Rendering on walls is the process of applying a coating of sand and cement (sometimes mixed with small stones, or "pebbledash") over external brickwork. The main usual reasons to render brickwork is to protect the brickwork, increase insulation, or increase the damp-proofness of the internal walls. Good quality rendering jobs can achieve these goals. But it's worth remembering that rendering has a limited lifetime, and faulty rendering can cause a lot of problems in itself.
Moreover, rendered brickwork may require just as much maintenance as the old brick walls you're covering up. Old brickwork may need re-pointing (morter added or replaced between bricks, or whole bricks replaced), but rendered walls need to be cleaned and repainted fairly frequently else they can look rather shabby. Old render can peel off slightly, encouraging internal damp areas (which defeats the purpose of it being there).
Pebbledash in particular has fallen out of fashion and may actually detract from the value of the property if not painted.
Once a property has been rendered it can be very difficult to ever completely remove the rendering.
Moreover, rendered brickwork may require just as much maintenance as the old brick walls you're covering up. Old brickwork may need re-pointing (morter added or replaced between bricks, or whole bricks replaced), but rendered walls need to be cleaned and repainted fairly frequently else they can look rather shabby. Old render can peel off slightly, encouraging internal damp areas (which defeats the purpose of it being there).
Pebbledash in particular has fallen out of fashion and may actually detract from the value of the property if not painted.
Once a property has been rendered it can be very difficult to ever completely remove the rendering.