What sand for rendering

I've decided that once I've put tanking slurry onto my internal wall, I want to use render to flatten the wall so that I can use foam adhesive.

I was going to use board adhesive but will regret it if moisture comes through years down line.

What sand should I use for the internal render? It's not a fi ished coat, just to flatten before boarding over.

I've got a bag of yellow building sand, would that do?

Do I add mortar plastickser to my 3:1 sand cement mix?

Cheers

 

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youll probably be better off rendering it first if your’e not a plasterer.
rendering over tanking can be tricky as there’s little suction and it’ll want to fall off.
5:1:1/2
sand cement lime.
you can also use sbr waterproofer in the mix.
jewson only do one type of building sand which is perfect.