ᐅ Wall construction: 15 cm calcium silicate brick plus 25 cm external thermal insulation composite system (ETICS)

Hello everyone,

Our detached single-family house KfW 40+ (9 x 16 m (30 x 52 feet), 2 floors with basement) is being built from sand-lime brick.
Interior walls are 11 cm (4.3 inches) or 15 cm (6 inches), exterior walls are 15 cm (6 inches) plus 25 cm (10 inches) of external thermal insulation composite system (ETICS).
The 15 cm (6 inches) exterior wall seems quite thin to me, especially considering the large rooms.
Of course, everything has been statically calculated and designed. Nevertheless, I would feel more comfortable with a 17.5 cm (7 inches) wall.

Are my concerns justified or unfounded?

Many thanks

There is nothing more stable than sand-lime brick available on the market. Structural calculations always include a significant safety margin, so the concerns are unfounded. But if you feel more comfortable with 17.5 cm (7 inches) and the additional cost is affordable, why not?

A KfW 40 standard in a solid masonry house is generally economically impractical just for peace of mind. If you add a bit more brick on the inside, you’ll have more thermal mass to buffer the heat in summer. So go ahead.

I built with 17.5cm (7 inches) calcium silicate bricks plus 20cm (8 inches) external thermal insulation composite system (ETICS) and can confirm that, based on my personal experience, the sound insulation of this wall construction is very good. And yes, even the 17.5cm (7 inches) walls don’t look particularly solid in the shell construction phase – but the high bulk density of the bricks is noticeably apparent when carrying them. :-)

Better have the requirement for 24cm (9.5 inches) of insulation – even for KfW 40 – checked. Sounds like overkill.

We have 24cm (9.5 inches) of sand-lime bricks and 16cm (6.3 inches) of 032 external thermal insulation composite system (ETICS). This setup complies only with the energy saving regulations. The bricks are really heavy. I was surprised. 🙂

Sparfuchs_:p schrieb:

We have 24cm (9.5 inches) calcium silicate brick

If Putin attacks, you don’t even have to go down to the basement... Just stay a little away from the window 😉