What is a permit-required confined space?

A permit-required confined space, or permit space, is a confined space with one or more of four characteristics: a hazardous atmosphere or the potential for one, a material that could engulf an entrant, a configuration that could trap or asphyxiate an entrant, or any other recognized serious hazard.

By Cairn. Updated October 29, 2026. Sources: eCFR text as of October 27, 2026.

The legal definitions

General industry

“Permit-required confined space (permit space) means a confined space that has one or more of the following characteristics:
(1) Contains or has a potential to contain a hazardous atmosphere;
(2) Contains a material that has the potential for engulfing an entrant;
(3) Has an internal configuration such that an entrant could be trapped or asphyxiated by inwardly converging walls or by a floor which slopes downward and tapers to a smaller cross- section; or
(4) Contains any other recognized serious safety or health hazard.”

29 CFR 1910.146(b), definition of “Permit-required confined space”. eCFR, text as of October 27, 2026.

Construction

“Permit-required confined space (permit space) means a confined space that has one or more of the following characteristics:
(1) Contains or has a potential to contain a hazardous atmosphere;
(2) Contains a material that has the potential for engulfing an entrant;
(3) Has an internal configuration such that an entrant could be trapped or asphyxiated by inwardly converging walls or by a floor which slopes downward and tapers to a smaller cross-section; or
(4) Contains any other recognized serious safety or health hazard.”

29 CFR 1926.1202, definition of “Permit-required confined space”. eCFR, text as of October 27, 2026.

Where it applies

29 CFR 1910.146, Permit-required confined spaces 107 paragraphs use the term. Read the text on eCFR.
29 CFR 1926.1202, Definitions 23 paragraphs use the term.
29 CFR 1926.1203, Confined Spaces in Construction: General requirements 37 paragraphs use the term. Read the text on eCFR.

In the enforcement record

Federal and state-plan agencies issued 10,155 cited violations under 29 CFR 1910.146, Permit-required confined spaces, from January 2016 through September 10, 2026. The section ranks 27th among the 248 sections of 29 CFR cited at least 50 times. This is the count for the whole section, not for the term alone.

Cairn data, October 2026 snapshot.

See the full record for 29 CFR 1910.146

Related terms

Confined space A space large enough to enter and work in, with limited or restricted means of entry or exit, not designed for continuous occupancy.
IDLH In the respiratory protection standard, an atmosphere that poses an immediate threat to life, would cause irreversible harm or would impair escape.
Hazardous chemical Any chemical classified as a physical hazard or health hazard, a simple asphyxiant, combustible dust or a hazard not otherwise classified.

All terms in the OSHA glossary

Sources

29 CFR 1910.146, Permit-required confined spaces. eCFR, text as of October 27, 2026.
29 CFR 1926.1202, Definitions. eCFR, text as of October 27, 2026.
Cairn data, October 2026 snapshot. Cairn analysis of the OSHA enforcement record.

Written by Cairn, updated October 29, 2026. The quoted text is copied from the sources above. A test compares each quotation with a stored copy of the source, and a separate script compares that copy with the live sources. This page explains the law and is not legal advice.