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Detector Spacing Calculator
Work out the applicable detector spacing rule for a corridor of a given width, per BS 5839‑1.
Assumes a flat ceiling within the standard height range. Reduced spacing may apply on higher or pitched ceilings — check the current BS 5839‑1 tables for your specific site.
Methodology
How this is worked out.
In an open area, BS 5839‑1's standard coverage radius is 7.5m for point smoke detectors and 5.3m for point heat detectors — no point on the ceiling should be further than that from the nearest detector.
Corridors get a relaxed rule where the corridor is 2m wide or less: smoke detectors can be spaced up to 15m apart along the centreline, with a maximum of 7.5m from the end wall to the nearest detector. Where a corridor is wider than 2m, it's treated as an open area and designed to the standard coverage radius instead of the corridor rule.
Heat detectors are generally not recommended in escape‑route corridors — smoke detection responds faster to the kind of fire most likely to threaten an escape route, and is the usual choice there regardless of width.
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