Confined spaces are common on construction sites, manholes, tanks, silos, crawl spaces, and vaults, to name a few. But not every confined space is the same. Some of these spaces are more dangerous than others and require a legal process before anyone can enter.
This article explains what a permit-required confined space is, how to spot one, and what the law says about safe entry procedures on construction sites in the U.S.
What Is a Confined Space?
According to OSHA (Occupational Safety and Health Administration), a confined space meets three conditions:
- It is large enough for a person to enter.
- It has limited ways in and out.
- It is not meant for regular or continuous work.
These spaces often have poor airflow, limited visibility, and tight working areas. They may seem harmless, but in many cases, they hide deadly risks like toxic gas, low oxygen, or moving machinery.
What Is a Permit-Required Confined Space?
Some confined spaces are so dangerous that workers must follow a strict process before entering. These are called permit-required confined spaces, or “permit spaces.”
OSHA says a confined space becomes permit-required if it has one or more of the following:
- A dangerous atmosphere (like low oxygen, gas, or vapors)
- A material that could engulf a worker (like sand, grain, or water)
- Walls that slope inward or floors that slope down, which could trap or suffocate a worker
- Any other serious safety or health hazard (like exposed wires or unguarded machinery)
On construction sites, these conditions are common in sewers, tanks, pipelines, storm drains, and crawl spaces.
Legal Requirements for Permit Spaces
OSHA’s Confined Spaces in Construction Standard (29 CFR 1926 Subpart AA) applies to all construction work that involves permit-required confined spaces.
Here’s what the law says employers must do:
1. Identify All Confined Spaces
Before starting work, the contractor must identify all confined spaces on the job site and decide which ones are permit-required.
They must:
- Survey the job site before or during work
- Mark permit spaces clearly (signs, barriers, etc.)
- Inform workers and subcontractors about these spaces
If a confined space has any serious hazards, it must not be entered without a written permit and safety procedures.
2. Use a Written Permit Program
No one can enter a permit-required confined space unless a written permit is filled out and approved.
The permit must include:
- The name and location of the space
- Purpose of entry
- Date and duration of the job
- Names of authorized entrants, attendants, and supervisors
- Hazards present in the space
- How hazards will be controlled (like air testing or ventilation)
- Rescue plans and emergency contacts
The permit must be reviewed and signed before entry, and kept at the site during the entire operation.
3. Train Workers for Their Roles
All workers involved in confined space work must be trained before they begin.
Roles include:
- Authorized Entrants (people who go inside)
- Attendants (people who stay outside and monitor)
- Entry Supervisors (people who approve and oversee the job)
Each role must know:
- Hazards of the space
- Signs of exposure (like dizziness or shortness of breath)
- Use of gas monitors and safety gear
- When and how to evacuate
- Who to call in an emergency
Training must be repeated when conditions change or if any errors are made during previous entries.
Subcontractors and Shared Worksites
Construction sites often have multiple employers on site. In these cases, the law requires coordination between the main contractor and all subcontractors.
For example:
- If a plumbing subcontractor needs to enter a sewer line, they must inform the general contractor.
- The general contractor must share any known hazards.
- Everyone must agree on who will provide air testing, entry permits, and emergency plans.
Failure to coordinate has caused many past accidents where one team wasn’t aware of the dangers inside a space.
Monitoring the Air Before and During Entry
Before anyone enters a permit space, the atmosphere must be tested for:
- Oxygen level (safe range is 19.5% to 23.5%)
- Combustible gases (like methane or propane)
- Toxic gases (like hydrogen sulfide or carbon monoxide)
Monitoring must be:
- Done by a trained worker
- Repeated regularly during entry
- Logged on the entry permit
If unsafe conditions are found at any time, entry must stop immediately.
Emergency Rescue Plans
OSHA requires a rescue plan for every permit-required entry. This is not just calling 911, it must be specific to the site and space.
Options include:
- On-site rescue teams (with training and equipment)
- Off-site rescue teams (fire departments that have confined space training)
Rescue teams must:
- Be able to respond quickly (in minutes, not hours)
- Know the layout of the space
- Practice simulated rescues once a year
- Be trained in first aid and CPR
If no rescue plan is ready, entry should not take place.
Temporary Removal of Hazards
Sometimes, a space can be made safer by removing or controlling the hazard, such as ventilating out toxic air or locking out a machine.
In these cases, the space may be reclassified as a non-permit space, but only if:
- All hazards are removed (not just controlled)
- The space stays safe during the work
- A written certification is kept on file
If hazards return at any point, the space becomes a permit-required area again.
What Happens If You Don’t Follow the Law?
Violating confined space rules can lead to:
- Heavy OSHA fines (often tens of thousands of dollars)
- Job shutdowns
- Criminal charges (if negligence causes death)
- Loss of life
In past cases, workers have died after entering spaces without permits, without air monitoring, or without proper training. These deaths are preventable when the rules are followed.
Conclusion: Safe Entry Starts With Knowing the Law
Permit-required confined spaces are some of the most dangerous places on a construction site. But when the legal process is followed, clear identification, written permits, training, and rescue planning, most accidents can be avoided.
Before starting any job, take the time to:
- Check the space
- Read the rules
- Get the permit
- Work as a team
Safe work isn’t just good practice, it’s the law.
