Insulated fagade system

The invention concerns a ventilated building facade as described in the preamble of claim 1. Furthermore the invention concerns an insulation panel to be used in the ventilated facade, a method for providing such a building fa- gade and a method for manufacturing insulation panels.

It is known to build a facade comprising an inner wall of e.g. concrete or bricks, an insulation layer of any type of insulation, an outer cladding layer of e.g. tiles, wood, metal, boards of compressed fibres etc. Furthermore the facade comprises profiles fastened to the inner wall extending through the insulation layer and used for securing the outer cladding layer. The profiles extend vertically from ground level and to the top of the building. During construction the profiles will be secured to the inner wall, and afterwards the insulation is arranged between the profiles. Finally the outer cladding layer is secured to the profiles. The outer cladding layer is made as boards, which are often placed with small gabs in between the boards in order for ventilation air to be able to pass.

All types of insulation may be applied in such a faςade system. However, often fibrous insulation materials such as mineral wool are preferred. Also for fire safety reasons especially stone wool or glass wool insulation materials are preferred. The insulation may be in rolls or in the form of panels or boards. When glass wool has been used it has been in the form of rolls with a density around 18 kg/m ³ . Stone wool has usually been used in the form of panels with a density around 40 kg/m ³ . Low density insulation is usually preferred due to the price. This also makes handling and transport on the building site easier.

One problem with these relatively low densities of the insulation materials is that more fasteners are needed in order to make the insulation fit closely against the inner wall. A close fitting is important for ensuring optimal heat

insulating capacity, and also for preventing the ventilation gap from being blocked.

This problem could be solved by applying an insulation material with a higher density. This will improve the rigidity of the insulation. However, some of the advantages of having low density insulation will be lost, and such a solution will also increase the costs for the insulation.

Another problem is that the soft insulation layer is more sensitive to me- chanical damages during installation on the surface facing the outer cladding layer. Furthermore, the surface of the low density insulation is less resistant to weather influence. Especially for higher buildings the action of wind and precipitation, e.g. rain, may be significant, and also the precipitation may easily penetrate the openings for ventilation in the outer cladding layer. These two problems could be solved by applying an insulation material with a higher density as this would result in a more resistant surface.

It should be noted that the air gab for ventilation is essential for keeping the temperature of the building as low as possible in the summer time. The ra- diation from the sun on the external cladding can bring the temperature on this surface up to 60 - 70 degrees Celsius or more and without air gab this would also be the temperature of the outer surface of the insulation. Preferably there are also openings for ventilation air in the outer cladding layer. When having the air gab, and especially when also having the openings in the outer cladding, the outer surface temperature of the insulation is more or less equivalent to the air temperature which is often significantly lower than that of the outer cladding layer. Thus the air gab ensures a lower temperature gradient across the insulation layer and thereby a reduced heat flow into the building during summer time. Furthermore, it ensures that any hu- midity will dry out. It is essential that the insulation panels are sufficiently rigid and/or are supplied with a sufficient amount of fasteners to prevent the

insulation from bending out from the inner wall and blocking the ventilation air gab.

Another known method for improving mechanical properties of the insulation layer is to provide the mineral wool with a fleece layer (e.g. glass fibre fleece) on the outer surface. This will improve the mechanical properties of the surface and reduce the risk of mechanical damage. A fleece layer will also improve the resistance to the disintegration of the insulation caused by weather. However, a fleece layer is a relatively expensive solution, and it does not increase the stiffness of the insulation layer much, and therefore a high number of fastening means is still necessary.

The objective of the present invention is to obtain a more rigid insulation material with a surface being resistant to mechanical action and the influ- ence of weather without sacrificing the advantageous of the presently used low density insulation.

This has been solved by a ventilated facade comprising insulation panels having layers of insulation of different densities where a layer with a density above the average density is facing the outer cladding layer.

The advantage of this new solution is that the higher density of the outer surface layer will provide the mechanical rigidity of the insulation layer facilitating a reduced number of fasteners and it will also provide good resistance against mechanical damages as well as against weather influences.

One further problem with the existing solution is that when installing such a fagade system there will often be a tolerance on the distance between the profiles for holding the outer cladding layer. This tolerance may cause a dif- ference in the distance between the profiles from ground level to the top of a

building. This difference could be a few centimetres (e.g. from 53 cm to 55 cm) making it difficult to attach a closely fitting insulation layer.

Further to this tolerance the necessary distance between the profiles in or- der to comply with different standards for dimensions of the panels for the outer cladding layer may vary from e.g. 54 to 61 cm. So in order to limit the number of different insulation dimensions manufactured it is necessary that one dimension of the insulation panels can be used for an interval of distances between the profiles.

