Raising floor: chipboard or ply to take porcelain tiles?

gez · Post by **gez** » Mon Jun 01, 2009 9:10 pm

Hi,
I have a utility room that currently is tiled on the floor. I need to raise the floor level by about 40mm and then will tile with porcelain tiles. The area is approx 2 x 1 metres.
Should I use layer(s) of flooring grade chipboard or ply, or a layer of chipboard and then ply?
Do I need to fix the flooring through the existing tiles (concrete floor underneath) or can it float?
I assume that as it is a utility room I should use water resistant materials?
Any recommendations on tile adhesive to use?
Thanks,
Gerry

m3 fitter · Post by **m3 fitter** » Tue Jun 02, 2009 4:57 am

remove the tiles for ease of fixing of the battens, try and use 1" ply or as thick as you can for rigidity of the tiling substrate , alternatively ply with 1/2" and then overboard with Knauf aquapanel 12.5mm which will give you the rigidity of 3/4" ply, the only potential problem is getting the correct rigidity suitable for tiling afterwards, use flexible powder adhesive with a polymer suitable for porcelain and flexible grout after this procedure, hope that helps

gez · Post by **gez** » Tue Jun 02, 2009 7:27 am

Thanks for the quick response and advice, especially the use of aquapanel that I had not considered.
One point I want to check is regarding the recommendation to remove the existing tiles; not just as it would be extra work, but they are solid and secure and as you state, rigidity is the key to a good finish.
So I wonder if it would be better, though initially more difficult to make the first fix, to leave the existing tiles in place, secure 1" ply to the floor (should I use a plastic vapour barrier?) and then overboard with the 12.5mm aquapanel. This will give me the 40mm or so height increase I need and the rigidity?
Is this practical and would I still need flexible adhesive or is a readymix tub OK?
Thanks again.