Under the stairs that take to my bedroom there is a tiny room, as big as a cupboard.
I can barely stand in it.
I smell mould in it, I tried keeping its small door opened and I think situation vastly improved.
With door closed I get 80% / 90% humidity and with door open around 50% / 60%.
For this reason I would like to improve its ventilation and I thought about cutting the door to put a vent with or without a fan or just shorten the door.
Am I going in the right direction?
Is there a safe and easy way to calculate the fan / vent I need?
Thanks for your help!
Edit after comments: In the room one wall is communicating with a tiny toilet (closed, no windows) another one is shared with my neighbor (I guess, I don't know if there is any space between us), one is the one with the small door you see and then there is the one where the stairs are.
I also attach a couple of pictures that are often worth much more than words