Vapor barrier in workshop, replace roof? (photos included)

Good morning, dear ones,

before I hire an expensive company, I would rather get information and a briefing from you ^^

I would like to repurpose my second building into a workshop and garage. Currently, there are still two horses in the second area until about the end of September.

After that, two large Hörmann sectional doors will be installed, and I would like to clad the roof and the interior.

My wish is to install a small amount of insulation, not to retain a lot of energy but to provide some noise protection. If I ever work late in the evening on repairs, not much noise should escape through the roof. I understand it's not possible without it, but it can be reduced with insulation.

As you can see in the photos, a vapor barrier (is it really one?) has been installed so far. However, since the building has stood like this for 3-4 years, the swallows were able to damage it a bit.

Now my question to you:

I would like to stuff insulation between the rafters and then install OSB panels underneath (with roll plaster on top).

As you can see, the foil is damaged in some places... what can I do now? Patch the holes and seal everything to make it tight? Use special insulation materials that don’t mind a bit of moisture?

Before I, as a layperson, am lectured by a roofer, I prefer to hear some ideas from you and implement them.

No one has an idea?

What is supposed to happen temperature-/heating-wise inside the hall? A vapor barrier is generally necessary when there are temperature differences and water condenses.

The existing vapor barrier/underlay or whatever it is, would (if I interpret your construction correctly) be in the wrong place, because it would then be above the insulation, meaning condensation would occur inside the insulation. Generally, OSB boards already act as a vapor barrier if installed properly. Whether that is sufficient or whether another layer should be installed underneath, I am unsure as a layperson.

So, the only plan is a workshop chimney to have a bit of warmth when needed. Primarily, I actually want to insulate to reduce noise.

The question now is whether the underlay membrane can be patched? If OSB boards are sufficient and I can do without the vapor barrier, that would of course be great ^^

What you insulate for is secondary when it comes to condensation. As soon as larger temperature differences occur, you have the condensation problem. Even in steel garages without heating, condensation can occur in unfavorable weather conditions. That is why an anti-condensate layer is installed under the ceiling there.

If OSB boards are enough and I can do without the vapor barrier, that would of course be great ^^

For that, you would have to do your own research or preferably consult a specialist. You don’t want to have to remove the insulation after half a year because it is completely soaked. In my opinion, this is also the wrong forum for that. Mainly house builders who have their houses built visit this forum.