Uncoupling membranes :
How they work
put one hand flat on a desk sit an egg on it ..... slide the hand away...egg smashes right........
Now put 2 hands flat on top of each other on the desk and get an egg put on top .....slide the bottom hand away..............egg is safe
Thats how it works uncoupling membrane 2 hands = 2 layers with the tiles on top, when the floor moves the bottom layer moves while the top layer keeps your tiles safe.
Now this only aplies to lateral movement thats movement accross the surface not vertical movement. eg the floor expands or contracts.
Therefore if you have any doubt that the floor is going to move lateraly you use an uncoupling membrane especialy with stone
Heated floors expand and contract
Wood floors expand and contract
New screeds expand an contract
This pdf will help you out
Durabase Ci uncoupling matting or have a read of this which is on the forum
Durabase uncoupling membrane And yes I sell it its how I make a living and no it's not bl**dy orange.........prices are in the arms...........
tiler