Steinfrage => Summer Thermal Insulation

Hello everyone,

we are currently planning our house and our builder is currently offering us 40 cm Ytong for the exterior wall. Some time ago, I had a conversation with an independent building surveyor because I am looking for the right stone also with regard to

- sound insulation between rooms
- summer heat protection
- winter thermal insulation

He said that the only thing that really protects against the sun the longest is a KS with WDVS (e.g. 17.5 cm KS with 16 cm WDVS (possibly also in other designs or as a natural product)). According to him, this is the only way to keep the heat outside, the warmth inside in winter, and provide sound insulation, although for sound I could also use Ytong on the outside and KS on the inside, which requires good workmanship (trowel cut) so that the walls do not crack.

From the interior point of view, he said that a KS stores the heat of an oven etc. better than Ytong.

So now here I am... I really did some reading... but no idea again :-(

Can someone help me? To what extent is it possibly "old-fashioned or cheap" to rely on a KS? Or is Ytong with KS interior walls the optimum?

Thank you all.. have mercy on a construction beginner ;-)

Best regards Markus

KS & aerated concrete are almost the same price - and old-fashioned? You obviously can't achieve anything monolithic with KS anymore - but you have slim walls both inside and outside, have sound insulation (which fails again at the doors/windows anyway) and of course also summer thermal insulation.

However: once the heat is inside the house, it stays in there as well - which can sometimes be unpleasant.

We had our house built entirely from KS walls except for the basement exterior walls.

@ Sebastian, from KS with ETICS or is there also the correct version without ETICS? Which KFW standard can be achieved with it then?

No plastic on the wall (ok, it does go on the two bay windows with plaster :D), but mineral wool - we have 14 cm insulation and easily achieve KFW55, but only applied for KFW70.

Well, apart from the bay windows ;)

Ok, all right.. until now I have only been thinking about filled stones like Ytong or Poroton to achieve the Kfw value 70/55 concerning the exterior masonry.

Ytongg is a manufacturer - primarily aerated concrete, which is not filled ;).

KFW values are always an overall interplay of various factors - not always just focusing on the exterior masonry, which you can see with us (currently energetically rather poor masonry).