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Joint sealing

Small detail, big impact

Every structure is individual and as a result planners, architects and fitters are always faced with new challenges. But all projects have one thing in common: Construction components and elements made from any number of materials have to be connected together – and that’s where joints come in. To be able to fulfil their diverse roles in the best way possible and to ensure that points of structural attachment do not become a weakness in the design, the sealing of joints must be planned carefully and carried out professionally using suitable sealing material.  

Overlooking structural attachment is a no-no 

Points of structural attachment were once low down on the list of priorities. They were seen as a design detail of rather minor importance. But in reality, they are much more important than that. They accommodate movement in the structure, help to insulate buildings from noise and keep them airtight. The joint itself may well be unremarkable, but the impact it has is crucial. Architects are therefore well advised to take joints into account early on, in the planning and tendering phase – not least because the German Energy Savings Regulation (EnEV), with its much stricter energy standards for new builds as of January 2016, imposes an obligation on planners.

Structurally significant: Expansion joints and connection joints

Depending on the area of use and the load to which the joint will be exposed, different joint designs are available. A basic distinction is made between two types:

  •  Movement joints – for example expansion joints and settlement joints – prevent cracking and deformation in adjacent components that would occur because of divergent expansion properties in the materials involved and static forces in the structure.
  • Connection joints connect construction elements. These take the form, for example, of window connection joints, door frame connections and sanitary joints.

Professional joint sealing: A must, not an option

When carrying out sealing work, sealants are introduced into a structural connection that prevent water, air and noise getting in between construction elements, components and parts of the structure, and at the same time accommodate movement between different parts of the building. This is how the German Institute for Standardization (DIN) puts it, and by means of a range of relevant standards sets out comprehensive guidelines for different application areas.

After all, professional jointing using suitable sealing material is crucial if the joint is to perform its role well.

  • Moisture-proofing Floors must be protected against rising damp, moisture-sensitive components and insulating layers in wet rooms must be protected against water.
  • Airtightness For new builds that are heated, the EnEV stipulates that the building envelope must be airtight and diffusion-open in order to reduce energy losses. It is important that joints are sealed professionally, particularly at connection points and points of penetration – for example windows, doors and in the façade. This minimises thermal bridges, which lead among other things to damage caused by damp and the build-up of mould.
  • Noise insulation Even small noise bridges can significantly reduce the effectiveness of a wall’s noise insulation. Joints must therefore be designed with acoustics in mind and fitted with appropriate insulation.
  • Weather-proofing Particularly in the installation of windows, inadequate protection against the weather is a building defect that occurs time and again. Under the EnEV, windows should be installed completely in the composite thermal insulation system in front of the façade, as far as it is possible to do so. Although this makes sense from a thermal technology point of view, such installation is not often easy in practice. If the window connections are poorly carried out, the advantages of having high-quality glazing and window frames are easily negated.

A little aside: The physics of sealing

The function of sealants is essentially influenced by two factors: their adhesion – or ability to stick to the component’s surface – and their cohesion – the inner strength that prevents rupture. Joint sealing products can also be distinguished in terms of their mechanical behaviour:

  • Elastic sealing materials are resilient and return to their original shape again after a load has been applied.
  • Plastic sealing materials deform under continued load and are suitable for connection joints that are exposed only to a little movement. Every sealant has these two properties to a certain degree. That’s why, depending on the relative nature of these properties, sealants can also be referred to as elastoplastic and plastoelastic


The right sealing material for every joint

Most sealants are based on silicones, acrylates or polyurethanes. Various compositions are available for special application areas.

  • Silicone sealants are very versatile in use: they can be used as sanitary silicone for sealing tiles or with natural stone. All have a high tensile stress value, are weather-proof, resistant to ageing and UV, are highly resistant to abrasion, non-corrosive, inhibit the growth of mould and bacteria and adhere to many substrates.
  • Acrylic sealants are suitable for expansion joints and connection joints that are under low load and exposed to no or only a little moisture. The advantage of acrylic over silicone: It can be painted. Such sealants can therefore be used to seal window joints and door frames well in the interior environment.
  • Polyurethane sealants are available as single-component products for insulation applications in general construction and civil engineering. They are resistant to driving rain and are highly permeable to water vapour, which makes them particularly suited for RAL-compliant installation in the outdoor environment.

Very best possible joint sealing for any application area

Joints are small. But they make a big difference to the overall structure. With joint seals in the form of sealants that can be sprayed on, brushed on and scraped on, strips, films, fillets, adhesives and foams, tremco illbruck can provide users with the very best possible product for any application area. It should always be borne in mind that careful planning and preparation is important when jointing – and quality counts. Joints exposed to greater movement need a higher quality material to seal the joint.  

System solutions can be the perfect option

System solutions have many advantages and the best results. For example when connecting windows: The adhesive-based illbruck front-wall installation systems meet the specific requirements for RAL-compliant window installation and are designed for the installation of windows and doors in the insulating layer so as to be statically secure, suitable for passive houses and perfect in terms acoustics.

Permanent wind-proofing and airtightness of the entire building envelope can only be achieved when all transitions between materials are sealed in an airtight and wind-proof manner. The adhesives and sealants used must be harmonised for this purpose. The illbruck airtight concept brings together products that are carefully matched to form a complete airtight solution for roofs, façades and interior walls.  

What’s your next challenging job? We can help you master it. With expertise, experience and innovative product solutions. Our team will be happy to advise you over the phone or at your premises – including at the construction site. Just contact us.