Joist spans, beam sizes, and footing requirements for residential decks. Ensures your deck meets structural requirements and building codes.
| Joist Size | 12" O.C. | 16" O.C. | 24" O.C. |
|---|---|---|---|
| 2×6 | 9' 9" | 8' 8" | 7' 0" |
| 2×8 | 12' 10" | 11' 6" | 9' 3" |
| 2×10 | 16' 5" | 14' 8" | 11' 10" |
| 2×12 | 19' 11" | 17' 10" | 14' 5" |
Based on typical residential loads. Check local codes and adjust for material species.
| Beam Size | 4' Joist Span | 6' Joist Span | 8' Joist Span |
|---|---|---|---|
| Double 2×6 | 6' | 5' | - |
| Double 2×8 | 8' | 7' | 6' |
| Double 2×10 | 10' | 8' | 7' |
| Double 2×12 | 12' | 10' | 9' |
Post Sizing
Post Spacing
Frost Line: Footings must extend below frost line (check local codes)
Diameter: Typically 12" minimum, larger for heavy loads
Post Attachment: Use post base hardware set in concrete
Spacing: Under each post location
Depth:
Spacing
Fastening
Height: 36" minimum (measured from deck surface)
Post Spacing: 6 feet maximum between posts
Baluster Spacing: 4" maximum gap (sphere test)
Top Rail: Able to withstand 200 lbs force
Required When: Deck is more than 30" above grade
Graspable Handrail: Required for stairs
Always verify with local building codes - requirements vary by jurisdiction
Riser Height: 7-3/4" maximum, 4" minimum
Tread Depth: 10" minimum (11" recommended)
Stringer Spacing: 16" O.C. maximum
Stair Width: 36" minimum
Landings: Required every 12 feet of vertical rise
Handrails: Required if more than 3 risers
Uniformity: All risers must be within 3/8" of each other
Pressure Treated
Economical, durable, requires maintenance, use .40 retention for ground contact
Cedar/Redwood
Natural beauty, rot-resistant, requires sealing, more expensive
Composite
Low maintenance, won't rot, higher initial cost, can fade
PVC
No maintenance, won't fade, most expensive, can get hot
This comprehensive deck building cheat sheet provides essential reference information for planning and constructing a residential deck. From joist spans and beam sizes to railing code requirements and stair specifications, this guide covers the structural and safety requirements for a deck that's safe, code-compliant, and built to last.
Building a deck is one of the most popular DIY projects, but it's also one where mistakes can have serious consequences. Undersized joists, improperly attached ledger boards, or inadequate footings can lead to structural failure - and deck collapses cause serious injuries every year. This reference provides the specifications and code requirements you need to build a safe deck.
Deck construction requires permits and inspections in most areas because it's structural work that must meet specific safety standards. This guide helps you understand these requirements so you can plan your project properly, communicate effectively with building inspectors, and build a deck that adds value to your home while providing years of safe enjoyment.
Having quick access to deck building specifications helps ensure your project is structurally sound, meets code requirements, and will pass inspection. This guide prevents costly mistakes and safety hazards.
Post spacing, concrete footing requirements, board patterns, and gate construction
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Zone planning, head types and spacing, pipe sizing, controller programming, and winterization