Composite decking is the low-upkeep choice for a Greater Victoria deck and it is the expensive one. Third-party Canadian data for the 2026 season puts composite and PVC at $100 to $130 per square foot installed, western red cedar at $60 to $90, and pressure-treated at $35 to $60 (RenoQuotes, Deck Cost in Canada 2026).

Lifespan is not what decides it here. Two other things do. Composite warranties cover mould staining only if you wash it off within a week of it appearing, which is a live condition in a shaded, damp yard rather than a footnote. And US Forest Products Laboratory testing found composite deck boards lose flexural strength on the underside, the face that never sees sun, with some specimens falling to 15 percent of their original strength (Ibach and others, 2017).

So composite decking is the right choice on a Greater Victoria lot when the frame underneath can breathe and you will wash the surface when growth appears. Cedar is the right choice when you want warmth, board-by-board repairs and no warranty arithmetic, and you accept re-coating every year or two. Pressure-treated is the right choice when the budget leads. Everything below is the evidence for those three sentences.

The clause that decides composite on a shaded lot

Read the two biggest composite warranties side by side and they point in different directions on the one thing our winters guarantee: surface mould.

Trex names it in what it covers. Its decking warranty warrants the boards against permanent staining from food and drink spills "or mold and mildew naturally occurring in the environment," but only if the growth is removed "with soap and water within one (1) week" of first appearance. The same document then states that the warranty "does not cover mold and mildew which is not properly cleaned as provided above within one (1) week of first appearance" (Trex Limited Warranty, 2023).

TimberTech's composite fade and stain warranty, effective October 2023, never names mould in its covered list. That list runs to condiments, salad oils, grease, tea, wine, coffee, fruit punch and sodas. Mould appears only in the exclusions, grouped with air pollution as an "environmental condition" (TimberTech Fade and Stain Limited Warranty, 1 October 2023). Trex puts it in both places at once.

The practical answer is the same either way. If green or black staining appears on a shaded deck in February and you deal with it in April, you have no stain claim on either brand. The wash schedule is a warranty condition, not housekeeping advice.

Composite is mostly wood, and it fails on the side you never see

Start with what the board is made of. The US Forest Products Laboratory describes composite lumber as wood or cellulose fibre blended with plastic, with wood content running as high as 70 percent and a 50 percent wood, 50 percent plastic blend common. Its review records the early expectation that plastic would encapsulate the wood and stop both moisture uptake and fungal decay, then reports that after a decade of outdoor exposure the products showed wood decay, susceptibility to mould and polymer degradation, which is why manufacturers began adding fungicides, mildewcides and photostabilizers to the mix (Ibach, Durability of Wood-Plastic Composite Lumber, 2010).

Where the damage shows up matters before anyone frames a low deck. In a 2017 study of composite deck boards left outdoors in Hilo, Hawaii for 9.5 years, the laboratory found that UV radiation had no impact on flexural properties and that loss occurred mainly on the side opposite the sun-exposed surface. Some specimens degenerated to 15 percent of original flexural strength, and wood particle decay, moisture and elevated temperature were named as the major factors (Ibach and others, Laboratory and Environmental Decay of Wood-Plastic Composite Boards, 2017).

Hilo is not Saanich, and a wet-tropics exposure is harsher than any Greater Victoria backyard. The mechanism still travels. The shaded, damp underside goes first, which is exactly what a low deck over a soggy lawn creates. TimberTech states that decking should not be installed where ventilation and airflow cannot be achieved, and that on-grade decks must have additional provisions for drainage beneath the deck structure (TimberTech Composite Decking Installation Guide). Air and drainage under the boards are a durability requirement here.

What each material costs installed, from third-party data

These are published Canadian market ranges for the 2026 season covering framing, decking and basic labour, not our numbers (RenoQuotes, Deck Cost in Canada 2026):

Material	Installed, per square foot	Stated lifespan	Upkeep
Pressure-treated wood	$35 to $60	10 to 15 years	High, annual stain or seal
Western red cedar	$60 to $90	15 to 20 years	Moderate, oil or stain
Composite or PVC	$100 to $130	25 to 30 years and up	Very low, basic cleaning

The same source puts a standard 12 by 12 foot deck of 144 square feet at roughly $5,500 for a pressure-treated build, climbing past $18,000 for a premium composite one with glass railings and helical piles (RenoQuotes, 2026). Read that as a surface premium of two to three times against a maintenance bill you stop paying. No national range accounts for your access, your slope or your soil.

