Hi,
just some info:
the HE-HBO from 2006 still included the following:
"The areas of garages integrated into buildings are added. Areas of attached garages are disregarded in the measurement of the area. Due to the purely planning-law significance of the full-storey concept, the assessment of whether the garage is integrated depends on the external appearance of the building and not on the structural separation between garage use and other use."
And I am of the opinion that this also includes boundary garages. Maybe they overreached, as this statement was removed in the new edition.
Likewise, the following text was included in 2006, but it has also been removed. I find that a bit odd. I think the responsibility should be assigned to the builder or architect.
"The 'gross floor area of the underlying storey' is measured in accordance with DIN 277 Part 1 according to the outer edges or outer surfaces of the building envelope walls or - insofar as the storey does not have building envelope walls - according to the outer edges or outer surfaces of the components delimiting the storey. This means:
• Areas of building parts that protrude beyond the building envelope walls, e.g. balconies, are disregarded in the measurement of the gross floor area; this does not apply insofar as balconies are covered and not for covered terraces,
• Areas that lie behind the alignment of the outer wall, e.g. loggias, are included in the measurement of the gross floor area."
best regards