ᐅ Flat Roof: Insulation Requirements When Ownership Changes and Exceptions

Hello everyone,

As is well known, when ownership of an older house changes, there are various renovation obligations, including insulating the roof if the living space is directly adjacent to it.
Section 47, paragraph 2 of the Building Energy Act provides an exception (or a relaxation of the obligation) in the case that:
“If the thermal insulation according to paragraph 1, sentence 2 is installed as insulation between the rafters and the insulation layer thickness is limited due to interior cladding or the rafter height...”
This exception is frequently used for pitched roofs and is widely discussed online.
But what about flat roofs? In my understanding, their insulation cannot be equated with insulation between rafters, which would be the literal application of paragraph 2.
Are there any exceptions for flat roofs as well? Or do the U-values of 0.24 W/m²K specified in section 47, paragraph 1 generally need to be met for an older flat roof?

Important: Although my question includes some legal references, I am not expecting legal advice. Perhaps some of you have bought, inherited, or renovated a house with an old flat roof and have dealt with this issue?

Best regards,
Pröter