Execution of expansion joints

Execution of expansion joints

As a consequence of the expansion and contraction of the materials used, it is of vital importance to execute movement joints both on floors and façades, for the purpose of preventing the appearance of cracks and fissures.

Preliminary analysis

Both in the design of façades and execution of flooring, we cannot overlook the correct execution of expansion joints, so they can absorb any possible expansion and retraction movements to avoid damage to the construction materials.

Therefore, we can ensure that both a good joint planning design and the correct subsequent sealing thereof will directly impact the durability of the construction work.

Technical considerations

Joint width must be at least five times greater than the maximum expected movement.

Seal depth (using G#color Elastic-MS) will be chosen depending on joint width.

In the case of joint widths greater than 16 mm, the depth should be equal to half of the width.

  • The substrate on which the grout is applied must be clean and stable, in order to ensure the correct union with the sealant.
  • Before sealing the joint, a base coat of a mechanically stable, inert, homogeneous, antioxidant and non-adherent to the sealant must be applied. This will allow us to control the depth to be filled and the joint will be joined only on two of its sides, thereby avoiding unnecessary stresses.
  • In order to facilitate subsequent cleaning, before applying the sealant place two adhesive tapes along the edges of the joint.
  • If the joint to be sealed is wide, we recommend applying it in three steps.

The first two on the edges of the joint and the third at the bottom.

  • To ensure a perfect finish, smooth the putty with a spatula dipped in soap and water, pressing the putty against the sides and bottom of the joint, and remove the tapes disposed earlier and scrape the hardened paste.
  • If it must be painted, wait until the mastic is completely polymerized, using any acrylic paint of the GECOL Cril range.

Recommended products

Flexible mastic

Elastomeric mastic


Warnings: The data provided by this Constructive Solution were prepared based on standard onsite installation processes. However, we recommend that you consult our Technical Department in the event of any specific circumstance info@gecol.com