Land purchase of 319 sqm for 191,000 euros and house construction realistic?

A lot has already added up here. Thank you very much for all the feedback.
I hope I don’t forget anything.

Regarding financing. Yes, I apparently forgot half of it.
With a 20-year fixed interest period, which I also prefer, I would have an effective interest rate of 3.46%. In addition, I lost 90 euros on my possible rate. So I would be at about 1,600 euros. But it would still be an initial repayment of 1% with a calculated term of about 44 years.

yes, we have been married for almost a year now. As you mentioned, the 20-year fixed interest period makes more sense.

I have read several times on the internet that the costs for a construction road are between 700 and 1,000 euros. I have now assumed 700 euros since the plot is not large and the crane etc. doesn’t have far to go.
Regarding the outdoor area: the yard would initially only be gravelled and when money is available again for paving, it will be paved by ourselves since it is not that many square meters. My father also paved his yard himself, so there is experience.
The garden will be seeded with grass seed and a few bushes as privacy screens and done. I have to plant a tree, but such a small young tree does not cost the earth. Later on, one can think about a small fountain, raised bed, and garden shed when there is money again.

The self-contribution I deduct from the construction costs refers to the interior finishing, i.e.: laying tiles, laying floors, installing underfloor heating, installing sanitary objects, screwing on plasterboard, filling/sanding, wallpapering and painting.
I had an offer from a house provider where a total of 54,000 euros was set for these works including materials as a package price. If I deduct material costs which I have anyway, I roughly come to this amount.

What I still don’t quite understand are the square meter prices, whether they relate to usable area or living area. I am currently calculating 3,000 euros with 135 sqm of usable area. That would make a difference in terms of costs. I have read both, so I am not sure.

With a 20-year fixed interest rate, which I also prefer, I would have an effective interest rate of 3.46%. In addition, I lost 90 euros on my possible rate. So I would be at about 1,600 euros. However, it would still be an initial repayment of 1% with a calculated term of about 44 years.

Do it and lean back. That covers the interest rate risk. We have all already written enough about the rest.

What I still don’t quite understand are the sqm prices: usable area or living area. I am currently calculating 3,000 euros with 135 sqm usable area. That would already make a difference in terms of costs. I have read both, so I’m not sure.

The prices that always circulate are 300/400 euros costs related to the living area. Calculation of the living area is classic according to DIN 277 (including house connection room etc., but without basement and garage). That’s how the numbers come about, which are also used in the press by the housing industry.
And there you are at approximately +/- 3,000€/sqm.

The 20-year fixed interest period of course costs some money, but in return you can sleep peacefully for the next few years and possibly still enjoy lower interest rates in 10 years. Believe me, anyone who took out a one million loan at zero interest rates during Corona times in a big city (there were quite a few) with only a 10-year term can certainly have restless nights, even if the world may look completely different again in 6 years. With only 1% repayment, a 20-year fixed interest period is not wrong, although not mandatory.

By the way, it currently even makes sense to leave your money in the instant access savings account and earn 4% interest due to the inverted yield curve (short-term interest rates higher than long-term rates). You just have to be willing to switch providers 2-3 times a year to benefit from new customer conditions.

I am aware of that. However, inverted yield curves are not permanent and it will certainly have turned by the time the two of them are in the house. Realistically, we will then plan with a normal yield curve. And since interest rate cuts have been announced, we can assume that short-term interest rates will then be below the loan interest rates.

The costs for a construction road I have read several times on the internet. It was indicated there as 700 - 1,000 euros. I have now assumed 700 euros since the plot is not large and the crane etc. does not have to go far.

General price indications from the internet, in my opinion, can pretty much be ignored. On the one hand, prices have risen very sharply in recent years and only a few sites indicate when these figures were published. On the other hand, it is very region-dependent. And then of course depending on the property. With 40cm of gravel, you can build up a truckload faster than you can look (a semi-trailer with 26 tons is enough for about 6x6m, which is almost the crane area directly by the street).

when there is some money again.

Carport, driveway, landscaping... and you still forgot the path to the house. Because you don’t want just gravel on that in winter, as you carry an incredible amount of dirt into the house.
In my opinion, you are postponing too much there. Something is always missing in the first years that you are currently not even thinking about. The construction will always be more expensive than planned and the budgeted buffer is rarely enough. Then comes the child or two, children are expensive and one income disappears. If you plan like that, the money for the outdoor facilities might only be available in 10 years. In the meantime, you will live on the construction site. Do yourselves a favor and plan the outdoor area at a decent level. It doesn’t have to be luxurious, and the fountain can be done later, but in a way that makes you feel comfortable and is finished after the first or second summer.

How many working hours have you actually planned for the interior construction and within what timeframe do you want to accomplish it? In the meantime, you are either paying rent or living on a construction site. And even if 35 hours isn’t much: if you don’t live very close to the construction site, realistically only the weekends remain mostly for the construction.

And then of course from the property. With 40cm of gravel, you can build in a truck faster than you can blink (a semi-trailer truck with 26t is enough for about 6x6m, that’s the crane area almost directly on the street).

For a 319sqm property in a new development area that is currently being developed, completely different construction road costs apply. Namely none at all! Why would there be any. Bet that construction takes place directly on the street? Maybe the classic 3-5m distance for the front garden. Then comes the 8m house and a few more meters for the garden before you are already leaving the property again. The crane – if one is needed at all – can also stand or comes as a truck crane for the roof truss.