Salting composite decks during winter weather requires consideration of potential risks versus reward for safety. While salt helps melt ice and improve traction, it can have unintended damaging effects on composite decking materials over time if used excessively or improperly.
Salt Damage to Composite Decking
Sodium chloride (rock salt) and other de-icing chemicals draw moisture out of the air and cause it to wick into composite deck boards. This leads to swelling as the materials absorb water. Repeated cycles of swelling and drying also cause warping and cracks to form. The salts may also accelerate fading of UV-protected coatings on the decking surfaces.
These chemical and physical changes undermine the structural integrity and intended lifespan of the decking composites. Damage happens gradually with each exposure but accumulates over multiple winters of salting. Within a few years, formerly flat and rigid boards may cup, gap, or need replacement prematurely.
Quality and Material Composition Matter
Not all composite decking materials are equally vulnerable. Lower-quality products incorporating a higher percentage of wood fiber or cellulose are more readily affected by salt due to their porous composition. Stability tends to increase with a lower wood content and the use of plastic polymers like PVC or HDPE in their place.
Premium composite decking containing as little as 51% wood cellulose may withstand occasional salt exposure without issues. But cheaper grades with 70% or more wood fiber content are strongly advised against salting to avoid jeopardizing the deck.
Safer Alternatives to Salt
If ice or snow accumulation requires a melting agent for safety reasons, consider using calcium chloride-based ice melt products rather than standard sodium chloride rock salt. Calcium chloride has less corrosive potential and a lower risk of damage. Non-chemical options like coarse sand or kitty litter also provide traction without chemical effects.
Best Practices for Winter Deck Care
Regularly clearing away fresh snowfall is preferable to allowing ice buildup. Shovel frequently before salt becomes necessary. Spot treat only stationary ice or heavy traffic areas prone to icing over rather than blanket salting the entire deck surface. Monitor for signs of damage and adjust practices as needed based on observed tolerance of the specific decking material. With prudent care, composite decks can thrive through many winters.
