Control joints are there because it s not a question of if the slab will crack but rather when the slab cracks it hopefully happens at the joint.
Ceramic tile over expansion joints.
If you tile over an expansion joint then you need to honor that joint in the tile as well.
Expansion joint locate ctc joint in tile or stone surfaces directly above joints in sub floor full length may be fastened to sub floor using a construction adhesive trowel setting material making sure there is full coverage over the entire leg to ensure a smooth transition mortar bed may be.
An expansion joint is in the substrate for instance in concrete.
Where should movement joints be placed.
1 8 movement with any sheet system typically and 1 16 with a few trowel on systems.
One of the most basic and important facts an installer should know when working with ceramic including porcelain glass and natural stone tile is to always have expansion joints in place.
It allows for movement in the tile.
Control joints may be relocated.
However depending on the tile size and system up to 1 4 movement is possible on the horizontal.
An anti fracture membrane should also be used under the tile to minimize the chance that cracks in the slab will telegraph through to the tile.
Recognizing that tile is a facade movement joints are needed to eliminate stresses that can occur between the substrate and the tile due to differing amounts of expansion and contraction.
If expansion joints are not part of the installation failure is lurking in the shadows waiting to strike.
The tcna handbook recommends allowing for expansion and contraction in every tile installation.
The short answer is that you do not span control expansion joints with the tile.
Tile over expansion joint no membrane or installation system is designed to bridge any joint with verticle displacement.