EP2113617B1 - Underlay to make the roof sub-structure rainproof - Google Patents

Description

The invention relates to a backing sheet for producing the rainproofness of a roof structure, comprising a built up of any number of layers of material, permeable membrane layer, and at least one partially attached to the membrane layer, preferably made of a bitumenhältigen material, impermeable barrier layer, according to the preamble of Claim 1 and to a reverse roof structure according to claim 14.

Such underlays are well known and serve to protect a roof construction of a building against rain and moisture drench. In this case, the underlays on a respective existing sub-roof structure, e.g. a wooden formwork mounted before peripheral roofing elements such as a counter battens and roof tiles or other cover elements are attached to the roof construction.

In any case, generic underlays do not come as the outermost layer of a roof construction for use, but are covered in ready assembled state each by any number of roofing elements such as fiber cement boards, metal sheets, clay, concrete, sheet metal or plastic shingles, which the peripheral completion of each Constituting the roof and exposed to weather conditions. As roofing elements and stones or gravel beds can be used, these directly to the underlay web according to the invention be heaped up and ensure a secure fixation of the underlay on Unterdachaufbau according to their weight.

Moisture or rainwater which overcomes the overlapping roofing elements or creeps through the roofing elements in the overlapping area is prevented from advancing to the subfloor structure by the underlying underlays and is directed to defined collection points, e.g. derived in the form of roof drains.

Generic underlays also serve as rainproof cover for non-ventilated roof structures of buildings, which are still in the shell state or are not yet covered with roofing elements.

In particular, the construction of non-ventilated thermally insulated loft conversions taking advantage of the entire existing rafter cross-section by filling with heat-insulating material (full rafter insulation, blow-in insulation, etc.) requires the use of sheet-like roofing materials, on the one hand safely derived rainwater, on the other hand, however, from the building interior to the outside urgent or . upwards in the direction of the under-roof structure ascending air moisture can carry away. A removal of humidity or water vapor is sought for environmental reasons and space, in particular, a prevention of mold formation is due to excessive humidity and the maintenance of scheduled insulation properties.

For this reason, in such constructions Underlays produced diffusion-open. Such diffusion-open underlays have a membrane layer, which is composed of several mostly textile material layers including any binder layers, see for example the DE 198 19 085 A1 or the WO 00/37751 A1 , The EP 1 632 345 A2 again shows a backing sheet according to the preamble of claim 1 from water vapor permeable plastic material, wherein a layer is provided with macroscopic holes. There are also underlay webs whose membrane layer is provided in regions with an impermeable barrier layer preferably consisting of a bitumen-containing material, which is thus only partially open to diffusion. Usually, the membrane layer is composed of two to four textile material layers. The usually transported in the rolled-up state underlay web is first loosely placed or rolled out on the under-roof structure and then anchored windproof by means of mechanical attachment such as nailing. Usually, so many underlays lined up overlapping each other until the entire surface of the under-roof structure is covered.
To increase the rainfall, the overlapping areas of the backing sheets are either subsequently glued tight with adhesive tape, or there are already applied at the sides of the backing sheets seam tapes, so that only the transverse to the longitudinal sides of the head joints or the cut end portions of the backing sheets glued with an adhesive tape Need to become.
Sufficient wind suction security is often only with the application of a counter battens laid on the substructure on the sub-roof structure, wherein in sub-roof sheets according to the prior art according to the thinner version in each case an additional, arranged under the counter battens nail sealing tape is required.
By the direct resting of the underlay on the Substructure may be due to the high impact pressure of the rain water for penetration of water droplets in the membrane layer and come through it in strong rainwater intrusion (so-called "Meteorwasseranfall" or "driving rain"). A case of sucking in the rainwater is also referred to as "tarpaulin effect".
A further problem area is that the water absorption capacity of the membrane layer upon contact with wood preservatives, such as those present in such as wood cladding executed under-roof structures, due to the surfactants present in the wood preservatives is increased undesirably.

The usually small layer thickness known underlays causes a low mechanical resistance to architectural practices such as handling slats, roof tiles and various tools, so that a particularly gentle handling of already laid underlays is required. A required gentle handling of the underlays is, however, unrealistic in the construction practice, so that in the course of construction occurring injuries or cracks in the underlays can cause a difficult to locate at the time of a finished roofing moisture ingress into the building.

