KfW 55 Single-family house - Brick or Ytong?

You’ve already given yourself the answer. Have the contractor check whether he is allowed to build with Ytong there, and then that’s that.

In general, you can say that you will get five different opinions from five different people regarding the brick/Ytong topic. Some swear by Ytong, others will tell you that the stones create a oppressive room climate. You write that you know someone who has built with Ytong. If you feel comfortable there, then you already have your answer.

Yes, similar to controlled residential ventilation... There is also no uniform and "correct" opinion here. But yes, we would have gone with bricks anyway, because we simply feel "more comfortable" with them. In the end, you just have to decide on something.

You still forgot to discuss the breathable diffusion-open walls...

Generally, you can say that you get five different opinions from five different people on the brick/Ytong topic.

Two of these opinions are quite relaxed user reports on each of the different stones, and the other three are hate speeches about which stone is the only true one and that the others might as well all go home, if not straight to hell. It's the same topic with interior walls, and many others as well.

You still forgot to discuss the breathable diffusion-open walls...

But yes, we would have gone with bricks anyway, because we simply feel "more comfortable" with them.

From beech smoke, from Rügenwalder Mühle, or hand-crafted from free-roaming clay lumps This is truly a more emotional thing than could be captured in conventional medical Excel tables, and (one could quote Wowereit).