Degrees of Cleaning

Some of the most frequently asked questions to our company are:  How do I clean my deck before I seal? 

That is a heavy question.  There are so many variables.

• What kind of wood is it?

• Is there a coating on it?

• Is there two or more coating under the first one?

• What do I use to clean it?

• What kind of pressure washer should I use?

• How much pressure?

• What kind of tip?

• Do I work with or against the grain?

• What cleaner if any?

• How old is the wood?

All these variables must be taken into account before beginning work. 

If you have owned your home for a while, (4 years or more) you will know what coating, if any, the deck was treated with. 

What degree do you have to go to?

Your 1^st step will be to do a bit of a water test. Scrub a small area on your deck with deck cleaner, rinse it off, and let it dry.   Next spill some water on this area and watch and see if the water soaks in. The water should soak in within a few moments. If it does, consider it as raw wood. If it doesn’t soak in there may still be sealer on your deck. That will require a different approach than listed below. 

Lets start with raw wood.  Whether its cedar or treated pine it has to be cleaned.  There are several good retail brand deck cleaners out there.  Stay away from those containing sodium hypocloride.  The cleaner is essentially bleach.  Sodium hypocloride can discolor wood decks.  Try to choose one that contains some oxalic acid.  Oxalic acid has a brightening effect on cedar and certainly can’t hurt treated pine. 

Application of these products will vary. We believe that just applying the cleaner is not enough, it should be scrubbed in.  A stiff bristle brush is best tool, commonly called an acid brush, which screws on to a threaded broom pole.          

Scrub a dub dub

Use a brush like this to scrub in your cleaner.  You can spray on the cleaner as long as you scrub and even out the application.  Try not to let any areas dry throughout application. Use a light mist of water to keep it wet till your ready to wash it off. 

Now it’s time to wash off what you have just been scrubbing.  You can use a hose with a concentrated stream from a nozzle with limited results of course. 

Power Washing

You can use a power washer for improved results.  This is the most popular method.  Using a power washer is the tricky part.  Too much pressure (to close to the wood) will splinter it.  To little pressure you might as well use your hose.  Using the wrong tip and you could have disastrous results. 

This contractor (must have been his first job and last) used a turbo tip to try and strip away a clear coating the entire deck had to be re-planked.  A turbo tip is great for concrete but it will shred cedar. 

How much pressure is too much pressure?  Well let’s start with the pressure washer.  If you rent one, look for something with around 8 plus horsepower.  These usually produce about 2500 PSI and 2.5 – 3.0 gallons per minute.  A pressure washer this size you should be using a 25 to 40 degree tip and about 18 inches away from the deck.  Work with the boards lengthwise.  Use a fanning motion taking care not to stop or dwell while the high-pressure fan is in contact with the wood.  Start in an inconspicuous area. Practice on your neighbors deck first (just kidding). Clean your side walks first to get the feel of the power washer. This should remove the dirt and brighten your deck. 

Remember to let your deck dry thoroughly before coating.