Everything you need to know about expansion joints
What is an expansion joint and why is it important?
An expansion joint or movement joint is a controlled gap between building elements that accommodates movement caused by temperature changes, moisture, shrinkage or expansion of materials. Without expansion joints, stress can build up, leading to cracks, deformation or damage to the structure.
By correctly installing and sealing an expansion joint, you extend the lifespan of the building and maintain a durable, aesthetic finish.
Which products are suitable for expansion joints?
For sealing expansion joints, we recommend a silicone sealant. Silicones are specially developed for durable and elastic sealing, with excellent adhesion to various building materials. They remain flexible and withstand both UV radiation and extreme weather conditions.
For specific applications where high elasticity and crack resistance are required, a high-quality polymer sealant from our Parabond range is also a reliable choice.
For interior applications with joints subject to limited movement, an acrylic sealant that is perfectly paintable can be recommended.
How do I finish an expansion joint correctly?
Preparation
- The substrate must be solid, even, dry, clean, and free of dust and grease. If necessary, degrease with Parasilico Cleaner.
- If required, apply a suitable primer for optimal adhesion. The use of a primer may be necessary on highly porous substrates, in case of adhesion difficulties or under demanding conditions.
Filling the joint
- Place a suitable backing material (round foam cord or other backing material) in the joint to determine the correct joint depth and to avoid three-sided adhesion.
- Apply the sealant evenly using a sealant gun.
- The size and shape of the joint are very important. Avoid thin joints.
- Do not subject the joint to thermal, mechanical or chemical loads before curing is fully completed.
Tooling
- Smooth the sealant before skin formation using a suitable tool, so that it adheres well to both sides and forms a neat surface.
With the right sealant and careful finishing, you ensure a long-lasting elastic seal that easily accommodates the movement of the structure.
Always consult the technical data sheet of the product used for all information such as joint dimensions and curing speed.
Tip: A well-executed expansion joint is not only functional, but also contributes to the appearance of your project. We are happy to help you choose the right product and method.
