A confined space meets three conditions: a worker can bodily enter it to do work, it has limited or restricted means of entry or exit, and it's not designed for continuous occupancy (lesson 1). Whether it's also permit-required depends on its hazards (lesson 2). Here's how that plays out in real workplaces.
Examples by industry
| Industry | Common confined spaces |
|---|---|
| Water and wastewater | Wet wells, lift stations, digesters, clarifier troughs, manholes, sewers, valve vaults, meter pits |
| Utilities and telecom | Electrical and transformer vaults, cable manholes, utility tunnels, pipe chases |
| Manufacturing | Process tanks, mixers and reactors, ovens, degreasers, pits under presses, baghouses, dust collectors, ductwork |
| Chemical and petroleum | Storage tanks, vessels, columns, heat exchangers, tank trucks and rail cars, sumps |
| Food and agriculture | Silos, grain bins, hoppers, fermenters, cookers, manure pits, vats |
| Power generation | Boilers, condensers, turbines, air preheaters, scrubbers, ash hoppers |
| Construction | Crawl spaces, attics, pits, drilled shafts, pier holes, precast vaults, enclosed beams, HVAC ducts, storm drains, water mains |
| Facilities and property | Elevator pits, sump pits, boiler rooms with restricted access, plenum spaces, rooftop units entered for service |
| Marine and transport | Ship tanks and voids, cargo holds, ballast tanks, tank trailers |
OSHA's construction rule lists many of these, including bins, boilers, pits, manholes, tanks, incinerators, scrubbers, concrete pier columns, sewers, transformer vaults, HVAC ducts, storm drains, water mains, precast manholes, drilled shafts, enclosed beams, vessels, digesters, lift stations, cesspools, silos, air receivers, sludge gates, air preheaters, turbines, chillers, bag houses and mixers or reactors.
Quick answers for borderline spaces
Is a crawl space a confined space? Often, yes. You can bodily enter, access is usually a small hatch, and it isn't designed for occupancy. Whether it's permit-required depends on hazards such as exposed wiring, insulation, pests, sewage, mold or low headroom.
Is an attic a confined space? It can be, especially attics reached through a small hatch where heat, insulation and electrical hazards are present.
Is an elevator pit a confined space? Many are, because of restricted access by ladder, and hazards such as moving equipment, oil and the car above. Lockout of the elevator is a standard control.
Is an open-top tank or pit a confined space? An open top doesn't rule it out. Open-top pits, vats and degreasers can collect heavier-than-air gases and may still have restricted exit.
Is a trench a confined space? Excavations are normally covered by OSHA's excavation standard, Subpart P. A deep, narrow excavation or a pit with restricted access and a potential hazardous atmosphere may also meet the confined space definition.
Is a room with a normal door a confined space? Usually not, because a standard door isn't a limited means of exit and rooms are designed for occupancy. A room can still have hazardous atmospheres, though, such as a CO2 storage room or a cold room with refrigerant.
Other OSHA rules that may apply
Some industries have their own or additional confined space-type rules:
- Grain handling bin and silo entry: 29 CFR 1910.272.
- Electric power generation, transmission and distribution enclosed spaces: 29 CFR 1910.269.
- Telecommunications manholes and vaults: 29 CFR 1910.268.
- Shipyard employment confined and enclosed spaces: 29 CFR 1915 Subpart B.
- Construction: 29 CFR 1926 Subpart AA.
Build your inventory
List every space that meets the three conditions, record its hazards and classification, post signs at permit spaces, and review the list whenever processes or equipment change. Start with our hazard evaluation checklist and the permit-space decision tool.
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.