In contrast to described diffusion-open sub-roof sheets made of textile fabric, sub-roof sheets also find application, which are made of bitumen or polymer bitumen. Depending on their layer thickness, such bitumen sub-roof sheets have a significantly higher mechanical resistance and thus greater resistance to injury. In addition, decades of durability or moisture resistance of bituminous sub-roof sheets attached to the substructure is in practice demonstrated. In particular, self-adhesive bituminous membranes or polymer bituminous membranes with sufficient layer thickness increase the rain protection of the under-roof structure, since a penetrating the sub-roof fastening nail or a fastening screw of the bitumen material is elastically or plastically enclosed and thus enters a self-healing effect against tears in the nail area.

The chemistry of bitumen materials, however, requires a pronounced vapor pressure resistance in full-surface bituminous layers, so that already bitumen membranes of 1 mm layer thickness must be referred to as vapor-damping and no longer open to diffusion. Thus, the technical requirement for vapor-permeable designs of generic sub-roof sheets with a sd value ("water vapor diffusion equivalent air layer thickness") of <= 0.3 m from conventional bitumen membranes can not be met.

In roof structures with particularly high stress, e.g. According to special altitude (> 1000 m above sea level), special weather conditions, increased precipitation amounts (alpine areas) or flat-inclined roof coverings, particular attention is paid to the function of the under-roof structure with sub-roofs. The above circumstances increase the probability that rainwater or melt water (due to ice accumulation) penetrates through the roof cover elements which are usually laid overlapping and therefore has to be diverted to a greater extent from the substructure or from the sub-roof tracks resting thereon.

The relevant standards and guidelines therefore stipulate in the case of "increased requirement for rain protection" that vapor-permeable roofing membrane materials intercommunicate material homogeneous and waterproof must be connected. For this field of application, in the practice of open diffusion plastic sheets of flexible polyolefins (FPO) are known, which are loosely placed on the under-roof structure, wherein the seam and joint areas are thermally welded with hot air. However, this requires the use of special processing equipment the presence of a corresponding power source and thus an increased installation costs.

According to the applicant's internal state of the art, underlay webs are also known, which are constructed from an upper and a lower textile membrane layer, between which bitumen fillings arranged in strip form are arranged. The sandwiched between the membrane layers bituminous fillings to increase the mechanical strength of the backing sheet, but do not fulfill a sealing or adhesive function. It is also known to perform narrow marginal areas such underlays partially self-adhesive. A disadvantage of such underlay webs according to the prior art is that their predominant area fraction is still exclusively formed by the (diffusion-open) membrane layers, which furthermore requires a relatively high sensitivity of the underlay webs to damage or tears as well as the risk of increased moisture sanding.

A special field of application of diffusion-open membrane layers are reverse roof constructions in the flat roof area. In the case of inverted roof structures, a heat-insulating layer made of a moisture-insensitive material, such as extruded polystyrene, is arranged in a known manner on a flat-roof structure provided with, for example, a bitumen-containing sealing strip. This mostly consists of several thermal insulation elements or panels, outside the Flat roof construction arranged thermal insulation layer is secured by a gravel bed against wind suction. In such Umkehrdachaufbauten is accepted that from outside accumulating driving rain or meteoric water passes over butt joints of the thermal insulation elements under the thermal barrier coating to be derived there to drainage facilities.

The disadvantage here is that the passing under the thermal barrier coating and draining water already passes through a heat-protected area of the roof structure and causes such a loss of heat of the respective building. According to this heat loss, the layer thickness of the thermal insulation layer designed for winter operation must be larger.

Another disadvantage of conventional inverted roof structures is that the thermal barrier coating must be weighted with a relatively large (gravel) load in order to prevent buoyancy of individual thermal insulation elements in the event of a strong water rush. In practice, it turns out that the thermal insulation elements in heavy rainfall raise and lower again due to the water reaching under the thermal insulation elements, the thermal insulation elements sometimes being moved away from their laying position and no longer fittingly sink back into this. The usually end-to-end, e.g. By means of a stepped rebate toothed thermal insulation elements drift apart, so that arise between originally adjacent thermal insulation elements thermally undesirable joint gaps.

Although in this case solutions are known in which by means of a laid above the thermal barrier coating, water-barrier fleece a superficial discharge of rainwater to drainage facilities or shafts is effected, but these fleeces are only loose and without Connection to each other laid over the thermal barrier coating. In case of heavy rainwater rush, it must therefore still be expected that considerable quantities of water will pass below the fleece and thus cause a buoyancy of the thermal insulation elements or an undesirable formation of joint gaps between adjacent thermal insulation elements.

