Home purchase financing with little equity?

We would like to use these flexible composite pipes completely for the lines, they are cheap and relatively easy to install/crimp.

That is the state of the art anyway. But don’t fool yourself about this system: you need a pressing tool, at least 2 different sized heads, and - the fittings, T-pieces as well as corner pieces are anything but inexpensive.

All in all - financially - I see no significant savings compared to copper. That the composite pipe is easier to handle is the only advantage.

Rhineland greetings

Do you want to live in the property during the renovation? I would completely advise against it because it makes many things more complicated and time-consuming. If not, you will have to live with a double burden for a longer period. That means you have to pay both the loan and the warm rent. How long do you plan for the renovation?

And tools, as construction experts have already said, are not cheap either. You either have to buy or rent them. And the small stuff creates a lot of hassle during construction.

Yes, I have seen the tool, but you can sell it quite well afterwards or "borrow" it directly. The pipes themselves are actually quite cheap on the Internet from good "recommended" manufacturers; the fittings and such are what cost more, I have seen that too. Nevertheless, water and heating pipes make up a small overall proportion, it's just the work of knocking out the old pipes. The boiler can probably still be used, we will take a look at that. All in all, it's not a palace but just a small 120 sqm semi-detached house with an extension.

the substance is fine, the roof is good, windows and doors are also good

Are you saying that or an expert?

Are you calculating 2,000 for the floors throughout the whole house? That would be about 17 €/sqm including adhesive or whatever else is needed.
You will also need plaster, not just a little if you want to relay everything new. But someone who knows what they’re doing should apply it, otherwise it will look bad. And for a new bathroom (I’m not talking about the guest bathroom) I would cautiously estimate at least 7,000 euros. Then you want a new heating system; with installation it should be around 10,000 euros. You might also need new radiators.

And then the question arises: a 60+ year old house, is the roof really in good condition? Maybe it will have to be redone in about 5 years anyway.

And last but not least, don’t underestimate the amount of work you can do yourself. Besides the job, it will be very, very hard. For one room, it can take weeks to months.

living on the premises during the renovation only in case of emergency, otherwise not. we are also aware of the double burden ....

The majority of the equity capital is used up by the incidental purchase costs.
I would suggest you calculate the material costs more precisely again. Besides the visible coverings, you also need, for example, the subfloor, adhesive, moldings, so about 1/3 more than the covering itself.
With a good calculation for the bank.

P.s. Don't imagine it to be so easy with a large number of online orders: delivery is often slow, then small parts are missing...
Therefore, always calculate generously with the average price value. And include a buffer.