Calculation of the floor space index for a stepped floor

Hello,

We are planning to build in Hessen. We plan two full floors and a setback floor. The development plan is from 1975, so the [Baunutzungsverordnung] of 1968 should be applicable. This means that attic floors must also be taken into account when determining the floor area.

We plan to have a storage room without windows in the setback floor, which is therefore not a habitable room. Do we still have to include the entire floor area of the setback floor in the floor area calculation, or is there an option to subtract the storage room?

According to the development plan, the floor area ratio is only 0.6. Therefore, it will be a bit tight.

Thank you very much for your help

Uli B

Do we still have to use the entire floor area of the staggered floor for the calculation of the base area, or is there a possibility to deduct the storage room?

According to the development plan, the floor area ratio is only 0.6. Therefore, it will be a bit tight.

I think in Hesse this is possible, not to include the non-habitable room (for the floor area ratio) (in the green forum there is a strange guy from Hesse who doesn’t want to leave even a single square centimeter of margin when exhausting the floor area ratio). However, I believe the full floor question has to be clarified independently of that. 0.6 does not sound tight to me, but as a clue to a non-full floor (at least with a base area ratio of 0.4 – with a base area ratio of 0.3, two full floors would be "usual").

This means,

... The areas of habitable rooms on other floors, including the stairwells belonging to them and including their enclosing walls, are to be included. (§20, Abs. 2 Baunutzungsverordnung)
So only habitable rooms and areas necessary for their access, such as stairs and corridors, are included. Storage rooms, bathrooms, toilets, or technical rooms are excluded. But not only in the attic, rather on all floors that are not full stories. If you set up a fitness room in the basement, that is also included, along with the stairs and corridor. So be careful with the room designation.

Hello,

thank you for your answers. The input has been very helpful.

Best regards

Uli