The invention relates to a wall construction, more particularly to a construction for a partition wall or system wall.

Such partition walls are generally known and are generally used for later subdivision of spaces in a property. The usual method of placing such a wall consists of attaching to the floor and to the ceiling U-shaped metal stud profiles between which C-shaped metal stud profiles are generally placed as uprights at a mutual distance of for instance 60 cm. Formed in this way is a support construction against which plasterboard panels are arrangeable. Created between the plasterboard panels and the profiles is a space through which (electrical) wiring can be fed and which are if desired filled with thermal and/or acoustic insulating materials. In addition to having good sound-absorbing properties, rock wool also has advantageous fire-retardant properties.

Plasterboard panels comprise chemically bound crystal water, whereby they display good fire-retardant properties. If the plasterboard is heated by a source of fire, this crystal water will evaporate and extract from the fire the energy required for the conversion. As a result the increase in temperature of the plasterboard and the system wall construction is slowed and held

substantially constant for a period at about 110°C, and the wall will remain standing for longer. During the fire a layer of burnt plaster will develop which has a higher thermal insulation. The glass fibres in the fire-retardant plasterboard panels act as reinforcement of the gypsum core so that the structural cohesion is even improved for a long time during the fire load.

The fire retardance of the plasterboard depends, just as in the case of other building materials, on the whole construction in which it is applied. For this reason it is therefore only possible to assign a fire retardance to the overall construction. The present application relates to an improved wall construction comprising one or more plasterboard panels.

When the temperature rises too high, the wall will eventually collapse. This occurs more quickly particularly in the case of high walls, which can be explained by the greater length of the metal stud profiles. Because of the heat the metal profiles expand and the increased length will first clamp the metal stud uprights between the floor and ceiling and, in the case of still further thermal expansion, cause them to bulge outward. The wall collapses as a result.

US-A-1425507 shows a paper upright which is assembled from two curved paper parts and which acquires strength and stability because of this shape. A double-walled construction can be formed by strengthening these uprights with concrete or gypsum members which are held in place between plasterboard panels with a piece of bent iron wire. The whole wall construction is plastered with a layer of gypsum so that gaps between adjacent plasterboard panels are on the one hand filled and iron wires protruding through the plasterboard panels can on the other be concealed under a layer of gypsum. US-A-5347780 discloses a door frame manufactured from gypsum.

An object of the present invention is to provide a wall construction for a partition wall or system wall wherein the stated drawbacks do not occur, or at least do so to lesser extent. A more particular objective is an increased fire retardance.

Said object is achieved according to the invention with the wall construction according to the invention, comprising:

- at least two cardboard uprights;

- at least two plasterboard panels which are each attached to at least two uprights and span the space between the two uprights;

- wherein at least two plasterboard panels are arranged on opposite sides of the uprights and enclose an inner space between the at least two plasterboard panels and uprights;

- wherein the plasterboard panels comprise chemically bound crystal water; and

- wherein the cardboard uprights have flat sides against which the plasterboard panels lie. During a fire the bound crystal water issues from the plasterboard panels and moistens the cardboard uprights. For the purpose of an optimal transfer of this issuing water the uprights lie with their fiat sides against the plasterboard panels.

Due to the combination of cardboard uprights and plasterboard panels relatively soft materials are moreover applied, this enhancing the sound-damping properties of the wall construction.

Cardboard uprights have a linear temperature expansion coefficient which is less than 10 x

10 ⁶ mm/ ⁰ C at 20°C. Opting for a material with such a linear expansion coefficient guarantees that in the case of fire the absolute expansion of the uprights remains within acceptable limits. This prevents the uprights expanding so far that they bend outward and cause the wall to bulge outward.

Such a limited linear expansion coefficient excludes the following materials which have an expansion coefficient expressed in mm/°C at 20°C of: aluminium (22.2 x 10 ⁶ mm/°C), steel (12 x 10 ⁶ mm/ ⁰ C) and stainless steel (16 x 10 mm/°C). Examples of materials which would be suitable are for instance glass (7.6 x 10 ^~fi mm/°C at 20°C) and plasterboard (5 x 10 ^fi mm/°C at 20°C) as well as cardboard, bamboo, porcelain and a fire-retardant version of an adhesive-bound fibreboard, known under the name 'medium density fibreboard - fire resistant' , and under the generally known acronym MDF-FR.

