To pressure wash a Deck or Fence is a dense process. True wood restoration is a chemical AND pressure process, sometimes I wish I would’ve achieved a masters in Chemistry in college for this business. There are companies who would pressure wash a deck or fence and simply use way too high of a pressure or only spray bleach and wash it off. A knowledgeable deck or fence cleaning and staining company would approach this differently though.
You do need to kill mold, algae, and other organic contaminants on the wood. You do need pressure to get into the wood pores and pull out those contaminants. BUT you also need to neutralize any cleaners, and use acids to open the pores of the wood to stain, seal and condition very deep and protect your investment for years to come.
I have attached a picture of wood that has been brightened with acids on the left side and not on the right. With just this one piece of the process you can see the dramatic difference. Of course like everything this is only a few pieces of the puzzle but there is far too much misinformation out there, and far too many guys with a truck and a pressure washer that don’t fully understand the complexities of the work. So be sure to ask the right questions, and look for a reputable deck or fence cleaning and staining company before you make a decision.