Expanding OG room - Is approval necessary?

Hello everyone,

after what felt like an eternity of googling, I give up and ask my question here

In our new house, there is a room (in the upper floor about 2.75m ceiling height) in shell condition that was used by the previous owners as a storage room. There are windows, the sloped ceilings are insulated but without drywall, connections for underfloor heating are present at the transition to the hallway, there is no screed and the walls are not plastered. The room was also not included in the living space calculation. With relatively little effort/money, the room can be made habitable.

Do I need a building permit to make the room "habitable" (underfloor heating, screed, electrical installation, drywall, plastering, painting)? The new room will also have an impact on the living space. Do I then have to have it recalculated, for example for the building insurance?

Thanks in advance!

I say: Never wake sleeping dogs. Only go to the Emperor if he calls you. Ask your insurance broker.....

Do I need a building permit to make the room "habitable" (underfloor heating, screed, electrical installation, drywall, plastering, painting)?

Does the building permit allow the use of the room as living space?
If not, just do it and don't talk about it. If in doubt, it simply isn't living space and is used as a storage room for a couch, a wardrobe, a television, etc. It's just a coincidence that the furnishings, uh, the items to be stored are arranged like in a living room.
Who is supposed to come and check?

Nobody cares about that. When a responsible gentleman was here once for a different matter, we casually asked him what we have to do if we want to change a window into an entrance door. He looked at the plan and was confused: there was a door marked. It had been replaced by a window 50 years ago, no one noticed and/or no one cared.

So I would prepare, furnish, and use the room as usual. In the end, nobody asks about it.

Thank you for the answers. In general, I am on your side, but somehow it is too risky for me regarding the building insurance. I will talk to the insurance. Currently, the room is not included in the living space calculation and is not indicated as "Speicher" on the floor plan.

Currently, the room is not included in the living space calculation and is not indicated as "Speicher" on the floor plan.

Then it stays that way. Don’t stress yourself.