Floor plan concept idea bungalow 12x11m

Building a house on rock that you only plan to move into in twelve years (= "after the children") is already crazy, although your simplistic calculation has at least become more understandable (but unfortunately not functional!). The house is to be heated centrally by instantaneous water heating and split air conditioning, you are an amateur but have specific building materials in mind that you want to screw together with (a lot of) God's help, bon appétit. But thanks for the amusement, someone with the topic of house building is still missing in the comedian scene ;-)

Thank you ypg for the first constructive response,

regarding the floor plan - Ok, I have to discard it and have it planned.
Of course, I will get the local construction company on board.

But I really don't understand why the cabin should cost over 300,000.
Where do the enormous costs come from?
I can do some things myself, install the shower, lay tiles, install the kitchen - all already done.
Three months ago I had a photovoltaic system (4kwp) mounted on the roof, connected with a registered electrician - done, cost less than 3500€.
It's all not rocket science and is affordable with DIY.
The split air conditioning heating/cooling is cheaper compared to the air-water heat pump.
I would only realize the open roof truss if I use the sandwich modules (220mm), as the insulation is then included in the panels. (Top U-value)

The house we currently live in (paid off) will of course not be sold, it is perfect for families (maybe one of the children wants it).
My wife and I definitely want to downsize as we get older.
The financial means upwards would also be open.

Is there a plan of the property with a north arrow and dimensions? Preferably with neighboring buildings and street.

In the construction area, the road was just paved last week; the size specifications of the parcels are no longer correct (they are getting smaller). North points straight up. Parcel 2 would be the favorite. The parcels still need to be measured precisely. Therefore, there are no neighbors yet.

Where do the enormous costs arise?

It is 2023. Why does a bread roll at the baker cost 1.00 € if you want one with seeds or grains? Is it because of the energy crisis? War? Or simply the conditions that a house nowadays has to meet?

I can help myself,

Help! Nobody denies that. Help! Sometimes helping a neighbor here, sometimes doing something at home there. It is something else to drive to the hardware store to shop for a project. If you only want to _help_ yourself, you will never finish. Those who can afford to keep a property and acquire a second property should then also be able to afford it. ;)

Suppose you have plot #2 then with your floor plan like this?



Is the garage allowed at the boundary? Then definitely the windows facing east. Even better a door.

Your statement "no slope" is probably a bit optimistic. I see contour lines that unfortunately do not contain numbers. Is there a larger excerpt from the development plan?

827m2 is more than 700 m2 though