Mosaics over electric UFH & chipboard?

[J Sid]

Thanks. So I'd essentially be tanking/waterproofing it twice? Once with the Waterguard & again with the Isomat?

all depends on how you do the water guard. if you are just doing it on the deck and not doing upstand round tray and corners then I would use a uncoupling and waterproofing membrane after the ufh and slc is done and take this over the whole floor , up walls in wet area and do pipe outlets, also turn this membrane up 50mm behind skirting/tiles outside the shower are.