Can a construction company suddenly increase costs despite a suspensive condition?

Hello dear house building forum,

newly registered here, we are a bit desperate, looking for an assessment of the following situation or experience values:

My husband and I are in the process of planning a house. The plan is to do the basement ourselves, then a shell house (walls, windows, roof) by the construction company, and finally the interior finishing by ourselves.

[*]The house contract was signed on 20.07.2023. We needed the contract to apply for a family loan at the L-Bank. The construction company made us an apparently attractive offer and uses the prices from 2022 (this is also stated in the service specifications). This was, of course, also a reason why we ultimately decided on them.
[*]The contract contains a suspensive condition that is linked to the loan. This means: as soon as the funds from public sources are approved, the contract becomes legally binding.
[*]Our building project has so far been characterized by many setbacks and long waiting times, so that we only signed the contracts for the main loan this year on 29.07.2024.
[*]We have been in frequent contact with the construction company since early summer, have been on site several times, and had various appointments to finally move forward and complete our building project. Now, on 6.12.2024, we received an email from the company with an adjustment to our purchase price.
[*]The percentage increase in prices from 2022 to 2024 is almost 16%.
[*]They now want to use as a basis the calculation from 2023, where it is 14% (they accommodate the 2% until 2024).
[*]So the company offered us a house in 2023 that was already no longer economical at the time of signing (+14%).
[*]They mitigate the now required 14% by 5%. Ultimately, they want 9%. From their point of view, the 12 months have already passed.

We are of the opinion that the 12 months started at the end of July this year and that we have not had to comply with any requests.

Our contract contains the sentence: "Fixed price guarantee 12 months from contract confirmation."
We have practically never really received a confirmation, as we have been working together continuously, and for us the contract was activated with the L-Bank loan. Is that wishful thinking and can we insist on our right that we actually do not have to concede anything to the company, or are we overlooking something?

Many thanks for an assessment

This will probably be difficult to assess here if the exact contract text is not available. If you do not want to pay the money, then you might want to invest a few euros in legal advice if you are unsure.

Lay opinion: You have received a contract signed by both parties = contract confirmation. Topic closed. Even if it is annoying for you, you cannot sign a contract in 2023 with a 12-month price guarantee and assume that this guarantee actually applies for 24 months or even longer. Go to a lawyer. We do not live by the text of the contract nor the written communication of the last 1.5 years.

I agree with (but also as a layperson)
but I must also mention:

Our contract states the sentence: "Fixed price guarantee 12 months from contract confirmation".

Meaning: As soon as the funds from public authorities are approved, the contract becomes legally binding.

That is not the wording of the contract. The contract must have already been legally valid in 2023, but could be withdrawn free of charge by you if the bank did not grant the loan (among other things, a point of a legally valid contract).
The contract confirmation is basically the signature of both parties plus the two weeks you have to withdraw. And this confirmation is basically tacit (I don’t know the exact word).

If the contract had not been legally valid since 2023, then theoretically the contractor could have changed everything to your disadvantage.

Whether and when the contract was confirmed, the lawyers can exchange arguments about that for several months, even though it is already certain that you will not have certainty that you will be in the right. What happens in the meantime regarding prices and loans you don’t dare to guess.
Ultimately, one must also mention: anyone who enters into a contract with a dumping price must face their own fault. At least that’s what is said about online offers that are 20% below market price.

uses the prices from 2022 (this is also stated in the specifications).

It seems that a lot of things on your side are sewn on the edge. Did you never expect that prices would become more expensive?
If you were to submit the building application at some point now, construction would start around May/June. And the increase will hit you anyway.

P.S. A contract with terms is legally binding as soon as it is signed. I learned that in two semesters of law during my business studies. At least you cannot claim that the contract only became legally binding with bank agreements.

For a lawyer it is now too late, your mistakes have long been made. The suspensive condition does not postpone price increases, the contract was implicitly activated through the interim correspondence, so the 12 months only run until next summer (however, the house will not yet be "finished" in terms of the scope of delivery). Now the manufacturer wants a 9% price increase, and will also be able to claim it. You can of course request conversion (i.e. the contractual object into a house 8.3% smaller at the old price, since you have not yet built the basement and the building permit is also still pending).