Vinyl vs composite vs cedar on Vancouver Island

On Vancouver Island, the deciding factor between vinyl membrane, composite, and cedar is water. The coast's wet winters and salt air punish any surface that holds moisture. Vinyl membrane sheds water and keeps the space below dry; capped composite resists rot without sealing; cedar looks the part but needs the most upkeep. Here is how the 3 compare.

Which decking lasts longest in a wet coastal climate?

Longevity on the coast comes down to how a surface deals with standing water and constant damp.

A vinyl membrane is a single waterproof sheet — a 68mil PVC layer heat-welded at every seam and run up the edges, so water has nowhere to sit and nowhere to get in. Because it is continuous, it also protects the structure underneath: the joists and any space below stay dry. We back the waterproofing for 15 years and the appearance for 5.

Capped composite is a board product — a wood-plastic core wrapped in a hard plastic cap on the top and sides. The cap is what matters on the coast: it does not absorb water, so the boards do not rot, cup, or splinter the way wood does. Water still passes down between the boards, so the framing below has to be built and flashed to shed it, but the walking surface itself is close to maintenance-free and holds up for decades. Composite boards carry their own manufacturer warranties.

Cedar is natural wood. Western red cedar has oils that resist rot and insects better than most lumber, which is why it has been the Island's traditional deck material. But it is still wood in a wet climate: left alone, it absorbs rain, weathers to grey, and its lifespan drops sharply. Sealed and maintained, a cedar deck lasts; neglected through a few coastal winters, it does not.

How does each material handle salt air?

Salt accelerates corrosion and speeds the breakdown of unprotected surfaces, so it is the usual reason waterfront decks fail early.

Vinyl membrane is unaffected by salt — it is an inert plastic sheet, and a rinse clears any salt film. Capped composite is similarly indifferent; the cap does not corrode and salt does not degrade it. Cedar handles salt reasonably well as a wood, but salt-laden wind dries and greys it faster, and the fasteners and any steel hardware become the weak point. On exposed sites like the Sooke waterfront or the outer Gulf Islands, the surface is only half the question — the fasteners and the railing have to be corrosion-resistant too, which is why aluminum railings pair well with any of these decks.

What maintenance does each one need?

This is where the 3 separate most clearly.

A vinyl membrane needs almost nothing: an occasional wash to keep it clean and clear of debris. There is nothing to sand, stain, or seal.

Capped composite is close behind — a wash 2 to 3 times a year to lift pollen, mould spores, and grime, which the coast's damp encourages on any horizontal surface. No sanding, no sealing, no refinishing.

Cedar is the high-maintenance choice. To hold off the greying and slow the moisture uptake, it wants cleaning and resealing roughly every 1 to 2 years on the coast — more often on the faces that take the most sun and rain. Skip a cycle or two and the wood starts checking and cupping. Some owners let cedar silver out on purpose and accept the shorter life; that is a valid choice, but it is a choice, not a maintenance-free one.

Does composite decking get hot or fade on the coast?

Both, mildly, and less than people fear on the Island. In direct summer sun a dark composite board runs hotter underfoot than cedar — lighter colours stay cooler, and the Island's moderate summers keep this from being the problem it is in hotter regions. Fade is real but slow: modern capped composite holds its colour far better than early generations, lightening a little over many years rather than blotching. Cedar, by contrast, changes colour quickly unless it is sealed. Vinyl membrane comes in a set range of colours and textures and holds them, since there is no wood to bleach or fade.

Which is safest underfoot when the deck is wet?

On the coast a deck is wet for a good part of the year, so traction matters more here than in dry climates. Vinyl membranes are made with an embossed anti-slip texture pressed into the surface, and because the sheet is sealed, algae and moss have little to grip — a wash keeps it clean and grippy. Capped composite boards are moulded with a grain or brushed texture that holds reasonably well when wet, though a smooth, dark board in deep shade can green up and turn slick if it is never cleaned. Cedar is the one to watch: in the Island's damp shade, bare or worn wood grows a thin algae film that gets genuinely slippery, which is one more reason the sealing cycle is not optional. Whichever surface you choose, keeping it clean is what keeps it safe underfoot.

How does installation differ between the 3?

The way each surface goes down explains a lot about how it performs. A vinyl membrane is bonded over a solid plywood substrate and heat-welded at the seams and edges into one continuous waterproof surface — it is skilled work, because the waterproofing is only as good as the welds and the flashing at the walls and posts. Capped composite clips to the deck frame, usually with hidden fasteners between the boards, so joist spacing has to be right and the framing below has to be built to shed the water that passes through. Cedar is fastened down as individual boards and lives or dies by the maintenance that follows. The common thread on the coast is what sits underneath: any of the 3 only lasts if the structure below is framed, flashed, and drained to keep water moving away from the house.

Is a waterproof deck worth it?

It depends on what is under the deck. If the space below is used — a patio, storage, a suite entrance, a dry spot for firewood — a vinyl membrane is the only one of the 3 that turns the deck into a roof for that space. Composite and cedar are open-jointed surfaces: water runs between the boards to the ground below. A membrane is also the standard answer for a balcony over living space, where a leak means water in the ceiling underneath. That is why vinyl membrane decking is the default for balconies, second-storey decks, and anywhere the area below has to stay dry, while composite decking is the default for an open ground- or upper-level deck where drainage below is not a concern.

Which should you choose for your deck?

Match the material to the site. Choose a vinyl membrane when the deck sits over usable space, or when you want a fully waterproof, near-zero-maintenance surface. Choose capped composite for an open deck where you want low upkeep without the waterproofing. Choose cedar if you want natural wood and will commit to sealing it every year or two. All 3 work on Vancouver Island — the wrong one is only wrong because it was matched to the wrong deck.

If you are weighing a resurface or a new build in Sooke, on Salt Spring Island, or anywhere on the south Island, request an estimate. We will look at what is under your deck, how exposed the site is, and how much upkeep you want to take on, then tell you which surface fits.