Is it possible to build a house with little equity?

Unfortunately, I also cannot imagine that all the points I mentioned before are included in the 250k. And as Musketier already mentioned, without a soil survey, the costs for the earthworks cannot be estimated at all, and if you are building with a basement, there could possibly be additional costs for a white tank or drainage, etc.

Please do not underestimate the costs for wall and floor coverings and the work involved if you do it yourself. Depending on the flooring you choose, you might even have the problem that you do not have the skills to lay it yourself. For the wall coverings, you should also inform yourself in advance about what you want, because depending on that, the substrate needs to be prepared differently and some house providers do not even offer the level you might need in their overall package.

thought my listing was good?^^

By listing I actually meant the complete mention of your expenses and income, for example rent xx EUR, insurance xx EUR, car xx EUR, mobile phone xx EUR, pension insurance xx EUR, food, clothing XX EUR, savings xx EUR, etc.
Only this way can you really see where the money is spent, if something is missing, and whether you might need to spend the money on something else (keyword: underinsured).

You also haven’t said anything about your current life situation: age, married yes or no, children yes, no, or planned (if children are planned this should definitely be taken into account as partial loss of income and additional costs are to be expected), working conditions (permanent employment, salary increases in sight, commissions, etc.)

Don't be discouraged

What exactly is your plan? Why is it supposed to be building a house?

Tell me.

Well, I still have to write something:)
If I see it correctly, you lack equity and experience. You shouldn’t do 250k without a single cent of equity.
Buying from an uncle is not exempt from real estate transfer tax. Berlin 6%.
Then there are still many open questions regarding the property!
I would advise you to buy the property at a good price. Then build a house when you are better off with equity.
I am currently buying in Berlin myself, but I also have 1/3 equity and a fixed financing until the end = 18 years.
Costs are about the same as rent including heating. Since you are also in Berlin, we can gladly meet.
For me, this is the fourth time I am acquiring or building property.

Regards

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For me, this is the fourth time that I acquire or build property.

That's cool.
How did you get started?