Insulation, subject of vapor barrier and holes

Hello everyone,

we are currently buying a prefab house built with timber frame construction from 2022.
KFW55, lots of insulation accordingly and many layers



Now, nobody wants to do anything wrong with the house.
Common sense tells you that no reputable manufacturer builds houses where you are not allowed to hang a picture or a shelf on a wall because you would puncture the vapor barrier.
And yet, there is a lot of info on the internet saying this is not good, even calculations that for every mm² hole in the vapor barrier, 10m² of house rot away per year (just kidding, but only partly). A series of points

Can I assume that holes for shelves, curtain rods, etc., in reasonable amounts, are harmless?
What do you think?

Thanks

Hello,

there should be additional sections for the construction of the interior walls. There must also be an installation layer (electricity, etc.). Normally, this is placed in front of the exterior wall structure and also allows for the attachment of objects.

It is best to ask about this specifically again. If applicable, it was a shell construction house, meaning the interior finishing was done by the previous owner, so there may be fewer documents/documentation available.

Problems could of course have arisen during the creation of the interior finishing (i.e., the sealing/insulation layer was compromised).

Documentation of a blower door test would also be useful here.

Hello,

there should be additional sections for the construction of the interior walls. There must also be an installation level (electricity, etc.). Normally, this is located in front of the exterior wall structure and also allows for mounting objects.

It's best to ask about this specifically. Possibly it was a shell house, meaning the interior finishing was done by the previous owner; in this case, there might naturally be fewer documents/documentation available.
During the creation of the interior finishing, problems may also have arisen (i.e., the sealing/insulation layer was damaged).

Documentation of a blower door test would also be useful here.

Thanks for the answer. Yes, certain construction steps, such as the interior finishing, were carried out separately. However, as seen in the pictures attached, it is exactly the red parts, the so-called owner’s scope of work. This was done accordingly, as far as I know. Thus, the innermost layer (8 in the first picture, 10 in the second) is also the last; behind it comes only the wallpaper. It can therefore be assumed that there is no installation level on the exterior walls, roof slopes, etc., and even the smallest drill hole damages the vapor barrier. As I said, common sense tells you that with such a construction it cannot be expected that the vapor barrier will remain undamaged.
By the way, these pictures are from the construction service description of the construction company, built like this thousands of times in Germany. That is why I am actually 95% sure that everything is fine. But the 5% still worries me :-) Maybe there were some standards regarding this, which are communicated to the owner (= for me then the seller), about in which zones it should be done and where better not, or which plugs/sealing materials to use. The seller could say nothing about it, but that doesn’t necessarily mean anything.

PS: A blower door test was performed during the house acceptance, with top results. Thus, it can be assumed that everything is fine without the holes I intend to drill.

Are there any pictures of the interior / have you visited the house? Are there absolutely no furniture, sockets, switches on the exterior walls?

The critical area is, of course, the inner sealing. Was the previous owner a professional? Carrying out all connections throughout the house correctly with the foil requires care.

If the house stays as it is, and everything was really done neatly, it can work. But any change / extension / fault-finding almost inevitably leads to large-scale work to restore the tightness. Which can sometimes be practically impossible.

Are there any pictures of the interior / have you visited the house? Are there absolutely no furniture, sockets, switches on the exterior walls? The critical area is, after all, the internal sealing. Was the previous owner a professional? Carrying out all connections in the entire house correctly with the foil requires care. If the house remains as it is, and everything was really done cleanly, it can work. But any change / extension / troubleshooting almost inevitably leads to large-scale work to restore the tightness. Which can sometimes be virtually impossible.

After all connections / sockets / switches were installed, only then was the Blower Door Test done with good results, after that the owner hardly lived in the house and installed nothing, so I assume that the current state regarding tightness is OK. My question is whether there is a risk of ruining this current state with a few holes for fastening things like curtain rods etc.

Maybe there were some standards regarding this, which one informs the client (= for me then seller) about, in which zones it should be done and where better not, or which dowels/sealants to use. The seller could say nothing about it, but that doesn’t necessarily mean anything.

That he can’t/won’t say anything about it would personally already make me think. It certainly is not state of the art technology. The house is not that old yet that long-term problems could appear. He must know whether he has taken or had taken special precautions during interior construction / electrical installations.

Especially with exterior walls, moisture possibly introduced cannot go anywhere due to the additional EPS/XPS insulation, but remains in the insulation and framing.

Personally, I would go through it with an expert and look for abnormalities.