Experience / Opinion on home financing with a high loan amount

Total construction project costs approx. €545,000 Of which the land costs approx. €170,000 House costs approx. €300,000 (city villa, 162m²)

170 + 300 = 470, where does the €545 come from? 10 years and 15 years fixed interest rate on the sum - hope you can sleep well with that, I couldn't. Regards

I also see a nominal 1.4% fixed for 15 years for the 400,000 euros, and nowadays I would no longer even sign a loan without a repayment rate change option. But I really don't understand why 400,000 euros are fixed for only 15 years? Here, splitting into 15/20/25 year fixed interest periods is recommended.

My partner thinks (I’m not quite sure yet, which is why I’m seeking advice here) that it makes more sense to pay off more quickly in 15 years than to pay for 20 years at a lower repayment rate. He has calculated that with 15 years and a higher repayment rate (2.75), we would have paid off the same amount in the end as after 20 years with a 2.5% repayment. His other arguments are inflation, salary increases, interest rate trends (which he believes will no longer decrease further, but he also assumes they won’t rise as much as in the early 90s – I’m just more cautious about that).

170 + 300 = 470, where does the 545 come from? 10 years and 15 years fixed interest period on the amount - I hope you can sleep well with that, I couldn't. regards

300 = just the house, plus acquisition and incidental construction costs, plus outdoor facilities, KfW appraiser, construction supervisor, etc.

After 10 years, the borrower always has a statutory (special) partial termination right anyway (similar to an agreed special repayment). 489 Abs. 1 Baugesetzbuch.

Does your partner - regardless of the fact that the 15 years at 1.55% are too expensive and the option to change the repayment rate should be a must - know the conditions for 20 or 25 years or the interest rate difference, thus also the low repayment loss with the longer fixed interest period in relation to the remaining debt assuming the same interest and repayment rate?