What is a significant risk associated with improperly designed deck joists?

Improperly designed deck joists primarily pose a significant risk of structural failure. Deck joists serve as the main support framework that carries the load of the deck, including the weight of furniture, occupants, and environmental factors like snow and rain. When joists are not designed correctly—whether due to inadequate spacing, insufficient size, or erroneous materials—they can buckle, sag, or collapse under typical loads. This structural integrity is crucial; a failure can lead to dangerous situations where people might be injured if the deck gives way.

While water damage, pest intrusion, and air leaks can also be relevant concerns related to decks, they are typically secondary issues that arise from other factors, such as poor maintenance or construction techniques. Addressing structural failure is of utmost priority since it directly endangers the safety of the occupants and users of the deck.