ᐅ Poroton or lime-sand brick

Our concerns about the sand-lime brick solution are not directed against the brick itself, but rather the necessity of the external thermal insulation composite system (ETICS), which we actually want to avoid due to algae growth and durability issues (we have some examples in the neighborhood where the outlines of the panels are still visible).

Is it really the case that with monolithic construction using Poroton blocks, the risk of mold growth due to thermal bridges is increased? Or does ETICS significantly reduce the risk of mold because it insulates the thermal bridges?

If both methods are carried out reasonably well, there is no risk of mold...
Besides external thermal insulation composite systems (ETICS), there is also the option of cavity wall construction (brick veneer).

Thanks for the assessment! Brick veneer is visually not desired and probably too expensive.
However, thermal bridging in itself is not necessarily a reason to rule out masonry units, even though retrofitting insulation might be easier from a design perspective. Then the question arises why the architect is so strongly opposed to masonry units. After all, it is their job to design the building in a way that minimizes thermal bridges...

This is not always rational – you either believe in something or not, or you have experience with it or not.
As already mentioned here, with calcium silicate blocks and VDVS there is a functional separation, while with brick there is a combination.

Peanuts74 schrieb:
Cracks in calcium silicate bricks? You can hardly break those. You would also see them inside an unfinished basement or garage, for example...

No cracks in the bricks themselves; the cracks appear in the mortar joints and at the transition to other materials, such as the concrete ceiling.

If the bricks are not plastered or wallpapered after plastering, you simply won’t notice them. But believe me... they are there...

The construction method is completely secondary; the main thing is that the company carrying out the work is experienced with the system. If you live in the house and everything is properly installed, you will never notice a difference (except when drilling, of course). The indoor climate is the same, with exceptions proving the rule (for example, if you live on a main road and need a lot of sound insulation, sand-lime brick is probably superior).

Personally, I am a fan of functional separation, meaning masonry plus external thermal insulation composite system (ETICS) / external wall insulation (EWI), but that’s simply a matter of taste. I would have adapted to anything, as long as my general contractor (GC) had extensive experience with the system...