Is a funding framework of 520,000 realistic?

Hello everyone,
my partner and I are planning to build a house.
We have found a plot of land and have initially reserved it for ourselves.
We have already had some discussions and planning with the builder, as well as preliminary talks with banks and financial brokers.

Personal Information:
My partner, 31, technical employee, has a monthly net income of 2200 EUR.
I, 30, xxx/ civil servant, have a monthly net income of 2800 EUR
- 2 children planned / in the next few years

The fully developed plot (125,000 EUR) is tied to a developer.
- Own contributions planned / or outsourced otherwise
- approx. 150m² living space
- Kfw 70 house
- Heating: brine/water heat pump with deep drilling
- Underfloor heating
- Prefabricated garage

We have received a preliminary total price of 420,000 EUR for the plot.
Real estate transfer tax 26,600 EUR (although this value will likely be lower, as we will not take everything from the developer)
Notary: approx. 9,000 EUR
Outdoor facilities: 13,000 EUR
Other: 4,000 EUR

Total financing volume: 472,600 EUR
Less equity 55,000
= 417,600 EUR


Income 5,000 EUR
- Expenses 3,250 EUR (cold rent, car, ancillary costs, private insurance, living expenses, etc.)

Surplus: 1,750 EUR

I calculate with an interest rate of 2.5% + repayment 3%

Possible financing framework would probably be 420,000 EUR
Since the interest rate is currently quite low, we would probably choose a variant where we have a fixed rate for 15-20 years.

I would just be interested to hear what those who have dealt with this topic in more depth or have some knowledge about it have to say

Thank you very much in advance

Possible financing with a 1750 € installment at 5.5% annuity would be more like 380 K€ for me... What do you pay for cold rent? Actually, 5 K€ net should be enough - actually. The exciting question is what happens if you have children - with half a salary, that might quickly evaporate.

right.. I had calculated with 5% instead of 5.5%. - cold rent is 700 EUR - of course with children you would initially have to "give up" the income, but would work in part-time so that not "everything" is lost

Anyone else who can comment on this?

- of course, with children you would first have to "give up" the income, but would work part-time so that not "everything" is lost

It's easy to say to go part-time with something you have still experienced. I would wait until the first child is born and you become aware of all the changes.

- Experience shows that the total price will still increase! ([Bemusterung], unplanned, outdoor facilities, other incidental costs such as furniture and moving and and and ...).
- In case of loss of income, it will be very, very, very tight.

My advice: Leave it. Either downsize ([Doppelhaushälfte], [Reihenhaus], [Eigentumswohnung], ...) or quickly have two, three children first and at the end of your 30s (you are still young!) take another look.