Decoupling membrane on self levelling

Afternoon all, I will be self levelling a 20sqm floor to a depth of 20mm using a flexi levelling compound. My question is, should I fit a decoupling membrane before tiling commences? Thanks in advance, Stu.

 

What tiles are being fitted ? Is it heated ? What room is it ?

 

Not sure as yet, customer yet to choose. There will be no UFH fitted and it’s an entrance hall.

 

Have you considered installing 20mm insulation boards?
Might be a cheaper faster option, and if you're fixing porcelain I would be happy with the uncoupling properties of the boards replacing a dedicated membrane.

 

Thanks guys.