The Joys of Pressure Washing

A pressure washer is an essential tool for outdoor cleaning work. It's a very satisfying feeling to point a pressure washing "gun" in the direction of an offensive spot and clear it off. I don't know why that's the case, but it's very calming. The focus of the present article is to provide some information about pressure washer applications on outdoor wood (decking, fences) and stone (pavers, slabs, concrete).

Wood is something that you should be gentle with when pressure washing. If the machine's PSI, type of nozzle used, and distance to the work surface is not managed you may find yourself destroying pieces of wood, etching lines into it, or causing further damage to spots that require repair. For these reasons, you should rely primarily on chemical cleaners to remove previous deck stain/paint or for general wood deck cleaning. Chemicals and an abrasive brush need to do most of the work while a very light pressure washing does the rest.

Stone and concrete should be handled with some care as well, though they are far more forgiving than wood. Pressure washing between paving stones removes sand from joints and may cause some paver instability. The use of the wrong nozzles, PSI, and distance may also etch concrete/pavers/stone. It is far harder to do that with stone/concrete than with wood, so it's a good idea to start pressure washing in a small out-of-the-way area and observe the surface being cleaned for damage (start from a distance, move in closer, start in an out-of-the-way area).

When it comes to useful chemicals for wood, I've had success with Behr deck brightener and Behr deck cleaner (two products sold at Home Depot, one with oxalic acid and the other being a deck stripper). The combination of these two products peels off pre-existing stain from a deck and then causes the top layer of wood to peel off, creating a brighter finish. These products require a bit of know-how and it is possible to make a new deck look worse. I recommend using these products on older decks that are already gray and not in the best shape. When used in this situation, these behr products and pressure washing can bring a deck to a better appearance.

When it comes to useful chemicals for concrete, I've had success with strong household bleach. Bleach is not a safe chemical and should be handled with appropriate respiratory PPE, Goggles, and gloves. However, it is wonderful at removing stains (particularly organic mildew/mold) from concrete. When used along with a pressure washer, the results are pretty great