ᐅ Opening for underfloor heating accidentally filled with expanding mortar

Hello everyone,

A brief description of the problem: Today, while I wasn’t present, fortunately a family member helped out at the construction site. The opening for the underfloor heating pipes to the basement was closed. Unfortunately, not with screed concrete, but with expansive mortar. I should have explained it better beforehand. The packaging states “non-expanding, non-shrinking.”

I’m not very familiar with the properties of building materials, but I understand expansive mortar to mean that it expands slightly. Is there a chance that the mortar could damage the underfloor heating pipes by pressing on them? Or is my worry a bit exaggerated? I’m a little panicked…

Thanks and good luck

So basically, you’re saying it is neither shrinking nor expanding. That means it does not expand either, so nothing should really happen there. As for whether it is otherwise suitable for the application, I prefer not to judge. However, it should not damage the pipes of the underfloor heating system. It is usually used exactly where you want to avoid the mortar shrinking while drying.

Without being an expert, I would also want to press the safety release button.

Firstly, because it says "quillt nicht" on it,
and secondly, because pipes are extremely durable due to their round shape.

🙂

Hmm. Swelling mortar expands. Not as much as foam insulation, of course. But it does expand slightly, which is why it’s called that.
I’m not too worried about damage to the pipes from the swelling itself. More so from the heating?

Screed for underfloor heating usually has fibers mixed in to allow for movement. Swelling mortar doesn’t have that. That’s where I would have some serious concerns.

This concerns pipe penetrations between two floor levels.
These penetrations have now been sealed or are in the process of being sealed. Whether you use an expanding mortar or a repair mortar is actually irrelevant from the task perspective. Any reasonably strong mineral-based mortar can be used, as long as there are no fire protection requirements.
The mortar should not be in direct contact with the pipes. If the pipes expand during heating operation, they are restrained there and may detach with a more or less loud cracking sound. When the heating system restarts in the early morning hours after the night setback, this can be audible.
Screeds, including heated screeds, can be installed without fiber additives (what a term!). Fibers do not serve any purpose in terms of the screed functioning or "working."
Fibers have only one purpose during the drying phase: minimizing cracks (not preventing them!). Cracks cannot always be avoided in mineral construction components, especially those based on cement.
It remains to be emphasized (as already stated by "ateliersiegel"): Press the calm-down button :-)
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Greetings to all: KlaRa