Can we afford the solid wood house KFW70?

You are right, of course the bank has also counted both of our full-time jobs. The idea with the household budget is a good one. We have already drafted it, and in addition, we have already "simulated" paying the installment for over half a year. Specifically, we have simply transferred the due installment monthly to a savings account. Of course, minus the current rent, and so far it has worked wonderfully. You do notice that you can no longer eat out twice a week and can only go on vacation once a year. You just have to restrict your habits. I can only recommend that everyone test the installment payments this way. A pleasant side effect is also that you save quite a bit of money during the simulation phase.

We live 40 km east of Munich and I would say that €2100 / sqm is not normal. We are definitely in the lower range with €1400 / sqm, but even if I assume €1800, I still come out quite well.

So a bit of luxury after all, right?

My husband once thought of building just once as well. Now his ex-wife lives in his first house. So never say never!

@jaydee:
Yes, there is a bit of luxury involved
The €2100 really cover the entire construction for us. From planning costs to the complete finished execution.
I have noticed that many here on the forum often calculate completely different prices.
For some, for example, only the house itself is described, without planning, ancillary construction costs, earthworks, etc...
Do you also include all costs in your €1400 per sqm?

The once building thing is true, you never know what will happen.
For this reason, we had a partnership agreement drawn up by a notary.
Since the land belongs to my girlfriend, I simply had to secure myself in case of a separation.

By the way, we still plan to make special repayments annually, so the follow-up financing won't be as bad.

I really don't want to spoil your fun, but:
3000.00 € per month for two people + child, 1,500.00 repayment (which is also not enough), living in a Munich suburb with "known low living costs," and then you still believe in special repayments? Either you have other sources of income that you haven't told us about, or this is really going badly.

And we simply transferred the monthly installment to a savings account.
Of course, minus the current rent, and it has worked wonderfully so far.
You do notice that you can't go out to eat twice a week anymore and can only go on vacation once a year.

But now there is no child yet, and your girlfriend still has her full salary. And no new house yet, where these things would be missing and would have to be covered. You deducted the rent, so what about garbage collection, water, sewage, heating, electricity, gas, and firewood?

It may all be possible, but then you would have a great house and would have to live far below the Hartz IV standard. Is it worth it?

The banks want at least 2% repayment, mostly the house banks are the ones who listen to the framework conditions (inheritance etc) and also lower them. One should then choose a fixed interest rate period of at least 15 years.

I really don’t want to spoil your fun, but:
3000.00 € per month for two people + child, 1,500.00 € repayment (which is not enough either), living in a Munich suburb with "known low living costs" and then you still believe in special repayments? Either you have other sources of income that you haven’t told us about, or it’s really going to be a problem.

I also see this rather critically. We have almost double the income but a lower rate. 800 € for living expenses, as the OP assumed, is never enough with a child. Especially when it’s small, diapers, baby formula, clothing, equipment, etc. can really cost a lot. Later on, childcare costs are added.

In the Munich metropolitan area (just barely with MVV connection), we paid 350 € per month for a daycare spot. My colleague in Munich paid 800 €.

Therefore, my suggestion is to build the house somewhat smaller and less luxurious. Otherwise, you’ll lose the house faster than you think.

We are building in the west of Munich and I already see a considerable additional effort compared to, for example, the Hessian hinterland where I come from. The differences in workers' hourly wages are not to be underestimated. I am surprised that you plan your financing on both incomes. To my (lay) knowledge, it should be covered by one income to cover future changes as well. Your girlfriend might have to stay at home longer with the children or something like that.