Therefore in a preferred embodiment of the invention the insulation panel is provided with a flexible zone along at least one edge surface so that the insulation panel is flexible in at least one direction and can be fitted closely against limiting surfaces. The advantage of this embodiment is that the edge flexibility ensures close connection between the insulation layer and the profiles.

Profiles are attached to the inner wall and extend through the insulation layer. The profiles provide a basis to which the outer cover layer is secured. Usually T-profiles will be applied for this purpose, but L profiles or C profiles or other types could also be applied. These profiles will usually be made of metal, preferably aluminium, but also steel, e.g. stainless steel, may be applied. The profiles could also be wooden beams.

When T-profiles are applied the thickness of the material will depend on the weight of the outer cladding layer. The width of the base portion fixed to the inner wall and holding the flange portion depends on the thickness of the insulation panels and the thickness of the ventilation air gab.

When profiles provided with flanges for securing the outer cladding layer are provided, insulation panels with a flexible zone offer the advantage of being

easier to install. This is due to the fact that they will be easier to insert between the flanges of the profiles, since the flexible zone can be compressed. This is a particular advantage when insulation panels having layers of different densities are applied.

The distance between the profiles is dependent on the dimensions of the external cladding. Different types of external cladding are delivered in different dimensions. Often a distance in the range 54 - 61 centimetres is necessary. Preferably the supplied insulation panels should be able to be flexible enough so that only two different insulation panel dimensions are necessary.

Preferably, the insulation panels are attached to the inner wall by mechanical means such as nails or screws. However, any adhesives may also be applied. The mechanical means will anyway secure that de-lamination of mineral wool insulation cannot take place.

The insulation material for the invention is preferably mineral wool e.g. glass wool or stone wool. It may be delivered to the building site as rolls or panels. When the insulation is of the stone wool type the low density layer facing the inner wall will have a density below 50 kg/m ³ , preferably below 45 kg/m ³ , even more preferably 20 - 40 kg/m ³ . The high density layer facing the external cladding will (in the case of stone wool) have a density of at least 70 kg/m ³ , preferably at least 80 kg/m ³ and even more preferably 80 - 120 kg/m ³ . The average density of the insulation material will often be in the range 45 - 60 kg/m ³ .

Methods for manufacturing dual density insulation panels are described in e.g. EP 1 111 113 A2.

The thickness of the insulation material will typically be in the range 40 - 250 mm, preferably 50 - 200 mm. The thickness of the high density layer is 10 - 20 mm. When insulation panels are used these will typically have a width of 400 - 700 mm, preferably closer to the actual distance between the profiles, i.e. often in the range 500 - 600 mm. The length of the panels is in the range 1000 - 2400 mm. When rolls are used these will preferably have the same width, while the length will be longer but dependent on the thickness of the insulation.

The soft part of the insulation material facilitates the possibility of adjusting to irregularities of the inner wall surface. Furthermore, the soft part of the insulation offers the possibility of providing the packages comprising the insulation material with some pre-compression thus reducing the volume which have to be transported and thereby the costs for transport. In order to facilitate the adjustment to the inner wall surface and the compressibility in packaging it might be advantageous to apply the method described in WO 03/042445 A1 for softening the low density surface by mechanical depth wise compression, e.g. by rollers.

In a further embodiment of the invention an insulation panel having a total thickness in the range 50 - 150 mm, preferably about 100 mm, of which 15 mm has a density of 100 kg/m ³ , and the rest have a density of 40 kg/m ³ , is being compressed on the low density major surface by a pressing drum with a compression of 50 %. Following this the product is compressed 35 % when packed.

If the same mechanical properties should be achieved by a mono-density insulation layer a density of at least 70 kg/m ³ would be necessary. Such insulation would not be compressible.

In a preferred embodiment of the invention the insulation panel is provided with at least one resilient or flexible minor edge surface. This means that the flexible minor edge surface is easily compressible by hand, and is elastically compressible in such a way that removing the compression will make the minor side surface of the board regain substantially its original dimension, however minor deviations from its original dimension should be expected. The rest of the board away from the flexible surfaces has a higher stiffness. The stiffness may be defined according to EN826. Preferably, the whole minor edge surface should be substantially equally flexible.

