K
Kaltluftfan21 Nov 2025 11:57Hello everyone,
Until now, I’ve only been a silent reader, but today I have a problem to share:
We have a solid concrete house built by a general contractor, with a concrete staircase. This staircase needed a temporary railing installed right away for accident prevention. The structural builder installed this railing immediately after the staircase was placed. The method used was to set beams directly on the floor slab, which then extended upward through the entire stairwell opening. After that, bitumen was applied, insulation, underfloor heating, and screed were installed. Now, just before laying the parquet flooring, this railing has been removed from the floor. There are now deep holes visible down to the floor slab. Our site manager dismisses this lightly, saying they will just fill the holes with concrete. I find that hard to believe... what would be the professional way to properly close such holes? Even with cracks in the screed, considerable effort is made, so I can hardly imagine it being that simple. Issues like moisture and thermal bridges come to mind...
You can see the floor slab directly, and in one hole there is even a piece of wood... how it got in there is a mystery to me.
Thanks to you all!
Until now, I’ve only been a silent reader, but today I have a problem to share:
We have a solid concrete house built by a general contractor, with a concrete staircase. This staircase needed a temporary railing installed right away for accident prevention. The structural builder installed this railing immediately after the staircase was placed. The method used was to set beams directly on the floor slab, which then extended upward through the entire stairwell opening. After that, bitumen was applied, insulation, underfloor heating, and screed were installed. Now, just before laying the parquet flooring, this railing has been removed from the floor. There are now deep holes visible down to the floor slab. Our site manager dismisses this lightly, saying they will just fill the holes with concrete. I find that hard to believe... what would be the professional way to properly close such holes? Even with cracks in the screed, considerable effort is made, so I can hardly imagine it being that simple. Issues like moisture and thermal bridges come to mind...
You can see the floor slab directly, and in one hole there is even a piece of wood... how it got in there is a mystery to me.
Thanks to you all!
Hi,
the holes look like someone worked more by feel than according to a plan. Simply "filling them in" is quite a bold statement, since you want to avoid both localized thermal bridges and later settlement issues under the floor. Ideally, you should first remove any loose debris, then fill the cavity with suitable insulation (PU mounting foam / rigid mineral wool), properly seal it with a vapor barrier, and finally level it up to the screed edge with a fast-setting repair mortar. By the way, I would remove the piece of wood before it starts to rot over time...
the holes look like someone worked more by feel than according to a plan. Simply "filling them in" is quite a bold statement, since you want to avoid both localized thermal bridges and later settlement issues under the floor. Ideally, you should first remove any loose debris, then fill the cavity with suitable insulation (PU mounting foam / rigid mineral wool), properly seal it with a vapor barrier, and finally level it up to the screed edge with a fast-setting repair mortar. By the way, I would remove the piece of wood before it starts to rot over time...
T
Teimo198824 Nov 2025 22:38I would also clean it thoroughly, then coat it with bitumen (I think there’s probably not enough space for Katja), then install insulation like under a screed (looks like EPS plus a fixing panel), and finally pour the screed. I would connect the new screed to the existing one using mechanical connectors. This would be my layperson’s solution that I would feel confident about.
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