Yes, the calculator includes joist calculations based on the selected spacing and estimates framing material costs. However, it doesn’t include more complex substructure elements like piers, beams, or footings, which may require separate calculations based on local building codes and soil conditions.

The current version is designed for rectangular, single-level decks. For multi-level decks, L-shaped decks, or decks with cutouts, you would need to calculate each rectangular section separately and combine the results. Future versions may include more complex shape options.

Diagonal layouts (typically at 45-degree angles) require approximately 15-25% more material than straight layouts due to increased cutting waste and the need for longer boards to cover the same area diagonally. The calculator automatically applies a 25% waste factor for diagonal patterns to account for this.

The calculator offers three options: 12″, 16″, and 24″ on-center. For most residential decks using standard 5/4 deck boards, 16″ spacing is standard. Choose 12″ for composite decking (as recommended by most manufacturers), heavy hardwoods like ipe, or if you want a sturdier feel. Use 24″ only for ground-level decks with additional support or specific engineered materials.

Not necessarily. Most builders use pressure-treated lumber for framing regardless of the decking material because it’s cost-effective and resistant to rot and insects. Even with composite or PVC decking, pressure-treated framing is standard. The calculator’s framing cost assumes pressure-treated lumber regardless of your decking material selection.

Joists are the horizontal framing members that support the deck boards. They run perpendicular to the house and are typically spaced 12″, 16″, or 24″ apart.

Beams (also called girders) are the larger horizontal members that support the joists. They run parallel to the house and transfer the deck’s weight to the posts.

Posts are the vertical supports that transfer weight from beams to the footings. They’re anchored into concrete footings that extend below the frost line to prevent shifting.

Footing depth depends on your local frost line, which varies by region. Generally:

• Northern climates: 36-48 inches deep

• Moderate climates: 24-36 inches deep

• Southern/warm climates: 12-24 inches deep

Always check your local building codes – they specify exact requirements for your area. Frost line depth is critical because frozen ground can heave and damage your deck if footings aren’t deep enough.

Common joist sizes:

• 2×6: For small, ground-level decks with short spans (up to 9′ for 16″ spacing)

• 2×8: Standard for most residential decks (spans 11′-13′ depending on wood type)

• 2×10: For longer spans or heavier loads (spans 15′-18′)

• 2×12: For very long spans or commercial applications

The exact size depends on your joist spacing, wood species, and span distance between beams. Online span calculators or local codes provide specific guidance.

“On-center” means measuring from the center of one joist to the center of the next. For example, 16″ OC spacing means joists are positioned so their centers are exactly 16 inches apart. This measurement method is standard because it accounts for the actual space between joists where deck boards will be fastened.