ᐅ Proper phrasing for a waterproof basement

According to the building specifications and scope of services, my builder is offering a basement sealed according to DIN 18195-4. Our consultant always refers to it as a "WU basement" in our preliminary designs. He briefly explained to me that the walls are poured on site and something from the floor slab extends up into the walls from below to maximize the water barrier path. The weak point is the connection between the floor slab and the walls. In addition, something is applied to the outside of the walls.

As you can see, I have no practical knowledge about the construction, but what exactly should I specify in writing for the basement?

A “white tank” according to DIN 1045 plus external waterproofing of the walls with bitumen membrane according to DIN 18195-6? And for the floor slab, internal waterproofing with bitumen membrane reinforced with aluminum insert?

I have roughly put these terms together myself, but what is the correct terminology? The basement should simply be waterproof...

Regards,
Aloadihoa

What kind of load case do you have?

I have no idea. The new development area will still be under infrastructure construction until next summer, and so far, there haven’t even been any appointments with the notary. My turnkey builder is preparing a cost estimate for me upon my request. I want a waterproof basement to be included in this, and I want to have that documented in writing from the very beginning. I just don’t know how to do that...

You should wait for the actual load case first – otherwise, it’s all just hypothetical. A true "white tank" waterproofing system involves a significant extra cost – using waterproof concrete and waterstop strips alone isn’t enough (this is a standard reinforced concrete basement, which is also made with waterproof concrete).

Bitumen sheets are not applied on the outside, and according to some expert opinions, they are not necessary on the inside either (we installed them anyway – but none with aluminum foil facing, as there is no reason for that).

I would like the cost estimate to consider a waterproof concrete basement (known as "Weiße Wanne") as the worst-case scenario. Is it sufficient to use the term "waterproof concrete basement" alone without specifying standards or additional waterproofing measures?

Probably not, if he has already explained it to you like that.

It seems that many companies have a lot of trouble with something like this – I only read up on it myself, but according to a green forum, there are apparently always defects (unless you build with them 😀).

You just have to google the standard you mentioned, then you’ll immediately know that it’s not a waterproof concrete tank (white tank), but a regular concrete basement.