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?

  • Phil Gledall


    Did the contractor remove the laitance from the screed before priming? This is the thin film that forms over the top of the screed.

    Ideally this should have been brushed off a day or two after the screed was laid. If it was not done then he should have used a floor sander to do this before applying the primer.

    Also, we always use a de-coupling membrane such as Dural Durabase when tiling over UFH on anhydrite screeds.

  • Kevin Ashton

    We have the same problem on a 90 sq m project. Recently had meeting with all involved, from screed supplier, screeder, plumber (UFH) adhesive supplier & tiler. I suspect that the screed has not been sealed correctly and that moisture from the adhesive has soaked into the screed, once the heating was turned on in December 2014 the tiles started to pop and lift within a week of moving into our new house. We are now in the process of trying to resolve this problem and have agreed with the adhesive supplier and the tiler to re-tile an experimental area using the screed manufacturers own adhesive, which I did advice the tiler to use. Once this has been carried out, the plumber is going to reheat the floor as per manufacturers specifications. Prior to completely retiling the full area we are going to leave the experimental area for at least 2 months to ensure that we do not have a re-ocurring problem. If you wish to contact me direct please do at kevin.carrgate@btinternet.com


    There is a product called Fix a floor which can be used for the problem of loose tiles. I believe this can be used on porcelain tiles as long as you can drill a hole in the grout around the tiles you inject it underneath without removing the tiles or having the nightmare of buying new tiles. http://www.fixafloor.co.uk have some videos that are quite interesting, It may well solve your problem

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