DE8433792U1 - Cover mat - Google Patents

Description

"\ Cover mat

The invention relates to a covering mat for a multi-layer roof covering, which is arranged as an intermediate layer between a water-bearing layer and a layer of soil or plant substrate.

Roof coverings are well known and cause particular problems when they are not only intended to protect the interior of a building from moisture, but also to provide a green roof. There are two cases of known green roof systems. It is known to cover the water-bearing layer with a water-permeable and diffusible filter fleece, on which the soil or plant substrate is then arranged. In the other case, the water-bearing layer is covered by a diffusion-tight coating element that supports the soil or plant substrate.

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In the first case, the water-bearing layer absorbs all the water, which is supplied either by rain or by an irrigation system. It has now been shown that when there is strong sunlight, the water diffuses upwards very quickly into the soil or plant substrate and leads to waterlogging in the root area. In dry periods, on the other hand, the water supplied by rainfall and initially accumulated is used up very quickly, so that after a short time, additional watering is required to prevent the soil and plant substrate from drying out. Wherever automatic irrigation is provided, it has also been found that in dry periods, fresh water must be constantly added, even though the root area is constantly wet through diffusion.

In the second case mentioned above, about 75 % of the water supplied by rain or irrigation is channelled into the aquifer and about 25 % is stored above the covering layer. This means that the soil or plant substrate is constantly kept wet from below. However, in strong sunlight or during dry periods, this water can evaporate very quickly and additional watering is required. This then leads to the same disadvantages as in the first case described. The water stored in the aquifer can only flow out at the joints

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the impermeable covering layer diffuses upwards and thus contributes practically nothing to the irrigation of the soil or plant substrate from below.

The invention is therefore based on the object of creating a covering mat for a multi-layer roof covering which can be used in green roof systems and which ensures that the water accumulated in the water-bearing layer is only gradually used to moisten the soil or plant substrate and that no unacceptable wetting of the root area in the soil or plant substrate occurs.

To achieve this object, the invention provides that the cover mat consists of a filter mat and a film, whereby the filter mat is a diffusible, highly tear-resistant fiber fleece made of water- and acid-resistant plastic fibers and the film consists of dense, water- and acid-resistant, non-swelling plastic and is provided with fine ^holes .

The measures mentioned ensure, on the one hand, that the excess seepage water that accumulates during rainfall is evenly drained down into the aquifer, so that the soil or plant substrate does not become waterlogged. Furthermore, the water that accumulates in the aquifer can be drained away by capillary action and

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Diffusion constantly releases water vapor to the root area of the soil or plant substrate on top. The size of the holes or the openings in the plastic film can be chosen differently according to requirements, whereby this depends on the type of plants and the thickness of the soil or plant substrate layer. The diameter of the openings in the film is at least one millimeter.

The invention is described in more detail below using an embodiment example, which is shown in the drawing. In the drawing:

Fig.1:

Fig. 2:

schematically and in section the layer structure of a multi-layer roof covering for a green roof system and

schematic and interrupted a longitudinal section.

The layer structure of a multi-layer roof covering for a green roof system comprises, according to Fig. 1, a multi-layer roof skin 2 on a roof structure 1, which is applied there in a known manner.

A root protection film 3 is placed on the roof covering 2, which can be made of nonwoven fabric or woven fabric according to the manufacturer. An insulating protection mat 4 is placed over the root protection film.

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above which the actual water-bearing layer is located. Expanded clay, gravel, porous or water-storing mats made of coarse-pored, foamed plastics and the like are used as the carrier material in the water-bearing layer 5. A covering mat 6 according to the invention is then placed on the water-bearing layer.

As the two figures 1 and 2 further show, in a green roof system, a layer of sand 7 is advantageously arranged on the covering mat 6 and directly supports a plant substrate 8 in the form of soil or a soil substrate.

