Is a flat carport possible without a building permit?

However, you must observe the maximum length per plot side of no more than 9m and a total of no more than 15m on all sides if applicable. Caution is especially required when building around the corner, as you quickly reach the 15m.

I want to put a carport next to my garage, preferably a lean-to carport, so does that require a permit? If I place it freestanding next to it, is it exempt from a permit?

That is at least my opinion. The legislator is silent on this. I am not aware of any rulings on this.

Does that also apply to a garden shed?

No. For garden sheds, 75m^3 applies regarding permit exemption. In the case of boundary construction, the privileged limits must be observed (e.g. 30m^3).

Escorda, you are simply awesome! Thank you. As long as I keep a few meters distance from the neighbors, I can build a 5 x 4m house with a 2.5m ceiling height - that would be at least 20m from the property boundary of the nearest neighbor,