I just had a look at the job - the substrate is a sand &
cement screed or self-levelling. There is UFH in the two bathrooms, which have a small control panel on the wall outside so I assume that UFH was used with self-levelling over the top. However the method of applying adhesive was dot & dab, I think it's called, so I assume that this is the cause of the tiles to working loose ?
These are 600x300 stone tiles so would it be practical to clean the adhesive from the back and relay ?
Also,
The depth of the tile and adhesive add up to about 30mm and I 've got to maintain the same depth - does that mean using more self-levelling and then tiling on top? If so how easy is it to be that precise with the self-levelling ? Given that the tile is say 10mm, the adhesive say 6mm, that would leave 14mm to make up.
Hi Fad, it sounds like you have quite a job there, and good chance to come out smelling like a rose in the eyes of the client. Once you have sorted out this mess that the previous tiler made of this job you will be looking like a pro to them.
One idea I had to deal with the 14 mm you need is to use SLC and to calculate the volume needed to fill the area you have X 14 mm in depth. THe bags of SLC should give you the volume per bag and then it's simple math to figure out the rest. Figure out how many bags per room, mix and pour only that amount.
On one job we had last year, we had todo the same thing. The subfloor was so irregular that I couldn't do an estimate of number of bags so what I did was use my laser and epoxy small bits of
tile (approx 2" X 2") down to the concrete, maintaining the height of the top of each in relation to the laser line. I used epoxy only because it set up fast, but if you don't have epoxy use a good setting material and give it a day to cure.
Then, we applied the primer in the normal fashion, including on the sides of the little monuments that we had made with the
tile and epoxy. We poured SLC on the whole thing and just poured and pushed it so it just barely covered the top of the monuments. That way, we got the floor very, very close to where it needed to be.