Financing model for expansion of a barn/warehouse

Do you get the material for free? Labor hours are not worth €50,000, which could be saved in that area.

Well, it’s not just the labor hours, but also the cheaply purchasable material. The profit lies in purchasing – for example, buying sanitary fixtures from Megabad & Co. and saving tens of thousands of euros. But also saving on warranty for the work.
The scale of the project definitely requires explanation – what is being done, material procurement, experience, etc.

Well, those are not just the working hours,

Exactly, that's what I said.

but also the cheaply purchasable material.

Yes, but that also costs euros.

Own contribution: €52,000

I see a romanticizing of an item there, which still causes costs, but is not listed. It is also a converted €52,000, so rather a placeholder from the bank for financing than a calculation of the service they "want" to save on.

Construction costs (including architect, structural engineer): €410,000 including kitchen, house connections, incidental building costs etc.

And honestly: the calculation of a bit over €400,000 all in reads to me as somewhat tightly calculated.

And honestly: the calculation of a bit over €400,000 all-in seems a bit tight to me.

It will just be a 100sqm apartment...

It will just be a 100sqm apartment...

A 100sqm apartment with SHK worth €52,000 purchase price/cost-neutral working hours..

The EL does not refer exclusively to SHK but constitutes a large portion in that area. Furthermore, planning services, painting work, flooring, and other smaller classic positions are included in the in-house services. There is a rather old planning thread on this. However, the project has naturally evolved over time. I can update that briefly. I do not want to focus too much on cost calculation here but rather on the financing model. I have a good handle on the cost side.