The present invention is therefore based on the object to avoid the disadvantages mentioned and to provide a backing sheet, which has an increased resistance to moisture penetration and damage or tears, but with sufficient diffusion openness or permeability of the backing sheet for the purpose of removal from within the rooms of a building existing humidity is to be maintained.

By the present invention, it is desirable to allow a simple and windsogsicherere fixation of the backing sheet on the under-roof structure. A use of fasteners and tools for mounting the backing sheet on the substructure should be made unnecessary.

It is a further object of the present invention to propose an advantageous way of reinforcing inverted roof structures. In particular, in this case a buoyancy of the thermal barrier coating and a thermally undesirable formation of joint gaps between adjacent thermal insulation elements of the thermal barrier coating should be prevented.

According to the invention these objects are achieved by a backing sheet with the characterizing features of claim 1. A generic underlay for the production of rainproofness of a roof structure, comprises one of a built any number of layers of material, permeable membrane layer and at least one partially attached to the membrane layer, consisting of a bitumen-containing material, impermeable barrier layer. According to the invention, it is provided that the at least one barrier layer is attached to a lower side of the membrane layer facing the lower roof structure in mounting position and has a contact side provided for resting on the lower roof structure, wherein recesses are provided per m ^{2 of} the underlayment web 50-100 of the barrier layer, which have a diameter between one and five centimeters and within which a vapor diffusion through the backing sheet is possible, (viewed in the mounting position of the backing sheet) located above the recesses Dampfdiffusionsareale the membrane layer of the contact side of the barrier layer, ie from a mounting position of the backing sheet the substructure or whose surface corresponding level are distanced by a distance measure.

In other words, a barrier layer penetrated by recesses is applied to the underside of the membrane layer, whose layer thickness is so great that sagging of the recesses covering the vapor diffusion areas of the membrane layer in the mounting position of the backing sheet, which contacting the surface of the under-roof structure by the membrane layer and thus in If a moisture run would have caused unwanted capillary action or an adhesive force-induced full suction of the membrane layer with liquid would result is prevented.

In contrast to hitherto known diffusion-open underlay webs, which also use bitumen materials, the membrane layer of an underlay structure according to the invention located in the assembly position is thus decoupled from the under-roof structure or spaced therefrom and it is Thus, in the area of the recesses not covered by the barrier layer, the membrane layer can be bathed with air from above as well as from below, and therefore dried quickly and naturally if necessary. The distancing of the membrane layer to the contact side of the barrier layer or to the sub-roof structure further prevents contact of the membrane layer with any wood preservatives or impregnations contained in the substructure, which could lead to an undesirable tendency of the membrane layer to moisture.

The vapor diffusion areas of the membrane layer are formed so that, although a vapor diffusion through the backing sheet is possible, while a fluid passage through the backing sheet is prevented.

In a preferred embodiment of the invention, it is provided that said distance dimension, by which the membrane layer is spaced in the mounting position from the surface of the sub-roof structure, corresponds to the layer thickness of the barrier layer.

This means that the vapor diffusion areas of the membrane layer are so stretched or held according to a corresponding arrangement of the surrounding barrier layer that they do not sag in the mounting position of the backing sheet in the direction of the contact side of the barrier layer or in the direction of the under-roof structure. In this case, the undersides of the membrane layer vapor diffusion areas thus run substantially in a common plane with an upper side of the barrier layer opposite the contact side.

The layer thickness of the barrier layer is preferably greater than 0.8 mm.

According to the present invention, the functions of a vapor-permeable sub-roof sheet are combined with the properties of a robust bitumen sub-roof sheet, by providing in a particularly preferred embodiment of the backing sheet, that the barrier layer covers more than 50% of the surface of the membrane layer bottom.

The barrier layer attached to the underside of the membrane layer therefore covers the predominant surface area of the membrane layer and prevents moisture penetration in these impermeable areas.

In this way, the requirement for an on the one hand diffusion-open, on the other hand robust and suitable for construction sites underlay can be ideally met. Since the predominant surface portion of the backing sheet is provided with a relatively resistant barrier layer, compared to known products significantly increased surface stability is achieved. In particular, an improved accessibility of the underlay webs in their assembled state is made possible.

It is understood that the more the surface of the membrane layer is provided with the barrier layer, the greater the mechanical resistance of the underlayment is. In a particularly preferred embodiment of the invention, it is therefore provided that more than 90% of the surface of the membrane layer is covered with the barrier layer.

