Pressure-Washing a Deck
Power washing a deck seems like a simple task. Just point and shoot, right? But the reality is that without the right equipment and knowledge, power washing your deck can potentially cause costly or even irreparable harm to the wood.
Choosing the right power washer and operating it at the correct pressure setting are the first keys to correctly power washing a deck. Power washers can be powerful enough to carve into brick or gentle enough to remove a few cobwebs.
For cleaning a wooden deck, you'll be best served by using the lowest pressure setting that's still effective. For soft woods like cedar or pine, this is usually about 500 to 600 psi. For harder woods, it can go up to 1200 to 1500 psi.
Choose the right tip to use as well. For wood cleaning, generally a fan tip or rotating tip (used carefully) will work best. Remember to always start the water pressure in a safe area pointing away from people and glass windows, and start at least two feet from the wood deck, then feather the pressure into range from about a foot to 18 inches from the deck. Never get closer than 12 inches from the deck unless you're using low pressure.
Remember to start in an area that would be easy to repair or replace. For example, try starting on a stair tread, which would be simpler to replace than an entire deck board. Once you're sure you've got the right pressure setting, work from the house outward and be sure to keep a consistent distance as you hold your arm steady and sweep, working with the grain of the wood. If the washing results in raised soft wood fibers, you will need to sand before staining your newly cleaned deck.
See also: Deck and Patio Design Ideas