DK178622B1 - Insulation system for a roof structure - Google Patents

Abstract

An insulation system (10) comprising an insulation structure adapted to be positioned above a supporting base layer (8), the upper surface of which defining a base plane (x,y), the insulation structure comprising one or more first insulation lamella(s) (1) having a length to be positioned parallel to said base plane (x,y) and having a support capability as seen in a direction perpendicular to said base plane (x,y). The insulation structure further comprises one or more second insulation lamella(s) (2) having a length to be positioned parallel to said base plane (x,y), where the support capability of the one or more first insulation lamella(s) (1) is greater than the support capability of the one or more second insulation lamella(s) (2) as seen in a direction perpendicular to the base plane (x,y) and where the insulation structure forms an alternating insulation structure of first and second insulation lamellas (1, 2).

Description

The present invention relates to an insulation system comprising an insulation structure adapted to be positioned above a supporting base layer. More particularly the invention relates to an insulation system comprising an insulation structure adapted to be positioned above a supporting base layer, the upper surface of which defining a base plane, the insulation structure comprising two or more first insulation lamellas having a length to be positioned parallel to said base plane and having a support capability in a direction perpendicular to said base plane, the insulation structure further comprises one or more second insulation lamella(s) having a length to be positioned parallel to said base plane, where the support capability of the two or more first insulation lamellas is greater than the support capability of the one or more second insulation lamella(s) as seen in a direction perpendicular to the base plane. The base plane is defined as the surface of the supporting base layer. The insulation structure forms an alternating insulation structure of first and second insulation lamellas where the greater support capability of the two or more first insulation lamellas is provided by a greater height in a direction perpendicular to said base plane of the two or more first insulation lamellas than of the one or more second insulation lamella(s), and use of the insulation structure.

When the roof structure of a hot roof, i.e. a roof where the insulation is positioned above the supporting roof layer, which often is a flat or low slope roof, is to be constructed, usually a layer of insulation is provided on a supporting layer of e.g. concrete, lightweight concrete or profiled steel plates. On top of this a pressure distributing layer and/or other roof covering means such as roofing felt is positioned, forming the exterior of the roof.

Generally the building regulations have been strengthened over the years in order to reduce energy consumption, which has resulted in increasing requirements for the insulation thickness on a roof. In order to meet current regulations, typically the insulation layer is provided by 3-4 layers of rigid insulation slabs, such as slabs of glass wool, or at least one layers of la-mellas, forming a 200-500 mm thick insulation layer.

The advantage of using lamellas is that high compressive strength is obtained and low weight is added to the roof structure than if using traditional insulation slabs with a low compressive strength. The reduced density is therefore also easy to handle for the workers who install the insulation. High compression strength also makes the lamellas easy to install as the lamellas keep their shape such that the insulation doesn’t get displaced or deformed when additional lamellas are added and pushed together with the lamellas already installed. Additionally, high compression strength also makes it possible for the workers to walk on the insulation, without risking that insulation will be tread down. The lamella shape also makes them quicker to install as compared to traditional insulation slabs since one layer instead of three or four may be enough.

However, as compared to traditional insulation slabs, the lamella with a high compression strength and a low density does have a lower thermal conductivity as compared to traditional insulation slabs because the fibers in the insulation lamella to a greater extent are extending in the vertical direction, i.e. perpendicular to a base plane of a roof structure, as compared to traditional insulation slabs, where the fibers are extending in the vertical direction, i.e. parallel to the base plane of the roof structure. The cost of production is also higher for the high compression strength lamella.

The present invention differs from EP2141303 in that a pressure distributing board rests on the two or more first insulation lamellas and air channels are formed below the pressure distributing board between the la-mellas.

Furthermore the present invention differs from WO 9908969 in that the greater support capability of the one or more first insulation lamellas is provided by a greater height in a direction perpendicular to said base plane of the one or more first insulation lamellas than of the one or more second insulation lamellas and in that air channels are formed below a pressure distributing board between the lamellas.

Additionally the present invention differs from W09842503 in that even though a facing covering the uneven lamellas is mentioned, it is not a pressure distributing board. Instead the lamella is sandwiched between the facings that follow the profile created by different heights of adjacent lamel-las. There is no air channel formed between the lamellas and a pressure distributing board.

