Realistic financing opportunity?

I don't know exactly how equity is always taken into account, but here is an example from a colleague in the neighboring department with similar data. Early 30s but single. Also about €2900 net per month, he got the desired €350K for the construction of his house. (Whether that was the limit, I don't know) With the difference that he paid for the plot entirely with equity. Around €160K including incidental purchase costs. It's not directly comparable now due to the "high" equity, but apparently the income is sufficient for this amount.

Additional income: my self-employment 350-500€ (only secondary activity) plus part-time permanent employment from November 900€); family allowance 200 €. So we actually still have (conservatively estimated) 1200 € additional income, which apparently cannot be taken into account.

Several points occur to me here: The family wants to help. Great. But instead of the 200€ monthly, wouldn't it be better to give a one-time payment in advance? The goal would be not to have to finance the incidental purchase costs.

Is the permanent employment from November already confirmed in the form of a signed employment contract? Could you still wait until November or December?

316,000 € is indeed the purchase price

And who pays the incidental construction costs?

But we don't want that at all. So don't get upset.

No one is getting upset here: you are being made aware of facts that concern you but are irrelevant to the forum members.

Terraced house in the middle; 145 sqm living space; homeowners' association, monthly additional costs approx. 350€;

Is there also a cheaper option, e.g., used?

Is there a cheaper option, e.g. second-hand?

Unfortunately not. This is the Berlin metropolitan area with a 25-minute train connection to Berlin (Zoo)... so that is already pretty good for the price.
Also, from our feeling, used properties are associated with uncertainties for us laypeople. With the purchase from the developer, at least you have a 5-year warranty. Safeguards in the form of experts also cost more again.

The family wants to help. Great. But instead of the €200 monthly, couldn't a one-time payment be given in advance?

Is the permanent contract from November already fixed in the form of a signed employment contract? Could you still wait until November or December?

No. There is no possibility of an advance gift. It simply does not exist and would also not be in the interest of sibling fairness and should not jeopardize family harmony.

Okay. I could get the contract quite quickly... the question is, does it help if I am not a co-borrower?

The property just has a good overall package: the relatively short commuting times, the schools and kindergartens, the motorway connection to Berlin. The developer will definitely sell that... so somehow buying time is not an option here.

Also approx. €2,900 net per month, got the desired €350K for building his house. (Whether that was the limit, I don't know) With the difference that he paid for the land completely with equity. About €160K including incidental purchase costs.
It is not directly comparable due to the "high" equity, but apparently the income is sufficient for this amount.

The land purchase of course ensured that the lending value was sufficient for him. In that respect comparable to our situation. The lending value would of course not be sufficient for us, but with the land and house of the mother of our partner (free of encumbrances), then yes.

Thanks for your assessment. We see that it is not a sure thing - but possible.

The ancillary building costs? The entire price seems surprisingly cheap

Even from a gut feeling, used properties are associated with uncertainties for us laypeople. When buying from a developer, you at least have a 5-year warranty. Safeguards in the form of experts then also cost more again.

But that is really just your feeling. With existing properties, at least the minor issues are known. With new construction, you only know about the quality after several years. I believe I have read or observed in a few projects that the companies behind them are sometimes only about 1 year old, apparently created just for a major project and then likely dissolved. Good luck with the "5-year warranty" in that case. You also can’t save yourself from hiring an expert when buying from a developer, or rather you shouldn’t. Therefore, there is no black or white here.