Construction defects? What do I have to accept?

3) We are building with a ventilation system. In the execution plans, the ventilation outlets in the attic are not marked because they go into the floor (that's what we were told). However, the 17.5 cm walls planned by the architect are apparently too thin for the ventilation ducts and exhaust outlets. Only the supply air goes into the floor. Therefore, now everywhere those drywall boxes have to come off the wall to cover these pipes.

How many outlets for the exhaust air do you have? Bathroom and possibly dressing room? You could put them in the ceiling, provided you have a warm roof. We are getting Geberit GIS (drywall profiles) in the bathroom, and the exhaust air will also disappear in there.

It is a general contractor. Well, the site manager said the subsequent approval is with the municipality.

But what to do? Have the entire gable torn down again?

Thanks for your messages! It is a general contractor. Well, the site manager said the subsequent approval is with the municipality. I also asked if we needed to sign anything. They said no.

We have an exposed beam ceiling, so outlets in the ceiling on the upper floor are unfortunately not possible. We have exhaust in the dressing room, in the laundry room, and in the bathroom on the upper floor.

But what to do? Have the entire gable torn down again? The roof is already covered, etc.