Wet screed causing lifting LVT - HELP

We had anhydrite screed installed in our house in October last year. We then followed the maintenance and drying guidelines, removing laitance and speed drying with UFH. Sadly, we’ve since had luxury vinyl tiles laid which are now causing ongoing issues with tiles lifting.

Our floor layer believes the issue to be a damp course issue at our bi fold doors- to be fixed by our builder before the entire floor is ripped up and fixed at our cost. However we have since had unbiased opinions from two professionals, a damp courser and another more experienced floor layer. Both of which are sure the issue is down to the screed not being dry enough for a floor covering and there being no damp course issues present. On inspecting the lifting floor tiles the floor layer could immediately identify the issue due to the laitance present (which was originally removed within 2 weeks of the screed being laid). We have also confirmed there is no issue with leakage from the UFH.

A brief history - after 7 weeks of the screed being pumped in and 1 hygrometer test (in the center of the house), our floor layer deemed the screed dry enough for the floor to be laid. We now know this is not sufficient testing for a 90sqm area and numerous boxes should have been placed around the area, for longer periods.

I am really looking for more experts advice/standards on anhydrite screed and hygrometer testing for floor coverings. OR even point me in the direction of any associations else? I ask for this information because as it stands the floor layer is now denying any responsibility or fixing the problems at their cost.

For example, one solution the floor layer provided was to rip the floor up, lay a DPM to avoid any more moisture rising up and then lay the floor on top, again of course at our cost. On talking to a more experienced floor layer he mentioned that he wasn’t aware of DPM being used on anhydrite screeds with UFH and that this would not be a suitable option?

 

Does look like its blown.
90m2 - should have had atleast 4 or 5 areas tested and not just one in the middle.

Seen a lot of anhydrite floors that have apparently been grinded but it was only every 'ran over' quickly with a copper plate.

Few planks need taking out and floor tested for moisture properly then go from there....

 

One of my costumers paid a firm to grind his after 4 weeks of it being laid.
They used a sanding disc

 

Preparation fail, 100%

 

Thanks all, i've since spoken to the floor manufacturer and the screed company.... turns out the floorer should have primed the floor with a suitable primer before using ardex na latex - this doesn't mix well calcium sulphate floor hence it not bonding to the screed and the floor just blowing. The primer provides a barrier.

So not only do I think the floor wasn't tested well enough in several areas with a hygrometer, but also I don't BELIEVE it was primed. Not sure how I prove that one, would I be able to visibly see a primer? Screed company are certain in wasn't primed from the photos I sent.

On my research anhydrite screed can be a beast to work with, but it is most definitely down the floor layer to know about preparation and testing of anhydrite screed - not me the homeowner. Even if he thought it was sand and cement i'm led to believe you can easily tell the difference between them by colour.

Also, he has given an incorrect solution... a DPM between floor and screed is a no no on heated screeds!

 

Primer would still be useless if subfloor still contains moisture. NA can be used without a primer but I never, I always prime regardless.

So what is your floorlayer saying now you have put this to him?

You are correct, it is down to the floorlayer to use the right materials accordingly but unfortunately you get plenty of them out there that will talk a good job, give you all the confidence you need and then blag it

 

You'll be able to see if there has been a primer used by checking the blown screed

 

I've been advised by the screed guys (and sent a data sheet) that Ardex NA is incompatible with calcium sulphate floors and does need a primer. I haven't put over my argument to the floorer yet. Just getting an email together. But having spoke to the manufacturer, screed company, another floorer and a damp courser i'm not sure what more I can do! Like you say, it is down to him to correct it at his cost. I think anhydrite screed it new to him so he'll have to take this as an expensive lesson!

What would the primer look like/what am I looking for on the blown screed?

 

Lift a plank up and look at the back of the compound that’s stuck to the back of the plank. You should see a film layer (normally coloured). Can you show us a pic of the subfloor after the plank has been lifted?

 

Is the attached ok?? All I have on my phone at the mo....

 

Not even a pva used

Your floorlayer is going to have to take the hit on this one and as you say an expensive lesson learnt. If he is a decent guy he'll hold his hands up.

I'm doing one next week funnily enough that a company did and left it to the floorlayer to sort out, now he's gone AWOL and wont return calls. Near 60m2 of a whole ground floor. Pure disruption and customer is ready to hang himself but it's got to be done.

Grinder ready for some action.

You'll need the whole lot ripping out and starting again

 

Pictures not the greatest lol, but as far as I can see there’s no primer. I think I can see pinholes in the smoothing compound on the back of the tile, which wouldn’t occur if the subfloor was sealed properly

 

You'll see a primer was used but no grinding was done to the calcium sulphate floor

 

Bloody hell he must have used some bags there! The compound looks at least 5mm thick

 

It looks ground to me