FR3072698B1 - FLAT ROOF INSULATION AND SYSTEM FOR THE THERMAL INSULATION OF FLAT ROOFS - Google Patents

Abstract

With a thermally insulated flat roof (1) based on a wooden structure with a supporting body (2) and a covering (14) suspended from the supporting body, thermal insulation (6, 8), especially mineral wool , is arranged between the supporting body (2) and the covering (14), a moisture adaptive vapor retarder membrane (16) being arranged between the thermal insulation and the suspended covering and a waterproofing membrane ( 10) PVC-based being arranged on the support body.

Description

The invention relates to a flat roof thermally insulated and a system for thermal insulation of flat roofs, particularly inaccessible, in wooden structure. The invention relates to a special field of building insulation, namely the thermal insulation of flat roofs, particularly inaccessible flat roofs, which are configured in the form of a wooden structure. The term wooden structure is to be understood generally within the invention and comprises, in addition to purely wooden construction elements, also the building elements which are made from Oriented Strand Boards. Or OSB), wood chips, wood fibers and the like, such as particle board, wood fibreboard and the like. For this special area of flat roof construction, there are instructions and professional provisions, such as, for France, the Rules of Art Grenelle Environment (abbreviated as RAGE), 2014 edition, according to the French NF standard DTU 43.4, which should therefore be considered in association with the construction of flat roofs. Generally, a flat roof made of wood structure comprises a support body which is regularly formed by particle board, oriented large particle board or wood fiber board to form a flat support area or floor area . Regularly, these support plates are supported on supporting plates or vertically standing carrier panels, again based on wood, which are arranged in parallel and at a distance from each other. Finally, a coating is suspended below the support body by means of suspension devices which are mounted on the carrier plates. The cladding faces the space below and is typically equipped and covered with slabs, particularly plasterboards, gypsum drywall or plasterboard.

According to RAGE, flat roofs can be fitted above, ie on the support body, with thermal insulation or below the support body. In the latter case, the thermal insulation is then regularly arranged between the carrier plates which are arranged at a distance from each other and which support the support body. Depending on the construction of the thermal insulation, a thermal insulation layer may be provided in the space between the lower face edges of the carrier plates and the suspended coating. The thermal insulation can be configured in monolayer or bilayer or multilayer form. Mineral wool or other corresponding thermal insulation materials may be used particularly used in the latter case.

Such wooden structure-based flat roofs are often prone to defects, depending on the building construction, particularly when insulated from the outside, which may be caused by construction or processing. For example, bitumen is often used for such flat roofs, a layer of bitumen being arranged above the support body to protect the substructure against external influences by forming a corresponding sealing layer. The disadvantage of this, however, is that specific experts must be deployed for this and that such an effort is not appropriate for smaller areas for cost reasons. The flat roof construction with the arrangement of the thermal insulation on the support body inevitably increases the building height of the flat roof cladding, which in turn, however, has a negative impact on the construction of the entire building. In addition, the space between the carrier plates that support the support body is not used, resulting to a certain extent a lost space between the support body and the coating.

For this reason, the construction of flat roofs has become increasingly common, where the space between the support panels that form the support body and the coating to receive the thermal insulation is used. This construction is called unventilated flat roof construction and also uninsulated roof or unventilated roof. Here, the thermal insulation is protected on the lower side, that is to say on the side of the space, typically by means of a vapor barrier against humidity that diffuses through the coating from from the space below him. As there is an ambient hygrometry in each building used, this hygrometry, respectively humidity, must be extracted through an appropriate ventilation because otherwise, the hygrometry condenses which can lead to the formation of mold inside the building. the wooden structure. If, moreover, hygrometry accumulates in the thermal insulation, the insulation loses its function. Therefore, the hygrometric gradient and the resulting disadvantages with such flat roofs always pose a serious problem, which often only appears after many years as a construction defect.