Consequently, the object of this invention is to provide an insulation system that is both easy to install, has a lower thermal conductivity and lower production costs than the prior art insulation structure comprising only high compression strength lamellas.

This is achieved with the insulation system further comprising a pressure distributing board supported by the two or more first insulation lamellas such that an air channel is formed between the two or more first insulation lamel-las forming the sides of the air channel, and the pressure distributing board and the one or more second lamella(s) forming the top and bottom of the air channel, respectively.

The alternating structure results in an alternating pattern of first and second lamellas.

In this invention insulation is perceived as a material having a heat conductivity below 42 W/mK.

The lamellas are preferably installed in one layer only.

As a non limiting example, the lamellas may form part of a roof system where a supporting or bearing layer in the form of concrete or lightweight concrete is provided, and on top of this the first and second insulation lamellas may be provided. The roof is sealed off by covering the insulation structure with roofing felt or other roof covering means. The first and second lamellas used in this construction may e.g. be 400 mm high.

Alternatively, the first and second insulation lamellas may be used in a construction where the bearing or supporting roof layer is profiled steel plates on top of which a layer of e.g. 50 mm insulation slabs, such as glass wool or stone wool is provided. Above the layer of insulation slabs a vapour barrier or other kind of membrane is provided and on top of this a layer of first and second lamellas are provided. In this example the first and second lamellas may by way of example be 300 mm high. The roof is sealed off by covering the insulation lamellas with roofing felt or other roof covering means.

Other roof structures not disclosed herein may also be imagined.

The greater support capability of the two or more first insulation la-mellas may be provided by a greater compressive strength in a direction perpendicular to said base plane of the two or more first insulation lamellas than of the one or more second insulation lamella(s), provided that the second lamella has an equal or lower height than the first lamella. A high compressive strength of the lamella makes it is possible to walk on the lamella, without risking that the lamella is being tread down. Additionally, when a pres sure distributing board is positioned on top of the lamellas, a difference in height between the first and the second lamella also contributes to that the higher lamellas provide more support than the lower lamellas. Both the first and the second lamella may have an equal compressive strength, but if the first lamella is higher than the second lamella, the first lamella provides a greater support capability than the second lamella due to the height difference only. Similarly both the first and the second lamella may have an equal height, but the higher compressive strength of the first lamella, increases its support capability when walking on it or when a load such as a pressure distributing board is positioned on it. The lower production costs are achieved by an alternating insulation structure of first and second lamellas, where the production cost of the second lamella, with reduced support capability generally is lower.

The term lamella covers an element where the slab, from which it is made, is cut into lamellas of a desired width and the lamellas are rotated through 90° about the longitudinal axis thereof. Subsequently they may be placed side by side for an insulation structure covering a desired area. Consequently the width during production ends up being what is defined as the lamella height.

When merely referring to lamellas in general it is to be understood as it may be both first and/or second insulation lamellas.

Furthermore the first and/or second insulation lamella(s) may have a height and a width, the height being perpendicular to the base plane and larger than or equal to the width but smaller than the length. The elongate shape, being higher that it is wide, reduces the number of layers that are required on a roof for the insulation to meet the requirements of most building regulations. The lamella shape being narrower than a slab of insulation, but higher than a slab of insulation also reduces its weight per element as compared to a large slab of insulation. A large slab of insulation usually have dimensions of at least 1200 mm * 900 mm (length * height). The thickness may be up to 200 mm. This makes the lamella easy to handle and install.

Likewise the width of the first insulation lamella may be different from the width of the second insulation lamella, the width being parallel to said base plane. For example the width of the second insulation lamella may be greater, so instead of installing one first insulation lamella for every two second insulation lamellas, one of each may be installed, the second insulation lamella merely being wider than the first insulation lamella.

It is understood that compressive strength is measured at 10 % deformation according to the standard EN 13162 Thermal insulation products for buildings - Factory made mineral wool (MW) products. The one or more second insulation lamella(s) may have a compressive strength below 20 kPa, preferably between 5-15 kPa as seen in a direction perpendicular to the base plane. The lower compressive strength is a result of a lower density. The lower density lamellas have normally lower heat conductivity and production costs than lamellas having high compressive strength and thereby a higher density. Therefore by using lamellas with a low compressive strength together with lamellas having a high compressive strength, the heat conductivity may be reduced and also, the economy in a building project may be improved.

