Tiling on Ply Floor - Tile Advice

[Liam D]

Hello

I'm a DIYer so apologies if I get the terminology wrong etc

I've started work remodeling my small upstairs bathroom and I am planning to lay down tiles in the main bathroom floor area.

The existing floor is 22mm Plywood and seems to be in good condition.

My plan was / is to prep the floor as follows...

• screw fasten additional 12mm wbp Ply (single sheet)
• cement in Ditra (using P9 Mapei) uncoupling membrane (I'm using Kerdi Board so went with this)
• floor tiles on top (10mm trowel), tiles are 450x450

This will give a total new height to the floor of...
12mm (ply) + 4mm (Ditra & adhesive) + 11mm (tile and adhesive)... So 27mm total.

Now I'm thinking I might just ditch the 12mm ply that I've already purchased and just go straight to Ditra and then tile over it. Meaning a new additional height of 15mm.

What do you reckon? Would 27mm be a big step up / transition? Is the 12mm ply overkill given I've already got 22mm?

One thing to add - the upstairs in my house is built on engineered trusses (Attic Trusses) running at 600mm centres.

Any advice / pointers appreciated.

Liam

 

[J K Tiling Cornwall]

Hi Liam, not much point in putting plywood on top of plywood, I would go for a 6mm cement board either Hardie backer or no more ply, bedded on adhesive and screwed to the existing plywood then ready to tile 👍

 

[Liam D]

Hi Liam, not much point in putting plywood on top of plywood, I would go for a 6mm cement board either Hardie backer or no more ply, bedded on adhesive and screwed to the existing plywood then ready to tile 👍

Hi JK
Thanks for the response.
I've been watching lots of YouTube videos and one had said you need to make sure your ply base is 1 3/8 inch (American site - 35mm in real money).
I bought the ply but then Googling yesterday that seemed like overkill.
So I'll ditch the extra layer of ply.
I've already bought Ditra so will use that on top of the existing ply base and then tile on top of that.
Cheers
Liam

 

[eddcottee]

Hi JK
Thanks for the response.
I've been watching lots of YouTube videos and one had said you need to make sure your ply base is 1 3/8 inch (American site - 35mm in real money).
I bought the ply but then Googling yesterday that seemed like overkill.
So I'll ditch the extra layer of ply.
I've already bought Ditra so will use that on top of the existing ply base and then tile on top of that.
Cheers
Liam

I'd take the Ditra back aswell as it's an unnecessary expense (unless you have UFH installed) and install some 6mm cement board as suggested above. Then tile onto that

 

[Liam D]

I'd take the Ditra back aswell as it's an unnecessary expense (unless you have UFH installed) and install some 6mm cement board as suggested above. Then tile onto that

Cheers for the reply

The Ditra was £30 so I'm ok with that.

I'm still half tempted to put the 12mm ply down as it will just end up in the shed. I've got a very high shower curb (200mm) because of having to raise the shower to get enough fall on the waste. The trusses really limited how the waste pipe could run because you can't drill through them.

So 12mm off the curb would help a little.

But then I would have a 27mm transition into the bathroom which is probably too much?

Cheers
Andy