What is the interest rate lock period in construction financing?

If you want to make special repayments, then split the 240k. 140k over 15 years and 100k variable.

Variable is too expensive, do not do it. In addition, the special repayment belongs to the most expensive loan.

What does the OP need a forward for?

To replace the KfW loan that expires in four years, which I would only take for the subsidy.

Variable is too expensive, don't do it. In addition, the special repayment belongs to the most expensive loan

What do you mean by too expensive? I paid exactly €230 interest on a €55k loan through special repayment because it was a variable loan. If you have the option to make special repayments and the standard 5% limit is exhausted, then you're glad to have financed a loan variably.

By variable I meant the savings rate that I put aside monthly extra for, for example, a 5% special repayment or an ETF savings plan in order to potentially take out a lower follow-up financing.

Which fixed interest period would you recommend to me now? I tend towards 10 years.

I calculated once comparing 10 years with 0.62% interest and 15 years with 0.95% interest. If the interest rate after the 10 years fixed period rises to about 2% for 5 years, that is the break-even point.

It is actually very unlikely that the interest rates will be over 2% in 10 years. Or what do you think?

The future cannot be predicted. Central banks will certainly try to keep interest rates low for a few more years, but the question is how long they can actually do that. If there is an expectation that inflation will come, corresponding bond yields will also be expected, and these are crucial for real estate financing. See last week.

Personally, I would go for 15 years when weighing up. The differences will not be particularly large, but at least you have certainty. I personally do not consider 2% unrealistic in 10 years. And ETF savings plans are basically a good idea but with three caveats. First, stocks are currently relatively highly valued (in plain English: the long-term average return is only to be expected to a limited extent since in recent years it was significantly above average), second, if interest rates rise significantly (say 3-4%), stocks would fall significantly, and third, stocks are fundamentally problematic if you have to sell them at a fixed point in time.