For manufacturing a mineral fibre panel with at least one flexible minor edge surface it must be realised that mineral fibre insulation comprises a large number of individual fibres having different lengths and diameters. For providing a stable mineral fibre board a binder is added to the mineral fibres. Said binder is cured in a curing oven and will thereafter make the fibres stick to each other at the points where the fibres are in contact with each other. A method for making one or more edge surfaces of this mineral fibre insulation panel flexible, i.e. elastically compressible, is to compress one or more rollers a distance into the edge surface. This compression by the roller will break some of the points of bonding in the mineral fibre board and thereby make the edge portion of the mineral fibre board softer and more elastically compressible than the rest of the board. The diameter of the compression applying roller(s) must be relatively small in order to concentrate the compression forces in the desired region. The diameter is usually 200 - 500 mm. The rollers are pressed a distance of 15 - 50 mm, preferably at least 35 mm into the edge. The numbers of rollers would often be 1 - 7, preferably 2-4. The resulting depth of the flexible zone should preferably be at least 35 mm, even more preferably at least 40 mm, in order for two different dimensions of the insulation panels to cover the whole possible span of pos- sible distances between the profiles holding the outer cladding layer.

On the production line the panels will pass a zone where rollers are compressed into the edge surface. Due to the high density layer of the insulation panels often only one board passes the zone with rollers at a time, and often the board is supported on the majority of its top and bottom surface while passing the zone with rollers. Typically, the rollers will extend different distances into the edge surface in order to gradually compress the edge surface and thereby forming a more homogenous resilient zone.

In a further embodiment of the invention three fasteners (typically screws or nails) or less are used per square meter for fixation of the insulation panels to the inner wall, preferably two fasteners are used, and even more preferably only one fastener is used per square meter. Any type of adhesive could also be applied for this fixation.

The ventilation air gap will typically be in the range 20 - 150 mm, preferably 70 - 100 mm. Preferably, there will not be any points or areas of direct contact between the outer cladding layer and the insulation panels. This will secure a free airflow in the ventilation air gap.

Especially for high buildings it is important to have openings for ventilation in the facade and not just at the bottom and the top of the outer cladding layer. Preferably the openings are made by having a given vertical distance between the external cladding panels, which will provide the necessary openings for ventilation. The distance between the outer cladding panels is pref- erably in the range 5 - 20 mm.

In an embodiment of the installation of the building fagade according to the invention profiles e.g. T-profiles are attached to the inner wall, insulation panels having at least two layers having different densities and at least one flexible edge, are installed between the profiles. Finally, the external cladding layer is attached to the profiles, ensuring that an air gab is provided

between the outer cladding layer and the insulation panels, and preferably with an opening in the vertical direction between the outer cladding panels.

In the following the invention will be described in more details with reference to the figures.

Figure 1 shows a cross sectional view of the facade

Figure 2 shows an insulation panel according to the invention.

Figure 1 illustrates an example of a building fagade (1 ) according to the invention. The inner wall (2) is often made of concrete but also other types of material such as bricks may be applied. Profiles (10), e.g. T-profiles as illustrated, are secured to the inner wall (2) by e.g. 90 degrees L-shaped fittings and screws (not shown). If U- or C-profiles were applied the profile would have a surface to be placed directly against the inner wall and it could be attached directly with e.g. screws without extra fittings. However, this further surface of the profile (10) would be placed against the inner wall along the whole length of the profile (10). L-shaped fittings, however, would be placed with certain distances. Therefore, a further surface on the profiles (10) might increase the cold-bridging slightly and, obviously also increase the used amount of metal.

When T-profiles are applied the profiles have a base portion (7) extending perpendicular to the inner wall and joined to a flange portion (8) substan- tially parallel to the inner wall. The outer cladding is secured to the flange portions (8) of the profiles (10), e.g. by screw or nails (not shown), or in the case of metal plates for outer cladding also welding could be applied.

The insulation is arranged between the base portions (7) of the profiles (10) in the vertical direction parallel to the inner wall, and the insulation (3) is arranged between the inner wall and the outer cladding layer in the vertical

direction perpendicular to the surface of the inner wall (2). The insulation comprise layers (4, 5) of different densities, with a high density layer (5) facing the external cladding and a lower density layer (4) facing the inner wall. Along at least one edge of the insulation, facing a profile (10) a flexible zone (9) is provided. This zone is more easily compressible than the rest of the insulation material.

Between the insulation and the outer cladding layer an air gab (11 ) is provided for ventilation air. Air for ventilating this gab enters between openings between the outer cladding panels (6). The outer cladding layer (6) should not be in direct contact with the insulation panels (3).

Figure 2 illustrates an insulation panel (3) according to claim 1 and 2 of the invention. The insulation panel comprise two major surfaces (12, 13) and 4 minor surfaces (14, 14', 14", 14'"). The high density layer, facing the outer cladding layer, preferably has a density of at least 70 kg/m ³ , while the low density layer has a density below 50 kg/m ³ . A flexible zone (9) is provided along one minor surface (14') extending a distance perpendicular to the minor surface (14') of at least 35 mm into the insulation.