Every employer must evaluate its workplace to find confined spaces and decide which are permit-required (1910.146(c)(1)). OSHA's Appendix A to 1910.146 lays out the decision as a flowchart. This tool walks through the same logic one question at a time.
How the decision works
- Is it a confined space? All three conditions must be true: bodily entry is possible, entry or exit is limited or restricted, and it isn't designed for continuous occupancy.
- Is it permit-required? Yes if it has any of the four characteristics: an actual or potential hazardous atmosphere, an engulfment hazard, a trapping configuration, or any other recognized serious safety or health hazard.
- Can a simpler route apply?
- Alternate procedures (1910.146(c)(5)): the only hazard is atmospheric and continuous forced-air ventilation alone keeps the space safe, supported by data.
- Reclassification (1910.146(c)(7)): no actual or potential atmospheric hazard, and all hazards are eliminated without entry.
| Result | What it means |
|---|---|
| Not a confined space | Subpart AA and 1910.146 permit rules don't apply to the space, though other rules still apply to the work |
| Non-permit confined space | Document the evaluation and reevaluate when use or configuration changes |
| Permit space, alternate procedures | Entry with continuous forced-air ventilation, testing and written certification |
| Permit space, may be reclassified | Non-permit only while hazards stay eliminated, with written certification |
| Permit-required confined space | Full written permit program, permits, attendant, rescue |
Limits of this tool
The tool records nothing and doesn't replace a documented evaluation by someone who knows the space. Hazards change with processes, cleaning chemicals, weather and the work itself, so reevaluate whenever conditions change. Use the hazard evaluation checklist to document each space.
Sources and official references
Last reviewed: October 25, 2026 · Free general education based on OSHA 29 CFR 1910.146 and 29 CFR 1926 Subpart AA. It does not replace the site-specific training, written program and hands-on evaluation your employer must provide, and it does not issue a certificate. Nothing you enter on this page is saved or sent.