Chevette1983

Hi, I have a small block wall and need to add just one more layer on top. Do I have to chip away all the existing render or can I just chisel lines in it like a scratch coat? Its solid render and I only rendered 3 weeks ago and now we've realised we really do need half narrow blocks on top. It’s seriously hard to chisel off. it’s not structural and won’t be taking any weight at all bar the odd ferret if they clamber on top! Thank you