Choosing between cedar and composite decking in Canada comes down to four factors: how your climate behaves across seasons, how much annual upkeep you are willing to do, what your budget looks like over a fifteen-year horizon, and how the board will look and feel underfoot. Neither material wins outright — they solve different problems.
How Each Material Behaves in Canadian Climates
Canada's climate zones range from ASHRAE Zone 4 along the Pacific coast to Zone 7 in the northern Prairies. The critical variable for decking is not average annual temperature — it is the number of freeze-thaw cycles per winter. In Ottawa or Montreal, that number can exceed 60 in a single season. Each cycle puts stress on fasteners, board edges, and any finish coat that has started to fail.
Western Red Cedar
Cedar's natural oils give it moderate resistance to rot and insect damage without any preservative treatment. In British Columbia and the milder parts of Ontario, a well-maintained cedar deck can last 20 to 25 years. The same deck in Winnipeg, exposed to 70+ freeze-thaw cycles annually, may need full board replacement in 12 to 15 years unless it receives a penetrating oil finish every two years.
Cedar is dimensionally stable along the length of the board but moves noticeably across the grain with moisture change. Installers in high-humidity regions leave a 3 mm gap between boards; those in drier Prairie climates often tighten that to 2 mm. Using the wrong gap spacing for your region is one of the most common cedar installation errors in Canada.
The Janka hardness of western red cedar is roughly 350 lbf — lower than most composite products. It dents from dropped tools, patio furniture legs, and high heels. Surface scratches are easy to sand out, which is one reason many owners prefer cedar for refinishing projects.
Composite Decking
Composite boards manufactured for the Canadian market — including products certified to CSA Group standards — are tested to handle temperature swings from −40°C to +50°C. The polymer cap layer on capped composites resists moisture absorption and significantly reduces the expansion-contraction cycle that wears uncapped composites prematurely.
Capped composite expands roughly 3 mm per 3 m run over a 50°C temperature swing, compared to cedar's 1.5 mm across the grain. This means composite requires careful attention to end-gap spacing at walls and posts — a detail often skipped on DIY installs that leads to buckling in late summer.
The surface of composite boards does not absorb stains the way cedar does, which is an advantage in food-prep or dining areas. It also does not splinter, making it easier underfoot for households with children or older adults.
Maintenance Requirements by Material
| Task | Cedar | Composite (capped) |
|---|---|---|
| Annual cleaning | Mild soap wash, check for mildew | Low-pressure rinse, occasional soap |
| Sealing / staining | Every 2 years for penetrating oil | Not required |
| Fastener inspection | Every 3–5 years; replace corroded screws | Every 5 years |
| Board replacement | Individual boards replace easily | Easier with hidden fastener systems |
| Sanding and refinishing | Possible; restores surface | Not possible |
Cost Over a 15-Year Period
Cedar boards at a Canadian lumber yard typically run $3.50 to $5.50 per linear foot for 5/4 x 6 decking grade, as of 2026. Composite boards range from $4.50 to $9.00 per linear foot depending on brand and cap type. The upfront gap narrows when you factor in labour for installation — composite hidden-fastener systems take longer to install than face-screwed cedar.
Over fifteen years, cedar requires two to three refinishing rounds at roughly $400 to $700 per 400 sq ft including materials. Composite requires no finish coats. A 400 sq ft cedar deck installed in Ottawa will cost approximately $8,000 to $12,000 all-in, compared to $11,000 to $18,000 for a comparable composite installation. The composite deck reaches cost parity with cedar between year 8 and year 12 when maintenance costs are included.
Which Material Suits Which Province
In British Columbia, cedar remains the dominant choice for covered porches and decks with good drainage. The mild winters reduce freeze-thaw stress, and the material is locally sourced. On the Prairies, composite or pressure-treated pine with a composite cap board is more practical for exposed horizontal surfaces. In Atlantic Canada, where salt air accelerates corrosion, stainless-steel fasteners are required with cedar regardless of the climate zone.
For a detailed breakdown of weatherproofing requirements by province, see the companion article on this site.
Summary
- Cedar costs less upfront and is easier to repair; it requires regular finishing in climates with more than 40 freeze-thaw cycles per year.
- Capped composite costs more upfront, requires minimal maintenance, and performs consistently across all Canadian climate zones.
- Gap spacing, fastener type, and end-gap allowance must be specified for your climate zone regardless of which material you choose.
- Neither material is better in absolute terms — the decision depends on your climate zone, how much maintenance you are prepared to do, and your fifteen-year budget.