Pressure washing wood deck? BAD IDEA? pressure treated.


I head conflicting advise on maintaining my deck. Some say you damage the deck by pressure washing it. Does pressure washing it remove the pressure treated chemical out of the wood? Also, If you do wash it is detergent required? Our deck is in good shape except in a few shaddy spots, it has mildew. I was going to pressure wash it then seal it. should I not pressure was the fence if I don't plan to seal the fence? Thanks.
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Wood treatment like CCA is in the wood from pressured treatment, when you buy it new its wet through with treatment. Kill mold with bleach then wash it. Oxcilic acid also cleans it well. Stain absorbes more and lasts longer on clean wood. Read sealer ratings at Consumer Reports online.
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lbbss wrote:

The damage comes from holding the wand too close to the wood or moving it too slowly, which removes some of the wood.

No. The chemicals soak into the wood because of the "pressure" part of pressure-treated. In really large pieces, like 8x8, it might not make it all the way to the center.

I recommend a detergent designed for wood decks, but it isn't a government mandate or anything. _Do not_ use dish detergent unless you want bubbles everywhere.

A little dilute bleach and a scrub brush should take care of that. The people who sell you the deck wash can also sell you a "deck brightener" which has some form of bleach in it. It will get rid of *some* of the grey oxidation. You'll have trouble getting back to the original color of the wood without taking off part of the wood surface.

The sealer is optional, especially since you have pressure-treated wood. PT wood is usually colored, so most people let it oxidize to grey, not liking a green deck.

You can certainly pressure-wash the fence, but it will be a big, wet job. Most of the grey will go away, but it will be back again in a year.

You're welcome. Post some pictures.
p.s. I learned to power-wash decks by practicing on my own. I found I liked the "rugged" look I got with aggressive power-washing. A smooth surface might be more important to you.
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Steve Bell
New Life Home Improvement
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wrote:

You can damage wood with a high-pressure washer. Pressure washing, washing by hand or rain removes some of the preservative in the wood. The typical solution to wash a deck is
3/4 cup TSP 1 cup household bleach 1 gallon warm water
Dissolve the TSP in a half gallon of warm water. Stir for two full minutes as TSP dissolves slowly. Add bleach. Add water to make 1 gallon in a garden sprayer. You can use a deck wash (JoMax) instead of the TSP. The bleach will kill algae and mildew. Lightly spray and brush a 3x3 foot area at a time and rinse with a garden hose after 5 minutes. TSP is a very strong detergent not good for your skin/eyes--wear old clothing and eye protection. Make sure the wood is well-rinsed and completely dry before applying a sealant.
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