Thin cracks appearing in latex laid over ufh

[Maiky]

Hi all,

We’re in the middle of a garage conversion and have run into some flooring issues.

The builders removed the old floor and screeded over the garage area to bring it level with the rest of the space. A DPM was added below the screed. We then installed Wunda underfloor heating boards ourselves, which were glued down securely using specially bought glue as we read reviews suggesting the wunda supplied glue isn't particularly strong, before the builders covered everything with latex.

Within a few days, cracks and small dips appeared in the latex (see: cracked latex). The cracks aren’t wide, no more than a 0.5mm, but they seem to follow the lines of the UFH pipes. The builder suggested possible movement in the UFH boards, but that seems unlikely as they were firmly glued down. The only areas where pipes weren’t perfectly flush were in the bends we cut ourselves, but most cracks don’t seem to line up with those spots.

My main concerns are:

1. Should we be worried about these cracks affecting the final LVT floor?
2. Is there a way to determine whether these are just cosmetic hairline cracks or a sign of something more serious?
3. Any ideas on what might have caused the dips and cracks in the first place?

Thanks in advance for any advice.

 

[cross thread]

Was the underfloor pressurised befor and during the top covering being laid

 

[dazlight]

So start with the screed. That went down with a visqueen Dpm under it
What date was that done ?
The the UFH on top direct ?