House, garage, and terrace positioning

However, I would still be interested to know whether the terrace now has to be within the building envelope or not?

Uh...not with us! Are you sure??? We have a building envelope for the house and the garage/carport. Everything else, terrace, paths, and driveway are outside.

I looked again at the land use ordinance. It is regulated under Par. 23.
If the terrace is an ancillary facility, then it may also be constructed outside the building boundary. Mostly! I had mistakenly defined it as part of the building.
However, I would have it approved by the building authority.

Will be regulated under Par. 23

Correct.

If the terrace is an ancillary facility

, which unfortunately it is not in this case, as it is directly attached to the house. Therefore, it does not enjoy the privileges of §19 (4) and must not lead to any exceedance of the floor space index.

I had mistakenly defined it as part of the building.

correctly

However, I would have it approved by the building authority.

Good suggestion. I do not know the details of 's building project, especially the development plan, but if there are no specifications regarding terraces, he was lucky that his caseworkers do not know the recent court decisions or do not consider them in favor of the builders. The expert community is quite divided regarding terraces, so I have no problem excluding the terrace from the building application and constructing it without approval after the last visit from the building inspector. The risk that someone objects to it is very low. Legalized i

Floor space index according to the Land Use Ordinance

What do you mean by that? The floor space index must be specified in the development plan, otherwise it would not be a qualified development plan, which is very unlikely. Are there specifications in the development plan for garages and parking spaces?

which unfortunately is not the case here, as it adjoins the house directly.

What do you mean by that? The floor area ratio must be specified in the development plan,

Well, I'm glad and don't have to doubt my knowledge after all

I would have liked to ask about the floor area ratio as well, but then I didn't want to anymore

Regarding the terrace: is this even checked afterwards? Or is the exceeding of limits seen more leniently by the building authority? I can well imagine that some steps at the house then turn into a 40sqm large terrace. No plaintiff, no lawsuit

Where do the development lines enter the property? This might be interesting for the lengths and because, as far as I know, they should not be built over. I have fewer concerns about this with a terrace than with a garage, but one should probably pay a bit of attention to it?

is this even checked afterwards?

As said, terraces are a controversial topic, which is due to the history of their significance in building law. In the past, they were insignificant ancillary structures in planning and building law, unnoticed by anyone. Then the Building Use Ordinance 1990 introduced the issue of soil sealing, and the terrace gained planning law significance, initially only related to the floor area ratio. Then, through court rulings, it moved from floor area ratio II to floor area ratio I, because someone had the idea that it belongs to the main structure. And with that, it suddenly also had to lie within the buildable area, which even city planners did not consider when drawing up development plans. In building regulations, it is still insignificant, e.g. Building Regulations NRW 2018, §62 15. e) other insignificant installations or insignificant parts of installations such as entrance canopies, awnings, roller shutters, terraces, ... And so it happens that everyone sees the terrace differently. Legally, it must be within the building boundary if there is no explicitly different regulation in the development plan. So anyone who ends up with a strict building inspector risks having to dismantle it. However, I am not aware of any such case from practice.