Financing single-family house construction approximately 140 sqm

Approx. 450sqm for a rounded 85,000 euros + additional costs + 17,500 euros investment costs for a heat pump that supplies the new development area (fully serviced, no hillside location or similar).

A single-family house of about 140sqm in medium standard without a basement could be built turnkey (ready to move in).
Here we calculate approx. 500,000 euros including additional costs, we will do the garden ourselves.

I am 37, earning between 5,000 and 6,000 euros net in part-time (freelancer)
my wife 31, currently on parental leave, then 1,500 euros net tax class IV in 50% part-time 14 hours, holidays and bridge days off – theoretically she could increase her working hours at the new place of residence with grandparents as caregivers on site, a school 7km from the place has demand).

2 children (1 + 5), family planning not necessarily finished

Equity currently amounts to approx. 310,000 euros (after we received 100,000 euros gifted from my parents) (tending rather more, I calculate conservatively here and prefer to have a buffer on the business account regarding possible regress claims or similar). In addition, further assets which I would not want to sell, in the worst case I could access them with a little lead time.
However, I am planning a practice takeover for approx. 80,000 euros in the vicinity of the new place of residence (through which, in theory, I could generate significantly higher revenue because I would have a full cash register position), which is why only 230,000 euros are available. The approx. 30,000-40,000 euros for my current practice with a half supply contract I do not want to include, as practice sales always involve certain residual risks.

Of this 230,000 euros, we would buy the plot (rounded 120,000 euros including additional costs and heating).
If we put 100,000 euros into the house construction, according to my advisor, with ongoing KFW300 + funding from the NRW.Bank without any further bank loan, we would end up at an interest rate of around 2% and, depending on the length of the interest-only start period with a ten-year fixed interest rate, initially have a rate of <1500 euros (with 2% repayment).
Currently, our warm rent is 1250 euros.

However, in order to get my wife relocated, we would first have to rent in our hometown. Otherwise, it would be difficult after parental leave.

What do you think, is this realistic and feasible, or should we wait and save more?

What do you think, is this realistic and doable, or should I wait and save more?

Honestly? With those numbers, I don’t understand the question. If you see problems managing your living expenses with €5,000-6,000 monthly (assuming the woman works part-time), then you’d better bury the project.

Honestly? I don’t understand the question given the numbers.
If you see problems managing your living expenses with €5,000-6,000 monthly (if the woman works part-time), then better bury the project.

Thank you. We are quite uncertain, as I have only been in the branch for about 4 years and am the main earner.
In the worst case, if I don't find an affordable space, it could be €4,500 (currently I am in a shared practice). That is very unlikely and I would have the option to work more (whether through selective contracts with health insurers, private patients, or fully utilizing the capacity of the seat in case of possible practice takeover).

Something can always happen. No matter what you do, there is never 100% security (you could get pancreatic cancer tomorrow, get run over, or get divorced - harsh, but possible). Live in the now. And even with a little less net income, everything is fine. A €1,500 installment plus additional costs is not much higher than your current rent including utilities. And even if you only earn €4,000 (+ €500 child benefit), the installment (and even a slightly higher installment) is manageable.

P.S. I find it admirable that you are planning "only a 140sqm house." Usually, we read here about 160-180sqm for a couple who then have less equity and income. I think that’s great of you!

I am 37, earning between 5000 and 6000 euros net in part-time (freelancer) my wife is 31, currently on parental leave, then 1500 euros net tax class IV in 50% part-time 14 hours,

I can give you the green light although you are not the youngest among home builders anymore

although you are no longer the youngest among home builders

Is that a criterion for debt service capacity? And if he only builds at 65, that wouldn't matter either – the main thing is that it is affordable.