Spindle Spacing Set-out

How to use the Spindle Spacing Set-out

1. Enter the clear opening between the finished newel or end faces.
2. Enter the actual narrowest spindle width and the maximum clear gap chosen by the designer.
3. Review the equal spindle and end-gap set-out and the impossible-geometry warning if shown.
4. Mark out and physically check the complete finished guarding before drilling or fixing.

Why use this tool

• Calculates against an explicit designer-chosen gap instead of asserting a universal 99mm rule.
• Calculates even spacing so every gap is identical — no awkward wider gap at the end.
• Fails closed when the proposed spindle widths consume the opening.

Approved Document K says that, in a building that may be used by children under five, a 100mm sphere should not pass through guarding openings and the guarding should not be readily climbable. It does not define a universal 99mm spindle rule or make gap arithmetic a whole-guarding compliance check. This tool distributes spindles evenly against the maximum clear gap supplied by the designer. Measure the narrowest clear opening over the actual turned profile, account for rake and installation tolerance, and separately verify guarding height and strength, deflection, fixings, handrail continuity, climbability, triangular openings and every project-specific requirement.

Part of Builder Tools Calculators — construction tools for UK tradespeople.