Kardean floor lifting

Hi need some advice we have recently had lvt floor put down on top of underfloor heating. (Water) then screed over the top think it was arbitex that is mixed with a bottle so no water. The floor was layed with f48 plus adhesive what was recommended by the floor company. Since the heating has been on its not started to lift on all the joints. Any ideas why ?

 

Did you have a rh test? Is it a new screed?

 

Sorry whats a rh test and yes it was a new screed

 

How long has the screed been down ?

 

It was down about 5-6 days before laying the floor

 

The new slab with the UFH pipes buried, how long was that base down before the floorlayer screeded over it?

 

The ufh is the polystyrene squares thats you stick down on top of a wooden floor and the pipes push down in the runs. Then 5mm screed over the top of that

 

Its an overlay system

 

Ah right. Whats beneath the overlay system?
Heating is probably too high. Have you lifted a plank to see if its just the plank lifting or the levelling compound lifting with it?

 

There are floorboards below it, yeah lifted one plank and it looks like the adhesive hasnt stuck to the lvt its clean underneath

 

5mm screed over the top of the boards?
Could have done with a 10mm minimum and also sounds like the fitters didn't lay your planks in 'wet set'

 

What's the name of your UFH system?

 

Also what temperature have you been running the heating at?

Did you raise the temp a degree a day or whack it straight up?

 

Was it cold when the floor was fitted?