Likewise the two or more first insulation lamellas may have a compressive strength above 30 kPa, preferably between 45-70 kPa as seen in a direction perpendicular to said base plane. This compressive strength makes it possible to walk on the lamella, and thereby easy to work with. Additionally, using lamellas with a high compressive strength as seen in a direction perpendicularly to the base plane will also increase the insulation’s ability to carry a snow load. The lamellas may have higher compressive strength in two directions compared to a third direction, where the third direction may be along the length of the lamella.

The two or more first insulation lamellas may have a substantially isotropic structure. This means that the fibers to a large extent are extending randomly in all directions, in particularly in the core of the lamella, instead of extending largely in the same direction parallel to the base plane. Consequently more fibers are extending in a direction perpendicular to the base plane compared to traditional insulation slabs, where fibers are to a large extent extending in a direction parallel to the base plane. The isotropic structure provides therefore for a high compressive strength as seen in a direction perpendicular to the base plane compared to insulation slabs where the fibers are largely extending in a direction parallel to the base plane. The isotropic structure may be produced my means of a so called crimping process which is described in DK157309 and as described below.

In the production process, corresponding to a crimping process, the glass wool fibers are being transported in a stream of gas and are being positioned on a receiving means being permeable to the gas, but not the fibers. During the transport of the fibers to the receiving means, the fibers are sprayed with a binder. The fiber layer formed on the receiving means is exposed to at least one longitudinal pressure operation, where the relationship between the fiber weight per area unit before and after the pressure operation is smaller than the value at which creases may be formed in the fibers forming a felt layer. Subsequently the felt layer is heat treated in order to fixate the fibers. The felt is used for providing the lamellas, where one layer of felt may be used for one lamella. As a non-limiting example, the lamellas may be made from slabs having a height of e.g. 200 mm. The slab may be cut in e.g. 300 or 400 mm wide lamellas and when the lamellas are used in an insulation system, the lamellas may be rotated 90 degrees such the width becomes the height, such that the dimension of e.g. 300 or 400 mm is laid perpendicular to the base plane.

The one or more first and second insulation lamellas may be made of a fibrous material, such as stone wool or glass wool. Other fibrous materials could be used as well. When the first insulation lamellas are produced of glass wool they usually have a density between 45-90 kg/m3, preferably between 50-70 kg/m3. Where as the one or more second insulation lamella(s), made of glass wool as well, may have a density below 45 kg/m3, preferably between 20-30 kg/m3. Both the first and the second lamella, or one of them, may be made by means of the crimping process as described in DK157309 and as described above.

In a lamella made according to said crimping process the difference in heat conductivity may be up to 3 mW/mK between a lamella of glass wool having a density of 60 kg/m3 and a lamella of glass wool having a density of 30 kg/m3, the low density lamella having the lower heat conductivity.

The alternating insulation structure may form a striped pattern. Typically the lamella may be in the shape of a cuboid or a rectangular prism, having a height, a width and a length, where the length is to be positioned parallel to the base plane and the height perpendicular to the base plane. In order to form a striped pattern of the alternating structure, the lamellas may be laid down in different patterns. The first and second insulation lamellas may be installed in alternating rows with first or second insulation lamellas in each row, positioned in lengthwise extension of each other. For example every second row of lamellas being first lamellas and every second row of lamel-las being second lamellas. Another possibility is that the first row is formed by first insulation lamellas and the second and third rows are formed by second insulation lamellas. More combinations forming a striped pattern or other patterns could be imagined.

The word row is to be interpreted as one or more lamellas in a line, where the length of the line corresponds to the sum of the individual lengths of the lamellas. Different kinds of insulation lamellas may be present in one row.

The alternating insulation structure may also form a staggered pattern.

The staggered pattern may be formed by rows alternating in the structure of first and second insulation lamellas. This means that the rows are not arranged in columns, as they may be when forming a striped pattern.

