floor preparation

[pickles]

I am about to tile a bathroom floor. This previously had carpet down and on taking it up I am left with an extremely flat flooring grade chipboard floor which seems to have been laid over the old floorboards when the property was renovated about 20 years ago.

It says in the sticky for this forum that when tiling over a chipboard floor it should be covered with plywood. Would this still apply in this case

Thanks in advance for your time.

 

[gcol]

If you can't replace the chipboard with ply then you should overboard it with ply. If it's as you suspect and the floorboards have been overboarded with chipboard, the floor should be pretty firm. As long as there's no movement in the floor when you walk on it, you'll probably be ok to use a thinner ply than mentioned in the sticky. You could get away with 6mm I reckon. 6mm is a bit thin to screw down so I'd glue it. Pin it to hold it in place until the glue sets.