Tips for Cleaning A Wood Deck this Spring

I hate the words “spring cleaning.” I hate long checklists that remind me of all the things I don’t feel like doing. I hate the hours of dirty, sweaty work required to clear out winter’s accumulation of disarray.

What I don’t hate is inviting friends over to enjoy cold drinks on my cedar deck all summer. So I do the work (mostly) and keep my grumbling to myself (mostly).

However, because I’m feeling a bit surly about the whole deal, I’m not going to tell you to hose off your patio furniture or get on your hands and knees with a putty knife to scrape leaves from between your deck boards – although you should. Instead, I thought I’d address a few of the finer points of spring cleaning your wood deck.

The Power Washing Debate

Some homeowners swear by pressure washing, while others will caution you to never, ever let a pressure washer anywhere near your deck. It’s a plain fact that pressure washing makes spring cleaning a lot easier. It’s also a fact that, if used carelessly, a power washer can cause significant damage to your decking material. Personally, I find a garden hose to be sufficient for cleaning a cedar deck.

Low Rise Cedar Deck Recently Spring Cleaned image via Ricks Fencing

If you must power wash, keep in mind that cedar is a soft wood. Too much water pressure can leave gash marks in your deck. Again, experts differ on the amount of pressure you should use. In my experience, it’s best to follow the recommendations of your decking manufacturer – or, barring that, I prefer to err on the low side, around 800 PSI. Use a wide nozzle – 40 degrees is good – and hold it at least a foot away from your deck’s surface. Keep the spray in constant motion, as if you’re making a low golf swing, and don’t get in a rush.

The Truth about Commercial Deck Cleaners

Chances are your cedar decking surface has developed mold or mildew growth, tannin stains left behind by leaves and other debris, rust stains, or just a general gray, weathered look over the winter. There are plenty of commercial products available that promise to help restore your deck’s natural glow, but a savvy homeowner knows the real value of these sorts of promises.

Generally, deck cleaners come in three main categories: chlorine bleach, oxygen bleach and oxalic acid.

* Chlorine bleach

Deck cleaners containing chlorine bleach are usually the most effective at killing mildew, but they’re also the most effective at damaging your decking material. Chlorine bleach breaks down lignin, which is basically the glue that holds the wood fibers together. This effect can cause visible damage as well as prevent your deck stain or sealant from properly bonding to the wood. You can tell whether a deck cleaner contains chlorine bleach by looking for the chemical term, sodium hypochlorite, on the label.

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* Oxygen bleach

Oxygen bleach, or sodium percarbonate, removes mildew and other residue from a cedar deck without destroying the wood. It’s also non-toxic, for plants as well as people, as it simply breaks down into oxygen and soda ash. The downside is you’ll probably need to do a bit of scrubbing with a stiff bristled brush to get your deck as clean as you’d like it.

* Oxalic acid

Unlike bleaches, oxalic acid does not kill mildew, nor is it particularly great at removing dirt. However, it does a bang-up job of removing tannin and rust stains and restoring the wood’s natural brightness – which is why it’s a common ingredient in deck brighteners. It’s also toxic and must be handled with care. (For a milder and more eco-friendly brightener, citric acid is becoming an increasingly popular alternative.)

Many professionals use a two-step process for cleaning a cedar deck: 1) Get rid of mildew with oxygen bleach and 2) Apply an acidic brightener for stain removal. And that’s the majority of what you need to know about spring cleaning your deck. The rest is mostly common sense.

Now for the pep talk finale: A day of cleaning will result in a re-energized deck you can enjoy all summer long. Or so I tell myself as I try to muster the motivation to put down my drink and get to work.


Dave Nichols writes about outdoor home improvement, including composite and cedar decking maintenance, for the Rick’s Fencing & Decking Blog.

For more from us on Outdoor Living, click into that Category there. Learn how to do Pressure Washing right, see our article Pressure Washing Basics. For more on Wood Decks. ~jb