Decks, Patios, Porches and Docks - Power Washing the Deck

Hello,

This is my first time posting, so please bear with me. I have a deck that is 6 years old and has been stained twice with Behr Semi-Transparent non-oil base (Latex) Cedar Natural Tone within those 6 years. I have to restain this month due to excess green mildew (backs to woods 25 feet away). The deck is 12x14 and only about 36 square feet is exposed to direct afternoon sun. The stain in the sun is starting to fade and can see the original surface of the wood, although grayish.

I just bought a Karcher 1600 PSI 1.7 GPM electric power washer (still in the box) from Costco. I bought it because I read a posted message or two suggesting to use nothing stronger than 1500. Would the electric power washer I bought be able to strip the old stain and remove any dirt and mildew? Or do I need 2000 or 2200 PSI? I used a 2000 PSI the first two times (first time was done 3 months after deck was built with PT wood) and was amazed how it lifted the dirt/grayish look right off. I also plan to buy Cabot Problem-Solver Stripper & Cleaner (do I need both?). I also plan to buy a stain that is non Lowes or HD (thanks to the suggestions!).

Thanks,
Ronnie

Ronnie,

Your pressure washer may be able to do the job. That's if you find the right stripper do remove the old Behr finish. Check with your local paint dealer to verify that the Cabots stripper will remove the Behr latex. I have not tried it.
I formerly used a caustic sodium hydroxide stripper.

Direct from Cabots " Stripper for oil-based coatings requires neutralization with Problem-Solver Wood Brightener." So you would not need the brightener for the latex.

Coincidently, I lent my 3500psi pw to my neighbor on Saturday. I mentioned that my wand handle adjusted the pressure/volume. Apparently he forgot.
Luckily, he built his pt wrap-around deck last fall and the syp is fairly hard.
I heard the honda crank up and after a few minutes I went over to see how he was doing. Well, he was cleaning with full pressure and the wood was not bothered at all. I then showed him (twisted the wand handle to minimal pressure and washed my hand off). Please don't do this with yours. It's probably not adjustable anyway.

I'm glad you have been reading the posts re the big box stores.
A quality paint store with knowledgeable people is the place to shop.

good luck,
fred

Thanks for the advice Fred! I just called Cabots' 800 line to verify if their stripper can strip the Behr Latex. He said it hasn't been tested on non-oil surfaces but thinks it should be able to. I guess I'll ask the quys/gals at the paint store next.

If I were to ditch my newly bought electric power washer (don't really like the word "electric" around all the water that will be produced), I could rent a 2200 PSI as long as I could either: 1. obtain an adjustable wand handle to reduce pressure or 2. if it doesn't come with adjustable wand handle, spray at a flat angle, 40 degrees or so, correct?

Thanks again!
Ronnie

First, your outdoor fixtures should be on a GFCI circuit. If not, you've got another project for the 'to do' list. Some of the electrics have their own gfci built in (I believe).

2200 psi will be okay with your deck if you use a 40 degree tip and don't get too close. Your angle mentioned should be fine. The adjustable wand is the cat's meow!!

fred

Thanks again Fred for your quick replies!

I'm all set. Just have to wait on nature to produce some good dry days.

I bought the same power washer for my PT deck. It worked fine. removed
a lot of loose paint. Got to playing with it on the asphault driveway,and very carefully on my vinyl siding. Did my patio blocks to,but used too much pressure ,or wrong technique. Blasted out sand filling between blocks.
Pretty happy with the Power Washer for the money.
I now need to Paint the deck again and wonder what i need to do this time to keep the paint on. Original problem was peeling.

Hope this helps.

If you paint it, it will peel!! I can guarantee that. Any paint or film base finish will peel because you cannot seal the deck boards COMPLETELY.
The deck boards will wick water from the ends and absorb moisture from the bottom and that moisture will be forced up to the top resulting in peeling, just like moisture from a poorly sealed wood painted house.

If you can remove the remaining paint and use an oil base stain you will be handling the maintenance every two or three years instead of every year.

fred

Thanks fred. Glad you posted to me. Will continue to sand and scrape.

Sorry for the late response. Thanks daswede for your reply. That's reassurring that the electric 1600 psi will do the job. I haven't used it on the deck yet. Waiting for all these storms to quit popping up!

In the meantime, went and purchased Sikkens SRD Redwood product.

Your welcome. By the way,mine and probably yours,is the homeowners version. Generall good all around.

Like yourself,here in Massachusetts it has been raining a lot.

I'm having a bugger of a time trying to get some areas of the deck that still has paint on it, off. I don't know if i should go out and buy some kind of paint stripper or what. I don't want to damage the wood by using some chemical stripper. Maybe some knowledgeable soul here can suggest something.

Most deck strippers for painted decks contain sodium hydroxide (lye).
A couple that I'm familiar with are by Flood and Wolmans.
You'll have to try one to see if it works. Acrylic paints are tougher to remove.


Be careful, and wear eye and skin protection. Cover any plants/grass in the area.

fred

Thanks Fred,
your input is a big help. I'll remember that.