We are frequently asked for advice on how to build in movement accommodation in existing floors where very wide structural movement joints are present.
In many cases it would be very hard to remove these products without considerable disturbance of the subfloor. This leaves a problem when re tiling.
The answer can often be to use an extra wide surface movement joint fixed exactly over the existing joint.
This will be successful if the following points are taken into account: –
1. The infill of the surface movement joint must be completely supported. No voids are allowed. Any gaps must be filled with a good quality flexible mastic. Be aware that the downward pressure of such items as a Ladies stiletto heel exerts tremendous force onto the infill. It is incapable of accepting these loads if not completely supported. If the infill can be driven downwards into a void – then it will be! This is not a failure of the product it is a failure of preparation.
2. The fixing legs of the profile must be fully embedded into the adhesive bed. This is good practice for all floor tiling but is absolutely essential at these vulnerable points.
3. When specifying these products, please ensure that the width quoted is such that the metal supporting profiles rest onto a solid structure, ideally the edges of the infill should also rest on these solid edges.