What interest rate is realistic?

Mistake with the loan-to-value ratio. These are not 35%. Because the bank bases the loan-to-value ratio on the land and house value. This will clearly be 560,000€, because the bank first deducts all incidental costs and a risk value. If 450,000€ results from this, your loan-to-value was 560,000 - 360,000 = 200,000, so 200,000€ loan from 450,000€ bank appraisal value already makes a loan-to-value ratio of 45% and not 35% of the total amount. Which does not mean that it is not very good, but unfortunately not as simple as you present it.

Tox was faster

Of course you are right, but no matter how much you deduct, the risk for the bank is zero. We are building a single-family house in Bauhaus style on a beautiful plot, which would be immediately realizable for a bank. Let's see what leeway the house bank still has, but I think a 1 should definitely be in front of the comma.

How much and how high the risk is for the bank is determined by the bank, not you

If you build out in the sticks and the bank looks into its real estate atlas and a sale is very difficult in case of emergency, it doesn't matter if you only got 50% from the bank. The bank doesn't want to be stuck with the house either.

We can gladly discuss this now and I will argue that the risk is not exactly zero, even if it approaches zero.

An interest rate of 1 point something should be realistic in my opinion.

Even though it usually should hardly matter: What does your [Schufa Score] say? Not that it spoils your balance sheet? Or are there any other ongoing loans?

We also need the same amount in debt capital, with about 40% loan-to-value we had the same experience with the house bank as you did, they wanted 2.8% from us.

Get an offer from other banks, we closed in May with 1.9%. We are now building without KfW funding.

The house banks usually make the worse offer, comparing is worth it.