How To Clean Decks
Deck cleaning is one of the most popular service performed by
power wash contractors today. The most important factor in deck
cleaning is surface preparation. Great surface preparation is
the KEY to outstanding results. Prep right, and the deck will
turn out GREAT. Rush through prep, skip a step (or two) to save
money and/or time, and the deck won't look nearly as good.
Thorough cleaning of the deck or fence is essential to get good
results. If the wood was previously sealed, you must strip off
the old sealer rather than just clean the wood. If any old
sealer remains, it might interfere with Ready Seal soaking into
the wood. If the wood has not been sealed within the last five
years, a deep cleaning is probably all that is needed. If you
are not sure if the deck or fence must be stripped, a simple
"splash" test is all you need to find out. Sprinkle a little
water from your fingertips on to the dry wood. If the droplets
soak into the wood right away, you don't need to strip. If they
form little droplets on the surface, you do have to strip.
High-pressure washing of wood is not necessary or advisable.
Instead, use the proper-strength chemical cleaners to do all the
work. Then you simply RINSE using your pressure-washer. Doing it
the right way means using your pressure washer to agitate
slightly with MODERATE pressure and HIGH water volume. Use the
pressure washer responsibly. Too much pressure on the surface of
the wood will cause furring damage.
Pressure washers are rated in PSI (pounds per square inch) and
GPM (gallons per minute). The ideal pressure washer for cleaning
wood will use at least 3-4 GPM (or more) at about 300 - 1000 PSI
for most outdoor wood.
Since your pressure washer probably puts out 3000 PSI, you need
to 'detune' the pressure. There are three methods for reducing
the pressure while keeping the volume of water. First one is to
hold the tip farther from the surface of the wood. The pressure
falls as the water is fanned out from the tip, so greater
distance from the surface means less pressure reaching the
surface. This is not a scientific adjustment, and is not the
recommended method. The second way is to invest in a proper
nozzle that will reduce the pressure to an acceptable range
without restricting water flow. These nozzles can be purchased
from Sun Brite Supply. The absolute BEST way to accomplish this
reduction of pressure is to use a dual-lance wand (also called a
chemical injection wand). This wand has a valve built-in that,
when opened, allows water to be diverted to the second tube (or
lance). With the chemical injector tip on that second tube
(black in color) the water going through that tip has little or
no pressure behind it. The more you open the valve, the lower
the overall pressure delivered by the wand is. With this set-up,
you can use low pressure for the deck and run full pressure to
clean the driveway afterwards - without carrying a second wand
or additional tips.
Cleaners and strippers have to be used carefully, too. Too much
chemical or too much "dwell" time will cause the surface of the
wood to develop "fuzzies".
Sun Brite's SEVERE STRIP or REMOVE strippers can be applied
through a DECKSTER sprayer, but can also be applied using a
pump-up sprayer in an emergency. SBS sells Spray Doc pump-up
sprayers in a model that is designed specifically for doing
decks. It features a brass wand and tip that are easily
adjustable, allowing you to fit the spray pattern to the job.
Allow either stripper to sit on the wood for about 10-15 minutes
to loosen the dirt and/or the old sealer. When stripping, be
careful to avoid getting caustics on any painted or aluminum
adjacent surfaces. If you accidentally get stripper on one of
these surfaces, rinse them gently as soon as possible. A caustic
stripper will not damage latex if it is gently rinsed off.
Most contractors use REMOVE for the bulk of their work. If you
run into a really tough finish that might take two strips to get
done, you are usually better off using SEVERE STRIP. This is
pretty strong stuff (almost three times as strong as REMOVE).
The disadvantage in using a product this strong is the danger it
presents to you if it gets on your skin. The real advantage is
that it will strip almost anything the first time through. We
don't recommend it for stripping acrylic finishes, for example,
but during our field product tests SEVERE STRIP even stripped
acrylic house paint off of rough-sawn cedar! Be careful out
there.
Before applying a stripper to the deck, wet down the adjoining
surfaces (such as plants, lawn, or house siding) with a hose.
Minimize any water landing on the wood to be cleaned. Consider
shielding plants and house siding with drop cloths to prevent
contact with the detergent.
Use the pressure washer to "rinse" the surface. Avoid holding
the nozzle too close to the wood or holding it in any one spot
too long. Hold the pressure wand about 8" away from the wood and
"sweep" it off in a rinsing motion. Use a "golf swing" motion,
and avoid washing each square inch of the wood. Keep the wand
moving smoothly over the surface to avoid leaving marks on the
wood. Proper technique determines the results, so take some time
to practice when you are able to.
Once the entire surface has been washed (and is still wet, but
without puddles) apply Wood Britener to the wood with your
DECKSTER sprayer. This will neutralize the pH of the wood and
brighten it. You may let Wood Britener dry on the wood overnight
without rinsing it off.
The wood is now clean, and it needs to thoroughly dry before it
can be sealed (at least a day or two). As the wood dries, you
will see a bright, clean, new-looking surface.