Guides
SST coordinator (CoSS): the role, not only the threshold
By Claude Piché, founder · Updated September 21, 2026
The health and safety coordinator (CoSS) is not a “bigger RSS”. They are a principal-contractor manager, full-time on site, above a headcount or cost threshold.
The threshold, once — then until the end
A CoSS is required at 100 construction workers present at once, or when job cost exceeds $12M. Articles live on the prevention-mechanisms sheet. This guide does not recompute them.
Once crossed, the duty lasts until the end of the work, even if headcount drops. Do not unplug the CoSS “because it calmed down”.
CoSS is not RSS
The RSS is designated by workers. The CoSS is a principal-contractor manager, full-time on site. Training hours differ (240 h for CoSS). Details on the thresholds sheet.
If one person wears both hats without lawful designation, you have neither role in the legal sense.
What the CoSS organizes
Keep the site prevention program alive. The program guide and LSST section 51 stay the employer duties — the CoSS does not absorb them.
Prioritize height, excavation, energy, traffic. Checklists are crew tools, not a CNESST mandate. The CoSS is not a CNESST inspector.
Committee, RSS, subcontractors
At 20 workers the site committee is added. The CoSS works with it, not instead of it.
Section 51.1.1: a contract cannot transfer those employer duties. An app invite does not transfer them either.
240-hour training
Plan the 240 h before you hit the threshold. Other certificates do not auto-make a CoSS. Read RMPPCC 17.
Below the CoSS threshold you may already need a program (10) and a part-time RSS. Do not skip floors.
Tools and limits
Lists and PDFs track work. They do not prove compliance. OK Sécurité is not certified by the CNESST and does not appoint the CoSS or RSS.
Read the mechanisms sheet for numbers, section 51 for employer duties, the prevention-program guide for the living document.
CoSS / RSS / committee thresholds (10, 20, 100, $12M) and training sit on the RMPPCC / LSST sheet. OK Sécurité is not certified by the CNESST. Informational only. Confirm with the official text and your prevention program. 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. Where there is any discrepancy, the official text published by Légis Québec or the CNESST prevails.
Sources
Informational only. Confirm obligations with your prevention program and:
- CNESST — Mesures spécifiques pour les chantiers de construction
- Safety Code for the construction industry (CSTC) and Regulation respecting occupational health and safety (RSST)
Official rules (French)
Related checklists
Lists that help when coordinating the field:
Common questions
- Does the CoSS replace the RSS?
- No. Designation, training and reporting lines differ. See the mechanisms sheet.
- Fewer than 100 workers but over $12M?
- Cost alone can trigger CoSS and full-time RSS. See LSST 215.1 / 212.1 on the sheet.
- Does OK Sécurité appoint the CoSS?
- No. The principal contractor does, under the LSST. The app records tours and lists.
- Which document first?
- Thresholds sheet, then prevention program, then section 51 for each employer. Lists come after the frame.