Is financing a single-family house feasible for us?

All three are points that are absolute price drivers and push the price up by at least a total of 100k.

Since we are building ourselves, we could only really estimate the costs very roughly.

What exactly are you building yourselves?

How many square meters of land is it? If it's enough, leave out the basement. And instead of a brick garage, rather a double carport. That way you have probably saved around 100k already. We have a 6k income and our family planning is complete. Our installment will be 1,550 € plus about 250 € additional costs. I personally find that already very much.

So personally, I wouldn't feel good about this rate. My wife unfortunately also rarely looks at the account or calculates whether we can actually afford certain purchases. I then unfortunately have to bring her back down to earth now and then. Maybe you also have to calculate for your wife exactly what would happen if unexpected costs come up and ask her how exactly she thinks you can finance that. You just shouldn't let yourself be brushed off with statements like "Oh, we'll manage somehow," but demand concrete proposals. At the latest then, the realization should come that some things are just doable. It is important that you both feel comfortable with the monthly burden. If you don't drive particularly expensive cars, I would first also give up the double garage and instead build a double carport with a storage room.

above all: the double garage isn't going to run away. You can always place it afterwards as well. And for the meantime: paving and setting up a carport kit you can manage yourself with help over two to four weekends for relatively little money...

A double garage 8x7m with foundation and roof corresponds almost to the shell construction of a terraced house (which usually has one more floor)!

Both officers, with that income and no children so far, 1,800€ is okay. Definitely not little, but in my opinion not too much either. With such a "higher" rate, it is of course always very individual to consider. Are you frugal? What is your lifestyle like? How high are the other fixed costs, etc.? We have a rate of 1,600€ with a slightly higher income, but only 1 officer. We feel very, very secure with that, but that is always individual to consider. There are people with 6,000€ income and a similar lifestyle who already struggle with 1,300€ just based on feeling.

So with this secure income, even with children, if you don't throw money out the window and are not wasteful, you can definitely manage with that rate.