Most of the decks built in Canada over the past 30 years have been framed with pressure-treated lumber, and a significant portion of them are surfaced with it as well. Cedar was the go-to premium alternative for much of the same period. The choice between the two comes down to a cluster of practical factors: upfront cost, how much maintenance you're prepared to do, and what you expect the deck to look like in year five versus year fifteen.
Cost at Purchase
Pressure-treated pine (typically southern yellow pine, SYP, or SPF species) is less expensive at the lumber yard. In most Canadian markets in 2024, 5/4×6 PT decking ran between $1.80 and $2.60 per linear foot. Western red cedar 5/4×6 decking ran between $2.80 and $4.20 per linear foot depending on region — consistently around 50 to 70 percent more expensive than the equivalent PT product.
For a 32m² deck (a size common in suburban residential builds), the cost difference in decking boards alone is roughly $800 to $1,500 in favour of PT. The framing is almost always PT regardless of which decking you choose, so that cost is constant.
Moisture Content and Workability
One of the more practical differences between these two materials is how they behave during installation. Freshly milled PT lumber typically arrives at a moisture content of 25 to 40 percent — significantly above the 19 percent threshold considered "dry" for construction purposes. Kiln-dried-after-treatment (KDAT) PT lumber is available at a premium and behaves more predictably.
Cedar arrives at lower moisture content and is dimensionally more stable during installation. It is also lighter — roughly 380 kg/m³ for western red cedar versus 480–560 kg/m³ for SYP — which matters when you're handling 16-foot lengths on a scaffold or installing overhead.
Both materials cut cleanly with standard carbide-tipped circular saw blades. Cedar's natural oils can cause staining on concrete when it rains over a new installation, which is temporary and washes away with time.
If you're using wet PT lumber and want to avoid excessive shrinkage gaps, install boards with no gap between them. As the wood dries, it will shrink to leave a natural drainage gap of 3–5mm.
Fasteners and Hardware
This is one of the most consequential practical differences. Modern PT lumber treated with ACQ or CA preservatives is corrosive to standard zinc-plated steel hardware. Using standard joist hangers, lag screws, or deck screws with ACQ-treated lumber leads to accelerated corrosion — sometimes visible within two to three years — that can compromise structural connections.
Approved fastener materials for use with ACQ and CA-treated lumber include:
- Hot-dipped galvanized (HDG) with a minimum zinc coating weight of 1.85 oz/ft²
- Stainless steel (Type 304 or 316)
- Fasteners specifically rated for ACQ contact by the manufacturer
Cedar does not raise this concern. Standard galvanized or stainless decking screws work without issue. For a project where you're using PT framing (virtually universal) with cedar decking, the fastener requirement is driven by the PT framing, not the cedar surface. Any fastener going into PT lumber — including joist hanger nails and lag screws into the ledger — must meet the ACQ-compatible standard.
Appearance Over Time
Fresh PT lumber has a characteristic greenish tint from the copper-based preservatives, which fades to grey over 3 to 12 months depending on sun exposure. Freshly milled cedar is a warm reddish-brown that many people find more visually appealing. Both materials will grey out to a silver-grey colour if left unfinished, and both can be stained to maintain a more consistent appearance.
Cedar accepts penetrating oil stains particularly well due to its open grain structure. PT pine also takes stain, but the denser grain and residual preservative salts can make the first coat uneven. Many contractors recommend waiting at least one full dry season before applying any finish to new PT lumber.
The weathered grey of aged cedar tends to be more uniform and finer in texture than the grey of weathered PT pine. PT pine, when it ages without maintenance, often develops a rougher surface texture and more prominent checking (surface cracks along the grain).
Lifespan in Canadian Conditions
Both materials are capable of lasting 15 to 25+ years in Canadian conditions with appropriate maintenance. PT lumber's chemical treatment provides reliable decay resistance regardless of maintenance frequency. Cedar relies on its natural oils, which do diminish over time — particularly in the sapwood portions of the board, which have little natural decay resistance and are present in most commercial cedar decking.
In wet coastal climates, untreated cedar sapwood can begin to show signs of surface mould and discolouration within three to five years without annual maintenance. In drier inland climates, cedar heartwood can go considerably longer between treatments. PT lumber is more forgiving in this respect — the preservative extends protection even if the board surface is neglected.
Environmental Considerations
Concerns about PT lumber's preservative chemicals are periodically raised in discussions about decking. The ACQ and CA preservatives currently used in residential PT lumber are considered low-toxicity to humans in the finished form, but copper does leach into soil and water in quantities that can affect aquatic invertebrates. In areas with sensitive watersheds or where runoff drains directly into water bodies, this is worth noting.
Western red cedar is a slow-growing species. Certified cedar from sustainably managed BC forests (look for FSC certification) is a reasonable choice if source tracking matters to you. Reclaimed cedar — salvaged from old barns, wharves, or demolished structures — is available in some markets and typically has high heartwood content, meaning excellent natural decay resistance.
Summary
- Choose PT if: Budget is a priority, you're in a wet climate where maintenance is unpredictable, or the deck will be in a location where aesthetics are secondary to durability.
- Choose cedar if: Appearance matters, you're prepared to do annual or biennial maintenance, and the cost premium fits the project budget.
- Either way: Use ACQ-rated fasteners throughout the frame, prime and stain before installation if possible, and plan footing depth to the local frost line.