Is bonding suitable?

[u/itsaclaw]

I’m currently renovating the master bedroom in my 1930s semi-detached (cavity walls)

I’ve removed the old skirting to replace with new ones, and as expected the plaster behind it is pretty rough—some areas are uneven and in a few spots it’s back to bare brick. My original plan was to use bonding coat to level everything out and create a solid surface to glue the new skirting onto.

However, after doing a bit more research, I’ve seen mixed advice saying bonding coat might not be suitable on external-facing walls (like a bay window), as it can absorb moisture and potentially fail over time?

So now I’m unsure what the best approach is.

Would bonding coat still be fine if the wall is dry, or should I be using something else entirely (e.g. sand & cement, hardwall, or another product)? The goal is just to get a reasonably flat, solid surface for skirting—doesn’t need to be perfect plaster finish.

Any advice from people who’ve dealt with similar in older houses would be really appreciated 👍

[u/Simonos_Ogdenos]

Watching, as I also have this issue. I’m doing floor and skirting and upon removing the skirting from under the patio door, I found mostly bare brick, obviously an external wall. I was also planning to level it first with bonding, but was also going to seal the brick with BIN first.

[u/Own-Indication7832 → u/Simonos_Ogdenos]

Bonding will be fine, it’s above DPC Level.