Due to more recent developments, vapor barriers are therefore very often replaced by vapor retarders, i.e. moisture-adaptive membranes or sheets, with which the resistance to vapor diffusion of water changes depending on the ambient humidity, or humidity. Such sheets are, for example, known from EP 0 821 755 B1. In this case, polyamide-based sheets are used, as a vapor retarder, which have a moisture-responsive characteristic, so that the sheet, in the case of relative humidity of the atmosphere, which surrounds the sheet, in the range of 30% to 50%, has a value of the resistance to the diffusion of water vapor Sd of 2 to 5%. equivalent diffusion air layer thickness and, with a relative humidity in the range of 60% to 80%, a value of the water vapor diffusion resistance Sd which is <1 m thick equivalent air diffusion. Due to this adaptive hygrometry characteristic of the sheet, there is a higher resistance to the diffusion of water vapor in winter conditions, with a comparatively dry external atmosphere, than in summer conditions. This can promote drying in the summer but prevent the hygrometry present in winter conditions can reach a value that leads to deterioration of building materials and building.

Here, the Sd value of a sheet is defined by the water vapor diffusion resistance factor μ and the sheet thickness, namely as follows

Sd value [m] = resistance factor to water vapor diffusion μ x layer thickness [m]

The resistance factor is a specific property of material and, therefore, the resistance value Sd for a given material can be established via the layer thickness. According to DIN EN ISO 12572: 2001, the determination of the Sd value of the material can be carried out according to the water absorption / desorption method ("Dry Cup / Wet Cup"). In this case, suitable measuring devices are used, such as GINTRONIC GraviTest 6300. The DIN 52315 standard in the dry zone and the wetland, as well as in two wet areas between them, is relevant in order to determine the resistance to vapor diffusion. The resistance to water vapor diffusion, referred to as the Sd value, which is defined as the equivalent water vapor diffusion air layer thickness, is a measure of the resistance that is applied by a water vapor structure. roof of water vapor diffusion. The higher the Sd value, the higher the resistance, which is caused by the structure, is high. An Sd value of 8 m for example means that the vapor retarder of the water vapor diffusion applies an identical resistance to an air layer thickness of 8 m.

Such polyamide vapor retarders with a moisture-responsive characteristic are particularly suitable for thermally insulated buildings in the northern hemisphere, where there are more pronounced temperature differences between winter and summer, and therefore more important. humidity between winter and summer changes proportionally more strongly. Other corresponding vapor retarders with a moisture-responsive characteristic are known from DE 101 11 319 A1, although in this case the sheet is made of polyethylene or polypropylene, which contains acrylic acid as the than polar component.

Finally, vapor barriers with a moisture-adaptive characteristic are known (EP 2 554 758 A1), with which the moisture-adaptive vapor retarder is configured in a multilayer form by additionally adding an additional layer to the layer that is essential for the adaptive feature to moisture. This layer is mainly invariable to moisture and thus independent of ambient humidity. Corresponding vapor retarders with a moisture-responsive characteristic can be collected, for example in EP 2 759 403 B1, with a moisture-adaptive layer and a moisture-invariable layer. As a result, a directional sensitivity distinct from the diffusion of water vapor occurs. Depending on where the higher humidity is applied to the vapor retarder, the impact of permeability to water vapor diffusion on the drier side is higher. Such vapor retarders are particularly suitable for the thermal insulation of rooms with high humidity, for example the bathroom, the kitchen or canteens.

However, despite this state of the art of refined vapor retarders, there is still a need to provide an adequate solution in the special field of flat roofs based on wooden structure, also in terms of moisture, which allows a quick assembly and also inexpensive with simple building elements. In this respect, the prevailing climatic conditions in southern European countries, particularly in the Atlantic coast region, must be respected with this new development.

This is accomplished with the features mentioned in the invention for a flat roof as well as with the features mentioned for a system according to the invention. In addition, this is solved by a vapor retarder according to the invention. Appropriate further developments and embodiments of the invention are characterized by the features contained in the respective dependent claims. The invention refers to a thermally insulated flat roof, particularly configured as an inaccessible terrace, which is made on the basis of a wooden structure and comprises a support body which forms the floor of the roof. This body is made of wood or wood and is formed especially from support elements, plate-shaped, wood or wood-like material. A coating is suspended from the support body. A monolayer or multilayer thermal insulation, particularly mineral wool, is inserted into the space between the support body and the coating. According to the invention, in the case of such a flat roof, a sheet-shaped membrane with at least one hygrometric-adaptive layer is arranged between the thermal insulation and the coating and a sealing mat to PVC base is provided on the support body, which support body has a vapor diffusion resistance Sd <5 m, preferably <4 m.

