Permeable pavement, clay soil, general water management

Combined cistern garden irrigation + retention with emergency overflow into the rainwater sewer. The full modern program ;)

Where do you end up price-wise for such fun if I may ask? Very roughly?

Well, let's think about it. A DN100 usually drains the water for half the roof, so maybe 50-70m².

Your gutter should drain the water that heavy rain combined with wind pushes to your front door. We're talking about 2 or 3m², your pavement in front of the door won’t be much larger than that. And it has a slope, I hope. That should be manageable with DN50.

Even heavy rain doesn't suddenly release 50l/m², as if someone poured out a bucket of water. If 120l fall in an hour, that’s 2l per minute, so for 3m² that’s 6l per minute the drain has to carry away.

The problem will rather be that your drainage can’t handle all that, and the water will stand in the pipe after a few minutes. Then it will overflow. This also happens with downpipes, it’s unavoidable.

With 100m² roof area and 50l/m²/h, a 10m² cistern fills up in 2 hours if it was completely empty before. And the emergency overflow is full then too, because the public stormwater drainage is not designed for heavy rain either.

Where do you end up price-wise for such fun, if I may ask? Roughly?

It was in the construction description, so I don’t have an individual price for what we paid. But you can find Mall’s price list on Google; Reto (cistern with retention and use) is about 3.5k for 8cbm. Plus of course earthworks, pump, and connection of the whole thing.

Your gutter should drain the water that heavy rain combined with wind pushes against your front door. We’re talking about 2 or 3 m², your paving in front of the door won’t be bigger than that. And it has a slope, I hope. DN50 should handle that.

The problem is not the paving. The problem is potentially the neighboring properties, because they are somewhat higher and slope towards me. And the eastern side of the property is also slightly higher. The water can flow around the house, but the question is whether that’s enough if it comes with force.

But even with DN75 you would have to significantly shorten the paving stone in height. You would have to see how many cm remain, otherwise the stone can of course break much more easily.

Above a DN75 there are only 2.5 cm left at the thin end, further at the pipe there are 4 cm. The paving bricks are 7.1 cm. But I believe that I'm slowly getting my girlfriend to align it flush with the channel directly in front of the wall. We want to lay everything out again tomorrow evening ;)

Oh. I have a similar problem.
Not the neighbors, but the street is partially on or above the finished floor edge.
But you have to act much earlier because a "surge" can't be handled by the small channel.

Channel, okay. But flat and with a DN50 drain?

As a measure towards the rear neighbor, who is about 50cm higher, I planned a stepped garden.
With drainage above the step, let's see how. And towards the street, I am putting a small trench with a "pump sump" in front of the hedge, which should anyway have a 50cm distance to the boundary.
Something like that.

Then in case of emergency, I pump the stuff back onto the street with a hose through the hedge. Not legal, but who will check that if the world is ending.

Price-wise... I paid 4k net at the beginning of 2022 for a 7m³ concrete cistern including installation. Without connection, which is still pending... but good luck finding a civil engineer.
Mine is probably bankrupt... for weeks Google shows "temporarily closed"...

A little update here. We solved it like this now Not flush, but with a complete row. Provides more workspace and saves a few cut pieces. When the paths are paved in autumn, we will connect to them. For now, there is only the small entrance area so you can wipe off your dirty shoes. During the paving action, the rest of the area will be raised a bit more, so we can then enter the house barrier-free (just in time as the stroller phase slowly comes to an end...) Pro tip: install the grids in the gutter before paving, otherwise it will compress and the grid will only fit back with force ;) Also, in the meantime, we learned a valuable lesson. A roof does not necessarily protect from anything. Two weeks ago we had a thunderstorm where it rained against the patio door up to head height. Despite the roof, you shouldn’t skimp on the slope.