Same price: Kfw55 with Poroton monol. OR Kfw40 with Poroton WDVS?

Already done in the meantime ;) Don't know how much 5 db make, but the difference is there.

6db more noise is a doubling of the sound pressure - very clearly audible to your ear (with 10db the noise level doubles for the ear). So conversely, 5db is a massive (positive) change in noise protection.

I would always choose the version without plastic special waste on the facade. Especially because the masonry in such ranges (0.08 lambda is really good, the equivalent in aerated concrete is Ytong Thermsuper) is no longer decisive. Then the windows come into focus.

With me, the windows "lose" about as much heat as the masonry (Porit 36.5 lambda 0.09). The windows only make up about 20% of the facade area.

And the noise from the neighbor's garden comes through the windows and over the attic with suspended ceiling and mineral wool...

We have come quite far by now and a provider has now designed our house for us

and unfortunately you have not shown it here (?)

and at our request created several offers with different masonry for us.

I hope you have considered the 11ant Steinemantra and have not asked him for variants with which he has no routine. A typical builder has two wall constructions that he processes as standard. If A and B are distributed approximately 60:40 or 40:60 among the houses he has built, one takes A or B equally well. With a ratio of 3:1, I would already clearly prefer the more frequent variant. Under no circumstances would I take X or Y (which would both be a premiere for him) or exchange the stone or one of the two shells of the wall within A or B for an unfamiliar product (unless it was only about an upgrade, i.e. opting from a standard unfilled stone to its filled variant). In this sense, in my opinion, it would always be the deadliest own goal if the builder offered "everything you want." For fun, I would ask such a candidate to explain the term overlap measure in layman's terms (or to "query" any processing specification).

Is it such a problem if the construction company only builds the more specialized masonry maybe 5 times a year instead of 50 times? Especially since you can regularly have an expert closely monitor the construction company if you want it done perfectly... How many cases do you know of where the construction company really screwed up and made serious mistakes that they then had to fix?

Is it really such a problem if the construction company only builds the more specialized masonry maybe 5 times a year instead of 50 times? Especially since you can regularly keep an expert on their heels if you want it perfect...

Who is more likely to grill a steak perfectly... the one who does it every day or the one who only throws one on the charcoal grill in summer occasionally?

Routine allows working at an economical speed without (major) mistakes. And in craftsmanship, the work consists of 90% routine.

With the expert. Sure, you can send the steak back from the charcoal grill until it’s just right. But why put yourself through that stress? It’s better to just go straight to the steakhouse.

Oh, and it’s not like the masons stand at attention and nod understandingly when the expert comes. Often the construction site comes to a halt until the legal issues are resolved. That can sometimes take years.

Is it such a problem if the construction company only builds the more specialized masonry maybe 5 times a year instead of 50 times? Especially since you can regularly keep an expert closely involved with the construction company if you want it done perfectly...

The expert initially acts as a companion, good planning already works preventively. Even a single-family house with a straightforward floor plan has about a hundred and ten corners where various materials meet. You can look for the thrill everywhere, but you don’t have to. Take, for example, stones with very different weights; for comparably manageable weights alone, you get completely different sizes—or vice versa: with similar specific weights and different dimensions, different techniques and tools are needed for their laying. If a construction worker doesn’t have the appropriate tool at hand, they’re more likely to improvise with something unsuitable than to go get the correct one. A classic case is using the bag of "we-always-use-this" mortar for a stone with totally different processing specifications. There is so much underdeveloped awareness bordering on criminal negligence that "perfection" would already be a completely wrong category, judging by the possible extent of the consequences.

@11ant How many cases do you know where the construction company really messed up badly and had to fix serious errors afterward?

For two reasons, “personally” meaning “firsthand” or with “my” clients, none at all. The first reason is “prevention” in the form of selecting contractors, whom I always regard as a system of techniques and materials. The second reason is simply that I am not a building damage expert, and such cases never come across my desk. Unfortunately, I know of many cases from this and other forums. Just enter the terms "overlap length" or "professionally done" in the forum search here, and you’ll get an indicator of the culture of carelessness in shell construction and component joint fabrication. Especially with wall and floor coverings, customers often increase the risk by wishing for à la carte materials and/or an extravagant installation method (or a hyper-format).