Is the overall cost estimation realistic?

I can't estimate the costs. For us, the cubic meter costs 5 euros + transport, for others a multiple of that. Transport costs depend on how far it is to the landfill. You really have to inquire about that directly.

Okay, it's now also on my long list of questions that I will ask the contractor again. Definitely good to know that the 80m³ will not be enough. That's exactly why I started the thread Multiple estimates = hopefully fewer unpleasant surprises with financing

So we had about 8500 euros for 160 cubic meters. Keep in mind that not only material has to be removed and transported away, but also frost protection or something similar has to be put in again.

Frost protection? We will start in spring and have a guaranteed construction period of 6 months. I hope there will be no frost problem, but you never know .... Since 80m³ is included for us, I will now just calculate an extra 5,000 EUR for earthworks. Maybe the amount will become more accurate when we talk to the company again.

So we had about 8,500 euros for 160 cubic meters. Also keep in mind that not only material has to be removed and transported away, but also frost protection or something similar has to be put in again.

True

Frost protection? We will start in spring and have a guaranteed construction period of 6 months. I hope there won't be any frost problems, but you never know.... Since 80m³ are included for us, I am simply calculating an extra 5,000 EUR for earthworks now. Maybe the amount will be more precise after we have spoken with the company again.

It has nothing to do with the outside temperatures during construction. You remove 50 to 80 cm. Your foundation slab is 20 cm thick and the rest has to be filled and compacted.

Be sure to check out the two pinned threads. If I had looked at them more closely, one or the other unpleasant surprise would have been avoided.

And use the search function. Someone here once asked what triggered a refinancing.

Then you have the experience and mistakes of the users here.

After many more conversations, I have revised my table again and am now hopefully slowly approaching a realistic result (see picture, I hope it is not too small).

Total costs now at approx. 400,000 EUR.
30,000 EUR equity.
Items such as kitchen, floors/walls, new furnishings will be fully financed through parental support.
So I come to a financing requirement of ~350,000 EUR.

Joint net income 4,600 EUR
Current rent including utilities: 600 EUR
What we currently have left every month: ~1,500 EUR

We now have two offers for this financing requirement from two banks.

1) Interest rate 1.88% fixed for 15 years, repayment rate 2%, resulting in a monthly rate of approx. 1,120 EUR. Remaining debt after fixed interest period: 228,000 EUR, special repayment once annually of 5% possible.

2) Interest rate 2.34% fixed for 20 years, repayment rate 2%, resulting in a monthly rate of approx. 1,250 EUR. Remaining debt after fixed interest period: 171,000 EUR, special repayment once annually of 5% possible.

Ideas, suggestions? Which offer would appeal to you more?

Also here, as in the parallel thread: calculate flooring with waste. A large item are the moldings.

Floor removal and disposal is more expensive.