According to a further preferred embodiment of the invention, it is provided that the barrier layer or the contact side of the barrier layer is made self-adhesive and is provided with a release liner for transport and storage purposes. In this way the further task of the present invention, a simple and windogsichere fix the underlay on the under-roof structure to allow met, and a use of fasteners and tools for mounting the backing sheet on the sub-roof structure can be omitted. According to the self-adhesive design of the barrier layer, a waterproof bonding of the underlays with each other in their overlapping areas as well as attachment to arrival and completion elements of the under-roof structure such as roof windows, ventilation elements or Kaminverblechungen is possible without the use of additional adhesive would be required.

The recesses already mentioned, ie those regions of the membrane layer in which no barrier layer material is applied, are distributed in a preferred embodiment of the invention in the form of a matrix-like pattern over the surface of the membrane layer. By a suitable distribution of the recesses (and thus the provision of Providence of the recesses vapor diffusion areas of the membrane layer) over the surface of the membrane layer can be guaranteed in any area of the backing sheet reliable removal of any existing, excess space humidity in the building periphery. In the present context, matrix-like patterns are understood as meaning regular or repetitive as well as irregular or non-repeating arrangement patterns.

According to a particularly preferred embodiment of the invention, the recesses are arranged in the form of mutually offset rows. Such a series arrangement can be clearly defined and allows an easy-to-implement manufacturing process.

According to a further preferred embodiment of the invention, the recesses are arranged equidistant from each other. In particular, such an equidistant arrangement of the recesses, a distribution of the recesses over the surface of the membrane layer is achieved, in which a reliable removal of room-humidity in the roof or building periphery is ensured in each area of the backing sheet.

By according to a further preferred embodiment, the recesses of the barrier layer are bounded on all sides, a particularly effective support or voltage of the vapor diffusion areas of the membrane layer can be achieved so that the vapor diffusion areas do not sag in mounting position of the backing sheet or not touch the substructure. Ideally, support for the membrane layer vapor diffusion areas is achieved by a circular configuration of the recesses.

In a development of the present invention, it is provided that the underlay web has one or more defined regions in which the membrane layer has no recesses or which are completely covered with the barrier layer. Such defined with the barrier layer defined areas, which is provided in a preferred embodiment, at least along one longitudinal side of the backing sheet, preferably along both opposite longitudinal sides of the backing sheet allow a reliable sealing connection of adjacent or overlapping underlays. Through such defined areas and fastening elements such as nails or screws can be driven without a leak in the backing sheet must be feared. A driven in the defined areas through the sub-roof fastener is of the

made of a bitumen material barrier layer elastically or plastically enclosed and prevents such a penetration of moisture in the critical mounting area.

In a further developed embodiment variant of the invention, it is provided that at least one additional barrier layer of preferably bitumen-containing material is arranged on the upper side of the membrane layer, wherein the vapor diffusion areas of the membrane layer are recessed in relation to an application of the additional barrier layer. By providing such an additional barrier layer at the top of the membrane layer, an even better impermeability to rain of the underlay sheet according to the invention can be achieved.

Claim 14 is directed to a reverse roof construction, in which a underlay according to the invention is used according to one of the preceding claims. In generic inverted roof superstructures above a provided with a waterproofing flat roof construction a thermal barrier layer is arranged on which a gravel is applied to secure the thermal barrier to wind and atmospheric influences such as UV radiation, temperature fluctuations or hailstorm according to the effect of a cover layer. In order to seal such reverse roof structures in an advantageous manner, it is inventively provided that the backing sheet is disposed on a top of the thermal barrier coating facing gravel pile. In this way, a large part of sudden rainfall or meteoric water can be derived from the top of the thermal barrier coating to defined drainage facilities. Underspray the thermal barrier coating can be prevented or significantly reduced.

In particular, when the underlay used for sealing of inverted roof structures is made self-adhesive, a significantly increased surface stability of the thermal barrier coating can be achieved. In a preferred variant of the application, it is therefore provided that the thermal barrier coating consists of a plurality of juxtaposed thermal insulation elements, wherein mutually adjacent thermal insulation elements are connected to one another by means of a self-adhesive backing sheet applied to their upper sides.

Should individual thermal insulation elements be distended in the event of a particularly high water contortion, they can not slide over one another as a result of their surface-side bonding and retain their original laying position relative to adjacent thermal insulation elements. Such a fixation of the thermal insulation elements also makes it possible to reduce the gravel bed quantitatively or to secure the thermal barrier coating and the backing sheet with a lower load. A reduction in the gravel fill or the ballast has an advantageous effect in static terms and also allows lower construction heights of the roof structure and various connection elements.

