Deck Calculator
Decking Materials
Board Sizes
Related Calculators
Deck Building Guide
Planning Your Deck
A well-built deck adds outdoor living space and increases home value. Proper planning ensures you buy the right amount of materials and builds a deck that lasts for years.
Boards Calculation
Decking Materials Comparison
| Material | Cost | Lifespan | Maintenance |
|---|---|---|---|
| Pressure-Treated Pine | $ | 10-15 years | Annual stain/seal |
| Cedar | $$ | 15-20 years | Every 2-3 years |
| Redwood | $$$ | 20-25 years | Every 2-3 years |
| Composite | $$$ | 25-30 years | Minimal |
| PVC | $$$$ | 30+ years | Almost none |
Structural Requirements
Joist Spacing
- 16" on center: Standard for 5/4 decking
- 12" on center: Diagonal patterns, composite
- 24" on center: 2× lumber only
Post Footings
- Below frost line (check local codes)
- Typically 42-48" deep in cold climates
- 12-18" diameter concrete
Hardware & Fasteners
Building Code Reminders
- Most decks require a building permit
- Railings required for decks 30"+ above grade
- Railing height: typically 36-42" minimum
- Baluster spacing: 4" max (child safety)
- Stair requirements vary by jurisdiction
Pro Tips
- Pre-drill hardwoods to prevent splitting
- Leave 1/8" gap between boards for drainage
- Stagger board joints for strength and appearance
- Use hidden fasteners for a cleaner look
- Let wood acclimate 2-3 days before installing
- Apply end-seal to cut boards to prevent splitting
Frequently Asked Questions
How many deck boards do I need?
Enter your deck dimensions (length and width) and board size in the calculator above. It will calculate the number of boards needed, including a waste factor for cuts. Standard 5/4×6 boards cover about 5.5 inches of width per board.
How many screws do I need per square foot of decking?
Typically you need about 350 screws per 100 square feet of decking, or roughly 3.5 screws per square foot. This assumes standard 16-inch joist spacing with two screws per board at each joist.
What is the best joist spacing for a deck?
Standard joist spacing is 16 inches on center for most decking materials. Use 12-inch spacing for diagonal patterns, composite decking, or heavy loads. Only use 24-inch spacing with 2× lumber. Always check your local building codes.
How much waste should I factor in for deck boards?
Plan for 10-15% waste for a simple rectangular deck with boards running parallel to the house. Add 15-20% for diagonal patterns or complex shapes. More waste occurs at cuts, angled corners, and around obstacles.