Slope position, basement open at the front, bathtub

: Yes, at least some offer according to DIN 18195-6. The additional effort is really minimal. In contrast, you seal according to 18194-4 and then at some point the drainage gives out because no one maintains it. I am not talking about a waterproof tank, but conventionally sealed against rising seepage water. In my career, I have never seen a real black tank according to DIN.

What is a "real white tub"?

Rhine greetings

Reinforced differently, sealed differently (prefabricated basements in sandwich construction are therefore very difficult to make as a white tub), different concrete mix.

Also very closely monitored during construction – and never additionally sealed from the outside.

That’s how it was explained to me and that’s how I have read it online so far.

We have a concrete basement that was fully poured and then sealed in two layers with thick coating and fleece. However, we have ideal soil conditions here.

Oh, and not even a soil survey was done – but that’s rather not something to always copy.

Good evening Andreas,

yes, a basement is expensive, no question, but it is FAR below the price for normal living space at about €750/sqm WE.

Sure. But what about the necessary earthworks, if things go wrong, with soil replacement, removal of excess soil, possible waterproofing, etc.?

And it gets worse: to realize the same living area as with a basement, I necessarily have to build the house bigger and/or add extensions to the house or garage. But then the garden gets smaller, so a bigger plot is required...

If your house is planned and calculated, each additional square meter of enlargement costs no €1,500.00. In this price/sqm, which I have also frequently used for calculations here in the forum, all technology & co. are proportionally included. If you now enlarge the floor plan, a significantly lower price/sqm is calculated than in a new calculation. And don’t fool yourself, you wouldn’t build 60 sqm bigger, but probably so many square meters that you could build a ground-level utility/household room without significantly restricting the previous room program.

Yes, a basement is an expensive storage room, but what is a CHEAPER alternative?

An attic, whose area is available anyway, like a larger garage with a rear storage room.

Rhenish greetings

: But that's not correct, is it? DIN18195-6 is a black tank, not a white one.

That is correct. Only that the black tank referred to in the DIN is almost never built in reality.

Okay, thanks for the information. That reassures me a bit. So the drainage will be executed as an OPTi Drän system for us, with drainage all around the house, discharge into the sewer (allowed), and carried out as described, with 3mm bitumen thick coating in the dry state. Under the floor slab, a 15cm gravel filter layer, on top of that PE foil. Floor slab in C25, about 15cm thick. That sounds okay, doesn’t it?