Another advantage of a possible by the self-adhesive backing sheet fixation of the thermal insulation elements in their respective laying position is to state that no significant thermally disadvantageous joint gaps can arise between the thermal insulation elements.

Since a trickle of water can now largely be prevented in a region of the roof structure located below the thermal barrier coating, and thus an undesirable loss of heat due to the provision of a underlay web according to the invention It is also possible to perform the thermal barrier coating with a smaller layer thickness and thus more cost-effective.

Fig.1

eine schematische Querschnittsdarstellung durch eine erfindungsgemäße diffusionsoffene Unterlagsbahn

Fig.2

eine diffusionsoffene Unterlagsbahn gemäß Fig. 1 in Montageposition an einem Unterdachaufbau

Fig.3

eine erfindungsgemäße diffusionsoffene Unterlagsbahn mit teilweise abgezogener Abziehfolie in perspektivischer Ansicht

Fig.4

eine an einem Umkehrdachaufbau angebrachte erfindungsgemäße diffusionsoffene Unterlagsbahn

The invention will now be explained in more detail with reference to an embodiment. Showing:

Fig.1

a schematic cross-sectional view through a diffusion-open underlay web according to the invention

Fig.2

a diffusion-open underlay according to Fig. 1 in mounting position on a substructure

Figure 3

an inventive diffusion-open backing sheet with partially peeled release liner in a perspective view

Figure 4

a diffusion-open underlay web according to the invention attached to an inverted roof structure

In Fig.1 is an inventive diffusion-open backing sheet 1 in cross-sectional view can be seen. Such underlay sheets 1 are provided for attachment to a sub-roof structure 2 (see Fig.2 ), wherein the sub-roof structure 2 is a stickable substrate, for example a timber formwork or a concrete surface or another diffusible substrate. According to Fig.2 a sub-roof structure 2 of a substantially horizontal flat roof or pent roof is visible. Likewise, underlay webs 1 according to the invention, however, can also be used on under-roof structures 2 of pitched roofs such as pitched roofs, barrel roofs, domes or other structures.

In any case, the underlays 1 between the respective sub-roof structure 2 and overlying peripheral roofing elements 11 are arranged. As roofing elements 11 may be any cover elements such such as fiber cement boards, metal sheets, clay, concrete, sheet metal or plastic bricks are used.

In particular, in the case of use of gravel packs as roofing element 11 can be dispensed with an attachment of the backing sheet 1 by means of adhesive or scarfing techniques and the backing sheet 1 loosely placed on the substructure 2. In principle, however, a loose attachment of the backing sheet 1 on the substructure 2 is possible even when using other roofing elements 11.

The underlay sheet 1 according to the invention has a membrane layer 3 which is constructed from any desired number of material layers, including any binder layers.

The material layers from which the membrane layer is constituted are a plurality of superimposed organic or inorganic textiles or tissue layers, each of which is diffusion-open insofar as it is, for example, a diffusion layer. is derived due to rain liquid flow at the membrane layer, while a passage of water vapor or humidity is still possible.

The objective diffusion-openness of the membrane layer 3 can have specific characteristics depending on the choice of material or the field of use, wherein a wide variety of types or degrees of permeability can be provided. Thus, the membrane layer 3 can be semipermeable or selectively permeable, possibly also partially omnipermeable. Preferably, the membrane layer 3 is designed such that a transport of moisture or moisture from a base 8 facing the lower roof structure 2 in the mounting position in the direction of the upper side 7 facing away from the lower roof structure 2 the diaphragm layer 3 (that is to say from a space located below the under-roof structure 2 in the direction of the building periphery) is permitted, while liquid transport in the opposite direction (ie located from the building periphery in the direction of the under-roof structure 2) is prevented or at least slowed down.

The material layers of the membrane layer 3 can be connected to one another with any number of binder layers. Instead of textile fabric, it is also conceivable to constitute one or more of the material layers of a film-shaped material, possibly also of a thin plastic layer, provided that it is designed to be open to diffusion in the sense described.

It should be noted that individual material layers of the membrane layer 3 can also be a bitumen-containing layer. However, the layer thickness of this bitumen-containing material layer must be made so thin that even a sufficient permeability of the membrane layer 3 is ensured and should therefore be only a few tenths of a millimeter.

