Installation of ventilation pipes through vapor barrier foil

Hello everyone,

We are building a KFW 55 single-family house, i.e. a blower door test is necessary.
In the attic, we have a collar beam ceiling to the cold attic. That means that insulation fleece is placed in the ceiling between the rafters, directly below that the vapor barrier foil, and above that 22mm OSB boards.

Now the heating engineer has installed the ventilation pipes for our central ventilation system.
In the following pictures you can see that the pipes will penetrate the airtightness multiple times.
I cannot understand how the vapor barrier foil can be sealed airtight afterwards, especially since no sealing collars can be installed anymore.
Supposedly, the foil can also be sealed underneath the pipes everywhere, but this would not help for picture 1 either.
The multiple penetrations worry me because of the blower door test, but even more so because of potential moisture damage caused by leaks in the foil.

Are our concerns justified? Or is this the standard nowadays and the airtight sealing of the foil will be possible without problems.

Best regards

For this reason, I always recommend installing in the floor on the upper floor. That makes many things easier. But as it looks for you now, pictures 2 and 3 are not a problem at all. For 1, the ventilation installer or whoever must seal the foil very well with the appropriate sealing materials.

For this reason, I always recommend installation in the floor in the upper floor. That makes many things easier. But as it looks for you now, pictures 2 and 3 are not a problem at all. For 1, the ventilation installer or whoever it is must very well seal the foil with the appropriate sealing agents.

Thanks in advance for the quick feedback.

At least the exhaust pipes lie in the floor; the supply pipes were then too much for the structural engineer. These now partly lie ON the floor and the rest as can be seen in the pictures.

Where the bundle goes up the wall, is it clad with drywall? If the supply air is now laid ON the floor, can it then not be distributed into every room and placed in the walls instead of the ceiling?

I also wanted to do supply/exhaust air through the ceiling in the upper floor, but I took into account the forum comments and had exhaust air in the walls and supply air come from the floor.

Where the bundle goes up the wall, will it be clad with drywall? If the supply air is now laid ON the floor, can't it then be distributed to every room like that and laid in the walls instead of the ceiling?

I also wanted to do supply/exhaust air through the ceiling in the upper floor, but took the forum comments into account and had exhaust air go into the walls and supply air come from the floor.

Yes, it must be clad there. It's in the children's bathroom anyway, where partial pre-construction is necessary due to sanitary installations.

Unfortunately, there is not enough space on the floor to lay all 7 flat ducts for exhaust air. Our hallway, which could be used for distribution, is only 1.5 m wide, and the pipes for water from the heating engineer are already laid there.

Laying the pipes in the walls is also an issue; we have many 11.5 cm walls, so in the end, there isn't much wall left. If so, drywall would probably have to be used there as well.

Search for Primur 600ml, my drywall installer uses something like that for every pipe "penetrating" the vapor barrier, etc. That might possibly solve your problem as well.

How far is the substructure planned under the rafters? Looking at picture 3, it should be at least 75mm (I'm assuming DN75 ventilation pipes?!). Ideally, it would go through the rafters (STRUCTURAL ISSUE, don't do that) or similar to picture 1, over the rafters. From above (since the attic is unused, not really relevant) it wouldn’t look very nice but would benefit the ceiling height.