Amtico floor failing on concrete substrate with central heating pipes underneath

Hi


I’m looking for advice about two issues we are facing with our Amtico floor.


We recently renovated the property which was build in the late 1950s. We moved a radiator in the living from an internal wall to the bay window area and since it’s a concrete substrate we grinded out two 50mm deep channels across the room to where the new radiator was going. Pipework was done by a plumber who used push fit connectors with plastic piping, attached to the existing copper network and wrapped any new/existing copper pipes in preparation to lay concrete in the channels.


I tested the heating over the next 24 hours to ensure no leaks or other problems. Concrete was then laid in the channels over the same weekend.


We let the concrete dry out for around a week before our amtico installer laid a self levelling compound. For reference he used Mapei Ultraplan Fast Self Levelling compound which is between 3-10mm.


The floor was then laid nearly two weeks after the self levelling compound was applied which finished around mid October 2024.


Now for the first issue. About two weeks after the floor was installed I noticed an area near where old radiator valve was, that the adhesive was failing and the floor was coming up. When I peeled back the floor I could feel moisture. My first thought was leak and immediately checked the boiler to find the pressure hadn’t dropped. I then kept checking at different intervals but still no drop. I called the installer out and he advised it could be due to the concrete not setting fully before the screed was applied and the heat from the pipes meant moisture was rising and couldn’t escape through the LVT - to which I thought was plausible. Anyway he lifted up the Amtico for the affected area, scraped away the glue and agreed that I would heat the floor top and bottom to dry out the moisture. I was using a combination of the central heating and an electric heating from above.

This seemed to cure the issue and left the area of the floor open for around 3 weeks after drying it out and bear in mind it’s now nearly December 24 so I’m using the heating everyday. Throughout this process I was also checking the boiler everyday to monitor any loss of pressure. The surface remained dry throughout and couldn’t feel any dampness


The installer came back out and repaired the floor and thought all was well.


Fast forward to February 25 and that same section has started to come away again and felt moist underneath. I’ve been checking the boiler and not seeing any loss of pressure.


I feel at a complete loss of where to turn next and have many questions in my head of the endless things it could be.

Do i speak to the plumber or the installer of the floor? Did he use the right adhesive for floors with central heating pipes running underneath? I just really don’t know.


And now to make things worse there is a slight raised bump starting to appear where the other channel is and now fear I have another issue which may get worse.


I fear both issues will cause destruction and cost and it’s in our living room and very difficult to do with two young children without disruption to daily life.


I’m looking for any advice on how to properly diagnose the problem without grinding out the floor again in the first instance. Also if anyone else has experienced these issues and if/ how they resolved them.


I’m also worried about the cost implications even though i don’t feel like I’m liable when I’ve used a plumber and installer to complete the works.


Sorry it’s a long story but wanted to give as much detail as possible so everyone can understand the problems.


Thanks in advance.

 

Well the 1st question is was the sub floor from the 1950s or has it been relaid after say after 1980 ?
If the answer is 1950s sub floor it won’t have a visqueen damp proof membrane. So the fitter should of put a liquid one down like ardex DPM1c before the smoothing compound ( Mapei )

also the 50mm concrete would take a lot longer to dry out then a week. Sounds to me that the installer didn’t test for moisture so in my book shouldn’t be laying LVT

 

Exactly what Daz said, was there any moisture readings taken to see?
Besides that, it should have had a Liquid Damp proof membrane laid before the Mapei and with the 50mm channels, what mix (sand & cement?) was used to fill these channels?


Have you any pictures of this hump that's appearing?

Have you have it a tap with your knuckle etc to see if you have any hollow sounds?