Install pipes for stove before or after installation of vapor barrier etc.

[freddemp5a]

We are about to insulate a house with a sloped roof (stone wool boards, vapor barrier, and drywall), which we will do ourselves.
However, our builder is responsible for installing the ventilation system with ducts and outlets for exhaust air, as well as installing a stove with associated pipes.

The ducts and outlets for the ventilation are about to be installed, but the builder wants to wait with the pipes for the stove. They say it is normally not done before insulation (instead after painting).
I think it sounds completely wrong - it must be much easier and safer to also install the pipes for the stove before the sloped roof is insulated.

I suspect it will be difficult to ensure the vapor barrier is tight when ductwork is done afterwards.

What do those of you who know say?

 

[Pumba]

I did the vapor barrier first, then the stove, but you get a kind of fabric that's supposed to connect to the vapor barrier so it probably works either way.
However, I insulated with loose fill.

The disadvantage of doing it later could be that you get a lot of tracks and debris in the insulation; I got mine on the plastic, and what didn't fall to the floor was easy to take with the vacuum cleaner.