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Tiling

Why are my porcelain floor tiles over underfloor heating lifting?

Anonymous user 28/02/2024 - 3.10 PM

I have a kitchen extension with wet underfloor heating encased in screed. Porcelain tiles were laid onto the screed using a proper adhesive & spreader. When the tiles had been laid the UFH malfunctioned and switched on permanently over a weekend (there was no-one home). Within 6 months the tiles started to lift. 2 years later the UFH stuck on again for 24 hours. Questions: 1) Is the problem likely to be caused by the initial or later UFH malfunction? 2) Is it possible that the later UFH malfunction has made matters worse? 3) If UFH jams on, is it likely to cause tile adhesive to fail, even several years after the tiles have been laid?

Are you a tradesperson and able to answer this question?

2 Answers

Anonymous user

The problem is that the tiles have been fixed direct to the screed there should have been a uncoupling membrane such as Schluter ditra uncoupling mat laid before tiling, which takes up the movement as the floor expands ,there is only one solution and that is to remove the tiles, and also the UFH should not of been switch on for 2 weeks and then gradually increase the temp giving the adhesive time to set to its tensile strength preventing thermal shock which can result in the floor failing.

Answered2 February 2015

J Davies Installations

Rating: 4.9 out of 5

Stockport

When you lay tiles on underfloor heating the heat should be increased slowly over a 4-6week period, if the heat is cranked up to the max there is a risk of tiles lifting, have you lifted a tile to see the if the screed is still intact? Screed often gets large cracks through it which is why I and most professionals use a crack suppression matting which is stuck to screed with tile adhesive then tiled on top of this guarantees your hard work and time of laying the tiles, once tiles have been down for 6 weeks+ you should be able to have the floor blaring hot 24/7 with no risk to tiles.

Answered24 January 2015