I'm fitting limestone tiles 900x600 using keraquick over UFH with schluter ditra matting and reading the mixing ratio says about potentially using mapei latex to make it s2 when using large format tiles (over 600x600) but from my research I've only come across needing it to be S1. Is that because of the ditra etc where as s2 can be used for wooden floors?
Cheers
Cheers