In short, cleaning your roof can damage it. A build-up of dirt and debris can cause a roof to wear prematurely, and in extreme cases, it can even lead to the roof caving in. That said, if you're careful and take the necessary precautions, it's generally safe to clean your own roof. Be sure to use a ladder that's tall enough so that you're not putting too much weight on any one spot, and avoid walking on the ridge of the roof (the elevated peak in the center). If you have any doubts about whether or not you should clean your own roof, it's always best to leave the job to a professional.

It depends on what kind of roof you have. If you have a tile roof, it is best to consult with a professional about the specific cleaning methods that should be used. Some methods, like high-pressure hosing, can damage the tiles and shorten the life of your roof. If you have a shingled roof, a good rule of thumb is to clean it every 3-5 years with a mild detergent and water.