Basement execution worries me

hello everyone,

we are building on a slope, a slight hillside with a natural terrain gradient away from the house towards the dead-end street. Access / entrance via the dead-end street into the basement (UG). Above our house there is also a street... about 2.5m higher than our single-family house.

Now to the question: we have a clayey, non-permeable soil and our basement is half exposed and used as an entrance and living space. So only one half is underground. The basement will be constructed as a black tank with bitumen membrane sheets and the water is to be drained via a drainage connected to the wastewater sewer. This has been clarified with the city. Since we have a separated system it is allowed.

According to the soil survey that is sufficient. Still, I am worried because a wet basement would be a nightmare for us. Therefore, I am now considering not to save at the wrong end and have a Thepro basement built. It is supposed to be better than a white tank because backflow is impossible. That would cost us €8,000 and the general contractor says we definitely don’t need that because our basement is largely exposed. Nevertheless, I am worried, especially thinking about the future with increasing storms.

What do you think? Is it fine or better to listen to my gut feeling and play it safe?

Best regards

Hi, the expert and the general contractor will probably be able to give you better information than we can here in the forum without knowledge of the exact situation.

For friends of mine, for example, a waterproof concrete shell [WU Wanne] was definitely necessary on the slope because the infiltrating rainwater presses against the house. If you can intercept this with drainage, nothing should really happen, but as I said; the expert can say more about that.

However, I would be more concerned about heavy rain events if half a river comes down the mountain. Flood-resistant windows and doors would be a MUST on the side facing the mountain!

Best regards,

Andreas

We have a similar configuration of a slope and 40% free basement! But isn't the [Noppen Folie] still missing? But I would trust your gu, especially since if something goes wrong, which is very unlikely, he has to take action and it won't cost you anything. Maybe also communicate your doubt to him in writing. Just in case.

We have a similar setup with a slope and 40% unfinished basement!

But isn't the dimple sheet still missing?

But I would trust your gu, especially since if something goes wrong, which is very unlikely, he has to take action and it won't cost you anything.

Maybe also communicate your doubts to him in writing. Just in case.

And how did you execute the basement? Yes, that's a good tip... I will do that.

Well, insisting on the warranty especially when building a house (and then also for the basement) is pretty bold.

That won't work...
[Dimpled membrane] is not intended for sealing and only protects the insulation. We had sandy soil, so we could do without it...