as peter for me, test the grout but with 10 by 10s you will have along job on your hands i would discuss this with customer and try to steer them to a re tile
agree with you saltire dont like the sound of him tbh....however you need paid seperately and wouldnt a repair be okay? 70 quid max normally looks brand new
update direct from the plumber....
they are battoning joists and sheeting then fitting kingspan and a screed to joist height
wonder why they used to endorse ditra but not anymore?
urgh.....thanks for that up to date info johnny...customer has just told me they are screeding in the ufh also my plan was ply and then ditra.... might have to re think