Financing and house construction planning - is this okay? Experiences?

Just use the search function: Baunebenkosten :)

Then it's best to ask Spitz again whether the energy saving ordinance certificate is included in the price.

In my opinion, they are obligated to do so, I've never heard otherwise. Once beforehand for the KfW application and again after completion for the final energy certificate. For the latter, it may be necessary to prove that the specified technology has actually been installed.

Hmm, no matter how I add it up, I somehow don't reach a total cost of €300,000...

- Additional construction costs 22,000
- Preparation of documents for building application 1,500
- Building application 1,000
- Soil survey 1,500
- Land registry office 2,000
- Construction electricity + construction water 1,000
- Connection costs 8,000
- Outdoor facilities 8,000
- Buffer 8,000

For me, the total is:
53,000
+ Land 100,000
+ House costs 170,000
= €323,000

Or have I just fundamentally misunderstood something in the list

It's pretty accurate... Your list all belongs to the ancillary building costs (I overlooked that), so you have ancillary building costs of over €50,000, which should be more than enough and include a buffer. However, I think the house costs will be higher. Oh, with EL? okay... The outdoor area is material with EL, right?

The proportions are about right, but no matter how I add up the list, I never reach the €300,000...

- Total house construction for 150sqm (offer is available) total 170,000 Turnkey house 140,000 of which own work electrical, sanitary, heating, laminate, painting Material costs total 30,000

I find that already very cheap, 30k for all that. Are doors and windows included in the turnkey house?