Basement - Combination White Tank / Black Tank

Hello everyone,

according to our construction performance description, the basement is constructed as follows:

"Kelleraußenwände als Betondoppelwandelemente in der Stärke 25 cm mit Ortbeton in WU-Güte verfüllt. Als Anschluss an die Bodenplatte wird ein umlaufendes verzinktes und beschichtete Fugenblech eingebaut, die Stöße verklebt und m mit Klammern gesichert. Die Kelleraußenwände werden als Schwarze Wanne mit einer KMB-Beschichtung nach DIN 18195-6 sowie einer Perimeterdämmung mit der Wärmeleitgruppe 035 in der Stärke 80 mm versehen."

If I understand correctly, then I have the White Tank due to the double wall elements and additionally the Black Tank on the outside, right?

Regards,
StarAce

Hello,

Your BU/GU describes its standardized wall construction for a WU basement; WU means "waterproof". In order for it to become a "tank" corresponding to DIN 18195-6, additional measures must be taken - described here as KMB coating. KMB stands for "plastic-modified bitumen thick coating".

This means that "without" the water sensitivity of the soil (ground moisture, non-accumulating seepage water, etc.), you would always get a normal WU basement. Only through the additional sealing according to DIN 18195-6 does it become a tank.

In my opinion, you seem to have commissioned a good BU/GU, as he names the relevant DIN in the contract documents; many would phrase it more vaguely.

Kind regards

Good, that reassures me. We constantly have pressing water here.

Here is the exact description of the basement construction:

- Floor slab according to WU guidelines with a thickness of 35 cm (without a blinding layer, but with a Delta dimpled membrane installed underneath)
- Vertical connection of the floor slab to the concrete double wall elements (d=25 cm) using coated Master joint sealing sheet
- Filling of the double wall elements with WU concrete of grain size 0/8 mm
- Fillet with HKS
- Sealing of the exterior basement walls using bituminous thick coating according to DIN 18195-6

What do you think of this? Our building expert from the Bauherren-Schutzbund said it is not an unusual solution and justifiable with a very low residual risk - however, there is always some residual risk

Hello,

What should one make of this? Our construction expert from the Bauherren-Schutzbund said it is not an unusual solution and justifiable with a very low residual risk – although the residual risk would always exist

Some so-called experts I just don’t have to understand To avoid "any" risk, you have to build a "real" white tank. This term originally comes from railway construction; here a basement shell made of waterproof concrete (WU concrete) is poured first (after hardening this basement was then additionally provided with a light-colored sealing; hence the term white tank) and only then the actual basement is constructed inside. So basement within basement!

If the execution of your BU/GU follows the results of the soil report, it is legitimate and completely sufficient. I also know people who break their finger while picking their nose ....

Best regards