Construction financing conditions expectations single-family house solid

Hello,
We, 34, 33, and 2 years old, want to build a solid single-family house.

Equity land 450m2 +50k€

Possible monthly repayment rate 1350€
is 40% of the net salary of the 1st person

350,000€ loan financing how is it best to set up without a building savings contract?

So interest rate fixation is speculative 15 20 25 years what do you think? How will interest rates develop refinancing?

I am grateful for ideas

If someone can reliably answer the last question here for you, congratulations. One more multimillionaire in the forum.

You are asking a question here and it is: save costs and risk or generate costs and security.

Unfortunately, only you can answer both yourself regarding what you feel comfortable with in your comfort zone.

Precisely phrased differently, where is the current break-even point in cost risk?

An acceptable risk with the lowest possible costs

There is no "one" break-even. And what do you consider to be an acceptable risk? And how do you determine that? At what confidence level would you like to calculate?

Unfortunately, it’s not that simple.

You will need to obtain offers with different terms for your project and then you have to compare. Consider which remaining debts will stay and what would happen if the interest rate level were to rise again.
Your monthly installment corresponds to an annuity of 4.6% for a €350,000 loan, which is manageable. 2% minimum repayment, up to 2.6% interest - otherwise your installment will not be sufficient. How much equity do you have?

Edit: Ah, €50,000 of €400,000 in total. 20 years should be possible, but finding an offer for 25 years at an interest rate up to 2.6% with that loan-to-value ratio might not be so easy.

Edit: Ah 50T€ of 400T€ total. 20 years should be possible, finding an offer for 25 years with interest rates up to 2.6% given the loan-to-value ratio is probably not that easy.

He has not yet revealed how much the property is worth. With that, however, 25 years at =2.5% interest or slightly less is quite realistic.

For 15 years it would be ~ 1.8/1.9

350,000€ loan financing, how best to structure it without a home savings contract?

Why actually without a home savings contract?

And which energy standard should/will the house have? Energy Saving Ordinance or KFW 55/40/40plus?