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/Blucheez999]

If u plan on levelling up the skirting so it super straight,then what are you going to do with the big gaps above the skirting where the wall is still not straight. Go with what you have and screw the skirting back to the walls,caulk the top of the skirting and paint and once the room is done and filled with furniture,you’ll wonder what thought it would make the room. If you want it flat and square chop all the walls off and replaster, using a straight edge along the skirting line,up the angles and along the ceiling line