The problem is someone's else has k rended some of it already so he wants it to match it but that was on block work . One section has been done over the old part and it's got a few hair line cracks in it . Could be a mare of a job as I told him it's only as good as what your going over ?I posted a similar question to the renddring/machine group on facebook. On my job the render is on brittle cinder block so you just destroy it using a small breakrr/kango as the render is rock hard.
They suggested a parex product called parinter and it can be used as a scratch base coat then top coat over that or you can finish flat with a sponge float?? Id do a test piece first mind you.
@plasterjfe
I think the cost to remove the render will be cheaper then going over it TBH ,and we all know its the best way .Been asked to quote around 100m2 over cracked painted sand & cement but the customer doesnt want to hack off old render . I'm saying stainless Steel mesh but that's gonna be £££ . Any other suggestions ?