Because of these arrangements, the flat roof according to the invention is particularly equipped for single-family homes in flat roof construction particularly with respect to climatic conditions as they predominate mainly in southern countries and regions of the world. Europe where there is very little freezing in winter and where temperatures in summer and winter are higher compared to northern countries. Typically, the wet conditions of the environment that prevail throughout the year are different, where, particularly in regions near the Atlantic, higher humidities in winter, in addition to high humidity in summer, must be expected. Due to the self-concerted construction according to the invention with a PVC-based waterproofing membrane on the support body, from the establishment of the support body to a vapor diffusion resistance Sd <5m, especially < 4 m, and a multilayer sheet with a layer with a moisture-responsive character, that is to say with a resistance to vapor diffusion Sd which changes depending on the ambient humidity, namely decreasing from the dry zone to the wetland, moisture penetration of the wooden structure of the flat roof, due to moisture entry, is prevented, on the one hand, and at the same time, a perfect drying during whole year is guaranteed. However, this is accomplished by a simple and easy-to-assemble construction of such a flat roof.

It is appropriate for the PVC sealing mat to be equipped with a Sd value of <35 m. In the context of the invention, it is appropriate to limit the PVC waterproofing membrane to a lower limit value> 15 m. It is appropriate that, in practical terms, the PVC membrane has a thickness in the range of 1.0 to 2.0 mm, particularly in the range of 1.2 to 1.5 mm. For the use and treatment of the PVC-based membrane, reference is made to compliance with standard NF EN 13956. In particular, the membrane is mounted mechanically on the support body or the wooden support panels. PVC membranes are preferably used, which are suggested in the French ATex instruction (Appréciation Technique d'expérimentation) for use on wooden support elements. ATEx is a rapid technical evaluation procedure, formulated by a group of experts, on any innovative product, process or equipment. This evaluation is often used either before a Technical Opinion, because it allows initial remarks on the implementation of the processes or for a single project. ATEx documents are created by CSTB and the construction industry in particular with technical controllers.

It is appropriate that a separating sheet for the separation of the PVC membrane against the wooden support body is provided between the PVC sealing mat and the support body, with respect to the wooden support body, in particular as mentioned in the ATEx. The sealing sheet is applied to protect the PVC sealing mat against damage due to movements of the support body. A preferred sealing sheet is a glass mat.

It is appropriate for the supporting body to use wood-based support panels, particularly particle board or fibreboard according to NF EN 312. In this respect, support panels are Particularly suitable, which are suitable for use in a humid environment, as well as panels that can be highly stressed for use in a humid environment. It is appropriate for wood particle board or fibreboard to be particularly used, the fibers of which are bound with a binding agent according to EN 634-2. In addition, particle board and wood fibreboard in the form of laminated panels, particularly so-called OSB panels according to NF EN 300, are particularly suitable. In the following table 1, a summary of proportionally appropriate wood or wood support panels is presented.

Board

As wooden elements for the wooden structure, especially those according to NF DTU 31.1 standard are appropriate.

For thermal insulation, preferably glass wool with a value λ for thermal conductivity is used in the context of the invention, the value preferably reaching from 0.030 to 0.035 W / (mK). The thermal insulation can be configured in monolayer, bilayer but also multilayer form. It is appropriate that the thermal insulation be arranged between the support body and the coating, in particular, the thermal insulation is arranged in the spaces between the wooden support plates which support the support body. In addition to this, a thermal insulation may be provided below the carrier plates, if necessary, particularly in the free space which is traversed by the suspension devices for the coating, that is to say in

the free space between the lower end faces of the support panels and the surface of the suspended cladding.

Preferably, the moisture-adaptive membrane is configured in multilayer form, particularly bilayer or trilayer, the upper layer which faces the thermal insulation, in case of a bilayer membrane, or the middle layer, in case of a trilayer membrane, preferably being formed by the moisture-responsive membrane layer. The vapor retarder, which is formed by the moisture-responsive membrane and preferably arranged between the thermal insulation below the support body and the ceiling, and which is formed by the moisture-responsive membrane, has Preferably, a vapor diffusion resistance Sd in the range of 10 m to 60 m, preferably 16 m to 48 m, which is advantageous for the steam blocking function and the airtightness. The thickness of the moisture-responsive membrane is in the range of 45 μm to 400 μm.

