WU-basement = white tank?

Hello everyone,

a general contractor, who is now in the final selection with us, offers as a basement

Quote:
Basement exterior walls instead of masonry execution alternatively

according to DIN 18195, part 6 as a waterproof

structure of usage class A, according to the guideline of the DAfStb

"Waterproof structures made of concrete" (WU-guideline)

for exposure to temporarily backlogged

seepage water (exposure class 1) up to max. 15 cm

below the bottom edge of the light wells

Does that mean it is a white tank or that the basement is simply sealed from the outside?
It would be nice if someone could clarify this for me.

Thanks!

White tank and wu are the same. If the cellar is sealed from the outside, it is a black tank.

@ muttley

The term "Weiße Wanne" is being misused these days. It originates from the railway sector and originally referred to a basement within a basement system.

What the GÜ offered you, however, refers to the modern usage of the term and thus to what you understand by "Weiße Wanne."

Costa's explanation is therefore not correct in this context; at the very least incomplete.

Rhenish greetings from the road
Construction expert

Hello you two,

thank you both. Now I am wiser and also more confident that the cellar will probably be the right one... According to the soil report, exactly this kind is required...

Thanks!

Hi,

from the wording it sounds like Büttner, right? We are currently building with them as well. Basically a great construction company, but they’re not welfare either… In other words, they want to make money too…

A few notes:

Important is the clause:

"Max. 15 cm below the lower edge of the light wells"

This means for you that the reinforcement in the concrete above this limit _is no longer_ WU tank reinforcement.

Explanation:
For the WU concrete to be watertight, it needs more reinforcement, which are the actual additional costs. The additional costs of WU concrete compared to normal concrete are negligible.

Above the light wells the same concrete is still used, but no longer the necessary reinforcement. In other words, if you really need a WU tank up to the basement ceiling, the first additional costs for reinforcement will come in there.

But unfortunately that’s not all, you also need drainage for the light wells or pressure-water-tight light wells. Depending on preference, flood-proof basement windows are also not a bad idea.

That will quickly add 4-8k€ in additional costs for you.

To be fair, this probably applies to all construction companies!

If you can do without basement windows because it’s a pure technical, storage or workshop basement, you can save a lot of costs here. A controlled residential ventilation system is then mandatory.

Furthermore, if it really is Büttner (if not, forget the next paragraph):

In the construction meeting they will want your approval for the following procedure:
“deviating from the DIN execution of the floor slab in WU execution with upper-side PE foil as vapor barrier instead of a welded membrane”
In other words, they would like to replace the actually prescribed welded membrane with a simple PE foil. That saves them about 15-17 euros/sqm and you have a higher risk of moisture in the basement. Absolutely reject and don’t even start discussing it!

By the way:

WU tank apparently is not really a protected term, according to my neighbor (project manager at one of the very large German construction companies) no one uses this term professionally because it is simply not clearly defined. Whether he is right or not I can’t judge, but this statement has made me more cautious.

Best regards,

Andreas

Hello andimann,

yes exactly, it would have been this company. We have now also received the offer. If we wanted the better execution, that would be an additional €9k. So this company is out. Another general contractor that we have in closer consideration has a "complete bathtub" and is overall cheaper. The thing with welfare is probably true . You just have to see that a lot of people want to be fed at the company...