Is this masonry structure sufficient for KfW55?

That's right, but especially in somewhat busier inner-city residential areas, I don't think that's wrong. In any case, we cannot complain.

Hello

I know that there are different components to achieve KfW55. However, I would be interested to know if this wall construction is at least sufficient for a new building:

[*]17.5 cm thick aerated concrete plan stone
[*]14 cm mineral wool
[*]2 cm air layer
[*]11.5 cm facing brick

That will be calculated exactly. If you want to be on the safe side, include a clause that KFW 55 will be achieved and priced in.
But yes, 17.5 cm insulating stone plus 14 cm mineral wool should be sufficient.

We have a similar structure and next time I would go for sand-lime brick. Houses with aerated concrete are extremely noisy by comparison.

That's true, but do you also have 11.5 cm facing brick in front? That adds mass again.

If this is a city villa with 2 upper floors then I wonder how scared my planners/structural engineers were to suggest a 2.0 KS24 solid brick to me, when 17.5 aerated concrete bricks would also have worked.

Fear is probably the right keyword here.
But don’t judge all aerated concrete by the same standard. For monolithic walls they are increasingly porous so that the thermal insulation capacity increases, and of course also more expensive. But there is also aerated concrete with higher bulk density, which is probably the case here, otherwise it would be pointless in the calculation.

True, but do you also have 11.5cm facing bricks in front? That adds mass again.

I would be interested as well. The building will be located in a residential area and not by the highway. Shouldn't the soundproofing then be sufficient?

In our residential area, the vast majority of houses were built from aerated concrete, ETICS, and plaster. The sound insulation is okay. However, if you add the facing brick, it gets significantly better, and if you replace it with sand-lime brick, there's another improvement. But it probably also depends on how sensitive you are. Some members here would probably consider this insufficient.

I have a Poroton T10 unfired, which is quite frowned upon by some due to the low sound insulation. I can only say, the neighbors don’t hear me cutting laminate. The sound of flexing tiles is heard as a quiet humming when everything is closed right in front of the house. So far, I can’t complain. Inside the house, it looks a bit different. And how it will be in everyday life still needs to be seen. But my fear of hearing everything from outside has not been confirmed for now.

True, but do you also have 11.5cm facing bricks in front? That adds more mass.

I would be interested as well. The building will be in a residential area and not next to the highway. Shouldn't the sound insulation be sufficient then?

Yes, fully faced with 11.5cm. I thought back then that it would be enough. Living on a moderately busy street (50 km/h) ... so not a classic residential area. When you're busy inside the house, you don't notice anything, but as soon as it gets quiet, you do perceive it. Inside, it’s still significantly more sound-transmitting... I would at least ask how much it costs and then weigh it up.