How much does my dream house actually cost...?

Hello,
I just planned my dream house with 3D CAD and estimated the construction cost.
Exterior dimensions 10m x 16m
2x rectangular bay windows (with dormer) approx. 5m x 1.5m
1 1/2 stories, knee wall 1.4m, roof slope approx. 30°
normal room height (approx. 2.5m)
1 large and one small bathroom
Building with basement, standard equipment

If I calculate the house by price per m², I get approx. 288m² x 1800€/m² = 518,400€ + basement + land
If I calculate by price per m³, I get approx. 960m³ x 300€/m³ = 288,000€ basement + land
If I calculate all trades in detail (e.g. price per m² exterior wall, price for roof, price per m² concrete ceiling, ...) I get approx. 290,000€ + 33,000€ [BAUNEBENKOSTEN] + basement + land.

Which estimate do you think is most realistic for a very rural region in Bavaria? There are huge differences between the usual values!

Regards
Meiko

Thanks, that’s roughly in the right direction. I’m just a bit puzzled by these big differences. I mean, you can precisely calculate what 1 m² of exterior wall, 1 m² of concrete ceiling, 1 m² of interior wall, 1 m² of roof surface, 1 m² of insulation, etc. cost... there can’t be that much deviation, right? Yes, in our remote area near the border almost everyone builds on that scale :-)

Hello, to be able to say which is the best estimate, one would need to know what your standard should be. High standard, low standard, something in the middle, solid construction or timber frame construction. Are the estimated cost values including incidental costs or pure construction costs? Are your calculations regarding area and volume correctly calculated? Where did you get the price per square meter for walls, ceilings, roof, etc.? What is meant by m²? Usable area or gross floor area? Are you sure your building is only 1 1/2 stories? With a 1.40m knee wall, I would check that again more precisely. At least you are just skirting around being two stories. Regards