Unfilled bricks and soundproofing - looking for experiences

However, I cannot confirm the poor sound insulation between floors from our current house either. We do have filled bricks, but the construction of the concrete ceiling is as described here: the ceiling is recessed by about 20 cm all around, and in front of that are insulation and an unfilled brick. I find the sound insulation from outside okay (not great), and the same applies to the interior walls, although different wall thicknesses of course become noticeable there.

Is it possible to use sand-lime brick with clinker without ETICS?

Certainly. In the past, people simply left some air between the interior and exterior walls; today, the (enlarged) gap is filled with insulating wool. We chose this approach partly due to our aversion to ETICS. It's a bit more expensive than ETICS with plaster, but you get dedicated experts for the different tasks: sand-lime brick for bearing loads and soundproofing, insulating wool for the ... well, insulation (ta-da!), and clinker as a robust weather shield (and additional soundproofing since it also has quite some mass), which can also store heat well.

I cannot confirm the poor sound insulation between floors in our current house either. Although we have filled bricks, the construction of the concrete ceiling is as described here: The ceiling is recessed about 20 cm all around, and in front of it are insulation and an unfilled brick. I find the sound insulation from outside acceptable (not great), and the same applies to the interior walls, although different wall thicknesses naturally become noticeable there.

So if you only have okay sound insulation with filled bricks, then it is due to the windows and not the brick.

So if you only have okay sound insulation with filled bricks, it's due to the windows and not the brick.

I dare to doubt that, but thank you very much for your analysis. It is probably simply because I previously lived in a house with walls made of sand-lime brick plus clinker. That is just a whole different level. And honestly, from a purely physical point of view, I don't see why the rather airy filling should make such a huge difference. This also seems to be confirmed by the data sheets (here from Wienerberger): T7-MW: 47.2 dB T8-P: 46.4 dB T10-36.5: 45.5 dB Yes, the unfilled T10 is the worst of the three, but the difference is not huge (despite the logarithmic scale).

For comparison: Only the 15 cm load-bearing shell of our sand-lime brick wall already achieves a sound insulation value of 54.6 dB. Including insulation and with clinker brick, you can add another 8 dB. (As I just see, the exterior plaster of a brick wall at the top is already included. Those rascals ...)

For comparison: only the 15 cm load-bearing shell of our sand-lime brick wall already reaches a sound insulation value of 54.6 dB. Including insulation and with clinker, you can add another 8 dB. (As I just see, the exterior plaster of a brick wall at the top is already included. Those rascals ...)

The difference is really huge. Still, standard windows are around 32 dB. With today's window sizes, the wall is almost irrelevant.