ᐅ Is energy efficiency worse with 36.5 cm masonry?

Good morning,

Yesterday we had a conversation with a general contractor. We mentioned that we would like to have a 365mm (14.4 inches) wall (Ytong or Poroton). The immediate response was: he doesn’t think much of that; 240mm (9.4 inches) with 120mm (4.7 inches) of Styrofoam insulation is much better than the 365mm wall.

He also said that the energy efficiency rating would drop from A (+) to D?!

I’m starting to not know what to believe anymore... everyone says something different.

What do the experts here say?

Thanks in advance.

PS: I also asked, because I had read and heard somewhere that aerated concrete (Porenbeton) is easier to work with than Poroton. The response was that this is complete nonsense... oops.

Best regards,

Steven

My advice is to find a different general contractor.

I agree with Bookstar. Regarding Poroton, I can't say much, but with Ytong, sometimes a 24cm (9.5 inches) exterior wall is enough to meet the energy saving regulations, so 36.5cm (14.4 inches) is definitely sufficient. Or are you aiming for a specific KfW house?

Yosan schrieb:

I agree with Bookstar.
I can’t comment on Poroton, but with Ytong, sometimes an exterior wall thickness of 24cm (9.5 inches) is enough to comply with energy saving regulations. So 36.5cm (14.4 inches) is more than sufficient, unless you are aiming for a specific KfW house standard?

No, we’re not =) So we will keep looking around.

Bookstar schrieb:

I would just say find another general contractor.

We kind of expected that O.o

A 24cm (9.5 inches) Poroton wall plus 12cm (5 inches) insulation already provides better thermal performance (depending on the Poroton block) than a 36.5cm (14.5 inches) wall. However, the claim that the house’s energy efficiency drops drastically because of this is simply nonsense.

Do not neglect sound insulation under any circumstances, as this usually leads to problems later.