How to Maintain Cedar Fencing, Decking & Siding: Staining, Sealing & Cleaning Guide

Cedar doesn't need much maintenance — that's one of the reasons people choose it over pressure-treated wood in the first place. But "doesn't need much" isn't the same as "needs none," and the difference between a fence, deck or siding job that still looks good in 15 years and one that's silvered, cracked and cupping in five usually comes down to whether it got a handful of basic maintenance steps on schedule. Here's what that schedule actually looks like in BC's climate.

Why cedar needs maintenance at all

Left completely untreated, cedar will naturally weather to a silvery-grey patina — and for some applications (a lot of West Coast fence and siding jobs are deliberately left to do exactly this) that's a legitimate, low-maintenance finish choice. The problems start when moisture gets into the wood unevenly: UV exposure breaks down the wood surface, rain gets absorbed into end grain and checks (the small surface cracks you see on aged, unsealed cedar), and in BC's wet coastal climate specifically, unsealed horizontal surfaces (deck boards, top rails) hold moisture long enough to develop mildew and moss. None of that is inevitable — it's what maintenance prevents.

The maintenance schedule

Every spring and fall — clean it.
A simple wash with a mild deck/siding cleaner (oxygen bleach-based cleaners work well and won't damage the wood the way chlorine bleach can) removes surface dirt, pollen, and the early stages of mildew before they set in. For decking, get into the gaps between boards where debris traps moisture. This alone — done twice a year — prevents most of the graying and staining people associate with "old" cedar.

Every 2–3 years — reseal or re-stain (horizontal surfaces).
Deck boards, top rails, and anything facing directly up at the sky take the most UV and moisture damage and need the most frequent attention. A semi-transparent oil-based stain with UV inhibitors is the standard choice — it lets the wood grain show through while giving real protection, versus a clear sealer (less protection, needs redoing sooner) or a solid/opaque stain (more protection and longer intervals, but it hides the wood).

Every 3–5 years — reseal or re-stain (vertical surfaces).
Fence faces and siding see less direct sun and pooling water than decking, so they hold a finish longer. Watch for the classic sign it's due: water should bead on the surface when you splash it. Once water starts soaking in instead of beading, the finish has failed and it's time to redo it, regardless of the calendar.

As needed — spot-treat mildew and moss.
BC's wet shoulder seasons are prime conditions for both, especially on north-facing fence sections and shaded deck areas. A diluted oxygen bleach solution, left to sit for 10–15 minutes and rinsed, handles most cases without damaging the wood the way pressure washing on high or chlorine bleach can.

What happens if you skip it

Untreated or neglected cedar doesn't rot the way people expect — it's naturally resistant to that — but it does check, cup, and grey unevenly, and neglected finish failures let moisture in at the worst points: end grain on deck boards, and anywhere fasteners have backed out slightly. The most common real-world failure we see isn't the wood itself, it's a finish that was left to fail on a horizontal surface for 4–5+ years, letting water sit in checks and joints long enough to start actual decay underneath a finish that looks fine from a distance.

A note on pressure washing

Pressure washing cedar is fine — cedar can handle it better than most softwoods — but only at the right pressure and distance. Use a fan tip, keep it under roughly 1,500 PSI, and hold the wand at least 12" from the surface, moving with the grain. Too much pressure at close range will strip soft grain out of the board and leave a fuzzy, damaged surface that then holds dirt and moisture worse than before you started.

Does the maintenance schedule change by product?

Not fundamentally — the same clean/reseal cycle applies whether it's fencing, decking, or siding — but exposure changes the timeline. Decking gets foot traffic and standing water; siding gets more consistent sun exposure but less direct water pooling; fencing (especially shaded or north-facing runs) is the most likely to develop moss and mildew rather than sun damage. If you're planning a new build and want to know which cedar species holds up longest with the least maintenance, our Western Red Cedar vs. Yellow Cedar vs. Sugi comparison covers the durability differences between species.

Whether you're maintaining an existing structure or replacing sections that were left too long, browse decking, siding & trim, or pergola & trellis stock for replacement boards cut to the same profiles as what's already on your property.