so now I am back again.... and hopefully was able to gather my info between the lines
Why we have the choice between 24cm Ytong + 12cm insulation or "just" 36.5cm Ytong.
There is a simple answer: In the standard you can choose the insulation package... and in the conversation afterwards we could decide (which we have not done yet).
Regarding the wall thickness: according to my calculation it remains +/- the same!
Soundproofing: Yes, good question... that Ytong here is not the best choice is OK but we then live in a residential area with a 30 km/h zone and additionally it is a ring road with about 20 houses and only one access road which is at the opposite end... Furthermore we are basically in the countryside...
Therefore the question is how good the soundproofing actually needs to be?? Probably no one can answer that...
My construction company only builds with Ytong so I just throw it out there that they are familiar with it.
If I summarize for myself:
Disadvantages: Sound
Advantages: Mounting objects is easier. Insulation is equally good compared to 12cm insulation.
and I also have this statement: Thus, even 36.5 cm thick, single-shell wall constructions already meet the energy standard of a KFW Efficiency House 55. Furthermore, the planning block is therefore already aligned with the energy saving regulation standards applicable from 2020.
Just enter the wall structure on u-wert.net. Then you have the comparison. I get a better U-value with 24 Ytong 12 cm insulation. Wasn't the statement that both wall structures are sufficient for KFW 55 and not that they are equally well insulated?
yes - that was exactly the basic statement. what does better mean? do you have these values for me? sorry, I am not a construction expert
the statement from the construction manager was that fw55 would be achievable with both... but what I have already read out is that kfw is initially a calculated value and only indirectly represents the heating demand. right?