So depending on the desired overall compressive strength, and the desire with regards to heat conductivity, and the size of the pressure distributing board or other roof element that are to be put on top of the lamellas, a suitable structure or pattern may be chosen. A combination of the two alternating insulation structures may also be envisioned, for example where some rows are alternating in the structure, while other rows consist of the same kind of lamella through its length.

The insulation structure may comprise one or more rows of first and second insulation lamellas, the rows being broken by one or more first or second lamella(s) extending transversely in relation to the rows of first and second insulation lamellas in a plane parallel to said base plane.

The transversely extending lamella may either be used as a support for a pressure distributing board, due to its height, where it is the same height or higher than the adjacent lamellas, and/or due to its higher compressive strength than the adjacent lamellas. Alternatively, a first or preferably a second lamella with a lower height than the adjacent lamellas may be provided such that an air channel is formed transversely to the rows, where to adjacent lamellas having a higher height forms the sides of the channel, and the lamella having a lower height forms the bottom of the channel and the pressure distributing board forms the top of the channel. In that way a network of air channels may be formed in the insulation system below the pressure distributing board between the lamellas.

Hence, the insulation system may further comprise a pressure distributing board being positioned such that at least one, preferably two edges of the pressure distributing board are being supported by the one or more first insulation lamella(s).The pressure distributing board may by way of example be made of a wood based material such as plywood or an insulating material, such as glass wool or stone wool, preferably with a high compressive strength.

Furthermore a height difference may be present between an adjacent first and second insulation lamella, preferably the height of the second insulation lamella being lower than the height of the first insulation lamella. The height is in a direction perpendicular to the base plane. Again air channels may be formed in the insulation system, no matter the orientation of the lamellas. The air channels may be used for ventilating the hot roof or for drying of the hot roof, by connecting these channels with ventilation gaps in the coping or connecting them with ventilation cowls in the roof surface.

The height difference between the adjacent first and the second insulation lamellas may by way of example be between 10-50 mm, preferably between 20-30 mm. If all lamellas were provided with the same height, or instead of lamellas, slabs of insulation were used, it would be necessary to cut out the channels in the slabs, or cut down some of the lamellas, such that a height difference could be obtained.

The height of the first insulation lamella(s) and/or second insulation lamella(s) may be 200-500 mm, preferably between 300-400 mm to achieve an U-value below 0,12 W/m2K of the roof construction.

The insulation system may be used in a roof structure, preferably for a flat roof.

In the following, the invention will be described in further detail with reference to the drawings in which:

Fig. 1 is a schematic perspective view of a first embodiment of an insulation system including a pressure distributing board.

Fig. 2 is a schematic perspective view of a second embodiment of an insulation system including a pressure distributing board.

Figs 3-7 are different alternating insulation structures seen from above.

Fig. 8 is a side view of the embodiment in fig. 7.

Fig. 9 is an embodiment of a lamella having an isotropic structure.

One embodiment of an insulation system according to the invention is shown in Fig. 1.

The insulation system 10 comprises in this embodiment a number of first lamellas 1, second lamellas 2 and pressure distributing boards 3, here made of an insulating material, such as glass wool.

Furthermore a plane x,y has been defined as extending along the surface of a supporting base layer 8.

The first and/or second insulation lamella(s) of the embodiments in fig.1-8 has/have a height, a width and a length, the height being perpendicular to a roof bearing layer and being larger than the width but smaller than the length. These dimensions make it possible to lay only one layer of insulation as opposed to the normally 3-4 layers required as the height of the la-mellas generally are 200-500 mm. As a non-limiting example, in the disclosed embodiment the lamellas 1,2, are 400 mm high.

Additionally a lamella is a block being cut from a larger slab of insulation and before being applied in an insulation system, the lamella is rotated 90 degrees, so what used to be the height of the slab, now is the width of the lamella.

