Bet many people didn't know this but pressure washing your deck can cause more problems than what you had in the first place!
Good advice, please read.
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!
Great re-blog. I live in a condo and they require a certain color stain to be put on them. I love the natural beauty of pressure treated lumber and fully agree. Alway seek a professionals advice, not a door knocker.
Good re-blog. I understand that you should not pressure wash a wood deck, however I have pressure washed mine as it is made from trex.
Thats good to know. I don't have a deck but a friend of mine does and she lets her dog do his business on it. I'll never step on that deck, unless there are other cleaning methods like bleach or better yet burn it! LOL
I sue a product called deck wash. Takes very little effort and if the wood is unfinished will bring the boards looking close to new.
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.