The covering mat 6 consists of two layers. It comprises a filter mat 9 made of a diffusible, highly tear-resistant nonwoven fabric made of water- and acid-resistant synthetic fibers. Mixtures with polypropylene and/or polyethylene fibers are suitable as materials for the nonwoven fabric. The best properties are shown by a fiber mixture consisting exclusively of polypropylene and polyethylene fibers. The tear resistance of this filter mat 9 must be sufficient in order to be able to absorb locally different tensile and compressive forces that arise from the plants and the water content in the soil and plant substrate 8. Furthermore, the filter mat 9 must compensate for pressures and forces caused by different thicknesses and densities of the fill in the water-bearing layer 5, which cannot be avoided when producing the roof covering.*

The cover mat 6 also includes a film 1o made of a dense, water- and acid-resistant, non-swelling plastic. The film 1o is provided with fine holes.

According to a preferred embodiment, the film 1o can consist of polyurethane. It is expediently laminated directly onto the filter mat 9.

The fine perforation in the film 1o comprises a large number of through-openings 11 per unit area. The diameter of the through-openings 11 is in the order of up to about 1 mm as the lower, clear width. The size and/or the number of through-openings 11 per unit area is selected in accordance with the thickness of the layer 8 consisting of soil and plant substrate, the type of planting and the local conditions. The size and number of through-openings per unit area determines the water permeability and the diffusion capacity for steam through the film 1o from the water-bearing layer 5 to the soil and plant substrate layer 8.

The total thickness of the filter mat 9 is, depending on the application, on the order of 3 - 6 mm. The thickness of the film 1o can be, for example, 1 mm.

Figure 2 shows a schematic longitudinal section through a multi-layer roof covering for green roof systems, where the layer sequence basically corresponds to that shown in Figure 1. However, the illustration shows that

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the various layers are perforated for an inspection shaft 12 of a water drainage device. The side walls of the inspection shaft 12 are porous or perforated in the lower area 12· so that water can flow out of the water-bearing layer 5 almost unhindered. The inspection shaft 12 is provided with a cover 13 and a retaining element 14 is integrated into the lower layers of the roof covering, which is made of copper, for example, and whose upper edge 14' defines the upper level of the water-bearing layer 5. A drain pipe 15 surrounds the retaining element and is inserted into the roof structure 1.

Wherever the cover mat 6 is in contact with the edge stones 16 bordering the green area or with the masonry 17, it is raised to the surface of the soil or plant substrate 8 or even beyond. The root protection film 3 and the insulation protection mat 4 are laid continuously on the roof skin 2 and are only raised to the edge level at the verge. The edge stones 16 can be placed on the root protection film 3 and the insulation protection mat 4.

Preferably, the areas adjacent to the verge, walls and also the water drain are provided with a stone fill 19 in a green roof. This can extend down to the insulation protection mat 4 or, as shown in the case of the inspection shaft 12 serving as a water drain, end on the sand layer 7 or on the cover mat 6.

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Claims (7)

t · ■ a Claims 1) Cover mat for a multi-layer roof covering for arrangement as an intermediate element between a water-bearing layer and a layer of soil or plant substrate, characterized in that the cover mat (6) consists of a filter mat (9) and a film (1o), whereby the filter mat (9) is a diffusible, highly tear-resistant fiber fleece made of water- and acid-resistant plastic fibers and the film (1o) consists of dense, water- and acid-resistant, non-swelling plastic and is provided with fine perforations. ?) Cover mat according to claim 1, characterized in that the film (1o) is laminated onto the filter mat (9) . 3) Cover mat according to claim 1 and 2, characterized in that the diameter of the through-openings (11) and/or the number of through-openings (11) per unit area are different. 4) Cover mat according to claims 1-3, characterized in that the diameter of the through-openings (11) in the film (1o) is at least 1 mm. 5) Cover mat according to claim 1, characterized in that the filter mat (9) has a thickness of 3 - 6 mm. &eacgr; · · ·
* it*» 6) Cover mat according to claim 1, characterized in that the filter mat (9) is a nonwoven fabric made of a mixture of polypropylene and/or polyethylene fibers. 7) Cover mat according to claim 1, characterized in that the film consists of polyurethane. IKl I I I I I I I I » '