Safety checklist — Confined space
Entry and work in confined spaces. Based on Québec's Construction Safety Code (CSTC) and CNESST standards.
Before entry
13 items- ✓
PPE worn: rescue harness, respirator if required, hard hat, gas detector
- ✓
Written 3.21.1 identification (tools, piping, contaminants, rescue)
ℹ️ CSTC 3.21.1: principal contractor + employer. Not the RSST permit model.
- ✓
Atmosphere tested: O₂ 19.5–23%, flammable gas ≤ 25% LEL (CSTC 3.21.2), contaminants < OELCritical
ℹ️ Construction site: CSTC 3.21.2 — O₂ 19.5–23%, LEL 25%. Establishment: RSST 302 — LEL 5%.
- ✓
Mechanical ventilation installed and functional
- ✓
Energy source lockout completed (CSTC 2.20)Critical
ℹ️ Construction site: CSTC 2.20. RSST 188 applies to establishments.
- ✓
Rescue means identified (3.21.1 f) — non-assigned kept out (3.21.5)Critical
ℹ️ CSTC 3.21 does not require an “attendant who never leaves the post”. That is the 3.21.1 f) rescue plan.
- ✓
Rescue plan documented — rescue equipment at hand
- ✓
Workers trained for the confined space (CSTC 3.21)
ℹ️ On a construction site this is CSTC 3.21 — not RSST section XXVI. The CSTC does not set an 18-year age threshold.
- ✓
Atmosphere readings every 2 h, or continuous alarmed instruments (CSTC 3.21.3)
ℹ️ Continuous alarmed instruments waive the reading log, not atmosphere monitoring.
- ✓
Ventilation maintained throughout work
- ✓
Communication with the attendant per the 3.21 procedure
ℹ️ CSTC 3.21 does not write a 5 min interval.
- ✓
Immediate evacuation if gas detector alarmCritical
ℹ️ Immediate evacuation — never attempt solo rescue
- ✓
No ignition source if explosive atmosphere possible
After work / Exit
5 items- ✓
All personnel out — headcount confirmed
- ✓
Tools and materials removed from confined space
- ✓
Access sealed or barricaded to prevent unauthorized entry
- ✓
Written 3.21.1 identification filed at end of shift
- ✓
Lockout removed per procedure
18 verification items — use this checklist on-site with the app
Use on-site — freePDF reports, history and team management in the app
For information only — this is not legal advice. OK Sécurité is an independent company with no affiliation to the CNESST: we are not mandated, endorsed or certified by it. Completing a checklist here does not by itself establish your compliance — your exact obligations depend on your job site and your prevention program. Where there is any discrepancy, the official text published by Légis Québec or the CNESST prevails.
More checklists — Cross-cutting Situations
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Related guides
Risks and prevention — Confined space
Confined spaces cause multiple deaths annually, often because improvised rescuers become victims themselves. On a construction site, a confined space is defined in CSTC 1.1 (17.1) and governed by 3.21 — not RSST XXVI.
Before entry, CSTC 3.21.1 requires a written identification (tools, piping, hazards, contaminants, rescue). 3.21.2 sets O₂ 19.5–23%, flammable gas ≤ 25% LEL, contaminants under Annex I. A continuous detector is practice; 3.21.3 allows alarmed instruments instead of the reading log.
Site lockout follows CSTC 2.20. The rescue plan is 3.21.1 f); 3.21.5 keeps non-assigned workers out. The Code does not require an “attendant who never leaves the post”.
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