ᐅ Permeable Pavements in the Building Permit / Planning Permission Application

Hello everyone,

What is the significance of permeable traffic areas in the building permit / planning permission? In our case, for example, the terrace is specified as made of water-permeable material, and for the driveway / access road, the building application lists "permeable eco-paving" (which is not required by the zoning plan). What happens if I want to use impermeable material instead? Regarding the floor area ratio and similar regulations, I believe it should not matter since everything counts there, even if grass is used for the driveway, as far as I know. The floor area ratio is being complied with; I am just uncertain about the permeability requirement.

Can someone help me with this?

Regarding the floor area ratio, I am also interested in who needs to apply for or approve changes if, later on, a larger paved area is planned than initially stated in the building permit / planning permission?

I wouldn't be so sure about the floor area ratio. To avoid exceeding it, we actually had to use permeable materials like gravel and crushed stone instead of paving in parts of the building application. I will stick to that as well.

Henrik0817123 schrieb:
Regarding the floor area ratio and such, it shouldn’t matter since everything counts, even if the driveway is grass as far as I know.

How do you come to that conclusion?
For example, permeable grass pavers are calculated by a municipality in southern Germany as 20%, if I remember correctly. I don’t know how other municipalities handle similar calculations—but pure lawn would not count as paved area just because you drive over it.

Floor area ratio limits also serve the secondary purpose of preventing a development area from acting like a basin that holds back heavy rainwater. Besides, proper sizing of wastewater drainage systems is needed.

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The floor area ratio generally refers to sealed surfaces. This does not include grass, gravel, or similar materials where rainwater can easily infiltrate.

Regards, Yvonne

ypg schrieb:
The site coverage ratio usually refers to sealed surfaces.

Exactly. However, there are also partly sealed surfaces, and different municipalities take different approaches: some base their calculations on permeability (and then, for example, count grass paver areas as a uniform surface), while others consider every non-continuous surface as open, including wide gravel joints (which they accept as sufficient not to count the area) between concrete paving stones.

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In our area, the floor area ratio may be covered with permeable materials.

The local building authority is responsible for this. Do they actually enforce it?