What is cheaper? OG or KG?

I agree with nordanny. Depending on how the plot is shaped (slight slope) or the soil conditions (keyword load-bearing capacity, etc.), it can be cheaper to build a basement. Under normal circumstances, however, an attic is cheaper than a basement. Is there already a plot? If so, you know the conditions (except maybe the soil condition, but that can be determined by a soil survey).

I would use the coming years to take a closer look at which rooms you use when and how. Also, how large they should be. Where is it currently cramped, where is free space currently wasted? How many beverage crates do you need to store, how many boxes with stuff (and how often they are taken out), how many meters of wardrobe do you need, how big should the hallway/wardrobe be, bathtub yes/no, kitchen size, living room usage, dining area size, overnight guests... and so on and so forth. Maybe make yourself, even if it sounds silly at first, a small notebook where you write down your spontaneous ideas and comments.

Hey guys,

I know you mean well, but most of it completely misses the point here

I already own a property. It was bought 4 years ago. Renovated from the ground up and has now been occupied by me for over 3 years.

The garden is very large and maybe a house could still fit in the back.
The plan was that maybe in 4 years we’d build a house there, which would then be rented out. (Thema Steuerersparnis)
And when the kids are out of the house, we would move into the self-built property. This is just a rough plan in my head for now. It might still change so that it becomes a property with two residential units, because then it finances itself better. Disadvantage: you don’t live alone in the house. Advantage: we build for ourselves on one level and barrier-free and the money comes back quicker.

For now, I was only concerned with the topic: better OG or KG.

@ borderpuschel:
It’s a completely level area. Currently used as a garden.
A soil survey can be done when the actual planning starts. But until then, probably another 1 to 2 years will pass, since the photovoltaic system is coming onto the current property first and then the facade insulation will probably follow.

I will certainly come here with more questions

Cheers
Specki