Pressure Washing Wood Decks
! ! Please Read Author's Notes at the end of this column ! !
DEAR TIM: It's time again to clean and seal our wood deck. I have watched a number of TV shows that advocate the use of pressure washers and a mixture of chlorine bleach and water. I am afraid that a pressure washer will harm my wood deck, but the TV shows made it seem so simple and easy to use. What is a good way to safely clean a wood deck? What is the best sealer to use once I have finished? Jackie F., Versailles, KY
DEAR JACKIE: Many of those TV shows bring a smile to my face. They often create a fantasy land where household projects go smoothly, the workers rarely sweat, and there are never any problems. My twenty plus years of experience in the field tell me that the exact opposite is true of most home improvement projects. Cleaning wood decks is no different. If you want excellent results you have to do some work, but it is not that hard.
Using a pressure washer to clean a wood deck is a huge mistake in my opinion. High pressure streams of water easily erode the soft light colored spring wood that is found in between the darker bands of summer wood on each piece of lumber. I have actually cut my hand on pressure cleaned deck handrails. So much soft wood was eroded by a pressure washer that sharp slivers of summer grain wood were left behind. The surface of the handrail resembled an upside down multiple blade razor.
To make matters worse, many of the pressure washed decks I have examined were cleaned by professional deck cleaning companies. If you have no experience working with a pressure washer, the last place to start is a wood deck.
If you want to make an even bigger mistake, then use chlorine bleach to clean your deck! In my opinion, it is the absolute worst ingredient to apply to a wood deck. Chlorine bleach, better identified on deck cleaning product labels as sodium hypochlorite, removes the natural color from your wood, it destroys the lignin or glue that holds together the wood deck fibers, is toxic to surrounding vegetation, and is corrosive to all metal fasteners and components that hold your deck together.
A far better wood deck cleaner is oxygen bleach. This powdered product when mixed with water releases non-toxic oxygen ions that kill mildew and algae. In addition, the foaming oxygen bleach loosens grey weathered wood fibers and dirt from the deck surface. In the process, it does not remove natural wood color, nor does it hurt nails and joist hangers. Possibly one of oxygen bleach's best attributes is that it will not harm plants, vegetation or you.
Wood deck surfaces need to be cleaned and sealed to keep them in good condition. The cleaner I recommend is oxygen bleach.
I have found that the best way to clean a wood deck is to mix the powdered oxygen bleach with warm water. Once the powder is dissolved, you liberally apply the solution to the wood surface. It immediately foams up as the oxygen ions attack the mildew, algae and dirt. I prefer to let the solution sit for 10 or 15 minutes. Using a scrub brush on a pole or a large push broom to gently scrub the surface to lift wood fibers and dirt. To complete the cleaning process you simply use a regular garden hose to rinse away all traces of dirt and grime.
Over the past few years popular consumer magazines have revealed that many deck sealers perform poorly. Most, if not all of the ones tested, contain animal fat, vegetable, linseed, and other natural oils that are food for mildew and algae. It is no wonder decks turn black and green after the water soluble mildewcides contained in these products are washed away by repeated rainfall. If you want lasting results from a deck sealer, you should apply one that contains synthetic resins.
Be sure to purchase a synthetic resin deck water repellent that penetrates into the wood. Do not buy a product that forms a film on the wood surface. Film forming wood sealants will eventually peel. I have applied penetrating wood water repellents to my outdoor wood porches and have achieved extraordinary results. I prefer to use ones that have some pigment in them. The pigment or color helps to slow down the wear caused by the sun's ultraviolet rays.
June 1, 2004
I just got this wonderful e-mail from a person who has been victimized. Read this:
Hi Tim ,
I've read everything you've written about cleaning and sealing decks and am even purchasing your Oxygen Bleach - Stain Solver tonight. However, the one thing you don't write about at all is what to do with deck wood that has been blasted to pieces by previous pressure washing so that now, it's like a bunch of razor blades on edge. I want to clean and seal the deck but it will then be a clean, sealed bunch of razor blades. Do you have any advice on how to repair this problem? It's apparent on the deck surface and on the railings and rail slats, as well as on the tops of the vertical deck posts supporting the deck.
I appreciate any help you can offer.
- - -
Great question! You have two choices: Sand the deck before cleaning or after cleaning with my product. If I was doing it, I would clean the deck with my Stain Solver, then I would wait until the deck was nice and dry and sand it with any number of electric sanding tools. You may have to rent a big pad sander, or at the very least use a belt sander for the large flat deck area. The spindles and railing will need lots of attention with palm sanders or even hand-held sanding blocks.
Read Sheryl's comments about using a pressure washer on her deck.
I am going to order some of your oxygen bleach to clean my wooden deck that is on "the list" this summer. I sure wish I had known about this product before I power washed it two years ago - as I wondered why the wood looked messed up afterwards."
- Sheryl W., State Park, SC
|Message from Tim:|
Years ago while researching a column about cleaning decks, I discovered the wonders of Oxygen Bleach. It is perhaps the 'greenest' cleaner I know of as it uses oxygen ions to break apart stains, dirt and odor molecules. There are no harsh chemicals, and it works on just about anything that is water washable.
I decided to create my own special blend using ingredients made in the USA. In fact, the raw materials in the active ingredient are food-grade quality registered with the FDA. I call my product Stain Solver. I urge you to use it to help clean your deck. You will be amazed at the results!