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Smoke detector spacing calculator

Estimate how many point smoke detectors a room needs and how to grid them out — a planning aid ahead of a full AS 1670.1 detection design.

The ceiling
Room dimensions and the maximum detector spacing.
Smoke detectors needed
6
A 3 × 2 grid covers the 288 m² ceiling — about one detector per 48 m² at 10 m spacing.
Ceiling area288 m²
Grid3 × 2
Detectors6
Area per detector48 m²

Indicative grid only. Detector spacing and coverage in AS 1670.1 depend on ceiling height and shape, beams, airflow, detector type and the design objective — a fire systems designer must set the layout.

traqR keeps detection systems, service records and test dates against the site so your AS 1670 maintenance stays on schedule.

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How it works

1

Grid the ceiling

Point detectors are laid out on a grid so no part of the ceiling is further than the allowed spacing from a detector.

2

Divide by the spacing

Dividing each room dimension by the maximum spacing and rounding up gives the number of rows and columns of detectors.

3

Allow for the real ceiling

Beams, high ceilings, sloped roofs and airflow all reduce effective coverage. The standards adjust spacing for these — this grid is a starting point.

Frequently asked questions

How far apart should smoke detectors be?

Point smoke detectors are spaced on a grid so every point on the ceiling is within reach of a detector. The maximum spacing depends on ceiling height and shape, structural beams, airflow and detector type, all set out in AS 1670.1. This tool uses a single spacing figure to give an indicative grid.

Does ceiling height affect coverage?

Yes. As ceilings get higher, smoke dilutes and spreads before reaching a detector, so coverage per detector reduces and spacing must tighten. Very high spaces may need different detection like beam or aspirating systems. The standards set the adjustments.

What about beams and obstructions?

Beams, bulkheads and other ceiling obstructions can trap or divert smoke and reduce a detector’s coverage. AS 1670.1 has specific rules for detector placement around beams and near walls, which a simple grid doesn’t capture.

Can I use this to design a system?

No — it’s an estimate for planning and budgeting. Fire detection systems must be designed to AS 1670.1 and installed and commissioned by a competent fire systems technician, with maintenance to AS 1851.

This calculator is an indicative grid estimate assuming a flat, unobstructed ceiling. Actual detector spacing, type and coverage must be designed to AS 1670.1 accounting for ceiling height, beams, airflow and the fire safety objective, by a competent fire systems designer.

Keep detection on its service cycle

traqR keeps detection systems, service records and test dates against each site. Try it free for 14 days.

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