Pressure Washing Your Deck

You've rented a pressure washer, and the DIY-er in you is ready to go! After hooking up to your water supply, it shouldn't take much more than squeezing a nozzle-right?

Actually, pressure washing your deck can be a little more difficult than it might seem. There are safety issues to consider when you're using a pressure washer, of course, and you also want to make sure that you're not damaging your deck. When you're using a pressure washer to clean your deck, it's very easy to end up removing around 1/4" of the surface wood, which can be extremely difficult and costly to repair.

Still, regularly cleaning your deck is probably the most important part of its maintenance. And this maintenance will add years of life to your deck. Plus, it can save you loads of money and time in the long run.

Before you begin cleaning your deck, remember these key tips:

• Less is more. You'll very rarely need any more than 1500 pounds per square inch (PSI) of pressure to clean your deck.
• That amount of pressure is still enough to do significant damage to your wood. Start small, and focus on the technique.
• The easiest way to keep the pressurized water from damaging your wood is to let your cleaner do most of the work.

Cleaners

Deck cleaners can come in many varieties. They could be a detergent, or they could be bleach, and there are even some chemical cleaners that are designed specifically for certain wood.

There's no black and white answer when it comes to choosing which cleaner you should use. But no matter which you choose, the most important thing to do is read the instructions for that cleaner carefully-and to follow those instructions. Also, your pressure washer should be used to remove the excess cleaner as much as it's used to remove the dirt.

Again, let your cleaner to most of the work.

Technique

When you first begin using your pressure cleaner, set the pressure fairly low. We recommend you start at around 600 PSI and work up from there as you need to. You want to make sure you have enough pressure to clean, but not enough to do any damage.

Now you're ready to start cleaning:

• Start from about two feet above the surface of the deck, then slowly lower the wand to about 12" above the deck.
• Use a sweeping motion to spray the deck. When you're sweeping, your arm will have a tendency to pivot, but try to resist that. You should attempt to keep a level and consistent distance from the surface of the deck at all times.
• Move from the house outward, and always spray with the grain to minimize the amount of damage you do to the wood grains.
• Overlap the areas that you've just finished cleaning with the areas that you're beginning to clean. This technique is called "feathering" and it will help to prevent any visible marks left behind from pressure washing, often called "hot spots" or "cleaning edges".

Once you've completed the work, allow the deck around 24 hours to dry before checking your work. Decks will have a very different appearance depending on whether they're wet or dry, and you'll want to be sure that everything looks okay before you call the job done. Inspect your work, making sure that you haven't left behind any cleaning edges, and that you've cleaned every part of the deck.

Then, you'll want to take care of...

Wood Fibers

There's no getting around it: when wood gets wet, the wood fibers will raise up. Hopefully, you've done minimal damage to the wood, and you won't notice too much of a problem with the fibers. But even a small amount of raised fibers can mean serious problems with splinters.

To keep your deck as hand- and foot-friendly as possible, you'll want to sand your deck after the cleaning is done. If you inspect the deck and find very minimal wood fiber exposure, you may just need to spot sand it. On the other hand, it may be best to sand the entire deck.

• Use an orbital sander with a 5" pad.
• For the deck surface, use a 60- to 80-grit sandpaper.
• For your handrails, use no higher than a 100-grit sandpaper.

Pressure washing your deck may be more difficult than it seems. However, with the proper knowledge, tools, and techniques, there's no reason you shouldn't be able to get a quality job done.