External damproof below ground

[GDiy]

Hi all, 
I'm building a retaining wall (gabion) that, when back filled, will result in a section of my house wall being underground. The external wall is rendered (bit damaged but i'm fixing that). Will render alone suffice if its now underground to prevent damp getting in, or do I need to be doing something else? 
Its impossible for me to tell what sort of damp proofing has been undertaken inside the house without ripping out panelling. Any advice is much appreciated.

[Conor]

You'll need to use an approved sublevel tanking membrane - e.g. self adhesive bituminous membrane. Once you are underground, you are dealing with water that has positive hydrostatic pressure, not "damp". Make sure you install a field drain and backfill with granular material.

 

Or is the gabion directly against the structure? If so, what's on the other side of the gabion? Is there a chance water could pool behind?

What depth are you talking?

Edited July 3, 2019 by Conor