ᐅ Grooves/Cutouts in aerated concrete for KfW 40 standard

Hello everyone,

In our shell construction (aerated concrete 42 cm (16.5 inches), KfW 40 standard), recesses for water connections, drains, downpipes, etc. are being built into the exterior walls. How deep/wide can such recesses usually be made before it becomes critical from a structural or energy-efficiency perspective?

Thanks and best regards

From an energy efficiency perspective, such chases are generally not significant.

@nordanney: Great, thanks a lot for the tables 🙂 ... Why are such slots not relevant for energy efficiency? Are the tapered sections in the mass negligible?

Markus254 schrieb:
Are the tapered areas in the mass negligible?

Exactly. That might affect about 0.5% of the exterior walls. And within that, there are also slots that only make up a small part of the wall thickness.

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

All right, thanks! What about concealed cisterns? 60 cm (24 inches) wide, 14 cm (5.5 inches) deep in a 42 cm (17 inches) wall.