Bathroom floor ??

[Jet]

Hi guys
Haven't been on here for a while. So my question is this... I have been asked to tile an upstairs bathroom for a friend. On lifting the lino the floor seems to be some kind of board like an OSB ( the house is about 20 years old).
Anyway the floor is quite sound so would i need to put a sheet of ply over this and if so what thickness..?
Thanks
Jim

[Maxsys]

Minimum BS spec is 15mm, however you may get away with 12mm depending on the size/pitch and span and centres of the joists, if however these heights are too much you have two choices, if there is no deflection in the floor, you could use a 6mm cement based tile backer board, laid on flexi adhesive and screwed down every 200mm, and don't forget to stagger the joins. If there is deflection of any note them rip it up and lay 25mm or 18mm ply, again the thickness used will depend on the size/pitch and span of joists and the centres. In both of these cases extra noggins maybe required.

And lastly always use quality trade materials, such as BAL or Mapei adhesives and grouts, in the case of Mapei not the one from BNQ, it ain't the same.

What size and type are the tiles?

[Jet]

Thanks Maxsys
You've confirmed what I suspected.The tiles are ceramic, 6in sq approx. The floor is quite sound to I think I will go with the 6mm backer board..
Thanks again for the advice...much appreciated..

[tictic]

6"inch square ceramic tiles.... Are they suitable for a floor.. I.e graded for a floor,just asking?