Additional financing. Bank wants a breakdown of construction costs

Good day,

unfortunately, we need to refinance €30,000 for our construction project. Although we had planned a buffer when finalizing the financing, the costs for the earthworks have significantly exploded. Due to pile foundation, excavation, construction road, as well as the beam grid for the pile foundation + waterproof concrete slab, the costs amounted to nearly €100,000. We had planned €50,000 as a buffer, and we were able to save €20,000 in the last 8 months.

We have taken out 2 loans. 1. through an insurance company with a term of 36 years 2. €150,000 through the KFW.

Our bank advisor recommended that we arrange follow-up financing through the KFW. Now they want a cost breakdown from our developer including all additional costs. However, we assigned all the earthworks as own work, and our developer had nothing to do with it. The price of the house has not changed since the financing was finalized; only the earthworks caused additional costs.

How do I now correctly communicate this to the bank? Should I prepare a separate cost breakdown for the earthworks? Our developer does not want to sign for the own work.

However, we carried out all the earthworks ourselves, our developer had nothing to do with that.

That doesn't matter. Just list the additional earthworks and attach the invoices. Possibly also the transfer of the 20,000€ from your liquidity. That should be sufficient.

The bank naturally wants to know that they are not financing your new car or furniture, but that the additional money went into the house construction.

Document the earthworks with a quote or the invoice. Should be sufficient

Did I understand correctly that the earthworks have become 100,000.-€ more expensive? If so, it is quite normal for the bank to become suspicious. Even a first-semester architecture student cannot make such a miscalculation. Or are you building on a greenfield site with no house within several kilometers and completely unknown ground conditions

I suspect that originally a normal flat rate for earthworks was calculated and then the soil expert wanted the pile foundation. This is quite complex and expensive. Usually, the areas where this is necessary are known (in the industrial area here at the Seerhein, construction is only done with pile foundations), but as an outsider you can of course fall into the trap.

There was also the other post "Baugrundgutachten vor Grundstückskauf"...