What you actually get if a composite claim succeeds

Less than the headline number suggests. Here are the current published terms, from Trex's 2023 limited warranty and TimberTech's fade and stain warranty of 1 October 2023:

Warranty document	Residential term	Recovery, final years of term	Removal and reinstall labour	Transfer
Trex Transcend decking and fascia	50 years	10% in years 43 to 50	Not covered	Once, within 5 years
Trex Select decking and fascia	35 years	10% in years 29 to 35	Not covered	Once, within 5 years
Trex Enhance decking and fascia	25 years	10% in years 23 to 25	Not covered	Once, within 5 years
TimberTech Legacy, Reserve, Terrain (fade and stain)	30 years	10% in years 27 to 30	Not covered	Once, within 5 years
TimberTech Prime+, Prime, Premier (fade and stain)	25 years	10% in years 23 to 25	Not covered	Once, within 5 years
Western red cedar or pressure-treated	No manufacturer product warranty of this kind	n/a	n/a	n/a

Recovery on every line is prorated from year eleven onward, so a valid claim in year 24 of a 25-year warranty returns ten percent of what you paid for the boards. Both companies also exclude the cost of taking old boards off and putting new ones down, and labour is the larger half of a re-deck. The proration schedules for the two 25-year lines are identical, percentage for percentage.

Why an angled layout changes the framing bill

Both manufacturers cap joist spacing at 16 inches on centre for a straight run and drop it to 12 inches the moment the boards go on an angle. Trex states that joists should be spaced no more than 16 inches on centre for standard applications and that 12-inch spacing is required for decking laid diagonally (Trex, How to Space and Install Deck Joists). TimberTech sets the same 16-inch ceiling, requires 12 inches on centre for all angled installations, notes that more severe angles may require closer spacing again, and asks for additional support under a picture-frame border (TimberTech Composite Decking Installation Guide).

Going from 16 inches to 12 inches is a third more joists across the whole frame, with the hangers, fasteners and labour that come with them. Diagonal and picture-frame layouts are common on the angled and sloped lots around Greater Victoria, so the pattern you like on a sample board is a structural decision made before anyone chooses a colour. Both documents add that local building codes still govern, so confirm requirements with your local municipality.

What cedar asks of you specifically here

More than it asks elsewhere, and the industry's own numbers say so. The Western Red Cedar Lumber Association's technical data puts summer equilibrium moisture content in the Pacific Northwest at 15 percent, against 12 percent for most of the United States (Western Red Cedar Lumber Association, characteristics and properties). Wood on this coast sits wetter, which is why the maintenance interval in a national article underestimates ours.

The same association is blunt about the finishing cycle. Semi-transparent stains and water repellents last "one or two years, depending on exposure conditions," and quality products carry mould and mildew inhibitors, the better ones with mildewcides or fungicides (Western Red Cedar Lumber Association, finishing choices). Even left to weather naturally to grey, cedar wants dirt and mildew removed regularly to look right.

What cedar buys in return is repairability and no proration table. A damaged board is a board, replaced with a board, at a price you can see at any lumberyard, and nothing has to be adjudicated by a warranty department.

Pressure-treated is under your deck either way

Whatever you walk on, the structure below is treated softwood. A 50-year board sits on framing that will not last 50 years in this climate without help, and the Forest Products Laboratory work above puts up to 70 percent wood inside the composite board as well. There is no plastic deck, only decks with less exposed wood in them.

As a walking surface, pressure-treated is the value option and behaves like it, moving and greying faster than cedar here. As framing, it is not optional. Detailing that frame properly with coastal-grade fasteners, flashing, slope and clear drainage under an on-grade deck is what actually decides how long any of the three lasts on the Island.

So which one

The verdict is at the top of this page and the evidence is between. Heat, the argument that drives most composite marketing, matters less on this coast than in the sunbelt, so let airflow, the wash schedule and the framing pattern decide instead.

We build in all three and detail the frame for the coast either way. Our guide to what a deck costs in Victoria covers how the rest of the build moves the total, whether your deck needs a permit covers the municipal side, and how to choose a deck builder covers who should hold the pencil. When you are ready, see how we build decks or send us the details and we will work through the trade-off against your yard and your budget.

Estimates vary by property. Book a site assessment for a scope and price specific to your home.

Composite Decking in Victoria: Cost, Warranties, and Cedar Compared