Because the uprights are manufactured from cardboard, they have several significant advantages compared to conventional metal stud profiles manufactured from metallic material.

Metals generally have a high temperature expansion coefficient, which is undesirable for the wall construction according to the invention. A further drawback of a metal frame construction is that, via the so-called Faraday cage, it can form an undesirable shield to indoor radiation, for instance for a WiFi signal in an office building. This adverse effect of a conventional metal stud wall is avoided by applying non-metallic materials.

A further important advantage of a cardboard upright is that the wall construction can be manufactured from non-metallic material. This is particularly advantageous in the case of the upright itself, because this is a supporting part which makes an important contribution to the sound transfer through the wall. The cardboard upright connecting the mutually opposite plasterboard panels according to the invention is of a relatively soft material, this resulting in a sound damping significantly greater than if hard materials, in particular metal but also wood or ceramic, were to extend between the plasterboard panels and can transfer sound through the wall. Particularly parts of hard material extending in transverse direction of the wall have a highly adverse effect on the sound-damping property of the war. The wall construction according to the invention can be manufactured wholly from soft material.

Tests have shown that a partition wall of plasterboard and cardboard uprights displays greatly improved sound-damping properties compared to a partition wall erected with metal stud profiles. Using the same thickness of plasterboard, the application of cardboard uprights can provide a 3 dB improvement in sound-damping compared to metal uprights.

Surprisingly, a particularly advantageous embodiment is also obtained in terms of fire retardance when the uprights are manufactured from cardboard. An upright manufactured from cardboard, which is generally known to have a low combustion temperature, is found to be suitable for increasing the fire retardance of the whole wall construction compared to conventional metal stud profiles manufactured from steel. Even when crystal water evaporates from the plasterboard panels as a result of being heated, the integrity will be preserved. The other generally known property of cardboard that it readily absorbs moisture surprisingly has no adverse effect on the integrity of the wall construction. Tests have however shown that, when cardboard uprights are applied, they absorb only a small measure of crystal water evaporating from the plasterboard panels and remain below the combustion temperature of cardboard of about 260°C. According to the invention a contact between the plasterboard panels and the cardboard uprights is made so that moisture issuing from the plasterboard panels during heating is absorbed directly by the cardboard uprights and hereby keeps them below the combustion temperature of the cardboard.

Another effect enhancing the integrity of the wall construction can also occur here. The inner space enclosed by the at least two plasterboard panels and uprights is bounded on the underside by the floor or a connecting member and on the upper side by the ceiling or a connecting member in the form of a window frame element to be further discussed below. The inner space hereby forms a substantially airtight sealed space and, in the case of a fire, the quantity of air enclosed in this inner space will expand and increase the internal pressure, this guaranteeing the integrity of the construction. When crystal water evaporates from the plasterboard panels and is partially absorbed by the cardboard studs, the increased air pressure will press the cardboard against the plasterboard panels and prevent the cardboard uprights collapsing or falling apart. The internal air pressure which results because the air enclosed in the inner space expands as a consequence of the heat thus increases the stiffness of the wall construction.

A further advantage of applying cardboard uprights is that cardboard is a material which is easy to process. It is hereby possible for recesses for doors and window frames to be arranged at the desired location only after a wall with uprights has been placed. In conventional building with metal stud profiles it is already necessary during erection to take account of the placing of windows and doors. In the case of metal stud this placing therefore has to be fully decided beforehand, while the cardboard uprights according to the invention leave all options open. This is highly advantageous particularly in new building developments.

The complete recyclability of cardboard and the fact that cardboard can be disposed of everywhere as waste are further advantages. Because of this, and also because the production of cardboard has less of an energy impact than the production of metal stud profiles, the application of cardboard uprights provides for a sustainable solution.

According to a preferred embodiment, the cardboard upright comprises a C- or U-profile with flat sides, wherein the web of the C- or U-profile extends transversely of the plasterboard panels and wherein both legs of the C- or U-profile extend along the plasterboard panels. A C- or U-profile provides on the one hand a profile of a sufficient strength and provides on the other with its legs flat wall parts against which the plasterboard panels can be arranged. The contact surface between the wall parts of the profiles and the plasterboard panels forms a surface where in the case of a fire moisture from the plasterboard panels is transferred to the cardboard uprights so that these latter are moistened and cooled to below the combustion temperature of the cardboard.

