Wall construction of a country house

... 17.5 Poroton + e.g. 16cm EPS to achieve the U-value already requires 50cm Poroton. ...

Not to forget is the sometimes low site coverage ratio: for a building on a 650sqm plot with a site coverage ratio of 0.2, you are allowed to build 130sqm.
That is sometimes barely enough for a bungalow ... if you can then gain a few square meters of living space through slimmer walls, you choose the ETICS version (or timber frame construction).

Right, with timber frame construction you also get very good insulation values with low wall thickness!

Yes, or also with solid wood walls and insulation on the outside.

Hello,

17.5cm Poroton T7 + 16cm EPS WLG 035 => U-value: 0.138 W/m²K
49cm Poroton T7 => U-value: 0.14 W/m²K

With these values, we no longer speak of 'built according to KfW 70' but are well below KfW 55; especially since the T7 is filled. Although this cannot be determined absolutely as other factors play a role.

I assumed a standard KfW 70; in this case, the hollow bricks (lambda value 0.09 W/mK) are not filled. If a decision is then to be made between a narrower brick + ETICS or a monolithic wall construction, the price differences are marginal.

Not necessarily. A monolithic wall is also plastered separately. For ETICS the painter does not need much longer. What the painter takes longer with ETICS is saved during masonry. The effort difference has rather little influence on the service life of the scaffolding.

I see this differently – from practical experience.

Best regards from the Rhineland

I am currently very interested in this topic as well! We would like to build a house this year. To receive the funding through the low-interest loan, we are aiming for KFW 70. I have read a lot by now, but I notice that I am reaching the limits of my understanding when I read the many different numbers regarding values and lambda values. Can someone tell me which exterior wall insulation/insulation thickness with ETICS (polystyrene) and KS 17.5cm is necessary to easily meet the requirements? Thank you very much in advance

You can't just say that, as the overall package of the house must be right. There are no direct requirements for a component such as the wall.