on the floor plate 320, and is attached to the floor plate 320 and to the underlying edge beam 329 by means of connecting screws 323.
Two steel plates 322 are provided in the side facing the external environment, which are attached respectively to the upper panel, the floor plate 320 and the edge beam 329 and to the lower panel, the joist 328 and the edge beam 329.
In the side facing the interior environment, the upper panel is coupled to the floor beam 320 by means of a steel L-shaped plate 321.
Figure 9 shows a second embodiment, with a configuration similar to figure 8. In the side facing the external environment a single connection plate 330 is provided, which connects the upper panel, the floor plate 320, the edge beam 329, the joist 328 and the lower panel. Similarly, in the side facing the interior environment, two angular elements for traction connection are provided. An upper angular element 331 is attached to the upper panel and to the floor plate 320, and a lower angular element 332 is attached to the lower panel, the joist 328, the edge beam 329 and the floor plate 320. The two angular elements are coupled to each other by means of a bolt 333.
Figure 10 shows in a sectional view a rolling shutter box suitably made for being comprised into the thickness of the panel.
The box has an envelope 13 of insulating material such as for example foam polystyrene, wherein the roller 12 of the rolling shutter is housed.
The box is comprised between the first structural plate 6 and the second structural plate 3, and it has such a thickness that it is possible to provide to interpose between the box and the second structural plate 3 a further insulating layer 20 for preventing thermal bridges from occurring.
In a preferred embodiment, such further insulating layer 20 is composed of Aerogel, preferably with a thickness of 40 mm.
Aerogel has a thermal k of 0.013 W/mk, and therefore it provides an optimal insulation also in the area of the rolling shutter box.

Claims

Building panel for external walls, comprising a load-bearing structure both for the floor above and for the upper storeys of the building, which structure is composed of a plurality of metal section bars (1), of which at least two head section bars (1') placed at two opposite ends of the panel and two or more load section bars (1") parallel to each other and perpendicular to said head section bars (1') and fastened to said head section bars (1'), thermally and acoustically insulating material (2) interposed between said section bars (1) and a first and second structural plates (6, 3) coupled on the opposite faces of the load-bearing structure,
characterized in that
the first and second structural plates (6, 3) are plates of gypsum fibre or cement fibre and have a thickness ranging from 8 to 20 mm,

said section bars (1) have a width in the direction perpendicular to their longitudinal axis corresponding to 250 mm and are provided with through apertures (10) for thermal break, wherein said through apertures (10) are shaped like segments adjacent with each other and staggered with each other to form eight lines parallel to the longitudinal axis of the section bar (1).
Panel according to claim 1, wherein at least one structural plate (6,3) is coupled to the load-bearing structure by glue.
Panel according to claim 1, wherein said through apertures (10) are only in a central part of the section bar (1) with respect to the width of the section bar (1) in the direction perpendicular to its own longitudinal axis.
Panel according to claim 1, wherein said thermally and acoustically insulating material (2) comprises cellulose fibre or polyester or stone wool.
Panel according to claim 1, wherein said insulating material (2) is composed of at least two panels of thermally and acoustically insulating material superimposed on each other, which panels have different thicknesses and/or densities with respect to each other.
Panel according to claim 1, wherein at least on the first structural plate (6) a vapor barrier film (5) is applied.
Panel according to one or more of the preceding claims, provided with an internal wall lining (31) comprising, successively superimposing the first structural plate (6), a first plasterboard plate (310), a second insulating material (311), a second plasterboard plate (312), the second plasterboard plate (312) being fastened to the first plasterboard plate (310) by spacing elements (314).
Panel according to claim 7, wherein a third plasterboard plate (313) is superimposed on the second plasterboard plate (312).
Panel according to claim 7 or 8, wherein the spacing elements (314) are metal section bars.
Panel according to claim 7, 8 or 9, wherein the second insulating material (311) is mineral wool.
Panel according to one or more of the preceding claims, provided with an external wall lining (30) comprising an external cement fibre plate (300) fastened to the second structural plate (3) by means of spacing crosspieces (302), there being provided a third insulating material (301) in the air space formed between the second structural plate (3) and the external cement fibre plate (300).
Panel according to claim 11, wherein the crosspieces (302) are made of wood.
Panel according to claim 11 or 12, wherein the third insulating material (301) is wood fibre.