Deck Joist Size Decision: 2x6 or 2x8?
When constructing a deck, one of the most critical decisions is the choice between 2x6 and 2x8 joists. This decision impacts not only the overall structure and safety of the deck but also the aesthetic and budgetary considerations. Understanding the factors involved will help you make an informed decision.
Factors Influencing the Choice of Joist Size
The choice between 2x6 and 2x8 deck joists depends on several factors, including the span between supports, the load the deck will carry, and local building codes. Here are key considerations to help guide your decision:
1. Span and Load Capacity
2x6 Joists: Typically suitable for spans of up to 10-12 feet, depending on the load. They are often used for residential decks that will support lighter loads. 2x8 Joists: Can span further, generally up to 12-16 feet or more, depending on the load. They provide greater strength and can support heavier loads.2. Building Codes
Check local building codes as they may specify minimum requirements for joist size based on the type of deck and its intended use. Compliance with these codes is crucial to ensure your deck is safe and legally built. Disregarding local codes can result in fines or safety hazards.
3. Deck Design
If you plan to have heavier features like a hot tub or built-in seating or if the deck will be used for gatherings, opting for 2x8s may provide added safety and stability. Stronger joists can help distribute loads evenly and prevent sagging, ensuring a safer and more comfortable deck.
4. Cost and Availability
2x6 joists are generally less expensive and may be more readily available. However, consider the long-term benefits of using 2x8s if your deck will be heavily used. Investing in higher quality materials can save you money in the long run by reducing the need for future repairs or replacements.
Building Deck Timber Standards
Building a deck requires adherence to specific standards to ensure the framework is durable, safe, and meets local regulations. The type of timber, spacing of piers, and use of standard sized ‘grid’ patterns are key components to consider:
1. Timber for Framework
Hardwood HWD is the best choice for external framework due to its durability. Hardwood has natural resistance to weathering, rot, and insect damage, making it a long-lasting option. The dimensions of hardwood timber can be significantly smaller compared to softwoods, allowing for more efficient use of space and materials.
2. Pier and Bearer Spacings
Determining the appropriate size of bearers and joists is critical for deck stability. Using a standard 'grid' pattern is recommended, with piers spaced at 6 feet or 1.8 meters apart. For this setup, 1' 4"x3" hardwood HWD bearers are ideal. Joists should be spaced at no greater than 450mm center to center (18 inches), ensuring compliance with legal requirements and preventing any 'springing' of the deck.
3. Adjustments for Reduced Pier Spacing
Removing the center row of piers can increase the size of your bearers, but be cautious as this may make the deck feel 'spongy' or springy over unsupported spans. It is essential to strike a balance between aesthetics and functionality to ensure a safe and comfortable deck experience.
4. Ensuring Legal and Safe Construction
It is unnecessary to use large dimension timbers if they are not required. By adhering to the specified plan and following local building codes, you can ensure that your deck looks great and is safe to use. Proper planning and adherence to standards can save you money, time, and effort, resulting in a high-quality end result.