Underground garden house / barn or garage with address

Hello,
I have two, perhaps somewhat quirky questions.
The first: I want to build a garden house, in the garden, but underground, so far it’s only theoretical. I want to use it as a place to stay inside, maybe put a small TV in or something similar. Would you build the walls with bricks or simply with wood? I’m concerned that the heat doesn’t escape too quickly and I don’t know how to insulate something like this best and cost-effectively. Suggestions and ideas are welcome.

The second: If I build a barn/garage on a meadow, can I assign it its own address, so that mail can be delivered there, for example? The meadow is 50m behind the last house on our street and the meadow is still accessible by the mail delivery vehicle.

I hope for factual answers.

Best regards

Address on the meadow? You need a) a building permit for the barn and b) you have to apply for a house number at your responsible authority (building department). It all costs money,.. Underground wooden shed: My first thought: it will all mold away. Check out prefabricated bunkers - they are currently very popular with the Americans. Dig a hole - put in the bunker - close the hole and you have everything done.

I hope for factual answers.

Best regards

Well, that can't be meant completely seriously, can it?! But I would be curious how old you are.

Just inform yourself about the state building regulations, then you will have at least the requirement that windows must be present as well as 2 escape routes. Wood to catch something underground is probably quite inappropriate. Besides, you will probably also have to comply with the Energy Saving Ordinance for your construction. Have you thought about that?

That barns or garages get house numbers would be news to me.

Getting the barn or garage house number would be new to me.

I haven't heard of that either, but our self-service car wash at work has its own house number. So I wouldn't rule it out. The number probably just has to be applied for.

I haven't heard of that either, but our self-service car wash at work has its own house number. So I wouldn't rule it out. The number probably just needs to be applied for.

I think that's the least of the problems with the project though

@Wastl: Thanks for the answer. @Perlenmann: I am 28 years young and engaged, I work as a designer at a medium-sized company (plant construction). Thank you for your answers, my questions are answered.