Building an outdoor wood or composite deck adds enormous curb appeal and living space to any home. But ordering framing lumber and decking surface boards without an accurate cut list can quickly inflate your budget.
Here is the carpenter guide to calculating deck boards, joist framing, and fastener hardware.
1. Calculating Deck Boards (Linear Footage)
Most residential deck boards are nominal 5/4 × 6 inch boards (actual width is 5.5 inches).
- With a standard 1/8-inch expansion gap between boards, each board covers approximately 5.625 inches (0.469 feet) of deck depth.
- To cover 100 square feet of deck, you need approximately 214 linear feet of 5.5-inch boards.
- Standard board lengths are 12 ft, 16 ft, and 20 ft. Choosing lengths that match your deck dimensions eliminates end-butt joints entirely.
2. Framing: Joists, Beams & Posts
The structural substructure requires precise pressure-treated lumber (typically #2 Southern Yellow Pine or Douglas Fir):
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Joist Spacing:
- For standard wood boards: 16 inches on-center (O.C.).
- For composite decking (Trex, TimberTech): 12 inches on-center to prevent foot flex and sagging.
- Rim Joists & Ledger Board: Equal to the perimeter perimeter length of your deck.
- Support Posts: Typically 6x6 pressure-treated posts set in concrete footings below the local frost line.
3. Fasteners & Hidden Clips
- Face Screwing: Requires 2 screws per joist intersection (approx. 350 composite deck screws per 100 sq ft).
- Hidden Fastener Clips: Grooved composite boards use hidden track clips (approx. 1 box of 90 clips per 50 sq ft).
👉 Calculate your linear board requirements, joist counts, and hardware quantities instantly with the free CraftCalc Decking Calculator.