The membrane layer 3 is in its mounting position (see Fig.2 ) the underside structure 2 facing bottom 8 partially with at least one, in the present embodiment of bitumenhältigem existing impermeable, thus preventing diffusion of moisture barrier layer 4. Due to the area-wise application of the barrier layer 4 on the membrane layer underside 8 is not covered by the barrier layer 4 recesses 5 or lying over these recesses 5 vapor diffusion areas 3a of the membrane layer 3, in which further moisture diffusion through the membrane layer 3 or through the backing sheet 1 is made possible in the direction of the roof periphery.

The barrier layer 4 has a contact side 13 provided for resting on the under-roof structure 2, wherein-viewed in the mounting position of the underlayment web 1-the vapor diffusion areas 3a of the membrane layer 3 located above the recesses 5, thus covering the recesses 5, from the contact side 13 of the barrier layer 4, Thus, from a in mounting position of the backing sheet 1 the sub-roof structure 2 and the surface corresponding level are distanced by a distance measure x.

In a preferred embodiment of the invention, it is provided that the distance dimension x corresponds to the layer thickness of the barrier layer 4, which requires that the vapor diffusion areas. 3a of the membrane layer 3 are held or stretched in such a way that they do not sag in the mounting position of the backing sheet 1 in the direction of the contact side 13 of the barrier layer 4 or in the direction of the under-roof structure 2. The undersides 8 of the membrane layer vapor diffusion areas 3a thus extend substantially in a common plane with an upper side 14 of the barrier layer 4 opposite the contact side 13 (ie, in accordance with FIG Fig.2 in a horizontal plane).

An inventive spacing of the membrane layer 3, the vapor diffusion areas 3a membrane layer 3 to the substructure 2 causes the advantageous effect that the membrane layer 3 in the area of the vapor diffusion areas 3a and the not covered with the barrier layer 4 recesses 5 both from above and from below with air and dried. A capillary action caused by the accumulation of moisture in the membrane layer 3 or the scenario a liquid-soaked membrane layer 3 is therefore largely prevented or a moisture accumulation in the region of the membrane layer 3 lasts only briefly in a backing sheet 1 according to the invention.

The number and the size of the recesses 5 formed by the barrier layer 4 can be chosen as desired according to the respective requirements respectively according to the respectively desired degree of diffusion of the underlay web 1. There are about 50-100 recesses 5 are provided per m ^{2 of} the backing sheet 1, wherein the recesses 5 are each circular in shape and have a diameter between one and five centimeters, preferably a diameter of two centimeters.

In a particularly preferred embodiment variant of the underlay web 1 according to the invention, it is further provided that the barrier layer covers more than 50% of the area of the membrane layer underside 8, preferably more than 90% of the area of the membrane layer bottom 8 (the latter embodiment variant is in FIG Figure 3 shown).

The layer thickness of the barrier layer 4 of bitumenhältigem material is more than 0.8 mm, to ensure Impermeabilität or moisture impermeability of the barrier layer 4.

Moisture or rainwater, which overcomes the contacting roofing elements 2 or trickles past at butt joints of the roofing elements 2, can be reliably prevented by the underlay 1 according to the invention from advancing to the substructure 2, according to which the recesses 5 or by these bounded Vapor diffusion areas 3a of the membrane layer 3 nevertheless a sufficient diffusion openness of the backing sheet 1 is ensured.

According to Fig.1 the barrier layer 4 is designed as a self-adhesive bituminous compound, which is laminated with a release liner 9. After a in Figure 3 shown peeling off the release liner 9, the backing sheet 1 according to the invention can be attached directly to the under-roof structure 2 without the aid of further fastening means or tools on the self-adhesive contact side 13 of the barrier layer 4 ( Fig.2 ).

The underlay sheet 1 according to the invention has a preferably rectangular ground plan shape and can be rolled up into a roll and transported in this form. A widthwise extension 12 of the underlay 1 may be e.g. 1 m. To produce the rainproofness of a roof structure 2, so many underlay webs 1 are strung together in an overlapping manner until the entire surface of the underbody structure 2 is covered.

As purely exemplary in Figure 3 1, the recesses 5 (and thus the vapor diffusion areas 3 a of the membrane layer 3) are arranged distributed in the form of a matrix-like pattern over the surface of the membrane layer 3. The geometric configuration of the recesses 5 and the barrier layer 4 can be made in any desired manner. The recesses 5 can be made approximately in circular or polygonal shape. Preferably, the recesses 5 of the barrier layer 4 on all sides bounded shapes (see Figure 3 ).

For the arrangement of the recesses 5 within the barrier layer 4 preferably matrix arrangements are used, through which an approximately uniform distribution of Recesses 5 is ensured over the entire surface of the membrane layer 3 and the backing sheet 1, so that in each district of the backing sheet 1 is given a sufficient permeability to humidity.

