Seal the window airtight

We are currently sealing our windows with the butyl tape according to the instructions from the window installer. According to him, we only need the seal on the sides because we have [Rollladenaufsatzkästen]. The boxes are flush with the ceiling-level lintels, filled with expanding foam. In his opinion, the airtightness is ensured by the gypsum plaster. Does anyone of you have experience with this topic? I prefer to play it safe and wonder whether it would also be necessary to seal the bottom of the window with butyl tape. We need to build as airtight as possible because we are installing a ventilation system. Thank you! Regards NundE

That should be enough. The foam also seals airtight if it's the right one. You could have also used [Kompri Band]. A self-expanding sealing tape.

PS: The airtightness also has its pitfalls. :) In the small rooms we have, you have to close the door slowly. Otherwise, overpressure develops and the door doesn't close properly.

Too bad, I only found this post today ... :o ... but I think it's great that you took over the (certainly not easy) responsibility from the window installers for the long-term functioning of the airtight component connections! This must have more than halved their warranty risk in this regard ... :D. How did it continue? Were or are there any moisture problems at the connections?

The foam also seals airtight if it is the right one.

Which foam would you recommend for that?

Hello,

nonsense, there is no foam that is airtight, if a representative tries to sell you that, ask to see the test certificate, to my knowledge there is no German approved institute that allows such a thing.

The question of the thread creator is 5 months old!

It makes no sense to discuss it now, as it is surely already resolved (otherwise he would have contacted us again).