New construction - How to build economically sensibly?

For me, the price per sqm is always for a house "move-in ready". Without additional construction costs, kitchen, land, etc.

When I subtract the additional construction costs for myself, I come to a house price of about 218,000
(I now count the earthworks, house connections, engineering costs such as architect, surveyor, structural engineer, the blower door test, and the €50 for the building notification at the office as additional construction costs)

That would put me at €1,557/sqm

If I had left out the garage and used plaster instead of clinker, I would probably have ended up at about €1,300-€1,400/sqm.

When I subtract the incidental building costs, I come to a house price of about 218,000
(I now count the incidental building costs as the earthworks, house connections, engineering costs like architect, surveyor, structural engineer, the blower door test, and the 50 € for the building notification at the office)

That would put me at 1,557 €/sqm

If I had left out the garage and used plaster instead of clinker, I would probably have ended up at about 1,300€-1,400€/sqm.

Seriously?! Of course the garage DOES NOT belong to the construction costs of a house!!! What is so hard about that? Everyone calculates the costs for building the building. Done. Congratulations on 1400 EUR per sqm. Enjoy it...

I would count the garage as part of the outdoor facilities anyway, as it is not living space.

That even seems too good to be true for me [emoji3]

Calculating out the garage is unfortunately not so simply possible, as we did not receive an invoice for 1 piece of garage, but items such as the concrete slab, masonry, and bricks are included in the fixed price from the shell builder. At most, I could quantify the garage door, the 2 doors, the window, electrical wiring, interior plaster, and garage roof.

I also arrive at 1700€/m2 for the turnkey base price from our construction company for the construction of the building + painter + floor coverings done by ourselves. But then come the surveying, the groundworks contractor, the usual incidental construction costs, the exterior facilities, the furnishings... So one should not base the construction project planning solely on this value...