Few questions on tiling ply and walls

[Trustno1]

Hi guys halfway through fitting my new bathroom just waiting for the plasterer to finish skimming walls. Got a few questions as keep getting mixed views.

1) I've ripped out the old floorboards and have fitted 18mm wbp ply with noggins all sound now no bounce or squeaks. Do I need to prime the ply I.e bal APD or SBR or can I tile straight on? Will be using a cement based flexible adhesive, tiles will be ceramic. Can't really over board with a cement board as that extra bit of height will knock everything out and cause me problems!

2) for the walls going to be using 600x300 porcelain tiles, will again be using a flexible cement based adhesive. Will the skim coat need priming?

3) would a 20mm x 10mm deep curved notch trowel be suitable for both floor and wall?

thank you gents

 

[Andy Allen]

How heavy are the wall tiles...?
There are weight limits for tiling on skimmed plaster.
I would definitely recommend overboarding will cement boards. .

 

[jollyroger]

As above, pretty sure you will be over the weight limit for skimmed plaster. Defo overboard floor with 6mm Hardi board or No More Ply.

 

[nybor62]

for the floor i would say you will be fine , cement board would be better , but as you said height probs , back skim the tiles with flat edge of trowel for a solid bed

as for walls , will be close with the weight i reckon ,

 

[jollyroger]

Can you check the weight of your wall tiles ? 600mm x 300mm tiles =5 tiles per square metre. I'm guessing each tile will be approx 5kg. So 25kg in total per square metre. Recommended weight limit for skimmed plaster is 20kg per square metre including adhesive. I would go with 8mm notched trowel for walls but still think its pushing it.

 

[widler]

Depends if you want to risk it,remember it's a guide line, not law,I've done it [emoji12]and I'm sure plenty on here have [emoji1]
I've been to a bathroom I'm doing in a couple of weeks, bloke has ripped all tiles off(600x300 porcalain) been on around ten years, needs complete replaster(dryline)he said they were stuck like baby poo to a blanket .

 

[Trustno1]

Lol! Ok we'll a box of 8 tiles comes in at 32kgs haven't quite worked out the maths!

if I was to find a way to lay 6mm cement boards on top of the ply does the term "glue and screwed" mean just a bed of cement adhesive and screwed into the ply? Would you leave a slight gap between joints to have them tight? Tape joints?

ta!

if I couldn't overboard do I have to prime the ply?!

 

[Martyn Leeds]

Get some quotes,
there might be the best tiler in your area living in the next street, he might even have a spare week, or even a 1 man band struggling to pay the bills...

 

[Trustno1]

Get some quotes,
there might be the best tiler in your area living in the next street, he might even have a spare week, or even a 1 man band struggling to pay the bills...

Hi mate I'm a plumber 90% of my work is maintenance I would say I've got a ok knowledge of tiling and done a fair bit of basic splash backs etc.

Would get a tiler in if I could afford it but just brought a new house which needed gutting, wife's off work looking after our first child so really need to save the pennies and want the satisfaction of doing the job myself!

 

[SJPurdy]

On the ply floor with most flex cement based adhesives there is no need to prime the surface before tiling. However, the bottom of the boards and the edges should have been sealed with eg. SBR before fixing.
Consider fixing a decoupling membrane eg. Ditra to the ply before tiling but if all is rigid and stable this should not be a necessity unless using more fragile eg stone tiles.
On the walls note all the above weight advice but if you decide to go ahead then the walls will need priming (to prevent a chemical reaction) prior to using a cement based adhesive. For fixing that size tile I would use an 8mm trowel and back butter the tiles.

 

[Daz]

On the ply floor with most flex cement based adhesives there is no need to prime the surface before tiling. However, the bottom of the boards and the edges should have been sealed with eg. SBR before fixing.
Consider fixing a decoupling membrane eg. Ditra to the ply before tiling but if all is rigid and stable this should not be a necessity unless using more fragile eg stone tiles.

If I have to tile a ply floor (generally under protest) I would always prime first with Ardex P51 neat as you do not want any moisture from the adhesive compromising the ply layers.
Ditra matting or any other decoupling membrane will only help minimise lateral movement so if you have any deflection in the floor you will need to sort that first.

 

[White Room]

Check the adhesive instructions some say prime some do not....