how flat does a floor need to be for LVT / Amtico?

[Colin Green]

I've just had under floor heating installed down stairs. They used latex self levelling compound over the top, but with my 1.5m spirit level on the floor, there are hollows up to 6mm deep in the middle. How flat does the floor need to be for vinyl tiles? Will small undulations like this be a problem or does the floor need to be rectified?

 

[cross thread]

The company that did mine certainly would not fit to that floor, they filled everything till flat.

 

[crazydaze]

The Amtico needs 10mm depth between itself and the UFH and you must use High Temp Adhesive.

As for level, if the surface is smooth, the Amtico will stick ok, but obviously undulation is'nt really ideal and a well, self levelled floor should be pretty flat.

Whatever self levelling you are using, identify what the builders have used to bury the UFH. If it's a Anhydrite or Calcium Sulphate Screed, it's imperitive this has had the latence ground off. If it's either of these and once ground, you'll need to take moisture readings with a hydrometer box before you can screed. If it's a regular screed, again, you'll need to take moisture readings to make sure it's dry enough to be able to self level over.

Make sure your self levelling screed is compatable with whatever is over the UFH!

Make sure the UFU is off for 72hrs before install and follow Amtico's guidelines for turning the UFH on after install to avoid potential issues.