ᐅ Drainage covered with geotextile fabric on only one side

Hello dear forum members,

Today I took a closer look at the drainage work on our construction site and became a bit concerned.

Until now, I thought the drainage pipe had to be surrounded all around by gravel, which in turn should be wrapped in a geotextile fabric. On our site, the drainage pipe was indeed laid on gravel, but the geotextile was only placed on top. Also, the amount of gravel used seems very small to me.

We have clay soil, so I actually assumed a much thicker layer of gravel would be required. Furthermore, clay soil is known to be difficult or even impossible to compact properly, so it shouldn’t really be used for backfilling, right?

So, the geotextile was simply unrolled directly from the roll and laid on top of the gravel, then nailed to the drainage board (which already has a geotextile factory-applied). I thought, as I said, that the geotextile should fully enclose the gravel and pipe, like a kind of bag.

Thanks and best regards

To put it differently, is your basement made of masonry so that you actually need a drainage system?

First of all, that was not my question at all. Regardless of the circumstances, I want to know how to do it correctly. It has been paid for and the work has started, as you can see. So your counter-question doesn't help me.

And no, we have a watertight concrete shell, but it is a slope and the soil is almost entirely silt, which means the runoff water must be properly drained. This is also based on a recommendation from the soil expert.

This is poor workmanship. According to DIN standards, the drainage pipe along with the gravel layer must be wrapped in geotextile fabric; otherwise, soil particles will clog the pipe.
If clay soil is placed back on top of the drainage, the whole effort is pointless, as it hardly allows any infiltration.

Thank you very much for your statement. The general contractor says he followed all DIN standards. I will now confront him with the fact that it is substandard work.

What would be a reasonable course of action here? Have him excavate everything again? And is the backfilling with silt also not in accordance with DIN 4095?

Thanks and regards

Sorry, I couldn’t edit the post anymore, so here is the addition: Doesn’t the drainage pipe also have to be positioned 15cm (6 inches) away from the drainage membrane according to the DIN standard? In the pictures, you can clearly see that the pipe is placed directly against the wall.