In a preferred embodiment, the multilayer vapor retarder membrane is configured with a moisture-adaptive core layer which is formed of polyamide (PA) / EVOH / polyamide (PA), preferably from a compound of which the sheet-like layer is produced via an extruder by means of a slot die. Such sheets are commercially available under the trade name Vario Xtra from Saint-Gobain Isover. A suitable thickness range of this moisture-adaptive layer is 20 to 40 μm, preferably 25 to 35 μm, preferably the layer has a thickness of 30 μm. As the appropriate polyamide, polyamide 6 is preferably used for the vapor retarder moisture-responsive middle layer, which essentially has an S-shaped curvature of vapor diffusion resistance Sd to moisture. For example, polyamide 4 or polyamide 3 sheets are suitable. In a suitable embodiment, the moisture-adaptive layer has a vapor diffusion resistance of up to 25 m in the dry zone, which decreases during an S-curve toward higher humidity. up to a value of <0.4, especially <0.3 m for vapor diffusion resistance. In another suitable embodiment, the reduction of the moisture-adaptive layer of the vapor retarding membrane (16) is in the form of an S-curve, with a change of direction in the range of a median moisture between 40 and 55%, the value Sd being in this median range between 15 m and 10 m.

Above the central layer of a multilayer membrane, and thus facing thermal insulation, it is suitable that a polypropylene (PP) layer be provided, which is preferably non-woven and preferably with a weight between 50 and 70 g / m.sup.2, in particular 60 g / m.sup.2, and serves essentially to reinforce the membrane present in sheet form or to influence additional desired properties of the vapor retarder sheet, depending on the specific application case .

For the lower layer of the moisture-adaptive membrane facing the coating, a vapor barrier sheet with substantially constant vapor diffusion resistance is used, which is preferably in the range of 14 m. 18 m, preferably at 15 m. This does not change its resistance to vapor diffusion and is thus invariable to moisture.

For this, particularly, a polypropylene sheet is suitable, such as, for example, that available under the trademark name Stopvap (Saint-Gobain Isover). It is appropriate for the thickness of this layer to be in the range of 20 μm to 30 μm and preferably 25 μm. Due to this vapor retardant membrane with this lamination, a crucial moisture entry into the flat roof wooden structure can be prevented during the entire season. At the same time, a corresponding drying of the wooden structure is allowed during the whole year, which effectively prevents the formation of mold and similar damage.

In the following, preferred embodiments of the invention are described purely schematically by means of the figures. In the figures: FIG. 1 represents an illustration of a flat roof inaccessible inside a wooden structure, illustrated in perspective view and in partial section; Figure 2 shows an approximate schematic illustration of a sectional view of such a flat roof according to Figure 1; Fig. 3 is a schematic diagram for a vapor retarder membrane used in accordance with the invention; and Fig. 4 is a diagram of the behavior of the moisture-adaptive vapor retarder membrane according to Fig. 2 during an annual cycle.

Figure 1 shows an inaccessible flat roof, which is generally indicated by 1, in cross section and in perspective view, which is configured as a wooden structure. In detail, this embodiment has a support body 2 of wood or wood-based, which - as is generally known - is formed of support elements in the form of panels, particularly particle boards or panels of panels. wood fibers. The support body 2 is carried on carrier plates or vertically arranged carrier panels 4 which are arranged in parallel with a distance with respect to each other. A thermal insulation 6 mineral wool, preferably glass wool, is arranged between the carrier plates. According to Figure 1, a thermal insulation 8 may be arranged below the carrier plates 4, also, which is formed of insulating panels, the insulation being suitably formed of glass wool, as well.

