To render something is to apply a plaster like mixture made up of cement, sand and lime that is applied over wooden or metal frames and mesh work, or applied over brick, stone or concrete. It can also be called stucco. It is mostly used for aesthetic purposes but can improve water resistance and fire ratings. Many of us use it on our houses and boundary fences.
Although stucco finishing is designed to be of low maintenance, like most other fencing materials, it is not entirely immune to weathering and can develop mould and mildew over time and will need to be cleaned every now and then to keep it looking fresh and clean.
It is NOT recommended to pressure wash a rendered or stucco. A regular hose nozzle on standard pressure will usually clean the cladding effectively. If your wall does require a tougher clean and a pressure wash is needed, you should hire the services of a professional to undertake the job and should only ever be done on a low pressure. Never apply bleach, acid or other abrasive materials that could cause damage. Always check the directions and ingredients of any commercial cleaner you purchase and that it is suitable for your stucco cladding.
Walls should always be washed from bottom to tops. This help prevent dirty water being absorbs into the cladding at the bottom.
Always read and follow instructions of any mould and mildew removal substance. These will usually come n a prepackaged spray bottle or container. If you are buying in bulk you may need to purchase a spray container, like a weed sprayer.
CLR and Sugar Soap are also good ways to get remove stains such as rust and water marks. Always follow instructions and it's probably a good idea to do a spot test.
Tougher stains may need to have any application repeated.
A brush can also be used to help remove tough debris.