ᐅ Floor Construction Screed – Tack Strip Panels vs. Schlüter Systems / Leveling Fill vs. XPS Insulation Boards

Hello everyone,

We are about to have the screed installed in our fully renovated house or floor.
The special feature of our apartment is that it has two different build-up heights: one area with 6–7 cm (2½–3 inches) due to an existing staircase, and another area of around 23 cm (9 inches) – as you can imagine, these two different heights are separated by a step. The idea was to have a proper build-up at least in one part (the living area) without needing to use thin-bed systems.

I have now received an offer from a screed company with a build-up that, as a layperson, seemed unfamiliar to me:

In the area with the 6–7 cm (2½–3 inches) build-up, a 2 cm (¾ inch) installation panel would be installed, plus 50 mm (2 inches) of heated screed with a specific additive to achieve the necessary strength. Until now, I had always assumed that you would have to use a "Schlüter" system here, i.e., studded panels or similar.

In the second area, they would level the build-up height using a cement-bound leveling fill (13.5 cm (5½ inches) high), plus a 20 mm (¾ inch) installation panel and 65 mm (2½ inches) of heated screed.
Here, I (again, as a layperson) had assumed that the entire height would be leveled with XPS insulation boards (multiple layers).

What do you think about the screed company’s proposed build-up?

Thanks for your feedback
Chris

Flitz86 schrieb:
In the area with a 6–7 cm (2.5–2.75 inch) build-up, a 2 cm (0.8 inch) staple plate would be installed plus a 50 cm (20 inch) heated screed with a specific additive to achieve the required strength. Until now, I have always assumed that you can’t avoid using "Schlüter", i.e., studded membranes, etc.

That approach is possible. There are guidelines regarding the screed’s composition to ensure that the 35 mm (1.4 inch) coverage is sufficient.
For example, with Retanol Extrem, the load table would look like this (assuming at least 30 mm (1.2 inch) pipe coverage for the smaller point and distributed loads):

Flitz86 schrieb:
In the second area, they would compensate for the build-up height with a cement-bound leveling fill (13.5 cm (5.3 inch) high) + 20 mm (0.8 inch) staple plate + 65 mm (2.6 inch) heated screed.
Here, as I said, as a layperson, I would have assumed they would compensate entirely with XPS insulation boards (several layers).

This approach is really good. Thumbs up. But: Is the load capacity of the ceiling sufficient statically? What is below the room—if it is soil or an unheated basement, insulation should be integrated into the build-up.

So does that mean a loose fill is better than a substructure made of XPS?