Bathroom Floor, Ply and/or Cement boards

[jmc1234]

Hi everyone, I would appreciate a little advice on preparing a bathroom floor for tiling, the area is only 2x2m and feels fairly solid underfoot. I have read lots of good info here but I am a little confused as some threads say you should overboard with a minimum of 18mm ply and then 6mm cement boards, others say the floors can be over boarded using only 6mm thick cement boards with no requirement for the 18mm ply.

Could someone also explain deflection and how to measure it and the minimum requirement before for tiling?

Thanks in advance

 

[kilty55]

hi jmc,this is not the way to go i would advise your friend of this.

platerboard takes a weight of 32 k per sq m 2 layrs of tiles will no doubt alreadfy exceed that and adding wetwall will do this again.....always best to strip the room and install a fresh

 

[jmc1234]

Thanks Kilty, if he wont listen I will ask if I can tile the floor before he fits the walls :lol:

 

[jmc1234]

Can the wetwall be fixed directly to the timber frame or would you recommend putting up cement boards/new plaster board first?
With the bare exterior walls would there be any benift of fixing 6 mm cement boards prior to the wetwall for insulation? If so would you fix it with adhesive or dot and dab with pink grip or the likes? Any recommendations welcome as it's a mate so don't wont to see him given duff info by this other guy. Thanks

 

[kilty55]

wetwall is fitted with an adhesive suited to whatever make it is...fix plasterboard imo dont just stick it to a timber frame

 

[jmc1234]

A little more help needed..........

When fixing the cement board to the ply do i just use adhesive should it be screwd down as well.

Does the decoupling mat go between the ply and cement board or the cement board and the tile?

Plumber wants to fix shower base directly onto the ply and has asked me not to fix cement backer board where the shower tray is going...is this correct?

 

[Mike]

you should also screw the cement boards down, every 150mm.
the decoupling mat will go on top of the cement boards.
the shower base will be okay on the ply provided the ply is fixed solid and that you don't have any height issues regarding the tiles being close to the top of the tray