Hi guys might not be much use to you now as the customer has already decided to use wood flooring .
I have a bloke from the tech department at Granfix visit my training centre on a monthly basis to give talks and demonstrations on adhesives / grouts and different fixing techniques.
He advises that floating floors can be tiled on if the correct technique and adhesive is used. The main problem with a floating floor is board separation caused when the floor expands and contracts. When they lay the boards on top of the insulation they don't screw them into place , they simply glue the edges together.
The advise given is to lay 6mm ply over the floor in the opposite direction to the floor boards and screw down every 4-6 inches, this will tie all of the boards together and stop board separation.
Then to cope with any movement or bounce use Ultimate Flex adhesive which is a Granfix version of a 2 part ady , its a powder with the flexi add mix already added in a powder form instead of a liquid.
This has been tried and tested both in lab and on site by granfix and my tiling company with no problems what so ever.
Just thought i would add this to the post so you don't have to turn these types of floors down if they come up.
