Slots/openings in aerated concrete KfW 40

Hello everyone,

in our shell construction (aerated concrete 42 cm, Kfw 40) recesses for the water connections, drains, downpipes, etc. are built into the exterior walls. How deep/wide can such recesses typically be made before it becomes structurally/energetically critical?

Thanks and best regards

From an energetic point of view, such slots don't really matter.

@ : Great, thank you very much for the tables :) ... Why are such slots energetically irrelevant? Are the tapered areas in the mass negligible?

Are the tapered areas negligible in the mass?

Exactly. That will perhaps affect 0.5% of the exterior walls. And of that, there are also slots which only make up a smaller part of the wall thickness.

Just remember to insulate carefully when sealing the openings from the outside. Otherwise, the wall will discolor in the corresponding areas.

All right, thanks! What about concealed cisterns? 60 cm wide, 14 cm deep in a 42 cm wall.