Realistic financing opportunity?

And who pays the additional construction costs?

What does the offer say about the additional construction costs? If those are added on top, you will ultimately be just under 400,000 if you also include painting, flooring, and bathroom furniture as well as the kitchen.

extended financing of up to €350,000 so that we can design the interior according to our wishes, e.g. underfloor heating, multi-split air conditioning (south-facing)... equipment that would be more complex and expensive to install later.

I'm reading that just now... Air conditioning is a nice-to-have for people who can afford it on top. If I were you, I would be a bit more modest. ... if underfloor heating is not included in the offer, probably other things aren't included either? Be that as it may: "tight budgets" can be quite confining in life. In the long run, that’s not good. In my opinion, a single income is not made for such financing. ... and I advise a reasonably priced existing property, then you know what you have.

It is observed in a few projects that the companies behind them are barely 1 year old, apparently set up only for a major project and then surely wound up afterwards. Have fun with the "5 years warranty" in that case. You can't skip the expert even with the property developer or rather, you shouldn't. Therefore, there is no black or white here.

Decisions have to be made somewhere, and "soft" reasons also play a role. And no: the property developer has certainly been on the market for about 25 years in the row house sector.

What does the offer say about the ancillary construction costs? If those are added on top, you are ultimately just under 400,000, if you also include painting work, flooring, bathroom furniture as well as kitchen.

I'm just reading that... Air conditioning is a nice-to-have for people who can still afford it on top. If I were you, I'd be a bit more modest. ... if underfloor heating is not included in the offer, other things probably aren't included either? Be that as it may: "tight spots" can be quite confining in life. That doesn't do you any good in the long run. In my opinion, the sole income is not made for such financing. ... and I recommend an affordable existing property, that way you know what you have.

Tight spot? On paper, yes. Actual income is higher by at least €1,200 per month & special payments like Christmas bonus, vacation pay, Baukindergeld are not yet included because they are planned as special repayments.

And we also have to cover our rental costs. These would soon increase to €1,300 per month for us since a move is unavoidable. With a rental apartment it would be similarly tight. And existing properties with the same public transport connection are rare and not cheaper.

So we are modest in that we do not want a new kitchen and also do not want to throw away our furniture but actually take it with us. Likewise, we also save on the fittings... it will just be textured wallpaper & laminate and done by ourselves. I find "bathroom furniture" more of a luxury. I think a simple Kallax that’s lying around here is enough.

We are also modest in the sense that we only drive one car and go camping instead of foreign trips. But that is more our lifestyle.

You suppress our constant demand for the incidental construction costs.

And you shouldn't assume that someone with not such a great wallet pays off the loan early either. The money is spent on ongoing purchases for the garden and so on. There's always something.
I just see: you also earn, so at least there is a buffer.
In the end, it doesn't really matter what we say here: you are convinced that you are more frugal than we assume here and that everyone else lives in luxury anyway, which you are not part of.
So, good luck!

You are suppressing our constant demand for the ancillary construction costs. And that you should repay with a not-so-great wallet you shouldn't plan for either. You spend the money on ongoing purchases for the garden and such. There's always something. I just see: you also earn, so at least there is a buffer. In the end, it probably doesn't matter what we say here: You are convinced that you are more frugal than we assume here and that everyone else lives in luxury, which you do not belong to. Then good luck!

Turnkey. Notary and property transfer tax included. We can still set aside €10,000 for interior finishing. I had already described that.

Turnkey. Notary and real estate transfer tax included. We can still reserve 10,000€ for interior finishing. I had already described that.

Yeah, I don’t really believe that. Two years ago, we looked at a semi-detached house that a developer offered turnkey for 310,000 euros. During the negotiations, we then realized that our idea of turnkey was completely different and the house move-in ready would have cost about 370,000 euros without outdoor facilities, without kitchen, and special interior features. Therefore, check exactly what is included in the offer. Also follow up whether the move-in date can actually be kept, otherwise you will keep paying rent alongside the loan. Also clarify at what stage of construction you buy the house and how much deposit you have to pay immediately. For us that would have been 80% of the purchase price and moving in after 12 months.

Is it even possible to get a loan with a term of 35 years at the age of 38? Isn't it the case that the loan can only last until the start of retirement, meaning up to the age of 67?