The short answer is no! Not without killing the infection at its root source first. Any green, red or black that appears on render is generally a type of algae that will continue to grow even if you paint it. This will make it an expensive waste of time. Call us in for a free quotation and we will advise the best way forward for you. We have had a particularly damp winter and if you look around there is alot of green algae out there.
It is not a problem to treat it, but make sure you ask an expert