Building according to the Energy Saving Ordinance 2016 or KfW55

You, I am not working in the construction industry myself and am passing on information secondhand, as I refer to the statements of our architect and energy consultant.

The link explains what a vapor barrier/vapor retardant foil is and when it is used. It may be possible to do without foil entirely, but since vapor tightness was not desirable for us, we did not look for alternatives.

The link explains what a vapor barrier/vapor retarder foil is and when it is used.

I’ll summarize the link (because it will be deleted since links are not allowed).
- Vapor... is needed on the roof
- Vapor... is needed with interior insulation

I don’t read anything about new buildings with ETICS or something similar.

You must have installed a foil on your roof too ;) .

but since vapor tightness was not desirable for us

But you build airtight!!!

This is the requirement for KFW 55. You have to comply with it just like a house with a foil. There is no difference!

Don’t let anyone feed you nonsense (and that is nonsense) that your house is not airtight. If it is not airtight, it won’t be a KfW 55 house and you can only dream of the subsidy, but that’s it.

This is what the Building Energy Act says (in the Energy Saving Ordinance the values were identical):

Some houses give you the feeling of living in a Tupperware container and others do not. We had the Tupperware feeling in 9 out of 10 model houses in the typical model house developments. Whatever you base it on – we wanted to avoid the Tupperware feeling just like , apparently received good advice, refrained from following the guidelines of the KfW standards, and achieved a successful result. Foil or no foil, airtightness aside.

What said is really once again a prime example of the nonsense people like to be told. Whether concrete, Ytong, bricks, wooden studs, etc., the houses are all equally airtight; the only real difference is basically the factor "botched construction."

Whether concrete, Ytong, brick, timber frame, etc., the houses are all equally airtight; the only difference is basically the factor "botched construction".

A sheet of paper is airtight with respect to air flow, but not with respect to moisture transport. Which kind of "airtight" do you mean? With this oversimplification, you cannot accuse others of "talking nonsense". Building physics is somewhat more complex, I’m afraid.

In none of the mentioned building materials does any significant moisture transport from inside to outside take place.

Even your solid wood house would mold without ventilation.