Tiling substrates, what do I need to do?

[Shanemac]

Hello,

 

Hoping for some advise on tiling onto different substrates.

 

I am tiling our ground floor, circa 135m² with 750mm x 750mm porcelain tiles onto a 75mm cemfloor screed with underfloor heating. The screed has been down for around 8 months and not a single crack visible, ufh has not been commissioned yet and I won't tile until it has been. 

 

Do I need to use a decoupling mat?

I've read posts saying its not necessary and others saying it absolutely is.

 

Upstairs I have 2 bathrooms to tile with 375mm x 750mm onto cabershield(waterproof coating) 22mm t&g glued and screwed onto posijoists at 400mm centres. 

 

Should I overboard this with 6mm cement board, ply or just use ditra etc as I've read both methods suggested?

 

Many thanks 

[jayc89]

For the price of the mat, why wouldn't you?

Commission the UFH first, make sure all's good, then get the screed primed and a mat laid before the tiles. 

 

Upstairs I have similar. I'm priming the caber floor (which is generously glued and screwed on 400 centres), laying UFH mat and using self leveller to bring it up to the same height as the shower former, then laying a decoupling mat across the lot and tiling. 

[nod]

Unless there is obvious cracking You won’t need matting 

If your installing a heating Matt You can put matting under it or insulated board But you can tile directly onto the self leveling 

[Shanemac]

9 hours ago, jayc89 said:

For the price of the mat, why wouldn't you?

Commission the UFH first, make sure all's good, then get the screed primed and a mat laid before the tiles. 

 

Upstairs I have similar. I'm priming the caber floor (which is generously glued and screwed on 400 centres), laying UFH mat and using self leveller to bring it up to the same height as the shower former, then laying a decoupling mat across the lot and tiling. 

Thanks for your reply.

Well the mat alone for the ground floor would be over 1k so if it was unnecessary that would be a nice saving.

6 hours ago, nod said:

Unless there is obvious cracking You won’t need matting 

If your installing a heating Matt You can put matting under it or insulated board But you can tile directly onto the self leveling 

I spoke to cemfloor and they suggested that it would likely be fine without the mat but it's become very common to use it and for that reason they would recommend it. Would different zone temperatures make a significant difference? 

 

I'm not putting a ufh mat upstairs, so just use hardie etc?

[nod]

25 minutes ago, Shanemac said:

Thanks for your reply.

Well the mat alone for the ground floor would be over 1k so if it was unnecessary that would be a nice saving.

I spoke to cemfloor and they suggested that it would likely be fine without the mat but it's become very common to use it and for that reason they would recommend it. Would different zone temperatures make a significant difference? 

 

I'm not putting a ufh mat upstairs, so just use hardie etc?

I’ve been a tiling contractor for over 30 years 15 years we never used matting Most of the commercial jobs I do don’t use it 

Make sure you give you cem floor a good scrape before you prime it 

[Shanemac]

54 minutes ago, nod said:

I’ve been a tiling contractor for over 30 years 15 years we never used matting Most of the commercial jobs I do don’t use it 

Make sure you give you cem floor a good scrape before you prime it 

Sounds good to me, thanks.

 

Is there much between the different adhesives? Where I got the tiles from recommended kerakoll h40?

[nod]

I tend to use Kellmore Flex 

Theres really nothing between any of them Except price 

I pay around £8 per bag A tenner should be your max 300 quid