ᐅ Is this masonry construction sufficient for KfW55 standards?

That's correct, but especially in somewhat busier urban building areas, I don't think that's a bad approach. In any case, we have no reason to complain.

MeinHaus45 schrieb:

Hello

I know there are various components needed to achieve KfW55. However, I’m curious whether this wall construction would at least be sufficient for a new build:

• 17.5 cm (7 inches) aerated concrete block
• 14 cm (5.5 inches) mineral wool insulation
• 2 cm (0.8 inches) air gap
• 11.5 cm (4.5 inches) facing brick

This will be calculated precisely. If you want to be sure, include a clause that KfW55 is reached and priced accordingly. But yes, a 17.5 cm insulating block plus 14 cm mineral wool should be sufficient.

danixf schrieb:

We have a similar setup and next time I’d go for sand-lime brick. Houses built with aerated concrete are much more echoey in comparison.

That’s true, but do you also have 11.5 cm (4.5 inches) of facing bricks on the outside? That adds a significant amount of mass.

Stephan— schrieb:

If this will be an urban villa with two full floors, I wonder how cautious my planners/structural engineers were in recommending a 2.0 KS24 solid sand-lime brick, when 17.5 cm aerated concrete blocks would also work.

Cautious is probably the right word. But don’t lump all aerated concrete blocks together. For monolithic walls, they tend to be made more porous to improve thermal insulation and, of course, they get more expensive. There are also aerated concrete blocks with higher raw density, which is probably the case here—otherwise it wouldn’t make sense in the calculation.

guckuck2 schrieb:


That's true, but do you also have 11.5cm (4.5 inches) facing bricks on the outside? That adds some additional mass.

I would be interested in that as well. The building will be located in a residential area, not near a highway. Shouldn't the sound insulation be sufficient then?

In our residential area, the vast majority of houses have been built using aerated concrete, external thermal insulation composite systems (ETICS), and plaster. The sound insulation is adequate. Adding a facing brick significantly improves it, and replacing that with calcium silicate brick results in an even higher enhancement. However, it probably also depends on how sensitive one is. Some members here would likely consider this insufficient.

I have an unfilled Poroton T10, which some people criticize due to its low sound insulation.
I can only say that the neighbors don’t hear me cutting laminate.
When cutting tiles with a flex tool, you can hear a faint humming noise if the house is closed up and you are right outside.
So far, I can’t really complain. Inside the house, it’s a bit different. How it will be in everyday life still remains to be seen. But my concern about hearing everything from outside has not been confirmed so far.

guckuck2 schrieb:

Right, but do you also have 11.5cm (4.5 inches) facing bricks on the outside? That adds significant mass.

MeinHaus45 schrieb:

I’m interested in that too. The building will be located in a residential area, not next to a motorway. Shouldn't the sound insulation be sufficient then?

Yes, fully clad with 11.5cm (4.5 inches) facing bricks. At the time, I thought that would be enough. Living on a moderately busy street (50 km/h (30 mph))… so not a classic residential area. When you’re active inside the house, you don’t notice it, but when it’s quiet, you do perceive the noise.
Inside, it’s noticeably more echoey... I would at least check the cost and then weigh your options.