In other words, the statistical distribution of the recesses 5 over the total area of the membrane layer 3 or the underlay web 1 is selected such that substantially uniform scattering of the recesses 5 -in particular in the middle region of the underlay web 1-results. The total sum of the area formed by the recesses 5 (<50%, preferably <10% of the area covered by the barrier layer 4) is thus divided into a multiplicity of recesses 5 preferably bounded peripherally by the barrier layer 4, which thus extend over the total area of the membrane layer 3 are distributed, that in all relevant areas of the backing sheet 1, a removal of steam or humidity in the direction of the top 7 of the membrane layer 3 is possible.

An ideal distribution of the recesses 5 over the total area of the membrane layer 3 can be achieved, in particular, if the majority of the recesses 5 are arranged substantially equidistant from each other.

Like also in Figure 3 can be seen, the recesses 5 are preferably arranged in the form of staggered rows.

Since the backing sheet 1, as already mentioned, also loosely placed on the sub-roof structure 2 and then by means of mechanical fastening such as nailing or screwing can be anchored to the sub-roof structure 2, it is provided in a preferred embodiment of the invention that the backing sheet 1 and the Membrane layer 3 one or has a plurality of defined regions 6, in which no recesses 5 are provided or which are completely covered with the barrier layer 4 (see Figure 3 ).

Such defined areas 6 covered with the barrier layer 4 are provided at least along one longitudinal side 10a of the underlay web 1, preferably along both opposite longitudinal sides 10a, 10b of the underlay web 1. Likewise, a circumferential arrangement of defined regions 6 around the entire peripheral region of the underlay web 1 is possible.

In this way, a reliable sealing connection of adjacent or overlapping underlay webs 1 is made possible. Fasteners such as nails or screws can be driven through the defined areas 6 in the sub-roof structure 2, without a leak in the backing sheet 1 must be feared. A driven in the defined areas 6 through the lower roof sheet 1 fastener is immediately enclosed flush by the elastic or plastic barrier layer 4, whereby penetration of moisture in the region of the fasteners is prevented.

In a further developed embodiment variant of the invention, an additional impermeable barrier layer of preferably bitumen-containing material may be arranged on the upper side 7 of the membrane layer 3 (not shown). In this case, only the vapor diffusion areas 3a of the membrane layer 3 are recessed with respect to an application of this additional barrier layer.

Figure 4 shows a specific application example of the application of the backing sheet 1 according to the invention in connection with an inverted roof structure 20. Such an inverted roof structure 20 comprises a flat roof structure 20, which is constituted for example of a reinforced concrete slab or concrete planks. The flat roof structure 20 has a low, not shown inclination. To ensure the rain-tightness of the flat roof structure 20, this is provided with a primer 18, a leveling layer 19 and a sealing strip 15. The sealing strip 15 is usually a water-impermeable bitumen or plastic sheet. A thermal barrier coating 16 which is composed of any number of plate-shaped thermal insulation elements 16 ', 16 "is arranged on this sealing membrane 15. The thermal insulation elements 16', 16" each have an impact region 16b on the end in which they are loosely interlocked by means of a stepped rebate are. According to the invention, a underlay web 1, which has already been described above, is arranged on an upper side 16a of the thermal barrier coating 16 facing away from the flat roof structure 20. Above the backing sheet 1, a gravel packing 11 is arranged, wherein instead of a gravel packing 11 and a provision of other cover elements such as concrete slabs or other vapor-permeable coverings would be conceivable.

To this providence of a conventional trickle nonwoven, which according to the prior art between the Thermal insulation layer 16 and the gravel bed 11 is arranged, can now be dispensed with.

Since the underlay web 1 attached to the upper side 16a of the thermal barrier coating 16 is preferably self-adhesive, the thermal insulation elements 16 ', 16 "are fixed relative to one another in their laying position, whereby a significantly increased surface stability of the thermal barrier coating 16 can be achieved than with previously practiced loose laying methods.

On the backing sheet 1 passing rainwater is along the top 3 of the membrane layer 3 of the backing sheet 1 to in Figure 4 Dewatering devices not shown in the form of gutters or shafts derived. Underspray the thermal barrier coating 16 can be largely prevented.

Should individual thermal insulation elements 16 ', 16 "of the thermal barrier coating 16 in the case of a particularly large Wasserandranges still be distended, then the thermal insulation elements 16', 16" according to their surface-side bonding do not push over each other and retain their original installation position. Between two adjacent heat-insulating elements 16 ', 16 "thus no joint gap 21 of thermally relevant size can occur.

