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Dumbo
I didn't say that it was @3_fall who said that. It's because he's not technically good , that is not true . It is because the tiles he fits are usually thin tiles and are not suited to a cavity type membrane . He will correct me on this if I'm wrong which I probably am .What are the technical reasons you cannot use bal flexbone matting, curious to know.
Actually he is technically very good .
Also you should get in the habit of reading technical data sheets whenever you use anything in a certain application for the first time and don't use it unless it specifically says you can and if you are unsure contact their technical helpline and get it in writing .