How Many Deck Boards for a 12×16 Deck?
Quick Answer
A 12×16 foot deck using standard 5.5-inch wide deck boards (actual width of a 2×6) needs approximately 48 boards running the 16-foot length, plus joists, beams, and fasteners.
- Decking boards (5.5" wide, 16 ft long): ~48 boards
- Joists (2×8 or 2×10, 16" OC): 13 joists at 12 ft
- Beams: 2 doubled 2×10s at 16 ft
- Posts (4×4 or 6×6): 4–6 posts depending on height
Formula
Divide the deck width in inches by the board width plus gap (typically 5.5" board + 0.25" gap = 5.75"). This gives the number of boards running the length.
Step-by-Step Calculation
- 1
Deck width in inches
12 ft × 12 = 144 inches
- 2
Board coverage
5.5" board + 0.25" gap = 5.75" per board
- 3
Number of boards
144 ÷ 5.75 = 25 boards × 16 ft each
- 4
Add 10% waste
25 × 1.10 = 27.5 → 28 boards at 16 ft
12×16 Deck — Full Materials List
| Material | Quantity | Treated Cost* | Composite Cost* |
|---|---|---|---|
| Deck Boards (16 ft) | 28 | $280–$560 | $700–$1,400 |
| Joists — 2×8×12 ft | 13 | $130–$200 | $130–$200 |
| Beams — 2×10×16 ft (doubled) | 4 | $80–$160 | $80–$160 |
| Posts — 4×4×8 ft | 6 | $60–$100 | $60–$100 |
| Joist Hangers | 13 | $40–$65 | $40–$65 |
| Deck Screws (5 lb box) | 3 | $45–$75 | $90–$150 |
| Concrete Footings | 6 bags | $30–$50 | $30–$50 |
*Pressure-treated at $10–$20/board. Composite at $25–$50/board (16 ft).
Frequently Asked Questions
How much does a 12×16 deck cost to build?
DIY with pressure-treated lumber: $1,500–$3,000 for materials. DIY with composite: $3,000–$6,000. Professional installation: $3,500–$7,500 (treated) or $6,000–$12,000 (composite) including labor.
What size joists for a 12-foot span?
For a 12-foot span at 16" on center, use 2×8 joists minimum. 2×10 joists are better and allow for heavier loads. Always check span tables for your specific lumber grade and loading requirements.
Do I need a permit for a 12×16 deck?
Almost certainly yes. A 12×16 deck (192 sq ft) exceeds the 200 sq ft permit-exempt threshold in most areas. Attached decks almost always require a permit regardless of size. Budget $100–$500 for permits.