problem: 33 year old house with the original cedar shakes. the shakes have some staining, mildew or moss and woodpecker holes. question is how to prepare the surfaces for a new semi-transparent coating. what is power washing, what gets rid of mildew/moss effectively/permanently and how to repair woodpecker holes to accept new coating. thanks for any help,suggestions!!! p.s. woodpeckers to be handled as a separate issue but any ideas now eagerly accepted. thanks again!