How to deal with this?

[Monkeysuncle]

Morning
I posted on this the other day but can’t find it…technically incompetent. Anyhoo, what the best way to fill in gaps in photos, where I removed rotten wood? I thought I’d be clever n fix no more ply in to fill it a bit. It turns out render doesn’t like sticking to it so I’m at a loss. Basically, I just want to level the channels with existing (sound) render so I can fix cut pieces of nmp on top, instead of using wood, which always rots/holds damp. The channels won’t be seen so they just have to be sound and flat, not pretty.

ta

 

[Dansouthcoast84]

you need to prime the brick before.render.

sbr and cement slurry brushed on so its a key

 

[Monkey Boy]

Uncle

 

[smoother09]

It's like shelling peas!