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Stairs Calc

Cable railing

A guard infilled with tensioned horizontal cables instead of balusters.

A cable railing fills a guardrail with horizontal stainless-steel cables stretched between sturdy newel posts instead of vertical balusters, giving a thin, almost see-through barrier popular on modern stairs and decks. The cables run parallel to the handrail up the slope. Because the infill is horizontal, the 4 in (102 mm) sphere rule still applies: cables are tensioned tightly and spaced about 3 in (76 mm) apart, and some jurisdictions limit horizontal infill where children could climb it like a ladder. Example: a 36 in (914 mm) guard needs roughly a dozen cables at 3 in centres, each pulled hard against end posts strong enough to keep the gaps from opening past code. Cable looks minimal but demands stiff posts and the occasional re-tensioning.

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Related terms

Guardrail (guard) The barrier protecting an open edge; minimum 36 in high (IRC residential). Glass railing A guard infilled with tempered glass panels instead of balusters. Baluster (spindle) The vertical infill posts of a railing; gaps must reject a 4 in sphere. Handrail The graspable rail along a stair; code height 34–38 in above the nosing line.

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Baluster Spacing Calculator Enter your railing length and spindle width to get the number of balusters, the exact even gap and center‑to‑center spacing — checked against your code’s 4‑inch sphere rule.
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Written by the Stairs Calc editorial team. Methodology and code references: see our methodology.

Built and maintained by builders, drafters and engineers who plan stairs for a living — every code limit is transcribed from the published standard and cited to its exact section.

Last reviewed 2026-06-20 against IRC 2021/2024

Stairs Calc gives accurate geometry and checks it against published building-code limits, but results are estimates for planning. Codes are adopted and amended locally and change over time. Always confirm dimensions against your local adopted code and a licensed professional before you build.