Deck Material Calculator
Calculate decking boards, joists, posts, beams, and hardware needed for your deck project.
Deck Dimensions
Decking Material
Joist Spacing
Materials Needed
29 boards
12 ft decking boards
Deck Building Material Calculator
Building a deck requires careful material planning. This calculator estimates decking boards, joists, posts, and hardware for ground-level and elevated decks using pressure-treated lumber, cedar, or composite materials.
Decking Board Coverage
Coverage depends on board width and spacing:
- 2×6 (5.5" actual): 0.458 sq ft per linear foot
- 2×4 (3.5" actual): 0.292 sq ft per linear foot
- 5/4×6 (5.5" actual): 0.458 sq ft per linear foot (premium decking)
Add 1/8" to 1/4" gap between boards for drainage and expansion.
Joist Spacing Standards
- 12" on center: Heavy-duty applications, some composite materials
- 16" on center: Standard for most deck lumber
- 24" on center: Not recommended for standard decking
Decking Material Types
Pressure-Treated Lumber
Most economical option at $15-20 per sq ft. Treated to resist rot and insects. Requires annual sealing. Lifespan 15-20 years with proper maintenance.
Cedar or Redwood
Natural rot resistance, beautiful appearance. Costs $20-30 per sq ft. Requires regular sealing. Lifespan 15-25 years.
Composite Decking
Low maintenance, long-lasting. Costs $25-35 per sq ft. No sealing required. Lifespan 25-30+ years. Check joist spacing requirements (often 12" OC).
Deck Framing Components
- Ledger Board: Attaches deck to house (2×8 or larger)
- Joists: Run perpendicular to decking (2×6, 2×8, 2×10)
- Beams: Support joists (double 2×8 or 4×8)
- Posts: Vertical support (4×4 or 6×6)
- Rim Joists: Outer frame perimeter
Hardware and Fasteners
You'll also need:
- Deck screws or hidden fasteners (1.5 lbs per 100 sq ft)
- Joist hangers (one per joist end)
- Post anchors or brackets
- Concrete for footings (one 80lb bag per post)
- Flashing tape for ledger board
Important Notes
This calculator estimates materials for the deck surface and basic framing. Actual requirements vary based on deck height, layout complexity, stairs, and railings.
Always check local building codes for joist span tables, post spacing, footing requirements, and railing specifications. Most municipalities require permits and inspections.
Professional deck installation costs $15-30 per square foot for labor. Total project costs range from $30-$65 per square foot depending on materials and complexity.
Frequently Asked Questions
How much does it cost to build a deck?
Material costs range from $15-$35 per square foot depending on materials. Pressure-treated lumber is cheapest at $15-20/sq ft, cedar costs $20-30/sq ft, and composite decking runs $25-35/sq ft. Professional installation adds $15-30/sq ft in labor costs.
How many deck boards do I need?
Calculate your deck's square footage (length × width), then divide by board coverage. A 2×6 board (5.5" wide) covers 0.458 sq ft per linear foot. For a 120 sq ft deck: 120 ÷ 0.458 = 262 linear feet ÷ 12 ft boards = 22 boards. Add 10% for waste.
How far apart should deck joists be?
Standard spacing is 16 inches on center for most lumber decking. Some composite materials require 12-inch spacing—always check manufacturer specifications. Closer spacing provides a more solid feel and is required for diagonal decking patterns.
Do I need a permit to build a deck?
Most municipalities require building permits for decks over 24-30 inches high or attached to the house structure. Ground-level decks under 200 sq ft may not need permits. Always check with your local building department before starting construction.
How deep should deck posts be?
Deck posts should extend below the frost line to prevent heaving. In Canada, this is typically 4 feet deep. Use concrete footings sized according to load requirements specified in local building codes. Footing diameter usually ranges from 12-18 inches.