I have just completed a self build using a Main Contractor. Having moved in a month ago we’ve called the Contractor back to look at a problem which is appearing with our 120 sq m of Porcelain Tiled ground floor. About 5% of tiles are coming loose. The symptom is a clicking noise when we walk on them. The Contractor having looked at the issue agrees that we have a problem which could be far reaching – but he doesn’t know why tiles are coming unstuck.The adhesive is well bonded to the tile but not so to the flo-screed floor. The Contractor followed the procedure below:-
1) Screed laid on the 11th of November. (Screed supplier recommends a drying time of 1mm per day)
2) Underfloor heating turned on 17th of December. Optimum running temp reached by Christmas and then slowly reduced to be able to have zero heat by tile laying start. 2 industrial dehumidifier’s used all the time. Tiled zones not warmed back up for 2 weeks and then only to the minimum boiler running temp.
3) Moisture readings taken during first week of January with a ‘green light’.
4) Floor prepared as per written specification from screed supplier.
5) Priming and tiling of floor commenced from 12th January by experienced professional tiler. Adhesive used was of a flexible type (Weber rapid set SPF I believe) and the primer also by Weber was AD250.
The tiles are large – 80cm x 80cm but otherwise unremarkable. They are laid over a relatively large area – 120 sq m. The tiler was very experienced and we paid a high price to have him do the job.
We’re all mystified as to why this is happening. Of course expansion and contraction have been considered but we can’t come to any conclusions. Everything seems to have been carried out correctly. Can anyone see a fault in our procedure or point to a possible reason for the tiles not remaining properly adhered to the flo-screed below?