Liability question - fire protection correction in a semi-detached house

Hello everyone,

after a longer period of inactivity (interior construction) I am now coming back with a topic that is currently bothering me.
Our building authority criticized at the shell construction acceptance over a year ago that the ridge beam running the entire length of both semi-detached houses is inadequately protected against fire.
However, the building authority had naturally reviewed and approved the construction documents beforehand.

We received the requirement to provide an appropriate separation there using Promat F90 boards.
At that time, the roof was already covered and the general contractor assured that this would be done afterwards.

Now, more than a year later, he told me that additional costs would be incurred for this. Because our "building authority is too picky" and the architect (they work together often) did nothing wrong anyway.
He also did not want/could not give me a price. The house is almost finished and I suspect he wants to make some extra money from this.
I see the architect as responsible. Who is right?

Are we talking about general contractors or developers? If the former, who planned and who hired the planner (alone, together)?

Are we talking about a general contractor or a property developer?
If the former, who planned and who commissioned the planner (alone, together)?

Each semi-detached house concluded a contract for work with the same company. The architect was included overall. We did not have much say in the matter.

I would also like to point out that it was 2020, there were hardly any affordable plots of land in the region or house construction offers.

The property was sold by the builder (=developer) or did you both freely decide to build with this company (=general contractor)?

The plot of land was sold by the contractor (=property developer) or did you both freely decide to build with this company (=general contractor)?

We purchased the land ourselves and subsequently commissioned the contractor

We purchased the plot ourselves and subsequently commissioned the contractor

Each semi-detached house unit concluded a contract for work with the same company. The architect was included in the total sum. We did not have much say in that.

I see the architect as liable. Who is right?

At first glance, this sounds to me overall like a disguised BT and a construction contract including architectural services (and thus rather not an architect contract with corresponding professional liability).

Our building authority criticized during the shell construction acceptance over a year ago that the ridge running along the entire length of both semi-detached houses is insufficiently protected in terms of fire protection.
However, the building authority had previously inspected and approved the construction documents.
We were required to ensure an appropriate separation there with Promat F90 boards.
At that time, the roof was already covered, and the general contractor assured that this would be done afterwards.

Here I do not understand the sequence of events: the building authority has to impose requirements already in the approval; construction may only begin after approval, so I do not understand the “afterwards” here. The separation (on which side, by the way, the ridge beam* is quasi “common” here?) should have been implemented before the roof covering.
*) Your semi-detached house is somewhat atypical in that the halves meet at the ridge, see

Now, over a year later, he told me that additional costs are to be incurred because our "building authority is too picky" and the architect (works together often) did nothing wrong.

The architect must also observe compliance with fire protection regulations, considering the particularity described above, and thus foresee the requirement linked to the building permit. There are no “additional costs” in terms of the construction contract, as compliance with building regulations and resulting requirements is obviously part of the construction contract even without special mention in the service specification or the like, and thus also part of any fixed price. The general contractor simply miscalculated here. The architect “made a mistake,” but the building authority reacted appropriately by issuing the permit with the requirement instead of refusing it due to non-compliance with fire protection regulations. The architect should have included the separation in the plans, and for the general contractor it was an integral part of the agreed work. Most semi-detached houses have halves adjoining at the gable side; presumably, the general contractor built a transverse twin for the first time here ;-)