Pressure Washing Decks
A beautiful wooden deck, properly maintained, can add
greatly to the aesthetic and resale values of a home.
Just look around, decks are almost everywhere. Not just
houses but both municipal and commercial facilities use
wooden decks and walkways extensively. Because of this
pressure washing decks can be a great profit center for your
business or even the whole business.
The great news is that decks need maintenance. As beautiful
as a wooden deck can be it can be a real eyesore if not
Why Decks Need Maintenance
When a wood deck absorbs water the natural resins and color
can be washed out over time.
The combination of wood and water creates a food source for
mildew, fungus and mold promoting their growth. Wood and
water combined with dirt and even air pollutiom will also
contribute to the proliferation of mildew, fungus and molds.
One thing to remember is that a wet deck with a thick
coating of mildrew is very slick and slippery. This creates
one heck of a "slip and fall" liability problem. Keep this
in mind when speaking to the decision makers of commercial
and municipal facilities.
There is a learning curve involved when getting proficient
enough to clean/seal/restore wood decks for the public. It
is best to learn on your own deck or on the decks of close
friends and relatives. When learning make sure to do more
than one. Different decks can present different challenges.
When organizing your project or preparing your bid make some
Has the deck ever been sealed? Is there old sealer that
needs to be stripped and reapplied?
Do I have all the chemicals, tools and equipment required
for this project?
( we will include a sample list at the end of this article)
Is there any damaged or rotted wood that needs to be
( Now is a good time to measure.)
Are the any missing or loose bolts, nails or screws?
Are there any adjacent bushes or plants that need to be
Are there any electrical appliances, outlets, light fixtures
or telephone jacks?
Note: these will have to be sealed water tight. Remember
water and electricity is a dangerous combination. Decks in
upscale neighborhoods will probably contain most of these
challenges. Make sure the circuit breakers will be
accessible to you prior to starting.
Ok you've cleared everything from the deck and placed it far
enough to be out of harms way. You've locked out the circuit
breakers that provide electrical service to the deck area.
Outlets, fixtures and jacks have been sealed water tight.
Close proximity plants and bushes have been protected with a
clear plastic tarp.
Loose bolts. nails and screws have been tightened or
replaced.with galvanized fasteners.
Rotted or damaged wood has been replaced.
Only now are you really ready to begin.
Clear the Deck of Dirt and Debris
With a stiff bristle broom or a leaf blower clear all loose
dirt and debris from the surface of the deck..
What Chemicals to Use
Sodium Hydroxide ( a high caustic chemical) is very popular
with professional deck cleaners. Because this chemical does
most of the work very low pressures of 500-1200 PSI can be
used which helps avoid the condition known as "furring".
Safety note: Always wear headgear with face shields and
cartridge type respirators when working with high caustic or
acidic chemicals. This is not a suggestion it's a must.
While Sodium Hydroxide is a very effective chemical it will
darken or may even blacken the deck. Because of this the PH
will have to be nuetralized with a mild acidic solution.
Acids used are Citrus,Oxalic or Phosphoric.
These acid solutions will act as brighteners. Neutralizing
the PH of a high caustic cleaner will restore a deck very
close to it's original color.
Add approx. 5oz. acid to each gallon of water.
Citrus Acid- Used on hardwoods.
Oxalic Acid- Primarily used on redwoods.
Phosphoric Acid- Used when an unfinished deck has turned
I'm very hesitant to suggest a pressure level when it comes
to cleaning decks because it's just so subjective. One deck
will have harder wood than another and
other decks will have softer and harder areas on the same
deck. In this respect only experience can really guide you.
As a general rule of thumb use the least amount of pressure
that will get the job done.
Test pressure on an inconspicuous area of the deck. The
underside works well for this
Excessive pressure will cause a deck to "furr".This is the
appearance of small hairlike fibers protruding from the
wood.. Your customers will not like the way this looks and
light sanding will be required to correct this condition.
Ready, Set, Go!
Soak the area to be cleaned thoroughly. This serves several
purposes but most importantly, the deck must remain damp
throughout the entire cleaning process.
Apply cleaning chemical with the applicator of your
choice.When just starting out a pump up type sprayer will
work nicely. Allow your chemical to dwell for 15-20 minutes.
Do not allow to dry. If necessary spray more water or
If you've sufficiently dampened the deck and haven't dawdled
this shouldn't be a big problem.
Clean. Remember when cleaning use low pressure. Never clean
against the grain or accross the grain. Feather each pass.
The pressure used should be enough to remove dead wood but
not enough to cause "furring" Experience will be your best
Rinse deck thoroughly removing all chemical. Apply
nuetralizer/brightener solution, wait 10-15 minutes and
rinse well again.
If you are going to seal wait 24 hours if not 48. If you
chose your day well rain won't become a problem.
Sometimes "furring will become apparent even at low
pressures. These short hair like fibers are the result of a
"tearing" action on the wood. These will probably be gone in
2-3 weeks but your customer will want them gone sooner than
later. Give them a light sanding with a bronze metal
scrubbing pad. Use bronze, steel wool can leave rust
What not to leave behind
Here is a general list of things to bring to your job site.
Some of this may not apply to you. The point is to always
work with a job list to avoid the embarrasment or expense of
missing that tool you need right now.
Pressure Washer- Cold water gas machine 5.5-11HP commercial
(Hot Washers are also used but at very low temperatures not
Hoses- Sufficient lengths of both pressure hose and supply
Brooms/Blower- A stiff bristled push broom (not metal)
and/or a gas powered leaf blower.
Chemical applicator - Pump-up type sprayer or Flo-Jet type
Mixing Buckets - 2or3 5 gallon plastic mixing buckets.
Mixers- Drill type chemical mixer.
Respirator- Cartridge type with spares
(When working with high caustics and acids)
Face and Eye Protection- Some type of helmet with face
Cordless Drill- With phillips screwbit and chuck large
enough to accomodate chemical mixer.
Hammer- If nails are required.
Deck Screws, Nails and Bolts- As required, use galvanized
Duct tape, Clear plastic sheeting,Cardboard- To protect
Extension Cords- Must be adequate length and gauge. 12 gauge
Electric Rotary Sander- With 60 and 80 grit sandpaper
Knee Pads - You didn't think you'd always be standing when
sanding did you?
Remember practice makes perfect get out there and start
About the Author
Randall Madon is the founder and president of ATT Pressure Supply along with a new educational resource site:
The-Power-Washer-Advisor.com">The-Power-Washer-Advisor.com - the-power-washer-advisor.com">Learn More.