Is the cement screed correctly laid as a leveling compound?

Hello dear community,

I urgently need support here in evaluating the work carried out on my house.

Initial situation:

Due to a low construction height, I decided on a BH system from Schlüter (Bekotec-Therm).
For this, the old covering including screed was removed.
Unfortunately, the floor was not level enough here and a leveling had to be created so that the BH can be laid cleanly to prevent possible tension.
For this, surface heights of 0-40mm were leveled. Due to the heights, the screed layer chose screed cement.

The floor is level here, but at the spots where the height did not need to be balanced, it was naturally left open. At these spots, an attempt was made to level the screed to 0. The surface is presumably not designed for this and crumbles off at these points.

The following steps still need to be carried out:

[*]5mm impact sound insulation will be laid on the leveled floor
[*]BH will be laid
[*]Self-leveling screed will be poured

I would like to make sure that everything has been implemented correctly before the next steps are initiated.

What do you think about it?

Thanks in advance.

Hello questioner.
Leveling layers must firmly bond with the substrate!
There are absolutely no exceptions or IFs or BUTs.
If the layers have come loose, everything must be sanded down again.
Simply laying impact sound insulation on top is technically nonsense and uncompromisingly WRONG!
We furthermore only need the system elements from Becotec Therm, no additional underlay membranes (this regarding the topic "impact sound insulation 5mm").
Regards: KlaRa

Hello KlaRa

Thank you for the feedback.

We only require the system elements from Becotec Therm, no additional underlayment membranes (regarding the topic "impact sound insulation 5mm").

--> Which system elements are you referring to exactly?
I assume you work for Schlüter.
Therefore, impact sound insulation is pointless here. Can I find this somewhere on the manufacturer's website or which substrate is required or recommended here?

Leveling layers must firmly bond with the substrate!
The screed is only loose in places where it was leveled down to zero. Everything else is firmly bonded.

Hello KlaRa

Thank you for the feedback.

We only need the system components from Becotec Therm, no additional underlay membranes (regarding the topic "impact sound insulation 5mm).

--> Which system components are you referring to exactly?
I assume you work for Schlüter.
Therefore, impact sound insulation is pointless here. Can I find this somewhere on the manufacturer's website or which substrate is needed or recommended here?

Levelling layers must bond firmly with the substrate!
The screed is loose only at the spots where it was levelled down to zero. Everything else is firmly bonded.

What would you recommend here as a levelling (material)?

Hello " ". No, I am not an employee of Schlüter-Systems KG, but a completely independent, öbv expert for floor constructions. All loose parts of the screed must be checked for adhesion by gently tapping with a medium hammer. Where the screed layer breaks off, it is primed again and leveled with a filler compound. Since screeds work with a maximum grain size (8mm), such a mortar can never be leveled "to ZERO". In any case, check (although this cannot be your task) the surface flatness with a correspondingly long spirit level or a torsion-free metal L-profile. The system elements of Beotec-EN 2520 consist of the screed stub plate BEOTEC-EN and a plastic-modified leveling compound. The stub plate is usually installed on an already existing, often old load distribution plate. This means, in residential construction, that the actual impact sound insulation is located beneath the screed. Everything that is built on as subsequent underlayment membranes should, in my opinion, not be allowed to bear the term "impact sound insulation." But that would go too far here to provide the reasoning for it. Regards and success: KlaRa