Deck Railing Calculator
Calculate posts, balusters, top/bottom rails, and cap rail for deck railing — with building code notes.
Deck Railing Calculator
Posts, balusters, rails, and cap for deck railing
Railing Layout
Railing Specs
Building Code Notes
• Railing required when deck is 30"+ above grade
• Minimum 36" height residential (42" commercial)
• Baluster gap max 4" (a 4" sphere cannot pass through)
• Post spacing typically 6-8 ft max
Materials
Formulas Used
Balusters
Divide total railing length by center-to-center baluster spacing (gap plus baluster width of 1.5").
Posts
Railing posts are typically spaced 6 feet apart.
Deck Railing Materials Guide
Components of a Deck Railing System
| Component | Typical Size | Purpose | |-----------|-------------|----------| | Posts | 4×4 | Structural support, bolted to framing | | Top rail | 2×4 | Upper horizontal rail | | Bottom rail | 2×4 | Lower horizontal rail | | Balusters | 2×2 | Vertical infill (code: max 4" gap) | | Cap rail | 5/4×6 | Flat top cap for comfort and looks |
Frequently Asked Questions
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