Green roof carport as a compensation area for floor space ratio calculation

Hello everyone,

this month we are starting with the construction of our house and we are currently working on the final changes to our plot. The floor area ratio of 0.2 + 50% is almost fully used up. What is still missing at the moment is the exact concept for the carport. We are currently considering whether a flat-roof carport with green roofing might be an ecologically valuable alternative that could also look quite nice.
My wife and I are both convinced that we have read that an outbuilding with green roofing does not(!) have to be included in the floor area ratio and virtually serves as a compensation area. That would give us a nice side effect of some leeway regarding the floor area ratio for future small things.
Unfortunately, we cannot find any firm regulations or legal texts on this anywhere; and we wonder why we think that green roofs do not count towards the floor area ratio. We must have gotten that from somewhere, but we have been searching for days without finding anything concrete.
Or is it perhaps something that has to be clarified individually with the building authority?

We would be happy if you could enlighten us on this. :)

Best regards,
Lennart

Please correct me if I am wrong, I researched this myself some time ago.
My result at the time was that any area that is built over, regardless of its design, is also counted 100% towards the built-up area.
Where it can look different, however, is in the calculation of charges for rainwater. Here, greened areas or permeable paving can reduce the factor or be deducted.

Please correct me if I am wrong, I researched this some time ago as well.
My conclusion back then was that any area that is built over, no matter the type, is counted 100% towards the built-up area.

Where it can look different is in the calculation of charges for rainwater. Here, greened areas or permeable paving can reduce the factor or be deducted.

We dealt with this topic a while ago as well and came to the same conclusion as .