A PVC-based sealing mat 10, which is present in the form of a sheet-like membrane, is preferably arranged on the support body 2. On this, any suitable cover can be arranged, if necessary. . A separating layer 12 is preferably arranged between the PVC membrane 10 and the support body 2, with which a chemical separation between the PVC membrane and the support body, made of wood or a material similar to wood, arranged in below, can be performed. Below the support body 2 there is a coating which is generally indicated by 14, which may be formed of mainly ordinary building elements, particularly gypsum drywall, plasterboard and the like. The coating 14 is suspended by suspension devices, known in themselves, which are mechanically attached to the carrier plates 4. A moisture-responsive membrane sheet-shaped layer 16 is preferably arranged on this coating 14. To As thermal insulation 6, mineral wool, preferably glass wool, is used in the embodiment shown. The glass wool may be present in the form of insulating panels which are arranged between carrier plates 4 and which extend from one side to the other of the free space between these carrier plates without gaps. Within this embodiment, it is appropriate that an additional layer of insulation is provided below the carrier plates 4, which extends from one side to the other of the free space between the lower edge of the parallel aligned carrier plates 4 and the cover 14 which is suspended via the suspension devices 18, and particularly fills this free space.

The vapor retarder membrane 16 is preferably arranged below the thermal insulation 8. It is appropriate for the thermal insulation to be arranged in the area of the wooden structure so that deviations can largely be avoided. because otherwise cold bridges would be present. This is part of the professional aptitude. This however also applies to the PVC membrane 10 which is applied to the support body, as well as to the layer 16 vapor retarder which is arranged above the coating and below the thermal insulation, which are arranged so that essentially no gaps remain or gaps present are suitably sealed. This can be done with suitable adhesive agents, particularly adhesive tapes, and the like.

It is appropriate, in the context of the invention, that wooden or wood-based construction elements for the wooden structure are used, whose water content is less than 18% at the time of assembly.

Finally, FIG. 2 represents an approximately schematic illustration of the composition of the flat roof construction according to FIG. 1 and also shows schematically the three-layer configuration of the vapor retarder membrane 16. In a similar manner to FIG. there is a PVC membrane 10 above the support body 2 and above the gypsum board covering 14, which is suspended via the suspension devices 18, there is the retarder membrane of vapor 16, which is preferably present in the form of a three-layered sheet, namely an upper layer 16a, a middle layer 16b and a third lower layer 16c which faces the coating 14. If necessary, two or more layers can be used.

In the illustrated embodiment, a PVC membrane 10 is used, whose resistance to vapor diffusion is <35 m. The thickness of the membrane is preferably in the range of 1.2 mm to 1.5 mm.

The wooden structure, with the building elements shown in Fig. 1, namely, particularly wood fiber plates as support body 2 and vertically aligned support plates 4, is designed for resistance to diffusion of steam <5 m, especially <4 m.

Glass wool is preferably used as the mineral wool, whose lambda value for thermal conductivity is in the range of 0.030 to 0.035 W / (mK).

The vapor retarding membrane is configured in a three-layer form in the illustrated embodiment, with an upper layer 16a facing the thermal insulation 67, preferably a non-woven polypropylene mat with a basis weight of, preferably 60 g / m2, this layer fulfilling a mechanical function and being particularly provided in the form of a reinforcing layer. The middle layer 16b is adaptively configured to moisture in the present embodiment, and preferably configured from a PA / EVOH / PA compound, with a thickness of 30 μm, as a shaped layer. of leaf. A moisture-responsive sheet of the Vario Xtra trademark of Saint-Gobain Isover is particularly suitable for this. The lower layer 16c facing the coating 14 is a vapor barrier sheet with a substantially constant Sd value, in this case preferably made of polypropylene, with a thickness of preferably 25 μm. The sheet which is distributed under the name of STOPVAP (Saint-Gobain Isover) is particularly suitable for this.

These details are, of course, in no way limitative, both as regards the choice of material as well as the thickness ratios and the like.

FIG. 3 shows the vapor diffusion behavior of the humidity-adaptive middle layer 16b and the lower vapor barrier layer 16c with the name STOPVAP, the vapor diffusion resistance Sd is constantly at 15 m, regardless of the ambient humidity. So, it is a moisture invariable layer 16c.

This leads to the directed moisture current shown in Figure 2 with the A direction arrow and the B direction arrow, A referring to winter conditions and B referring to summer conditions.

Figure 4 is a schematic diagram of the vapor diffusion resistance during the entire season, which is due to the processes of the invention. It is obvious that during the winter months or colder, from November up to, and including, February, there are higher barrier values for water vapor diffusion, thanks to Sd values in the range from approximately 25 m to just under 48 m and, for the warmer months from March to and including October, lower vapor diffusion resistances in the range of approximately 15 to 30 for Sd values. This means that during the winter months, less moisture passes from the interior, through the coating, to the upper side, into the thermal insulation in the wooden structure, which is important for drying.

