Calculation for a single-family house with 175m² living area, basement, and double garage

Very roughly, for an initial overview calculation, I added the land price + house price and all the costs already known to me and assumed 15% of that as additional costs for incidental construction costs and outdoor facilities.

The total costs for purchase price and incidental expenses therefore amount to 361,440.00 EUR.

Wow!

Double garage planned (solid)

Basement

That sounds like an expensive project!

175m² living space at 2,000.00 EUR per m² (reference value) amounts to 350,000.00 EUR - Double garage 20,000.00 EUR (I consider this value too low for now, would probably be closer to 30,000.00 EUR) - Outdoor facilities 35,000.00 EUR (there are no major demands here, the plot is already "fenced" on the right and back sides, so the focus was mainly on a property boundary at the front and left, as well as mainly turf. A small terrace [30m²?] towards the garden would also suffice) - Basement 50,000.00 EUR in addition to the above 350,000.00 EUR construction costs - Ancillary construction costs 35,000.00 EUR Makes manufacturing costs of 490,000.00 EUR.

No.
2,000 €/sqm applies to an Energy Saving Ordinance house... 2019, standard house!!! Without fancy blinds and so on.
If you start building, then in RP it can also be, the guideline is often the sqm land price in the area, 2,500 €/sqm. Added to that are 80-90,000 for the basement and various technical and equipment extras.
The garden does not consist only of turf and fence, but also planting.
I see seven figures there. Great if you can sleep well with that sum, because then your profit is correspondingly.
I already felt sick at the land price... our entire project didn’t cost that much.

First of all: Thank you very much for the input

The price of the plot already made me feel sick... our entire project didn’t cost that much

Well, what can I say. Worms isn’t exactly the center of the world, but it’s far from being “unfavorably” located. As I said, you are practically right in the intersection of Rhein-Main and Rhein-Neckar. I work in Mainz (30 minutes by car), my wife in Mannheim (15 minutes by car). Building land is also scarce - currently, there is only one (!) plot for sale in all of Worms (approx. 85,000 inhabitants) listed on Immoscout. Purchase price 550,000 EUR. Everything else only happens through “connections” and/or detours. Or you go out to the “country,” which neither of us wants. The last new development area in Worms (or suburbs) was built in 2017 - and there were at least 4 to 5 times as many interested parties on the waiting list as there were plots. Yes, the plot is expensive. And we struggled for a long time whether we were willing to spend that. But we have been searching for about 2 years. And the fact is: neither the plots nor the construction costs will get cheaper. The advantages are obvious for us: very good location in a nice suburb, which is still quite close to the center and well connected by transport - also sufficiently large with 640 m² (that’s the next point: when a plot is available, it is usually no larger than 400-450 m²) and directly located on a play street. So: now or never.

Regarding construction costs, I have now thought about it again. As I said, it should not be seven figures. This really has less to do with “can” and more with “want.” As far as the kitchen is concerned, I stick to my position: here we will rather stay under budget than exceed it. The first adjustment parameter is really the living area. The 175 m² were just a gut feeling for now. After we thought about it again yesterday, we came to the conclusion that 160 m² would be absolutely fine. We currently have no children but plan for one - an office must be available, my wife is a teacher and I have the option to work from home occasionally. The rough layout would be as follows:
Ground floor: living and dining room (50 m²), kitchen (15 m²), guest WC with shower (5-6 m²), entrance/hallway (10 m²).
Upper floor: children’s/guest room (20 m²), office (16 m²), bedroom (16 m²), dressing room (6 m²), main bathroom with shower/WC/bathtub (14 m²), hallway (7 m²)
That sums up to 160 m². Just a rough wish on our part. Possibly the office can also move to the ground floor, but that goes into more detail.

If I roughly multiply the 160 m² by 2,600.00 EUR per m², I get 416,000.00 EUR. Plus double garage 30,000 EUR + outdoor facilities 35,000 EUR + ancillary construction costs 41,000 EUR + basement 65,000 EUR + land costs 361,000 EUR, I come to 948,000.00 EUR.
Then there is also 50,000 EUR for pool and kitchen - and a buffer for any unexpected costs or special features would still be available.

How is the surface there?

I work in Mainz (30 minutes travel time) my wife in Mannheim (15 minutes travel time). Building land is also scarce - Currently, for the whole of Worms (approx. 85,000 inhabitants) there is (!) one plot of land offered for sale on Immoscout. Purchase price 550,000 EUR.

Or you just go out into the "countryside",

Incredible I live in the Hamburg metropolitan area... very quiet, but also good infrastructure... 10 minutes from the big city in the countryside... Building prices here are also very reasonable by now, but not like with you down “there”... well, that should not be the topic here... I digress.

that 160m² would be absolutely fine. We currently have no child but plan for one - an office must be available, my wife is a teacher and I have the option to work from home occasionally.

Why do you need a basement there?

Ground floor: Living and dining room (50m²), kitchen (15m²)

Upper floor: Children’s/guest room (20m²), office (16m²),

Everything is planned very generously. Smaller would be more relaxed regarding the costs... by that I don’t mean small.

I would also suggest putting the basement up for discussion. This is the biggest uncertainty factor in your calculation. Earthworks and landfill can bring really nasty surprises. Or the basement should be used better, for example with the office. Otherwise, it is a significant cost factor for pure storage space, which can also come with a lot of unforeseen problems. I would rather consider building a few more square meters above ground. Or (depending on the design) making the attic usable. We have friends who have an additional room and office in the attic. It was certainly much cheaper to convert the attic than to build a complete additional basement.