Is financing new construction realistic?

Hi everyone,
My wife and I are planning to build a house this year.
We have reserved a plot of land for ourselves and could purchase the plot in a few weeks.
We have already had some initial talks and planning with prefab house providers, as well as initial talks with banks and financial advisors.

Now specifically about the project:

1.) Construction:
- Location: Black Forest, rural area (about halfway between Stuttgart and Basel)
- Plot: 545m² fully developed, slight slope with about 3m height difference from the street to the property boundary.
- House: turnkey prefabricated house with pitched roof. Manufacturer not yet decided. But something like Schwörerhaus, Beilharz or Fingerhaus. Fingerhaus as favorite.
- no own work planned
- about 140m² living space
- knee wall height: 180cm
- Kfw 70 house
- Heating: gas condensing boiler with solar thermal.
- underfloor heating and controlled ventilation
- nothing special otherwise, no balcony, no conservatory, etc....
- fully basement (utility cellar)
- double garage.

2.) Cost assumptions:
- Plot: €90,000 (including land transfer tax and notary fees)
- House: turnkey approx. €350,000 (including basement, terrace and garage). First offer is at 330K, but something is still missing!
- Additional construction costs: €30,000 (estimated)
- Outdoor facilities: €30,000 (estimated)
==> totals €500,000
It should not be more than that!!
Are the assumptions realistic?

Financing:
- Equity: €200,000
- Loan: accordingly €300,000

3.) Personal circumstances:
- My wife, 35, currently on parental leave approx. (€1,400 for one year), then part-time work again in 2 years (net about €1,700).
- Me, 40, employee, net salary: €3,700
- Children: 2 (0 years + 3 years)
- Therefore, we want to manage the financing only with my salary for now.
- max. loan amount per month: €1,300
- Property should be paid off by retirement (25 years). (we hope for some special repayments) :)

What do you think? Is it manageable if you worst-case count only on my salary?
Banks are currently calculating without parental allowance anyway!

Regards
Blackforest

Something is missing in the calculation: The house is supposed to cost 350,000 turnkey. But floor coverings and walls [Bodebenläge und Wände] are still to be added. I think that should be quite possible.

Sorry, floor coverings and walls are included!

Purely based on the numbers. Equity / loan / income. If not YOU then WHO? :)

Hello,

should be fine.
Your conditions are quite similar to ours, ours should be a bit bigger and more expensive, the loan a bit larger but I still have 10 more years to repay, so the same rate over 30 years at today's interest rates (fixed for 15 years).

Have you taken the splitting into account with your net income?

What do you mean by Splitting?

Sorry for the long pause!
I'm currently considering whether to build now or take over the house (2-family house) from my parents (gift).
My parents (81+77) would move to the upper floor (80m²) and my family and I to the ground floor (123m²). The house is in good condition, still renovation costs max 200,000 (but then it will really be top).
Advantage: Lower costs. There's always a nice vacation in it.
Disadvantage: Parents or parents-in-law in the house, even if the units are separate.
Hm, difficult decision!