Price increase despite fixed price!

But the war is not here. Basically, building materials are available, many just more expensive and some only after a longer waiting time. In view of last year's price explosions, larger price fluctuations or increases and delivery problems had to be expected in January as well.

The war is not - but the effects are. The construction contractor really has to put his cards on the table and disclose his calculations. If comprehensible price increases after contract conclusion can be proven, then it's fair for the contractor. Aside from that, it’s also something different to see price fluctuations than to be indirectly affected by the consequences of a war in Europe with various sanctions.

That's exactly how it is. In this respect, I would question the move of Baugesetzbuch 313 for this young contract.

The age of the contract does not matter. From the entrepreneur's perspective, there is the time before and after the outbreak of war.

A conversation with a friendly reference to the facts might bring about an agreement. After that, you can still go to a lawyer.

Definitely. And also openly ask about the 313 in accordance with the calculation understandable to the OP. If only stammering comes as a response, it’s clear where the wind is coming from.

That sounds to me like a free pass for catalog calculations and then properly mark up according to §313. There is always something after all. It can't be that simple...

The age of the contract does not matter. From the entrepreneur’s point of view, there is the time before and after the war began.

I see that differently. So far, the war has been a frequently used excuse to drive prices up from all directions. The best example to understand this is the fuel prices at the pump. We were once at 2.35 euros/liter diesel even though the crude oil price only jumped briefly. It’s interesting how slowly companies adjust prices downwards. This can also be seen with many other materials. Prices are high, but they were already high before the war. Some things are now harder to get, very likely air-water heat pumps. But the materials are not much more expensive now than at the time of calculation and contract conclusion. With such a young contract, this approach is quite interesting. Normally, the company purchases and secures the materials directly after contract conclusion.

What I keep hearing is that companies have an acute staff shortage and that colleagues are repeatedly absent for longer periods due to Corona, which is hardly compensable.

That sounds to me like a free pass for catalog calculations and then properly mark up according to §313.

That is not true. 313 means disruption (external) of the basis of the contract. So external, unforeseeable influences must cause the price calculation to increase by at least 20% and/or the entrepreneur's costs are no longer covered. As I said, the entrepreneur must also prove it. Otherwise, he has slim chances.