Using 2x8 lumber for deck joists is possible, but it depends on the specific requirements of your deck and local building codes. Here are some factors to consider:
Span and Load Capacity: The size of the joists you use should be appropriate for the span between supports and the anticipated load on the deck. The maximum allowable span for 2x8 joists will depend on various factors, including the species of wood, spacing between joists, and the anticipated load. You should consult span tables provided by local building codes or consult with a structural engineer to ensure that 2x8 joists are suitable for your specific deck dimensions and requirements.
Spacing and Support: The spacing between joists is another important consideration. The standard spacing for deck joists is typically 16 inches on center (OC) or 24 inches OC. Using 2x8 joists will require additional supports at closer intervals compared to larger-sized joists to meet the required load-bearing capacity.
Deck Height and Structure: If your deck is elevated or has a higher height, you may need to use larger-sized joists to meet the necessary structural strength requirements. Building codes may specify minimum joist sizes based on the height of the deck.
Climate and Moisture Considerations: Decks are exposed to outdoor elements, including moisture and temperature fluctuations. It's important to select pressure-treated or rot-resistant lumber for the joists to ensure durability and prevent rot or decay.
To ensure the safety and structural integrity of your deck, it is recommended to consult with a local building professional or structural engineer who can assess your specific deck plans, local building codes, and environmental factors. They will be able to provide guidance on the appropriate joist size and spacing for your deck project.