ᐅ Monolithic Construction: Autoclaved Aerated Concrete vs. Brick

Assuming you want to build monolithically—that is, using aerated concrete or special insulating bricks—what is better, and why do so many people actually build with bricks?

I’m going to assume aerated concrete with a thermal conductivity (lambda) of 0.08, or bricks filled with perlite and unfilled bricks also with a lambda of 0.08.

The unfilled brick has very thin webs; any drilling damages the thermal insulation over a wide area (specifically where the webs break out), and there are technically inherent strong horizontal thermal bridges.

The filled brick is basically a brick with internal insulation, so it cannot truly be called monolithic anymore, but okay. The internal insulation can settle over the investment horizon (~50–70 years), meaning significant thermal bridges may develop.

Aerated concrete is truly monolithic, meaning a uniform building material (no thin webs or the like, no internal insulation—the block itself provides insulation). A real disadvantage might be sound insulation, which is not an issue here, and the supposed drawback that the material is quite soft. You can “scratch” it with a fingernail, but in practice, when installed, this apparently does not matter.

None of the materials are optimal for hanging cabinets or similar. On the one hand, our floor plan is arranged so that heavy hanging elements (kitchen, TV) probably won’t be attached to exterior walls anyway; on the other hand, there are special anchors available for everything.

Based on the facts, assuming you are building in a quiet area, I find aerated concrete the most convincing option, and it is also the more affordable building material. So I wonder why more people don’t build monolithically with aerated concrete? Of course, there are regional specialties, but in the 21st century, traditional preferences shouldn’t decide what is invisibly built between exterior plaster and interior plaster, and where in the end hardly anyone knows whether it’s bricks, external thermal insulation composite systems (ETICS), aerated concrete, or timber framing.

So why don’t more people build monolithically with aerated concrete, or are there disadvantages I have not considered?

Just as a note: 42.5cm (17 inches) aerated concrete with a lambda of 0.08 already meets the simplified KfW 55 criteria from 01.04.2016 onwards, and 41.5cm (16.3 inches) aerated concrete with a lambda of 0.06 (which does exist, but not in Germany due to low demand) meets the passive house standard with 0.14 W/(mK). But I don’t want to compare aerated concrete with other double-shell constructions or timber framing—my question is simply: why do not more people build monolithically with aerated concrete instead of insulated bricks? Provided, as often is the case, one builds in a quiet area and sound insulation is not primarily important.