ᐅ Leveling compound for existing bituminous screed

Hello everyone,

We are currently renovating a house built in 1969. Under some floor layers, we found mastic asphalt screed. Yesterday, the screed on the upper floor was milled to install underfloor heating. Now our question is: Which leveling compound is compatible with mastic asphalt screed? Has anyone done this before? Can anyone recommend brands/products or similar? What should we watch out for?

I have already searched the forum a bit but didn’t find anything suitable. I only found information about newly poured mastic asphalt. However, if I have missed a relevant topic, please let me know!

Thank you very much!

Drossel schrieb:

Yesterday, the upper floor was milled to install underfloor heating. Now our question is: Which leveling compound is compatible with the cast asphalt screed?

What does the contractor you hired for the job say? Most leveling compounds should work – check the product specifications.

However, the question I have is different. Usually, your screed is 30mm (1.2 inches) thick. If you have milling grooves for the underfloor heating, this screed – to put it bluntly – is no good anymore. It will crack and break under any kind of load at various points. It needs to be removed, and the entire job should be done properly.

SaniererNRW123 schrieb:

What does the craftsman you hired for the job say? Most leveling compounds should work – just read the product descriptions.

However, the question I have is different. Your screed is usually 30mm (1.2 inches) thick. If you have grooves milled into it for the underfloor heating, then, frankly speaking, this screed is not going to hold up. It will crack and break under loads in many spots. It needs to be removed and the entire thing done properly.

The craftsmen milled the grooves, installed the underfloor heating, and then left. We do almost everything else ourselves, including the electrical work and plastering (the electrician is professionally trained, of course). I need to check how deep the screed actually is. But the company is specialized in this, and they would probably be out of business by now if the screed broke after their work, right? Still, I will take another close look, thanks for the tip.

Drossel schrieb:

I would need to check how thick the screed is.

The standard thickness is 30mm (1.2 inches), single layer up to a maximum of 40mm (1.6 inches) is allowed.

Drossel schrieb:

But actually, the company specializes in this, and they would probably be out of business by now if the screed cracked like that, right?

It depends on the exact scope of work commissioned. I would also talk to the guys beforehand. That’s what they specialize in. And if you can measure or know the floor construction (maybe it’s a composite screed directly on a concrete slab), that also helps.