Claims (18)

claims 1. Thermally insulated flat roof made of wood structure with a flat support body (2) made of wood or wood, which is particularly formed of support elements in the form of wooden panels or wood-like materials a coating (14) which is suspended downwardly from the support body (2) and with thermal insulation (6, 8) which is arranged between the support body (2) and the covering (14), mineral wool material, characterized in that a sheet-like membrane (16) with at least one moisture-adaptive layer is arranged between the thermal insulation (6, 8) and the suspended coating (14), which a PVC-based sealing membrane (10) is arranged on the support body (2), and the supporting body (2) preferably has a vapor diffusion resistance <5 m, preferably <4 m. 2. Flat roof according to claim 1, characterized in that the PVC sealing membrane (10) has a vapor diffusion resistance value Sd of <35 m. Flat roof according to claim 2, characterized in that the value Sd of the PVC err membrane is> 15 m. Flat roof according to one of the preceding claims, characterized in that the thickness of the PVC membrane (10) is in the range of 1.0 to 2.0 mm, particularly in the range of 1.2. at 1.5 mm. 5. Flat roof according to one of the preceding claims, characterized in that a separating sheet (12) is arranged between the PVC membrane (10) and the support body (2), preferably a glass veil. Flat roof according to one of the preceding claims, characterized in that the support panels of the supporting body (2) are formed by particle boards or fibreboards made of wood with a value Sd <5 m, preferably <4 m. Flat roof according to one of the preceding claims, characterized in that the moisture-adaptive membrane (16) with at least one moisture-adaptive layer is configured as a multilayer, preferably a three-layer, layer between the body. support (2) and the coating (14). Flat roof according to claim 7, characterized in that the moisture-adaptive layer forms a central layer (16b) of the membrane (16). 9. Flat roof according to claim 7 or 8, characterized in that the moisture-sensitive layer (16b) of the membrane (16) contains polyamide, EVOH and polyamide, and is particularly formed in three-layer form. with these materials, the EVOH layer preferably being in the middle, or the layer (16b) being formed of a compound of these materials. Flat roof according to claims 7 to 9, characterized in that the thickness of the moisture-adaptive layer (16b) of the membrane (16) is in the range of 20 to 40 μm, preferably 25 to 40 μm. 35 μm, particularly 30 μm. 11. Flat roof according to one of claims 7 to 10, characterized in that the moisture-adaptive layer (16b) has, depending on the ambient humidity, a value Sd in the range of 25 m to <0 , 3 m, the Sd value decreasing as the humidity increases. Flat roof according to claim 11, characterized in that the reduction of the moisture-adaptive layer (16b) of the membrane (16) is in the form of an S-shaped curve, with a change of direction in the range of a median humidity between 40 and 55%, the value Sd being in this median range between 15 m and 10 m. 13. Flat roof according to one of claims 7 to 12, characterized in that the moisture-adaptive layer (16b) is provided with a protective layer, preferably polypropylene (PP) nonwoven, on its surface which faces the thermal insulation (6, 8). 14. Flat roof according to claim 13, characterized in that the protective layer has a surface weight in the range of 50 to 70 g / m2, in particular that the weight per unit area is 60 g / m2. Flat roof according to one of claims 7 to 14, characterized in that the moisture-adaptive vapor retarder membrane is provided with a layer (16c) on its side which faces the coating, the layer having a constant Sd value in the range of 15 to 18 m and preferably being formed of polypropylene. 16. Flat roof according to one of claims 7 to 14, characterized in that the moisture-adaptive membrane (16b) has a vapor diffusion resistance Sd in the range of 10 to 60 m, preferably 16 to 48 m. 17. Flat roof according to one of claims 7 to 15, characterized in that the thickness of the moisture-responsive membrane (16b) is in the range of 45 pm to 400 pm. Flat roof according to one of the preceding claims, characterized in that the thermal insulation (6, 8) is formed from glass wool, the thermal conductivity preferably having a value of 0.030 to 0.035 W / (mK), the thermal insulation (6, 8) being preferably configured between the support body (2) and the coating (14) with one or two layers.