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NEVER Pressure Wash A Deck!

Reblogger
Real Estate Broker/Owner with Dagny's Real Estate

Gotta pay attention to this!

Original content by Jay Markanich 3380-000723

I tell my neighbors.  I tell my clients.  I tell everybody who will listen.  NEVER pressure wash a deck!  When the pressure-wash companies send their college kids to knock on my door to "wash" my deck, I tell them why they should not be doing that to decks!  When I see their trucks*, they advertise cleaning decks, patios, siding, roofs - you name it!  Don't do it!

The older the deck, the worse the wood reacts to pressure washing.  The big mistake is that companies and homeowners have a tendency to set the pressure way too high.  But even at low pressures the deck can become damaged.

What does pressure washing do?

  • It removes loose material and leaves a gafillion dangerous splinters and gaps.  Those gaps open up further letting in more damaging sun and water.
  • It removes the natural oils in the wood that are not replaced with sealants.
  • It causes wood to dry quickly causing cupping and warping.
  • It causes damage.
  • It loosens nails as the wood expands.
  • It can cause water to enter the house.

So what to do instead?

There are various, excellent, gentle cleansers out there.  Be sure to select cleansers that do not have caustic lye or acid, or say not to use around children, pets or water features.  A company called Dekswood makes an excellent cleanser that can be followed with sealants.  And the so-called "oxygen" cleansers, with the active ingredient of sodium percarbonate, are great and don't damage the wood, the kids or pets, the house or the yard.

You MUST seal your deck after cleaning.  The sun does more damage to your deck than rain and snow.  BE SURE TO USE A SEALANT THAT HAS UV INHIBITORS IN ADDITION TO WATER PROTECTION.  Read the label.  It will tell you what the contents are.  Water proofing alone is not enough.

My recommendation:  Keep your deck gently cleaned and protected and it will last many decades.  Not doing so makes it unsafe and age much faster.

* I once gave my spiel to a guy sitting in his company truck in a parking lot (with a smile on my face) and he told me he would NEVER pressure-wash his deck.  He said he sees what damage it can do later!

Comments (7)

Ginny Gorman
RI Real Estate Services ~ 401-529-7849~ RI Waterfront Real Estate - North Kingstown, RI
Homes for Sale in Southern RI and beyond

dagny, what a great blog on powerwashing...i just had a client do it and i hope it was done correctly (they knew the guy).  I'm keeping this handy...

Jul 15, 2010 11:22 AM
Jim Frimmer
HomeSmart Realty West - San Diego, CA
Realtor & CDPE, Mission Valley specialist

To say "Never pressure wash your deck" probably is not the best advice. Pressure washing has its place, but as with home inspectors and Realtors, the best thing for someone to do is to check the references, education, experience, and years in business of the person or company doing the pressure washing.

Each material to be pressure washed - stucco, concrete, redwood, pine, oak, concrete, asphalt, etc. - has its own pressure that should be used. For some woods, not all woods, the problems described in Jay's post are inherent to the wood and how the wood was cut. Additionally, by the time the deck "needs to be" pressure washed, many of the problems described by Jay are there already due to lack of simple maintenance.

When my husband was doing research at the forest products laboratory at Texas A&M University many decades ago, one of their studies was for the Southern Yellow Pine consortium of lumber companies in the South. The purpose was to determine the optimum water content of the Southern Yellow Pine species (loblolly, slash, shortleaf, and longleaf) for holding, shipping, and destination arrival to help minimize cracks, splits, twisting, and warping. Much of it is dependent on the wood cut (flat, rift, quarter, rotary, etc.) but for that shown in the picture, pressure washing followed by planing can do a great job of restoring it. Of course, when he was building and renovating decks, he would have gone back a year later to "finish" the work once the water content of the pine had stabilized and the cracks and splits had manifested themselves.

Jul 15, 2010 03:53 PM
Dagny Eason
Dagny's Real Estate - Wilton, CT
Fairfield County CT, CDPE Homes For Sale and Condo

Ginny - thanks for the check in!   Lots of great info here, between Jay and Jim ......    I agree that it is a case by case situation.     In general,, if you powerwash too hard, you ruin the wood.   Super soft woods need a gentler job, and super hardwoods can take a tougher jpb.

Jul 15, 2010 07:05 PM
Al & Peggy Cunningham, Brokers
RE/MAX West Realty Inc., Brokerage - Brampton, ON
Our Family Wants To Help Your Family!

Thanks Dagny! We did not see this post initially and a new deck is on the list, because the old one is like Jay described.  Great advice and timely for us!

Jul 17, 2010 12:36 AM
Dagny Eason
Dagny's Real Estate - Wilton, CT
Fairfield County CT, CDPE Homes For Sale and Condo

I'm never sure what's right or wrong - my son just installed a redwood deck last year, put oil stain on it to preserve it, and this year it's black (I'm assuming that's mildew)  

Jul 17, 2010 02:52 AM
Harry F. D'Elia III
WEDO Real Estate and Beyond, LLC - Phoenix, AZ
Investor , Mentor, GRI, Radio, CIPS, REOs, ABR

Thanks for reblogging this information. Be careful when doing this to any house

Jul 17, 2010 03:24 AM
Dagny Eason
Dagny's Real Estate - Wilton, CT
Fairfield County CT, CDPE Homes For Sale and Condo

Harry - I only recommend my favorite most careful painter to do anything like this for anyone!

Jul 17, 2010 03:41 AM