According to a preferred embodiment, the plasterboard panels are fire-retardant plasterboard panels. Although any plasterboard with bound crystal water wheel will, when exposed to a source of fire, lose moisture which can moisten and cool a cardboard upright, fire-retardant plasterboard panels have the further advantage of being provided with a reinforcing fibre structure which preserves the integrity of the wall construction for a longer time during a fire. It is noted that the term plasterboard refers to gypsum cardboard and gypsum fibreboard as well as fire-retardant plasterboard (for instance types A, D, E, F, HI, H2, H3, 1 and P). Preferably used however are fire- retardant plasterboard panels.

According to yet another preferred embodiment, the cardboard uprights are impregnated in order to increase the fire retardance.

According to yet another preferred embodiment, the cardboard uprights are at least partially plasticized in order to increase the fire retardance.

If as according to yet another preferred embodiment the uprights are provided with one or more perforations, uprights are provided which can be easily glued. The glue then enters into and through the perforations and after curing will form a fixed glued connection. This greatly reduces the necessity of drilling into the construction.

A substantially flat wall surface is obtained when, according to yet another preferred embodiment, the wall construction comprises at least one connecting member, wherein the connecting member comprises a shoulder part configured to receive a wall connecting member lying substantially flush with an adjacent plasterboard panel. A flat wall has the advantage that there are no upright edges or deep joins in which dust accumulation can occur. Such a wall is hereby extremely suitable for an aseptic or low-dust space such as an operating room or a clean workspace, also referred to as clean room. In addition, a flat wall is aesthetically attractive.

When according to yet another preferred embodiment the connecting member is manufactured from gypsum, a material is applied which has good fire-retardant properties. It is thus possible to avoid metal or wooden elements being incorporated into the wall construction.

An increased strength of the connecting member is obtained when the connecting member is manufactured from glass fibre-reinforced gypsum.

According to yet another preferred embodiment, the wall connecting member comprises a floor covering. Because this floor covering bends upward from the floor and, because of the connecting member, is received substantially flush with an adjacent plasterboard panel, the floor covering transposes via a uniform curvature into an upright wall. Sharp edges between floor and wall where dust accumulation can occur are hereby avoided.

According to yet another preferred embodiment, the connecting member comprises a window frame element and the wall connecting member comprises a pane of glass arranged in the shoulder part of this window frame element. A substantially flush connection can in this way be obtained between a plasterboard panel and a pane of glass in a wall. It is hereby possible for instance to provide an aseptic or low-dust space with a window so that for instance natural light can enter an operating room or clean room.

The fire retardance of the overall construction is determined by the weakest link.

According to a further preferred embodiment, a pane of glass of fire-resistant glass is for this reason arranged in the window frame element.

According to yet another preferred embodiment, the window frame element comprises two parts arranged on opposite sides of an upright. By dividing the window frame element the part- elements can be applied on uprights of differing width dimensions, wherein in the case of a wide upright a join can be present between the two parts of the window frame element.

According to yet another preferred embodiment, the window frame element forms a substantially airtight wall of the inner space which is further enclosed by the at least two plasterboard panels and uprights and which is bounded on the underside by the floor or a further connecting member. When the window frame element comprises two separate parts opposite each other, a possible join therebetween is preferably filled in substantially airtight manner for the purpose of substantially airtight sealing of the inner space.

Preferred embodiments of the present invention are further elucidated in the following description with reference to the drawing, in which:

Figure 1 is a schematic perspective view of a space with a partition wall which is provided with the wall construction according to the invention;

Figure 2 is a front view of the wall construction shown in figure 1 ;

Figure 3 is a cross-sectional view according to arrow ΠΙ-ΙΠ in figure 2;

Figure 4 is a cross-sectional view according to arrow IV in figure 3;

Figure 5 is a cross-sectional view according to arrow V in figure 3; and

Figure 6 is a cross-sectional view according to arrow VI- VI in figure 2.

The space shown in figure 1 comprises a floor 1 and a (lowered) ceiling 2 between which a partition wall 4 according to the invention is arranged. This partition wall 4 is provided with a first recess 6 for a window 8 and a second recess 10 for a door (not shown). In the situation shown in figure 1 a source of fire F is located close to partition wall 4, which is thereby heated.

