Floor plan single-family house 160m²

Sorry, read inaccurately. I was under the impression we are talking about Ytongg plus WDVS.

Is the wall structure set or open for discussion? The 17.5 cm aerated concrete plus 16 cm insulation should comply with the U-value KFW 40. There is potential for savings also through area savings. A 1 cm air gap should also suffice.

According to the construction specification from Blohm Bau, it is 15 cm aerated concrete, 16 cm insulation, 1.5 to 2 cm finger gap, and 11.5 cm stone (NF) or aerated concrete. That would be 44.5 cm, as confirmed to me by phone (identical for KfW55 or 40).

Cheaper would be 36.5 cm aerated concrete without insulation. Stone price higher. But an entire work step is eliminated.

Basically, I see it the same way, however: a contractor knows his standard recipe for wall construction by heart, including all connections resulting from it. At this point, avoided "better rice than croquettes" changes are, in my opinion, also avoided sources of complication. Damn it for 2 sqm floor area.

Where do the 49 instead of 44.5 cm in the plan come from?

The floor plan was created by Poort/Sittensen. Originally, we had planned with Blohm. However, there were disagreements there, which is why we switched.

The floor plan was created by Poort/Sittensen. Originally, we had planned with Blohm.

So you are now building a Blohm FAM153 with Poort (and accordingly in Poort wall thickness)?

If the contractor is changed, I also see this associated with more leniency in questioning/changing details (since the executor then cannot be irritated anywhere by always having to do it as in the base model). And of course, in the sense of my statement from #20, also the "usual" wall structure of the new contractor as recommended.

Ah, I was already wondering why you still hadn't started construction, because you apparently were already quite far along in the planning back then.