An inexpensive way to spruce up the outside of a building is to clean the exterior paint. Over time, outside elements take their toll on the condition of your exterior. If you plan to repaint the exterior, you'll need to first prepare the outside surface by cleaning the existing paintwork. A thorough cleaning can give the appearance that you have already repainted the exterior without actually having to do all the hard work. Check the weather forecast ahead of time to choose a day to clean that is sunny with minimal wind.
Cover light fixtures and plants that are close to the exterior with plastic sheets.
Connect a garden hose to an outside water tap.
Connect a brush attachment to an extension pole, and attach the extension pole to the garden hose.
Combine 50 ml (1/4 cup) of trisodium phosphate (TSP) with 4.5 litres (1 gallon) of water for heavy duty cleaning.
Apply the TSP mixture onto the brush, and turn on the garden hose. Open the shut-off valve on the extension pole if applicable.
Start at the bottom of the exterior, and work your way up one section at a time. If you start at the top of the wall, the dirty water will streak; but if the dirty water runs down a clean surface, it will not streak.
Rinse the mixture off the exterior in a downwards motion.
Mix one part bleach to three parts water to remove mildew stains.
Apply the bleach mixture to the mildew stains, and leave it for 20 minutes.
Rinse the exterior thoroughly.
Wear old clothes and gloves when using TSP. It is a strong cleaner.
Soak plants that are close to the exterior with water before using TSP. Rinse plants afterwards as well.
Wear gloves and eye protection when working with chemicals.
Read and follow all manufacturer warnings and instructions.