Figure 2 shows a front view of wall 4, wherein uprights 12 which are present in the wall and which will be further elucidated hereinbelow are shown in broken lines. Plasterboard panels 14 are attached with screws 18 to these uprights 12 and the space between plasterboard panels 14 is filled by skimming 16 so that a substantially flush wall 4 is created.

The first recess 6 which is arranged in wall 4 and in which a pane of glass 26 forming the window 8 is arranged is bounded by a window frame element 22 functioning as connecting member 20. This window frame element 22 will be further elucidated with reference to figures 3, 4 and 6.

A further connecting member 20 is formed by a corner connecting element 28 which comprises a shoulder part 30 configured to receive a floor covering 32 lying substantially flush with an adjacent plasterboard panel 14 so that a substantially smoothly continuous corner connection is obtained between floor 1 and wall 4.

Window frame elements 22 and corner connecting elements 28 form connecting members 20 which are preferably manufactured from gypsum, and still more preferably from glass fibre - reinforced gypsum.

Arranged in figure 3 on the ceiling (not shown) are support beams 24 from which the lowered ceiling 2 is suspended. Arranged between floor 1 and support beam 24 is partition wall 4, which in the embodiment shown in figure 3 takes a double-walled form and comprises two mutually opposite wall parts.

Both wall parts comprise a plasterboard panel 14 and a pane of glass 26 which are arranged mutually in line, or flush, relative to each other with an exceptionally elegant and fire- retardant connection.

Arranged between the wall parts are the uprights 12 which, in accordance with a particularly advantageous and surprising embodiment, can be manufactured from cardboard. An upright manufactured from cardboard, which is generally known to have a low combustion temperature, is found to be particularly suitable for increasing the fire retardance of the overall wall construction compared to conventional metal stud profiles manufactured from steel. Even if crystal water evaporates from plasterboard panels 14 as a result of heat, the integrity will be preserved. The other generally known property of cardboard, that it readily absorbs moisture, surprisingly has no adverse effect on the integrity of the wall construction.

The integrity of wall 4 can be increased when uprights 12 and plasterboard panels 14 enclose an inner space 34 which is bounded substantially airtightly on all sides. This is possible on the underside with floor 1 or a closing element 36 and on the upper side with a window frame element 22 (optionally with a seal (not shown) in a join 40 located between different parts thereof) or a closing element 38. In the case of fire the quantity of air enclosed in this inner space 34 will expand and the internal pressure will increase, this guaranteeing the integrity of wall 4. When crystal water evaporates from plasterboard panels 14 and is partially absorbed by the cardboard uprights 12, the increased air pressure will press the cardboard against plasterboard panels 14 and prevent the cardboard uprights 12 collapsing or falling apart. The internal air pressure which results because the air enclosed in inner space 34 expands as a consequence of the heat thus increases the stiffness of the wall construction.

By providing the uprights 12 and/or closing elements 36, 38, and optional side elements (not shown) with one or more perforations, they can be easily glued with a glued connection. The glue then enters into and through the perforations and, after curing, will form a fixed glued connection. This greatly reduces the necessity of drilling into the construction.

Window frame element 22 which is shown enlarged in figures 4 and 6 comprises two parts in the shown embodiment. Although the skilled person will appreciate that window frame element 22 can be manufactured from a single part, the application of two separate parts has the advantage that window frame element 22 can be applied with uprights 12 having differing width dimensions. In the case of a wider upright 12 a join 40 with some clearance will result which, if desired, can be sealed with suitable (heat-resistant) sealant.

Window frame element 22 has a shoulder part 42 with a depth which is substantially equal to the sum of the thickness of the pane of glass 26 and glued connection 44 with which it is attached to window frame element 22. This creates a substantially flush connection between plasterboard panels 14 and the pane of glass 26 of window 8. Such a wall is hereby particularly suitable for an aseptic or low-dust space such as an operating room or a clean workspace, also referred to as clean room. Although it shows a preferred embodiment of the invention, the above described embodiment is intended solely to illustrate the present invention and not to limit in any way the specification of the invention. Where measures in the claims are followed by reference numerals, such reference numerals serve only to contribute toward the understanding of the claims, but are in no way limitative for the scope of protection. The rights described are defined by the following claims, within the scope of which many modifications can be envisaged.