THE REASON FOR EXPANSION JOINTS
Why are they essential?
All building materials have a coefficient of expansion.
All without exception. This coefficient is a function of temperature variation, i.e. with an increase in temperature material expands and with a decrease in temperature material contracts.
We must therefore provide an area where these high stresses can be “absorbed”: expansion joints.
Advantages:
With expansion joints we prevent compressive and tensile forces exceeding the respective resistance of the construction element (ceramic, brick, concrete, mortar,…) and with this we avoid fissures, cracks, detachments, spalling,…
The regulations:
One of the latest compendiums to appear is the Spanish standard UNE 138002 “General rules for the installation of ceramic tiles with bonding materials.”
From the text approved by the technical committee CTN-UNE 138 Ceramic Tiles, whose secretariat is provided by ASCER, our attention is drawn to section 5.3 and Annex D on “Materials” and “Sizing of movement joints” respectively, which graphically specifies how these expansion joints should be made and how often they should be implemented.
Architects will therefore define their location for structural, design and even aesthetic reasons, so that if they are visible, they do not distort the overall appearance of the building.
Types of expansion joints:
We distinguish between two types: open joints and sealed joints.
Open joints are the result of the exact calculation of the expansion movement of the material in question between two consecutive joints. This movement in mm will be the minimum distance to be left between one wall and the other. In short: the width of the joint. This type of joint is left unsealed. They are effective at a constructive level, but practice shows that they gradually fill up with dirt so end up not doing their job.
Sealed joints are separations between consecutive walls that have been filled with elastic fillers to prevent water, humidity, dirt, etc. from entering. They are effective in their function and are highly durable. The calculation of their width is the result of considering the movement needs of the facing and the movement capacity of the sealant filler.
Fillers:
The most suitable fillersfor sealing expansion joints are polyurethane or silicone-based elastomeric putties. These fillers stick perfectly to the materials commonly used in construction: bricks, ceramics, mortar,… and are highly elastic, durable over time, as well as highly resistant to water and weathering.
Our proposal:
At Fixcer we suggest using SELLALASTIC or SILICONA-NEUTRA-FIXCER to make expansion joints. These are elastic fillers, highly adhesive, waterproof and available in various colours. In particular, SELLALASTIC can be repainted in the same colour as the facing to 100% conceal it.
