Cracks can appear alongside perfectly placed movement joints. Typically these would be “half moon” in shape. This are due to a failure to ensure that the fixing flanges of the movement joint are fully embedded into the tile adhesive. All reputable suppliers of movement joints will stress the importance of this solid bedding. Not only is it needed to fully support the tiles at this vulnerable point but also to ensure that the extension and compressive forces within the floor are fully transferred through the supporting profiles to the flexible infill material.
A simple test for this fault is to take a £1.00 coin and use it to tap along the edges of the tiles alongside the movement joint. Where the tiles are solidly fixed the sound is dull. Over hollows in the bedding the sound will change to a sharper, clearer tapping. Invariably if the tiles are lifted for investigation this simple test has proved accurate.
Make sure that your fixing team are reminded that solid bedding is your absolute requirement.
Fixers given the job of constructing movement joints must be competent and it must be understood that the rules regarding the open times of adhesives etc are followed. Planning and pre cutting of the tiles can avoid delays which cause bonding problems.