Why is a minimum joint space of 4 mm used for ceramic floors?
. Most tiles are fired and dried with minor variations in size, which prevents “butt joining” them (laying them together with no joint space) since they would be uneven and the installation would look irregular. Also, ordinary tiles absorb moisture and swell up, which creates pressure between the pieces and can quickly cause them to break off. This does not occur in rectified tiles, which absorb very little moisture.