As can be seen, the two edges 31 of the pressure distributing boards 3 rest on two first lamellas 1. Two further first lamellas 1 are positioned here between the first lamellas 1 on which the pressure distributing board 3 rests. As an alternative to having two first lamellas 1 between the two first lamellas 1 that support the edges 31 of the pressure distributing boards 3, those two first lamellas 1 in the middle may be replaced with two second lamellas 2 depending on the flexural strength of the pressure distributing board 3. The pressure distributing board 3 may have sufficient flexural strength such that the pressure distributing board 3 doesn’t bend or break when being walked on, even though no first lamellas 1 are present between the first two lamellas 1 carrying the edges 31 of the pressure distributing board 3. The pressure distributing board may be larger and consequently more first lamellas 1 may be positioned between the first lamellas 1 on which the pressure distributing board 3 rests. Similarly the first lamellas 1 in the middle may be replaced with a similar number of second lamellas 2 depending on the flexural strength of the pressure distributing board 3.

Another embodiment of an insulation system according to the invention is shown in Fig. 2.

The insulation system 20 comprises in this embodiment first lamellas 1, second lamellas 2 and pressure distributing boards 3 here made of insulation or a wood material, such as plywood. Both the first and the second la-mellas 1, 2 are made of glass wool. The lamellas 1, 2 are positioned directly on a supporting base layer 8 made of concrete. Alternatively, the supporting base layer may be made of profiled steel plates on top of which layer of insulation, e.g. 50 mm of insulation and a vapor barrier is positioned before the lamellas are positioned on top of the vapor barrier.

The width of the first lamella 7a and the width of the second lamella 7b are the same in this embodiment but it can be different. The height 4a of the first lamellas 1 is greater than the height 4b of the second lamellas 2. The difference in height creates a series of air channels 11 between the first lamellas 1 forming the sides of the air channel 11, and the pressure distributing board 3 and the second lamellas 2 forming the top and bottom of the air channel 11, respectively. The first lamellas 1 have thus an increased support capability as compared with the second lamellas 2. The reason therefore in this embodiment is that both the compressive strength of the first lamellas 1 is greater and the height 4a of the first lamellas 1 is greater than the height 4b of the second lamellas 2.

The difference in compressive strength is often correlated with the density, such that the second lamella 2 with a relatively low compressive strength for glass wool lamellas is below 45 kg/m3, preferably 20-30 kg/m3, while the first lamella 1 has a density of about 60 kg/m3. The density may generally be between 45-90 kg/m3, preferably between 50-70 kg/m3. The pressure distributing board 3 thus rests on the higher first lamellas 1, which also have the ability to support it through a higher compressive strength.

If the lamellas where made of stone wool it is to be understood that the density likely would be higher to obtain the same level of compressive strength.

The higher compressive strength is obtained because the first lamel- las 1 are produced by means of a crimping process. A large part of the fibers in the lamella 1 are extending in different directions creating an isotropic structure (as seen in fig. 9) or substantially in a direction perpendicular to the base plane x,y, particularly in the core of the lamella, relative to other insulation slabs where the fibers generally are extending in a direction parallel to the base plane x,y. The first lamellas 1 may also be produced by means of other processes creating a similar structure or having a different structure, but the same level of compressive strength of approximately 45-70 kPa. The fibers in the second lamella 2 extend substantially in a direction perpendicular to the base plane x,y, but the second lamella 2 may also have a different fiber structure. This applies to the other embodiments as well. The insulation structure as shown in fig. 2 forms a striped pattern.

An alternating insulation structure 30 as seen from above, forming part of the alternating insulation system is shown in Fig. 3. The insulation structure 30 is similar to the insulation structure in the first embodiment shown in fig. 1, but may also be incorporated in other insulation systems not shown.

The lamellas 1, 2 are laid in rows 6a and columns 5 parallel to the base plane. The first and second lamellas 1, 2 are forming a striped pattern. Two columns 5 of lamellas are shown but more may be added and more rows 6a or bands 12 (encircled) of lamellas may be added as well. A band consists of two or more lamellas 1, 2 of the same kind positioned adjacent each other. In fig. 3 they are positioned in lengthwise extension of each other in the same row 6a. In this embodiment a band corresponds to a row having the same insulation structure along its length.

In Fig. 4 another embodiment of a different alternating insulation structure 40 forming a staggered pattern is shown. The pattern is staggered because the same kind of lamella is not arranged throughout the length of a row. Flere rows 6b having an alternating structure is shown alongside rows 6a having a similar structure along its length. That the rows have a similar structure means that only one kind of lamella is present in a row. That the rows have an alternating structure means that more than one kind of lamella is present in a row, such as a first and a second lamella. The first and second lamellas 1, 2 are positioned in lengthwise extension of each other such that the rows 6a, 6b are positioned in a plane parallel to the base plane (not shown).

