Is the construction project affordable? 570 k€ loan with a 5300 € salary

Most things have already been said. We're currently building with a baby/toddler, so I can say that we both underestimated:
1) the desire to no longer work full-time and spend time with our child
2) childcare costs

I imagine it would be very unpleasant if this were no longer feasible within a comfortable range due to a construction loan (for everyone). Therefore, I would plan and calculate very conservatively here. What if one income is smaller for longer than planned? (For example, if the child is sick and/or should not be cared for by others so early).
I am quite glad that we planned with a child, otherwise, we would have overstretched ourselves.
With two part-time salaries, we are roughly at your 5300€ and comfortably finance 290,000€. And this relaxed feeling is already worth a lot, I must say. We don't both have to work full-time to service the loan.

Well, this situation probably only exists once nowadays – or you're an exception with that :D

With a "projected" 10,000€ full-time salary and 290,000€? That’s peanuts.. Honestly :D That’s not just relaxed, that’s nothing :D
Either you’re over 40, inherited a lot, saved a lot, or don’t have a house but "only" a condominium in the countryside?

But seriously... If the OP wants a relaxed situation, he either must never build/buy a house or can save for another 10 years (then kids will be there, the time to pay off the loan shortens due to age, and you might also want to "offer something" to the child right away or have the possibility to have everything you want (a home) BEFORE the child.

I can understand that well... I also like to take one thing after the other: living together, getting married, building a house, having a child – nowadays things usually go differently.

But basically, you can never start building a house too early – in my opinion, it only has advantages financially. What else should the OP wait for???

What is so incomprehensible about that? Don’t you have any other six-figure wishes before retirement? I do. That only works to a limited extent if you still have to pay off €1800

If I want to realize other wishes, there is exactly one possibility: earn more money. If you have €5,300, you have €5,300, no more and no less. Now you can ask yourself the question and make a priority list of what is more important to you. One person wants to manage and do as they please on their own property for 30 years (or until the end of their days) and invests a large part into their own real estate. Another lives more cheaply renting, invests the savings (compared to buying real estate) in stock funds / ETFs and then has a nice sum by retirement. Much more important is the initial question of the original poster: Does it work or not. Answer: Yes, it works if you are willing to restrict yourself (or just aren’t victims of consumption and don’t want to show off with a €700 BMW M3 or similar).

If I want to fulfill other wishes, there is exactly one option: earn more money. If you have 5,300 euros, you have 5,300 euros, no more and no less. Now you can ask yourself the question and make a priority list of what is more important to you. One person wants to manage and do as they please on their own property for 30 years (or until the end of their days) and invests a large part in their own real estate. Another lives more cheaply renting, invests the savings (compared to buying real estate) in equity funds / ETFs and then also has a nice sum by retirement.

Much more important is the initial question of the original poster: Does it work, or not. Answer: Yes it works, if you are willing to make restrictions (or simply are not consumer victims and do not want to impress with a 700 euro BMW M3 or similar).

Exactly like that – that was nicely said :)

In the past, 300,000 DM (today €) were managed by a person with below-average income at 8% interest while at home the mother was employed full-time in the household without an additional income, with a child. You had to make sure to pay off the loan as quickly as possible, otherwise you would be eaten up by the interest.

That worked... due to lower living costs... Today people just don’t want to restrict themselves anymore. As you say, consume less and you can easily pay off the loan :)
Each to their own :)

No, no, that would be nice ;-) Here with us, we’re not talking about 50% part-time, more in the range of 70-80% for both. ;-) then the world looks different again. And no, we are under 40, but well saved up and also no house for 600K. That’s what I mean: setting priorities. Family time is important to us, so within our means, it’s basically the house discount store. ;-) Those who set their priorities differently just have to live with the fact that both might have to work a lot.

No, no, that would be nice ;-) We’re not talking about 50% part-time here, more like 70-80% for both. ;-) then the world looks different again. And no, we’re under 40, but well saved and also no house for 600K. That’s what I mean: setting priorities. Family time is important to us, so within our possibilities it’s basically the discount house. ;-) Those who set their priorities differently just have to live with both working a lot.

Part-time 80% omg. Should I start saying that I work full-time (40h) and my wife part-time (35h), because she simply works fewer weekly hours for a similar salary? :D :D :D :D

No, no, that would be nice ;-) We’re not talking about 50% part-time here, rather around 70-80% for both. ;-) then the world looks different again.
And no, we are under 40, but have saved quite well and don’t have a house for 600K.
That’s what I mean: set priorities. Family time is important to us, so within our possibilities, there is basically the discount house. ;-) Whoever sets priorities differently might just have to live with both having to work a lot.

Okay, then you have saved well!

But yes: "no house for 600k" is difficult nowadays, believe me...
Sure, you can say: without a basement, only 120m², no frills etc... Personally, I’d say: If already, then do it properly! I’d rather save in other areas.

We shouldn’t fool ourselves... I like to show friends/colleagues where they can save, because they always claim that no money is left or something like that.

Cell phone contracts for 30€ monthly <--> for 7.99€
Phones included, new every year for 500€ <--> 150.00€ per phone - works for me 3-4 years

Netflix, Maxdome, Amazon Prime, Sky etc. for 70€ monthly <--> for 10.00€ just one of these

Clothes shopping monthly dozens of hundreds of euros for brand clothes etc. <--> I just shop at H&M and then I don’t need 20 pairs of pants, maybe 4 are enough?

Food for about 600€ per month <--> I shop for 250€ per month, maybe sometimes you can go to a discount store instead of always running to Edeka? Sometimes you want to watch your diet, only buy environmentally friendly products etc. but buy the worst crap at Edeka because you say: "At the discount store, it’s only cheap stuff"

Ordering food somewhere every week for over 10€ / dish <--> I treat myself only once every two weeks or maybe even less

Every morning buying a coffee and a sandwich somewhere <--> bring a snack from home!! That’s easily 30€ difference during the week

I could go on forever... savings potential of several hundred euros without any restriction of quality of life (in my opinion)...

But this is all OFFTOPIC - SORRY! :D