Build your own sauna with a sloping roof - suggestions/notes/plans

I have a question: I attach the vapor barrier with a stapler. Do I then have to tape the staples with aluminum tape? Or can I skip that?

I - but beware: theorist! - say: a leak is a leak.

I definitely do not want to recommend sloppy work to Diur, I probably do some things too precisely and excessively. I simply assume that you see a sauna IN the living area every day and walk past it. You look inside and check it, just as you do with the grout or something similar in the bathroom or when you occasionally inspect the utility room. In a full bath, the room is also full of steam, sometimes for 2 hours with us o_O (I am innocent). Afterwards, there is proper ventilation, and you yourself notice if the air is still moist. I want to say that with usual private use of the sauna, the risk of moisture problems is no different than in some bathrooms. And a "sauna day" is not a real day during which liters of steam are sprayed for 24 hours.

The beginners with their tin foil hats :p I sealed the brackets... ;)

I will start with the cladding later, it will be installed horizontally, I will start at the top. The tongue always points upwards. Do I have to cut off the tongue on the top boards? I don't see it as technically necessary. Probably more a matter of taste, right? Is there a rule of thumb for how many nails you must use to mount a board at minimum? On 1.90m I can fasten it max 4 times, that's how I planned it as well.

4 brackets or 5, that is determined by the substructure, do not leave out any bracket, nail the first board in the corner, without tongue it is more stable when nailing

4 brackets or 5, that is determined by the substructure, do not omit any bracket, nail the first board in the corner, it is more stable without the tongue when nailing

Thanks for the tip about the stability. That is extremely important and correct. I cut off the tongue.