Can I use salt or ice melt on my composite deck in Saint John NB?

You should never use rock salt or sand on a composite deck — calcium chloride and calcium magnesium acetate (CMA) are the only safe de-icing options for composite decking in Saint John.

Rock salt, which is sodium chloride, is the most common de-icer sold across New Brunswick, but it is genuinely harmful to composite deck boards. It leaves a white residue that etches into the surface over time, and the corrosive nature of sodium chloride attacks the metal fasteners and connectors holding your deck together. In Saint John's coastal climate, where salt air is already accelerating corrosion on every piece of exposed hardware, adding more sodium chloride directly onto the deck surface compounds the problem significantly.

Sand is the other product homeowners reach for, and while it seems harmless, it actually scratches composite decking. Those scratches accumulate over a single winter and leave the surface looking scuffed and worn, especially on darker-coloured boards where marks show easily. Once composite decking is scratched, the damage is permanent — you cannot sand and refinish composite the way you would pressure-treated lumber.

Calcium chloride is widely available at hardware stores in Saint John and across the province. It works at temperatures down to roughly minus 25 degrees Celsius, which covers even the coldest stretches of a typical Saint John winter. It melts ice quickly and does not damage composite surfaces, stainless steel screws, or hidden clip fastening systems. Spread it sparingly — a thin application is enough to break the bond between ice and the deck surface, and then you can shovel the loosened ice away.

Calcium magnesium acetate, or CMA, is the more environmentally friendly alternative. It is biodegradable, non-corrosive, and safe for composite materials. It costs more than calcium chloride but is worth considering if your deck is near garden beds or if runoff drains toward the Kennebecasis or Saint John River, where chloride accumulation in waterways is becoming a growing concern for municipalities.

For routine ice management through a Saint John winter, the best practice is to shovel snow promptly before it compacts into ice, and then apply calcium chloride only to the thin ice layer that remains. A plastic-edged shovel prevents gouging. If you stay on top of snow removal after each storm, you will rarely need much de-icer at all. When you do apply product, sweep up any remaining granules once the ice has melted to prevent prolonged chemical contact with the deck surface.

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