ᐅ Concrete – How to Waterproof Balcony Columns?

Hello dear forum,

We have two balcony columns where the plaster is not adhering at the lower section. We suspect that moisture is rising from below. Each column stands on its own foundation and currently they are not sealed at all, sitting about 50cm (20 inches) deep in gravel.
How would you recommend sealing something like this?
Or do you see another reason for the plaster peeling off?

What type of concrete was used?

I would excavate as deep as possible and coat with bitumen, then plaster the rest with a base coat.

Unfortunately, I don’t know the type of concrete, and it’s not mentioned in the documents either. The supports were cast on site.

From what you’re saying, we also thought about digging out and applying a bitumen coating. Since the landscaper is coming the week after next, they can take care of it then.

Thank you

The columns are going to be plastered, right?

If you coat the concrete columns with bituminous waterproofing, you are only protecting the columns themselves. The plaster applied on top will still effloresce and flake off in the same way. You will definitely need to add a base waterproofing layer as well.