The insulation structure 40 comprises a number of bands 12, where a band 12 consists of two or more lamellas 1,2 of the same kind positioned adjacent each other. In fig. 4 two first lamellas 1 are positioned adjacent each other in the same column 5. A row 6a, 6b consists of one or more first or second lamellas 1, 2 positioned in lengthwise extension of each other. A band 12 may consist of two or more rows of the same kind of lamella extending over one or more columns as seen in fig. 4. A band 12 may also consist of one or more rows of the same kind of lamella extending over two or more columns as seen in fig. 3.The exact combination of first and second lamellas 1, 2 depends on the desired overall compressive strength, and the requirement with regards to heat conductivity, and the size of the pressure distributing board or other roof elements that are to be put on top of the first and second lamellas 1,2.

Fig. 5 shows an alternating insulation structure 50. The alternating insulation structure 50 forms a staggered pattern where every second row is offset in relation the adjacent row. The alternating insulation structure 50 may replace the insulation structure in fig 1 or 2 and thus form part of an insulation system. In fig. 5 the lamellas of a row 6b are shifted in relation the adjacent rows 6b. Like in the other embodiments the first lamella 1 is positioned next to a second lamella 2 in relation to adjacent rows. Only every second row 6b of lamellas is here aligned in a column. The alternating insulating structure 50 may also be separated by a one or more first and/or second lamellas extending transversely in relation to the rows 6b, as seen in figs. 6 - 8.

In figs. 3, 4 and 5 the height of the first and the second lamellas are the same, but the height of the first and/or second lamellas may be different, such that the first lamellas preferably are higher than the second lamellas.

Figs. 6 and 7 show two different alternating structures 60, 70 of first and second lamellas 1, 2, 2a. In both embodiments a second lamella 2, 2a, extending transversely in relation to the rows 6a, has been positioned between the two columns 5 of first and second lamellas 1, 2. However, in fig.7 the second lamella 2a extending transversely has a lower height, than the second lamella 2 in fig. 6. Additional first or second lamellas 1,2, 2a may be positioned between the two columns 5 and additional columns 5 may be posi tioned between one or more transversely extending lamella or lamellas. Instead of it being a second lamella 2a extending transversely in relation to the rows 6 of lamellas, a first lamella or lamellas 1 may be used, alternatively a combination of first and second lamellas 1,2, 2a.

In fig. 7 another embodiment of an alternating insulation structure 70 is shown. Two second lamellas 2 are used for every first lamella 1, providing a lower support capability or compressive strength but on the other hand providing a lower heat conductivity due to a lower density of the second la-mellas 2 as compared to the structure shown in fig. 6. As in fig. 6 every second lamella is a first lamella 1. A further difference between figs. 6 and 7 can be seen in fig. 8, where a side view of the alternating insulation structure 70 in fig. 7 can be seen. Here the transversely extending lamella 2a is lower in height, approx. 20-30 mm, than the lamellas 1, 2 arranged in columns 5. This creates an air channel in the alternating insulation structure 70 that can be used to ventilate the roof structure.

Finally in fig. 9 a first lamella 1 having an isotropic structure is shown. Such a lamella is produced by means of the process described in Dk157309 and as described above. The lamella 1 may be produced by means of other processes. As can be seen in the figure, it is mainly the core that has an isotropic structure of the fibers, while in the top and bottom of the lamella 1, the fibers are generally parallel to the top and bottom surface of the lamella 1. The isotropic structure contributes to a higher compressive strength of the lamella 1. The first lamella 1 is preferably produced in this way and has an substantially isotropic structure.

Furthermore, it is conceivable to make use of other configurations of the alternating structure. For instance, there may be two layers of lamellas, where preferably lamellas positioned on top of each other are of the same type, having the same compressive strength. A further alternative conception lies in the possibility of applying at least some of the principles underlying the present invention to insulation slabs or sheets.

The embodiments only show a section of insulation systems or alternating insulation structures, which may be extended to cover a greater area, such that both more rows and/or more columns may be added in order to cover a complete roof area.

