tiling Is a decoupling membrane needed with liquid screed + wet UFH + porcelain tiles?

[Jeezeeh95]

Building a new house and next is insulation & wet UFH, followed by liquid screed (then wait 28 days before tiling)

 

We'll be tiling all of the ground floor with the above set-up (wood effect porcelain tiles 120cm x 20cm) across 101m2 of floor area downstairs, however I'm not sure if it's necessary to spend £1k for Ditra Mat or some kind of membrane as well?

 

Some tilers said I do, but most have said it's not necessary if using liquid screed - my questions for you guys are:

 

• Do I need a decoupling membrane? If so, which one would be best for my set-up as there is a lot of choices (Dira, Durabase, Mapetex, Strata etc)
• Is there a special kind of adhesive I need to use with liquid screed? (e.g. Kerakoll H40 Gel Adhesive etc)
• Apparently liquid screed creates a layer on top which needs to be sanded down, is this required or can a membrane be laid straight on top?

 

Any help appreciated!

[JohnMo]

  On 09/04/2025 at 07:56, Jeezeeh95 said:

liquid screed

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You may need to include the screed type as the screed make up will affect the answers you receive I suspect.

[nod]

No

Thats the whole point of liquid screed 

 

[Beau]

We had an anhydrite liquid screed and tiled straight on to it. I did have to grind the top and prime it but no decoupling membrane which sounds weird as surly you need the tiles bonded to the floor anyway 

Edited April 9 by Beau

[nod]

To be fair 

I tile a lot of commercial jobs in traditional screed that have no decoupling Matt and most liquid screed are tiled within a week of being poured 

Hardly ever any problems with modern adhesives