Aerated concrete 42.5 lambda 0.08 or 0.09

Additional costs are about €2000 for our project. Good approach. Thanks!

If you include the lost living space, you are easily above €2k. Just see what makes sense from your point of view.

Ditto, I would also take a thinner stone (living area and costs), disadvantages are not noticeable with the high insulation and the small difference in terms of living comfort.

Take the 36.5, but definitely as a filled stone. Think about soundproofing and how porous these things are. This unfilled crap they're trying to sell you today only benefits the construction company because the stones are lighter and easier to work with!

I myself have 42.5 unfilled.

If you include the lost living space, you’re easily over €2k there. Just see what makes sense from your point of view.

The €2k is the surcharge for the same stone thickness, only with improved insulating properties.

Take the 36.5, but definitely as a filled stone. Think about sound insulation and how porous these things are. That unfilled crap they’re trying to sell you nowadays only benefits the construction company because the stones are lighter and easier to work with! I myself have 42.5 unfilled.

This is about aerated concrete; the question of filling does not apply. But I agree with you, unfilled Poroton is the cheapest. Our shell builder had offered Poroton as an alternative, it would have been €2,000 cheaper and he had it in stock, but we preferred to wait for the sand-lime stone delivery. Even if you think you don’t want to do anything for soundproofing on the outside, it comes back to bite you at the latest with the interior walls, unless you live alone. The neighbor has 11–17 cm of Poroton as interior walls, that is really not acceptable. He’s now trying to fix it with solid wood doors.

The 2,000€ is the surcharge for the same stone thickness, only with improved insulating properties.

This is about aerated concrete, the question of filling does not arise. I agree with you, unfilled Poroton is the cheapest. Our shell constructor had offered Poroton as an alternative, it would have been 2,000€ cheaper and he had it in stock, but we preferred to wait for the limestone sand brick delivery. Even if you think you don't want to do anything for soundproofing on the outside, it will pay off at the latest at the interior wall, unless you live alone. Neighbor has 11-17cm Poroton as interior walls, that really doesn't work at all. He's now trying to fix something with solid wood doors.

I have everything inside made of limestone sand brick myself, but honestly don't notice a difference compared to my neighbors' houses, where many have Poroton inside.

We also have 11 cm and 17 cm Poroton interior walls, you can't hear anything through them... who knows what went wrong with the neighbor.