Floor plan planning shortly before submitting the building application

Do you have the floor structure of the roof terrace? Normally, a proper insulation (even with a slope towards the floor drain) is applied on top, along with the waterproofing. Then the terrace covering, which is laid on pedestal supports, as Otus already mentioned.

I called; the question is now being clarified and will be answered for me.

Even if the answer is very negative, at the moment I don't see where to find the confidence to have a correction made at the contractor's expense. A correction at one's own cost in the five-figure range would be severe, and I don't think the matter is worth it.

(even with a slope towards the floor drain)

The note is good and correct. According to FDR (flat roof runoff), at least 2% is required – that is 2 cm per 1 m. That adds up over length! This must not only be drawn, but later also executed. And that requires plenty of substance. I believe we already pointed this out here at the beginning.

And for a seven-figure project, one does not expect a threshold to the exit on the DT as in social housing.

Whether the fun is worth 50 K in tuition fees for sunk costs to me...? Hmmhhh...

(Edit: Holding the expert liable, I also see as very difficult, but they should be insured).

The expert says that when reviewing the contract, he assumed that 201cm is the clearance height. This already results from the Landesbauordnung NRW, which stipulates a clearance height of 2m for escape routes.

I found this text related to it.

§ 5
Accesses and driveways on the properties

(1) From public traffic areas, a straight access or passage must be created, especially for the fire department

1. to the front of rear buildings,

2. to the rear of buildings, if a rescue of people is only possible from the rear of the building except from the stairwell.

The access or passage must be at least 1.25 m wide. For door openings and other minor narrowings, a clear width of 1 m is sufficient. The clear height of the access or passage must be at least 2 m.

What confuses me a bit is the title of the paragraph. Is such an "access" a terrace door designated as a second escape route?

On the roof terrace, a floor construction of 30cm is planned. Therefore, this test this morning with climbing through at 16cm was absolutely pointless.

Without wanting to offend the expert, but given his profession, one could expect that he can read a plan and also knows that rough dimensions are indicated in a factory plan. Or does he also assume that the dimensions for room widths/lengths or wall thicknesses are finished dimensions? Sometimes I really wonder how professionals become experts...

The expert says that when reviewing the contract, he assumed that 201cm is the clearance height. This already results from the state building code NRW, which provides a clearance height of 2m for escape routes.

For the building itself, the provisions of the 1st and 2nd escape routes according to § 33 of the state building code NRW probably apply, specifically § 38 para. 5 for windows:

§ 38 Windows, doors, basement light wells
(...)
(5) Windows that serve as escape routes according to § 33 paragraph 2 sentence 2 must be at least [I]0.90 m x 1.20 m in clear size. They must not be arranged higher than 1.20 m above the finished floor level. If these windows are located in roof slopes or roof structures, their [I]bottom edge or a projection in front of it may not be more than 1 m horizontally measured from the eaves edge. The distance can be increased in coordination with the fire protection authority. People must be able to signal to public traffic areas or to areas for the fire department from these windows.[/I][/I][/I][/I][/I][/I]

And:
It is sufficient if one escape route has the dimensions; not every window must function as an escape route.

There apparently is still an (older) administrative regulation to the state building code
- VV Bauordnung NRW - with further specifications, but from which, in my opinion, no further useful information regarding windows and doors can be drawn here.

I consider references and information in the legend to the plans to be authoritative (then this would also be recognizable to the expert); furthermore, the contract with the general contractor should contain a clause about what should take precedence in case of doubts/deviations: plan or text (construction performance description) (it must then be clarified whether this also applies to later execution planning after the conclusion of the contract).

That is the entire legend.

Excerpt from the contract:

"Should there be discrepancies between the client and the contractor regarding the proper execution of the construction during the construction process, and a neutral decision cannot wait until the final acceptance, a publicly sworn expert of the Chamber of Industry and Commerce (IHK) must be consulted, whose costs shall be borne by the losing party. The same applies to disputed points regarding acceptance."

A priority plan / text is not defined.