The same reference numbers refer to similar features throughout the application.

In general, the different alternating structures of the embodiments shown and described may be combined. The invention is not limited to the alternating insulation systems shown, but lamellas of different support capability, including differences in compressive strength and height, may be combined in different ways.

Claims (13)

An insulation system (10) comprising an insulation structure (30) adapted to be placed over a supporting base layer (8), the upper surface of which defining a base plane (x, y), the insulation structure (30) comprising two or a plurality of first insulation slats (1) having a length (9) positioned parallel to the base plane (x, y) and having a support capability seen in a direction perpendicular to the base plane (x, y), comprising the insulation structure (30) a further one or more second insulating lamellae (2; 2a) having a length (9) placed parallel to the base plane (x, y) where the supporting capacity of the two or more first insulating lamellae (1) is greater than the supporting capacity of the one or more insulation slats (2) (2; 2a) viewed in a direction perpendicular to the base plane (x, y) and wherein the insulation structure forms an alternating insulation structure (30) of first and second insulation slats (1, 2; 2a), where the greater support ability of the two or more first insulation slats (1) are provided at a greater height (4a) in a direction perpendicular to the base plane (x, y) of the two or more first insulation slats (1) relative to one or more second insulation slats (clays) ( 2; 2a), characterized in that the insulation system (10) further comprises a pressure distribution plate (3) supported by the two or more first insulation slats, so that an air duct is formed between the two or more first insulation slats (1) forming the sides of the air duct (11) and the pressure distribution plate (3) and the one or more other lamella (s) (2) constitute the top and bottom of the air duct (11) respectively. An insulation system according to claim 1, wherein the greater support capacity of the two or more first insulation slats (1) is provided by a greater compressive strength in a direction perpendicular to the base plane (x, y) of two or more first insulation slats (1) relative to the insulating member (s) (2) (2a). An insulation system according to claim 1 or 2, wherein the first and / or the second insulation lamellae (1, 2, 2a) have a height (4a, 4b) and a width (7a; 7b), wherein the height (4a; 4b) is perpendicular to the base plane (x, y) and greater than or equal to the width (7a; 7b) but smaller than the length (9). An insulation system according to any one of the preceding claims, wherein the (s) first and / or the second insulation lamellae (1, 2; 2a) have a height (4a, 4b) and a width ( 7a; 7b), where the width (7a; 7b) is parallel to the base plane (x, y) and the width of the first slat (7a) is different from the width of the second slat (7b). An insulation system (10) according to any one of the preceding claims, wherein one or more other insulating laminae (2; 2a) has a compressive strength below 30 kPa, preferably between 5-20 kPa as seen in a direction perpendicular to the base plane (x, y). An insulation system according to any one of the preceding claims, wherein the two or more first insulating lamellae (1) have a compressive strength above 30 kPa, preferably between 45-70 kPa as seen in a direction perpendicular to the base plane (x, y). An insulation system according to any one of the preceding claims, wherein two or more first insulation slats (1) have a substantially isotropic structure. An insulation system according to any one of the preceding claims, wherein the one or more first and second insulation slats (1, 2; 2a) are made of a fibrous material such as rock wool or glass wool. An insulation system according to any one of the preceding claims, wherein the alternating insulation structure forms a striped pattern. An insulation system according to any one of the preceding claims, wherein the alternating insulation structure forms a staggered pattern. An insulation system (10) according to any one of the preceding claims, wherein the insulation structure comprises one or more rows (6a, 6b) of first and second insulation slats (1, 2; 2a), wherein the rows (6a; 6b) are broken of one or more first or second slats (1,2; 2a) extending transversely to the rows (6a; 6b) of first and second insulation slats in a plane parallel to the base plane (x, y). An insulation system (10) according to claim 2 or 3, wherein there is a height difference between two adjacent first and second insulation slats (1, 2a), wherein the height of the second insulation slab (2a) is preferably lower than the height of the first insulation slab (1). ). An insulation system (10) according to claim 12, wherein the height difference between the adjacent first and second insulation slats (1,2a) is between 10-50 mm, preferably between 20-30 mm. Use of a system according to any one of claims 1- 13, for use in a roof structure.