Design & DIY

Cottage Q&A: Treating a slippery deck

Close-up of wet wooden deck By Helen's Photos/Shutterstock

We have a large, untreated 10-year-old cedar deck at our cottage. When the deck gets wet, it is extremely slippery. Several of us have taken a tumble while walking on it. Around the perimeter are several hemlock trees with some overhanging branches. How can we make the deck safer?—Gus Ezers, Crane Lake, Ont.

The deck is probably getting slippery because of algae growth, says Rod Stirling, an expert in wood protection with FP Innovations in Vancouver. “That’s often what we see with cedar.” 

The simplest solution? Assuming you want to leave the cedar untreated, wash the deck. Or, wash it more frequently. You should be doing annual maintenance and cleaning anyway—at the very least sweeping off leaves and debris, and scrubbing away any moss, mould, or algae. It’s possible to use straight water, a stiff brush, and sheer arm strength. “But a dedicated deck washing product is going to do a much better job,” says Stirling. You can find these at any hardware store; follow the instructions on the label. (Caveat: you’re best not to use a deck wash if there’s any chance the product could get into the lake. And be careful if you use a pressure-washer, since the spray can be powerful enough to gouge wood).

How do you extend the life of an untreated cedar deck?

If you have slick steps, you can add anti-slip or “grip” strips designed for wood. They don’t look glaringly conspicuous, and they’re usually simple to attach, says Stirling. Unfortunately, the overhanging tree branches probably aren’t helping the slimy situation. Trim them back. “Algae tends to grow where it’s shady.”

Even if you do all of this—even if you scrub the deck multiple times per year, “I wouldn’t want anyone to think, ‘Oh, now I can race around on the wet deck like crazy,’ ” says Stirling. “When things get wet, they get slippery.”

An extra step is to try an anti-slip coating. These are usually paints or stains containing added grit. They might change the look of the cedar, so coat a test spot before you treat the entire surface. 

Five spring deck maintenance tips

This article was originally published in the March/April 2021 issue of Cottage Life magazine.

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