Permeable traffic areas in the building application

Hello everyone,

what relevance do the infiltration-capable traffic areas have in the building application? In our case, for example, the terrace is specified with water-permeable material and for the driveway / entrance it says "water-permeable eco-paving" in the building application (however, this is not required in the development plan). What happens if I still want to use water-impermeable material in each case? As far as the floor area ratio etc. is concerned, it should not matter because everything counts there, even if it is lawn as a driveway as far as I know. The floor area ratio is also complied with, I am just uncertain regarding the water permeability.

Can someone help me with that?

Regarding the floor area ratio, however, I would be interested to know who has to apply for or approve something if you want to pave a larger area later than specified in the building application?

You, I wouldn't be so sure about the plot ratio. In order not to exceed it, we really had to use partially water-permeable materials like gravel and crushed stone instead of paving in the building application. I will also stick to that.

Regarding the floor area ratio etc., it should be irrelevant because everything counts there, even if it is lawn used as a driveway as far as I know.

How do you come to that conclusion? For example, a municipality in southern Germany calculates grass pavers at 20%, if I remember correctly. How far other municipalities create similar calculations, I do not know - but pure lawn would not yet count as paved area just because you drive over it. Floor area ratio limitations also have the secondary purpose that a building area does not hold back heavy rain like a "basin." And besides, one also wants to properly dimension sewage systems.

Floor area ratio refers in my opinion to sealed surfaces. This does not include lawn, gravel, or similar areas where rainwater can easily infiltrate.

Regards, Yvonne

Grundflächenzahl usually refers to sealed surfaces.

Exactly. However, there are also partially sealed surfaces, and different municipalities have different approaches to this: some municipalities base it on permeability (and then, for example, count lawn stone areas as one unit), others consider every non-closed surface as open, and also include, for example, wide gravel joints (which are sufficient for them not to count the area) between concrete paving stones.

With us, the floor area ratio may be covered with water-permeable materials. The building authority is responsible for this here. Do they really check that?