Never try to keep water out of a building using impermeable coatings, rubberised paint, ciment render, etc etc. A building MUST breath, even at the cost of some inward moisture during wetter periods, any water that will inevitably creap in,and even the moisture you create by living in the building,needs to escape, or I guarantee you will have mould and rot problems down the line. Water which can not escape from behind an impermeable coating is worse that no coating at all. I recommend a lime render for all building needs.