Construction loan via a building savings contract?

Hello,

since we unfortunately have little knowledge about financing, I hope you can help us.
A brief overview of the house:
Purchase price including land and all additional costs: = €256,000.00
Less equity and own contribution, a financing need of €214,880.00 remains.

We have a building savings contract (100,000.00€) which will be ready for allocation in about 10 years.
We pay into this building savings contract €100 and €40 VWL monthly.
Since we have already made a one-time deposit of €10,000 and the savings plan has already been running a bit, this amount is sufficient.

Now my question: we have obtained 3 financing proposals.
2 proposals are via an annuity loan and one proposal, which we find very interesting, is via a second building savings contract.
The installments are higher at the beginning with the option of the 2nd building savings contract, but after 10 years, when both building savings contracts are ready for allocation, it is significantly cheaper and I have interest rate security of 2.80% until the end of the term. By the way, if I recalculate, this (about 28 years) is also shorter.

A brief summary:
Loan amount of €214,880.00 is divided into two parts.

[*]€100,000.00 existing building savings contract, is provided via an annuity loan at 3.39%, the interest here amounts to €282 plus the €100 saved into the building savings contract.
[*]€114,880.00 new building savings contract (Flex building savings contract) is also provided via an annuity loan at 3.45% = €330.28 interest and €296.76 rate into the building savings contract

That makes a total monthly installment of €1010.

What makes me suspicious now is that I don’t know anyone who uses this option.

In the other two options, the installment is about €870 with 1% repayment as well as 1.56% repayment on the KfW (15 years fixed interest rate) loan. In addition, there are still the €100 for the building savings contract that we definitely want to continue saving into.
If I roughly recalculate, we still have such a high sum after 10 years that either a) the installments will rise significantly or b) we will still not be finished after 30 years. Furthermore, I would not know if I would still have an interest rate below 5% in 10 years. Additionally, and I find this a big advantage, we could incorporate very high special repayments both during the savings and repayment phase.

I hope you can give me a recommendation.

Regards Noel

We also did the [Bausparvertrag] with our first house. Besides the option for special repayments, the advantage was in the significantly lower interest rates we had to pay with a [Bausparvertrag].

Special repayments should also be possible, albeit to a lesser extent, with the regular loan, though not unlimited, as banks charge a premium for that.

The question is – can you even make use of the special repayment options, or is that rather unlikely?

At the moment, I would invest the money I can spare flexibly, even with a small interest rate, and after the fixed interest period ends, use it to reduce the amount to be refinanced, or simply increase the repayment rate from 1% to 2%.