ᐅ New Single-Family House Construction (KFW70) / Aerated Concrete vs. Sand-Lime Brick / Which Material to Choose?

Hi everyone,

We are planning to build with a general contractor and have collected some offers. Some use aerated concrete, others use calcium silicate bricks. Some combine the two, using aerated concrete for the exterior walls and calcium silicate bricks on the inside.

What would you recommend? Is this combination of aerated concrete on the outside and calcium silicate bricks on the inside common and preferable?
Should we be concerned about cracks due to the different expansion properties of the two materials, or is this not an issue with proper construction?

What would you currently choose to build with or have built—what is your preferred building material?

Thank you in advance,
Lacos

Do you need to worry about cracks because the two types of bricks have different expansion rates? Or is this not an issue if the construction is done properly?

Yes, it is actually a major issue... I would avoid mixing building materials... even though many say it works fine... the trouble comes later...

The wall structure is a matter of philosophy...

Are you considering: sound insulation, indoor climate, thermal insulation, fastening options, costs, environmental protection?

The wall construction is a matter of philosophy...

Is your focus on: sound insulation, indoor climate, thermal insulation, fastening options, costs, environmental protection?

Sound insulation is of lower priority since it is a single-family house. Thermal insulation and fastening options are more important.

Hello,

Lacos schrieb:

What would you favor from your perspective? Is this combination of aerated concrete on the outside and calcium silicate brick on the inside common and preferable?
Should one worry about cracks because both materials expand differently? Or is this not an issue with proper construction?

Quite a few builders use calcium silicate bricks for interior walls because this material offers better sound insulation; especially in the attic where the bedrooms are located, a frequently cited reason. This helps avoid later disputes with noise-sensitive homeowners.

I generally advise against mixed masonry. Whether you choose aerated concrete or hollow clay brick is really a gut decision. Those who prefer the traditional red brick often opt for hollow clay brick. Those who want to avoid rapid-setting cement usually choose aerated concrete; both require special anchors for almost every type of masonry. We address sound insulation in much thinner interior walls (with 36.5cm (14 inch) exterior walls, sound insulation is no longer an issue) by constructing the attic walls either with lightweight construction or on the upper floor — that is, the second story — with gypsum boards. Both are unproblematic with either hollow clay brick or aerated concrete but, inexplicably, have a poor reputation among potential homeowners. I attribute this to unfiltered statements from the internet, without practical knowledge of the subject.

Best regards, Bauexperte

For us, gypsum boards are also the preferred choice for the interior walls on the upper floor. We have this material in our current apartment for some interior walls as well (10 cm (4 inches) thick). The sound insulation is excellent, and it’s also very stable (above me hangs a wall-mounted shelf full of heavy binders while I’m writing this).

Drilling is very simple, standard anchors are sufficient, and you can easily hammer a nail into the wall.

Hello,

Lacos schrieb:
...What would you prefer from your perspective? ...

Monolithic external walls rarely meet all competing requirements equally well. They are always a compromise, but inexpensive!

Best regards