Joint sealing

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Under joint seal is understood in the construction of the elastic closure of a joint with sealing compounds or joint profiles . This article explains the techniques of grouting while covering the materials in the article about sealant .

Joint sealing with sealants

Usual sealants are silicone (see also silicone joint ) for the sanitary area or acrylic for connection joints . These plastics belong to the group of elastomers . They are elastic, good heat conductors but poorly electrically conductive. The joint closed in this way cannot be regarded as absolutely watertight, as the corresponding technical regulations explain.


A distinction is made between elastic and plastic sealants. The word “permanently elastic” is often used for silicone joints , but it is basically wrong, as silicone also lose their elasticity over time. The influencing factors include a. UV light, heat, movement of joints and microbiological colonization (mostly mold) and cleaning agents and disinfectants . This is why one speaks correctly of elastic grouting materials. But there are also differences here: Acrylic sealants e.g. B. are plasto-elastic in contrast to silicone . Their elasticity is less than that of the silicone-containing material. If the acrylic is stretched to a greater extent, it deforms permanently, while materials containing silicone either regain their original shape or tear.

Determination of the necessary joint width

In addition to its decorative function, the elastic joint material has the task of sealing the joint in a durable manner. The width of the joint must be adjusted so that the dimensional changes occurring at the joint lead to expansions of the joint material, which always remain smaller than its elongation at break . For a selected joint material, the minimum width for joints on large components or joints on components that are subject to major dimensional changes (e.g. wood, plastics) is larger than for joints on small components or joints on components with good dimensional stability (e.g. stone, Concrete, ceramic tiles). In order to enable the joint to function, the joint compound may only adhere to the surfaces of the components to be sealed with the joint as an intermediate space. Adherence of the joint to other components regularly leads to breakage of the joint material, e.g. B. when processing the corner or connection joints of ceramic tiles on the wall or floor. A harmful "three-surface adhesion", in which the joint compound also adheres to the substrate, reduces the effective joint width to practically zero. As a result, grout materials with high elongation at break also regularly tear. Proper processing of such joints always ensures that the joint material does not adhere to the base of the joint by using suitable aids, while at the same time promoting the desired adhesion to the connection surfaces. For example, a cord of suitable thickness inserted into the joint base can simultaneously prevent the joint material from sticking to the joint base and generate a cross-sectional profile of the joint that is advantageous for the durability of the joint. The joint width to be selected for individual projects depends on the material properties mentioned above. In the IVD leaflet "Sealing of floor joints with elastic sealants", published by the German Sealants Association, the minimum joint widths are specified depending on the temperature difference and the joint spacing. For example, with a joint spacing of 6 mm, temperature fluctuations of 40 ° C, and a ZGV (permissible total deformation) of the sealant of 20%, the minimum joint width is 14 mm. In outdoor areas with a temperature difference of 80 ° C, it is 25 mm in the same case. An overview table is available from the Sealants Industry Association (see web links).

See also


  • M. Pröbster: Building sealants. Vieweg + Teubner Verlag, Wiesbaden 2008, ISBN 3-8348-0290-5 .
  • E. Baust, W. Fuchs: Practical handbook sealants. German edition, IVD, 5th edition, no year, HS Public Relations Verlag GmbH, Düsseldorf.
  • E. Baust, W. Fuchs: The Sealants Manual. English edition, IVD, 5th edition, no year, HS Public Relations Verlag GmbH, Düsseldorf.

Web links