Claims (15)

1. An underlay (1) for making the roof sub-structure (2) rainproof, comprising a diffusion-open membrane layer (3) which is made up of a random number of material layers and at least one impermeable barrier layer (4) which is attached to the membrane layer (3) at least in sections, with the at least one barrier layer (4) being attached in the mounting position to a bottom side (8) of the membrane layer (3) which faces the roof sub-structure (2) and comprising a contact side (13) provided for depositing on the roof sub-structure (2), with recesses (5) being provided which are formed by the barrier layer (4), which recesses have a diameter of between one and five centimeters and within which diffusion of vapor through the underlay (1) is possible, with areas (3a) of diffusion of vapor of the membrane layer (3) which are disposed above the recesses (5) being spaced from the contact side (13) of the barrier layer (4) by a distance measure (x), characterized in that the barrier layer (4) consists of a bituminous material and 50 to 100 of recesses (5) formed by the barrier layer (4) are provided per square meter of the underlay (1).
2. An underlay (1) for making a roof sub-structure (2) rainproof according to claim 1, characterized in that the distance measure (x) corresponds to the layer thickness of the barrier layer (4), with the layer thickness of the barrier layer (4) being arranged to be larger than 0.8 mm.
3. An underlay (1) for making a roof sub-structure (2) rainproof according to claim 1 or 2, characterized in that the barrier layer (4) covers more than 50%, preferably more than 90%, of the area of the bottom side (8) of the membrane layer.
4. An underlay (1) for making a roof sub-structure (2) rainproof according to one of the claims 1 to 3, characterized in that the contact side (13) of the barrier layer (4) is arranged to be self-adhesive and is provided with a removable film (9).
5. An underlay (1) for making a roof sub-structure (2) rainproof according to one of the claims 1 to 4, characterized in that the recesses (5) are arranged in a distributed manner in form of a matrix-like pattern over the area of the membrane layer (3).
6. An underlay (1) for making a roof sub-structure (2) rainproof according to one of the claims 1 to 5, characterized in that the recesses (5) are arranged in form of mutually offset rows.
7. An underlay (1) for making a roof sub-structure (2) rainproof according to one of the claims 1 to 6, characterized in that the recesses (5) are arranged in an equidistant manner with respect to each other.
8. An underlay (1) for making a roof sub-structure (2) rainproof according to one of the claims 1 to 7, characterized in that the recesses (5) have shapes which are bordered on all sides by the barrier layer (4) and are preferably circular.
9. An underlay (1) for making a roof sub-structure (2) rainproof according to one of the claims 1 to 8, characterized in that the underlay (1) has one or several defined areas (6) in which the barrier layer (4) does not have any recesses (5).
10. An underlay (1) for making a roof sub-structure (2) rainproof according to claim 9, characterized in that the defined areas (6) which are covered completely by the barrier layer (4) are provided at least along one longitudinal side (10a) of the underlay (1), preferably along both opposite longitudinal sides (10a, 10b) of the underlay (1).
11. An underlay (1) for making a roof sub-structure (2) rainproof according to one of the claims 1 to 10, characterized in that the barrier layer (4) is made at least partly of butyl rubber or acrylate.
12. An underlay (1) for making a roof sub-structure (2) rainproof according to one of the claims 1 to 11, characterized in that the vapor diffusion areas (3a) of the membrane layer (3) are arranged to be impermeable to fluids.
13. An underlay (1) for making a roof sub-structure (2) rainproof according to one of the claims 1 to 12, characterized in that an additional barrier layer made of preferably bituminous material is arranged on the upper side (7) of the membrane layer (3), with the vapor diffusion areas (3a) of the membrane layer (3) being spared any application of additional barrier layer.
14. An inverted roof structure (20), comprising a flat roof structure (17) provided with a sealing sheet (15), with a heat-insulating layer (16) being arranged above the flat roof structure (17) to which a layer of gravel (11) is applied, characterized in that an underlay (1) according to one of the claims 1 to 13 is arranged on an upper side (16a) of the heat-insulating layer (16) facing the layer of gravel (11).
15. An inverted roof structure (20) according to claim 14, characterized in that the heat-insulating layer (16) consists of several heat-insulating elements (16', 16") which are arranged next to one another, with mutually adjacent heat-insulating elements (16', 16") being connected with one another by means of a self-adhesive underlay (1) according to claim 4 which is applied to their upper sides (16a).

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