Painted brick wall

[James robson]

I have painted garage wall is it best to dot n dab or use no nails

 

[Monkey Boy]

Neither.
Leave it as is probably.
If not a cavity wall will lead to many mouldy problems

 

[ChrispyUK]

Foam

 

[bobski]

I have painted garage wall is it best to dot n dab or use no nails

If your thinking about fixing things to it like shelving or racking, fix battens, insulate, then board.