Scratch coat mix

[newconnection]

Intending to plasterboard a wall (likely dot and dab but may batten it) and the Building Regs Drawings state a scratch coat render to the wall first.

Is a 4 (plastering sand):1 mix sufficient? Do I need to do anything else to the wall (which is back to brick) or add anything else to the mix?

Cheers.

 

[23vc]

Yeah or 5:1. Add plasticiser. What’s the purpose, acoustic? There may be better options, could be worth querying it