What can I seal an external already painted concrete wall with?

[Cackles]

During the Auckland Anniversary weekend floods our stormwater drains backed up as the culvert they empty into was completely full to capacity. The water pooled outside and found its way into the house, through the concrete wall. (The internal concrete floor has already been sealed with a resin(?))

I am redirecting a downpipe to reduce any water if this happens again but would like to also seal the external concrete. It's an old house wit about 30cm of concrete at the base the weatherboard above. The concrete has previously been painted so I gather most sealants won't work as they adhere by absorbing into the concrete. Any ideas?

Also, I want to seal along the base of this concrete where it joins the carport/ driveway concrete. What would be best for this?

[EricL]

Hello @Cackles 

Thanks for sharing your question about sealing your wall. One of the products that comes to mind is Gripset Betta 1L Waterproofing Membrane Bitumen Rubber. It can be applied like paint, but you must wait awhile for it to dry off. Ideally you would need to remove the paint that's there and apply the bitumen straight onto the concrete. Let me do a bit of an investigation regarding this. As soon as I have more information, I'll get back to you.

If you have any other questions we can help with, please let us know.

Eric

[EricL]

Hi @Cackles 

I've just been in contact with Gripsets technical department, and they suggest removing the paint before you apply the bitumen paint. The two ways that come to mind are to either use a chemical stripper or a mechanical steel brush head attached to a grinder. 

If you have any other questions we can help with, please let us know.

Eric