Aerated concrete vs. filled brick

Hello.

For our Kfw55 house, we need a 36 cm block with a lambda of 0.07. Possible options would be a filled block (which would probably mean, for example, MZ70 filled with mineral wool) or aerated concrete (Ytong).

In our area, aerated concrete is rather rare. At trade fairs, only the brick industry is present, which of course has nothing good to say about aerated concrete (for example, Ytong would soak up so much water during construction that the house would be significantly more humid in the first years than with bricks).

I would therefore be interested in where you see the advantages and disadvantages. The insulating effect would initially be the same. In terms of cost, there is probably no significant difference either.

How about the heat storage capacity? Are there differences in sound insulation? What are the properties once the wall is finished? Plastering? Can you hang pictures with nails or do you need anchors right away? Properties when the house is about 20 years old?

Thank you for your opinions!

(For example, Ytong would absorb so much water during construction that the house would be noticeably more humid in the first years compared to bricks).

Don’t you have a ventilation system with KFW 55 anyway? That should be able to effectively pull the "extra" water out of the house.

What are the properties once the wall is finished? Plastering? Can you hang pictures with nails or do you immediately need wall plugs?

Aerated concrete is very soft, you can basically scratch into a hole with your fingernail, i.e. a nail will probably be enough for a wall calendar and if you drive the nail in at an angle, probably also for a wall clock.

Otherwise, aerated concrete anchors are recommended, I used them to hang the coat rack, the kitchen is still hanging on the wall, and millions of home builders can’t all have chosen the wrong material.

For perforated bricks, you will always need special anchors.

Soundproofing is probably better with bricks. I have someone in my circle of friends who now regrets having built with Ytong; the brick buildings next to them are apparently significantly better. But of course, it always depends on where you build.

This topic keeps coming up, which is why there are already several threads about it here. I initially asked myself the question as well, but in the end I clearly came down on bricks.

I spoke with two general contractors in our area who said they build with both, but bricks account for about 90%. Aerated concrete is slightly more expensive but easier to work with on the construction site. Overall, the costs are therefore about the same.

The brick is roughly twice as heavy and therefore undoubtedly offers better sound insulation. In addition, the higher mass results in better heat storage capacity. The phase shift for brick is roughly about 20 hours, for aerated concrete only 17.

However, I see the main disadvantage in water absorption. Aerated concrete can soak up water like a sponge and may take several years to dry completely. Here, brick has clear advantages.