Rendered walls are masonry walls that have a covering applied to them. The rendering makes the wall's surface rough, which means that some care must be taken to paint the wall so that the paint adheres. The end result will be a wall that will look fresh and neat.
Inspect the walls for any signs of mould. Mix six parts of water with one part of bleach and scrub the walls with a brush. Let dry.
Clean any loose debris from the walls with a wire brush. Fill any cracks with quick setting mortar. Let dry.
Apply a stabilising primer to the walls. This will help to seal the wall, making the finish coats adhere all the better. Let dry.
Apply finish paint to the rendered wall with a paint roller. For the parts you can't reach with the regular handle, uses a longer, extension handle.