FI70286B - VIND- OCH FUKTSKYDDSSKIVA - Google Patents

Description

70286

WIND AND MOISTURE PROTECTION SHEET

This invention relates to the improvement of the wind protection capacity and the simultaneous water vapor permeability of a mineral wool-based thermal insulation board.

Another important feature of a building's thermal insulation system after good thermal insulation is its ability to prevent water vapor from penetrating the interior of the building into condensing and freezing on the outer surface of the insulation. A good insulation system therefore involves covering the surface of the thermal insulation facing the interior with a watertight moisture barrier, which is usually made of plastic film or special paper. However, it often happens that, for one reason or another, water vapor can penetrate through the moisture shield. This is the case, for example, if there is a small crack or tear in the moisture barrier or if its joints and fastenings leak. At the point of leakage, a water vapor flow then occurs, which condenses in the areas of the colder outer surface of the insulation 20, causing moisture that is harmful to the wooden structures here and cold bridges that reduce the insulation capacity in winter.

Thus, the properties of good thermal insulation also include its ability to simultaneously allow water vapor to pass through and prevent the colder air stream from penetrating at rate pressure into its internal structure, which may contain condensing water vapor. In other words, the insulation must be an effective barrier to the flow of cold air, while at the same time releasing the water vapor accumulated in it as easily as possible. The insulation must be equipped with a windbreak that does not easily penetrate the air, but instead water vapor. This contradiction is one of the big dilemmas of thermal insulation of buildings.

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There is usually a free space between the outer surface of the thermal insulation of the wall of the building and the outer surface structure of the wall where air can move to ventilate the moisture. The thermal insulation must therefore be windproof 5 on this very surface and at the same time provide the lowest possible resistance to water vapor penetrating from the interior of the building.

Usually, the outer layer of thermal insulation is formed by a stiff 10 and a relatively thin mineral wool board compared to the thickness of the actual thermal insulation layer. Thus, the described dilution is reduced to make the second large surface of the mineral wool board such that its air permeability coefficient is as small as possible at the same time as its water vapor permeability coefficient in the opposite direction is as large as possible. Both quantities are measurable. Usually, however, the latter is expressed as a water vapor penetration resistance coefficient, which must therefore be as small as possible.

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Attempts have been made to solve the problem by using long-known mineral wool boards, the second large surface of which is provided with a thin cloth or film. However, the fabric has a high air permeability coefficient because it does not act as an appropriate wind protection. The heat transfer through convection is unnecessarily high in the insulation, regardless of the density and quality of the fabric. The large surface covered with a dense plastic or aluminum foil, on the other hand, is an excellent wind protection, but it does not transmit water vapor. 30

It is also known to cover another large surface of a mineral wool board directly with a layer of pulp or paint. The mass is either applied to the surface in the form of a mortar or brushed as a paint. The disadvantage of this method is the rather large thickness of the layer. Because the surface of the insulation is not homogeneous, the thickness of the 70286 3 coating varies considerably. In this case, it does not smoothly adapt to the deformation of the plate during transport and installation, but cracks or fractures occur. Applying the coating to the board at the construction site has proven cumbersome and time consuming.

Surprisingly, it has been found in the experiments carried out that a glass fiber fabric selected with certain limitations and covered with a thin coating acts as an excellent surface coat. If such a fabric is attached to a rigid mineral wool board, a surface board that satisfies the desired properties is obtained. By spraying, the coating can be adjusted in a controlled manner so that a favorable compromise is found between good wind protection and a sufficiently low water-15 vapor resistance. The plate according to the invention is thus characterized by what is stated in the appended claim.

The surface plate according to the invention is manufactured at the factory.

The preferred surface plate is obtained starting from a known stone wool plate weighing about 90 kg / m 2 and having a thickness of about 5 cm. A non-woven fiberglass cloth with a basis weight of 30 to 100 g / m 2 is attached to the second large surface of this board already at the manufacturing stage of the board. Thereafter, a latex paint is preferably sprayed onto the fabric layer surface thus obtained so that the basis weight of the coating is of the order of 200 to 800 g / m 2.

The manufacturing method described is a preferred method of manufacturing a sheet according to the invention. Of course, other advantageous combinations can be found for fabric and coating grades. However, the possibilities for combination are quite limited due to the simultaneous fire safety requirements of the materials used. For example, a woven fiberglass fabric can be used as the fabric, but its properties are less advantageous for the purpose. Not only is latex paint an inexpensive coating for its purpose, it also meets the set fire safety requirements.

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The properties of the surface plate according to the invention are shown in the table below in comparison with the properties of the surface plates known today.

10 Eg Mineral— Surface— Coating Air- Water vapor permeability resistance no wool fabric Type g / m2 x 10-6nt / sPa x 109 m2 sPaAg 1 Rock wool Fiberglass Latex 400 1.8 1 90 kg / m3 no weft.

50-60 g / m2 15 ----__________ 2 "" Latex 800 0.3 4 20 --------- 4 - - 320 0.3 5 "Glass fiber - - 300 0.3 no whey.

2 5 50-60 g M2 6 "- Latex 730 14.5 0.4

Examples 1 and 2 represent a surface plate of the invention.

Example 4 is a semi-rigid stone wool board without any coating. Example 5 represents a surface plate having a non-woven fiberglass fabric on one surface without a coating. Example 6 represents a surface plate which does not have a surface fabric but whose second major surface is 35 directly painted.