New bloke, bathroom floor advice please

[tiggrrr]

Good morning, I am a reasonably competent diy-er always looking to improve my skills. I am currently about to start a bathroom floor that is 'L'- shape and I have 600 x 300mm tiles to lay on 18mm floor boards covered with 9mm plywood screwed down at 150mm centres.
How best to prepare the plywood?;
What size tile spacers?
Can I lay the tiles in a straight bond length-ways from the door and then where the 'L' is have a left turn at right angles so there is a herringbone effect just across the angle or would that be considered unethical?
Appreciate any advise, thank you.

 

[One Day]

Hi. First off plywood is a very risky substrate these days, mainly due to the gossamer thin veneer many have and the dodgy resins used. As a professional I would refuse to tile onto ply unless it is the new flooring grade ply and minimum 18mm as an overlay.
If you really want to keep your ply, then I'd recommend using a layer of ditra matting stuck down using ardex af207 adhesive, specifically designed for ply.
Otherwise, overlay with a 6mm cement board first.
As for your pattern idea, I've done it before and it can look good but dry-lay the area before you commit to it, to make sure the spacing works for you.

 

[Tommcd]

I'd be tempted to ditch the herringbone idea as I think it would look weird with that size of tile. I'd just go with the orientation you want to see from the doorway as you enter the room and stick with that right through. Of course it's up to you. You also have to remember that if the external angle is slightly out of square and you have made it a focal point it might look a bit naff.

 

[GoneGuy]

Hi tiggrrr and welcome to the forum,
I would have to agree with @impish I wouldn’t tile over ply. I would recommend using a cement board such as hardiebacker,no more ply etc.
As with spacers I usually go 3mm on floors.
It would be worth putting some tiles on the floor to see what the pattern you suggested looks like before you go ahead and do any cuts etc.

 

[tiggrrr]

Thank you so much for your valued advice. I have found the Hardiebacker boards available at B & Q - presumably stuck onto the plywood with the appropriate adhesive. I accept the issue with the herringbone idea which is complicated with the toilet sited in the diagonal line as well. As usual with tiling the layout is a compromise with various obstructions and variables to accommodate whilst displaying the tiles in a uniform fashion.
In this case the 18mm floorboards are imperfect so the plywood at least gives a smooth sub-base to build from.

 

[GoneGuy]

Thank you so much for your valued advice. I have found the Hardiebacker boards available at B & Q - presumably stuck onto the plywood with the appropriate adhesive. I accept the issue with the herringbone idea which is complicated with the toilet sited in the diagonal line as well. As usual with tiling the layout is a compromise with various obstructions and variables to accommodate whilst displaying the tiles in a uniform fashion.
In this case the 18mm floorboards are imperfect so the plywood at least gives a smooth sub-base to build from.

Don’t forget to screw the hardiebacker down as the adhesive is there to fill any voids, also for warranty you need to use a alkaline resistant mesh tape on joints.
It might be best to watch some YouTube videos to see how fitting goes if your unsure

 

[Lou]

Welcome! Please post photos of your finished job for the nosy ones of us.

 

[Steve_Bcs]

Hi All, I'm new here too. I've plenty of DIY experience tiling walls to a reasonable standard but never done a porcelain floor before, which I am about to do in my en-suite. Advice above is great & helpful. My question is can the hardibacker floor boards be laid straight onto the existing t&G floor boards with the adhesive; which adhesive do you recommend? and also will the adhesive be sufficient to level out any imperfections in the floor boards. or should I lay ply first as above?
Thanks.

 

[Tommcd]

I normally prime the floorboards first although think it’s probably unnecessary, then lay with rapid set adhesive - the cheapest I can lay my hands on which is usually granfix (tile choice). Then screw them down with some turbo gold screws 4*20 mm.

Minor imperfections in the floor will be cancelled out by the boards, but if your floor is bowing the hardiebacker will just follow it. Personally in this situation I lay the cement board as is then sort out the floor with some rapid set and a plasterers darby before tiling.

 

[Steve_Bcs]

thanks... out of interest how many screws do you place per board?