Financing project of a single-family house with hurdles and building blocks

Hello everyone, I do have a parallel topic running, but here it should only be about the financing plan. I am hoping for expertise from you, and maybe someone has a great idea how we can sensibly realize our purchase project.

Unfortunately, I have to use approximate values because we do not yet know all the parameters (here rather worst-case):

Purchase price (house and land) 500,000 euros
Additional costs are covered by equity contribution
Question:
How much equity contribution do we have to make so that the interest rate changes favorably for us?
There are certain thresholds. I once saw in an example calculator that above 80% loan-to-value ratio it does not make much difference?!

For the renovation requirement of 200,000 euros, we would (if it is worthwhile) incorporate 2 KFW programs/loans: 124, 261/262
According to my research, the interest rates here are below 3%, so it could be worthwhile. Especially since there are also repayment subsidies. The house anyway needs to be energetically modernized...

Ultimately, we still have the Bausparvertrag:
Our idea here would be to use it to reduce the renovation amount or to repay one of the KFW loans as quickly as possible. The Bausparvertrag contract has an effective loan interest rate of "only" 2.25% / Bauspar sum with additional allocation would be 100,000 euros.

Our goal is a sensible financing plan that is well calculable and keeps the monthly burden as low as necessary. Through a favorable mixed interest rate, we could possibly even increase the repayment. A monthly burden of 2,000 euros (plus/minus) is our main goal.

Or is it too complex and do you have a better / cheaper way for our project?

Thanks!!

(here rather worst-case):

For the renovation need of 200,000 euros

Is best case in my opinion. Please urgently check this before financing!

It is the best case in my opinion. Please urgently check that before financing!

Of course. I just like to gather a lot of information in advance. If it turns out to be more like 300K renovation needs, the whole project is no longer interesting for us anyway. I'm not building "castles in the air" here :)

A monthly burden of 2000 euros (plus/minus) is our main goal.

Then simply calculate backwards. With T€ 24 p.a., you can finance T€ 480 assuming 3% interest + 2% repayment. So besides the incidental purchase costs, you need at least T€ 220 additional equity to be able to finance at all. If the interest rate is 2.5%, it would be T€ 533, or with 3.5% interest T€ 436.

Flat approach loan-to-value: (purchase price + 50% of renovation costs) - 10% safety deduction = T€ 540. 80% loan-to-value for a "good" condition = T€ 432 = T€ 268 equity required.

This gives you initial rough estimates.

Then simply calculate backwards. With T€ 24 p.a. you can finance T€ 480 assuming 3% interest + 2% amortization. So you need at least T€ 220 additional equity besides the incidental purchase costs in order to be able to finance at all. If the interest rate is 2.5%, it would be T€ 533, or at 3.5% interest T€ 436.

Flat approach loan-to-value: (purchase price + 50% of renovation costs) - 10% safety discount = T€ 540. 80% loan-to-value for a "good" condition = T€ 432 = T€ 268 equity required.

This gives you initial rough estimates.

Thanks for the calculation and info. My approach here, however, is not to take out a loan for the entire amount, but to combine it. I expect an effective interest rate of just under 3%. So main loan plus KFW including building savings contract.

So does this combination make sense, or is the KFW component too inflexible and expensive?

My approach here is not to take out a loan for the entire amount, but to combine it.

It doesn't matter. You got the example calculation from me for 3%. So for €480,000 financing with 2% repayment. Whereas the KfW requires more than 2% (it's more like 4% and up). Also, with the building savings contract, repayment is often 4-7% (that's one of the drawbacks of these setups, that you have to repay quickly).

Does this combo make sense, or is the KFW component too inflexible and expensive?

You can do anything. You have to calculate or get interest rates from a broker. But it does not change the basic calculation that with your rate you can "only" finance a maximum of half a million.