New floor slab in an old building, experiences?

  • Erstellt am 2025-08-05 13:57:50

Nauer

2025-08-05 16:35:12
  • #1
You are already doing the sectional underpinning correctly, but be sure to ensure that a keyway is created between the concreted sections so that the new foundation remains rigid and force-locked. If in doubt, with clay this can also be easily solved by simple notches in the existing structure – this way the whole thing couples better later and you reduce the risk of settlement.

Regarding the question of water management: moisture relocations in the subsoil can usually only be roughly estimated in existing buildings. One possible approach is to carefully document the course of layers, any existing old plaster or discolorations in the soil, as well as the capillarity of the surrounding clay. More than that, observing over several months by creating small trial pits and temporary moisture sensors, is not possible on your own.

Pay very close attention to the penetrations, e.g. in installations, and do not forget the wall connections in detail – are the planned vertical rises accessible from the outside or are you working purely from the inside?

Good luck!
 

manu986

2025-08-05 19:03:17
  • #2
Oh dear, I will never manage the water drainage. I will have to think of something else or get a professional company involved. It’s really not that easy to completely renovate an old farmhouse. I am only working from the inside. Later, I will set a strip foundation on the outside so that I have space for insulation and a new brick wall (2-layer masonry) on the affected wall.
 

DoTrouv

2025-08-06 10:23:11
  • #3
There is also an interesting YouTube channel. He has been working on his construction site for years and has shored up the half-timbered house in sections, excavated soil, refilled it, and then poured several concrete foundations. You can take a look, maybe there is something helpful. The construction project is comparable to the building of the pyramids for me; the guy has stamina.
 
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