Posted on: June 22, 2023
What is a Permit Required Confined Space vs. a Non-Permit One?

Around 2.1 million US workers climb into tanks, silos, storage bins, vaults, pits, or other permit-required confined spaces every year. Between 100 and 150 of them will never make it home.
Confined spaces present all sorts of hazards to any worker that enters them, compounded by the fact that they're difficult to escape. OSHA's confined space standard is designed to prevent as many deaths and injuries as possible due to this environment.
Read on to learn more about the difference between permit-required and non-permit confined spaces and how it can help you and your team stay safe.
What Is OSHA's Confined Space Definition?
Under §1910.146(b), OSHA defines a confined space as a space that:
- Is large enough and so configured that an employee can bodily enter and perform assigned work,
- Has limited or restricted means of entry or exit, AND
- Is not designed for continuous employee occupancy.
OSHA further divides its definition of confined spaces into those that require an entry permit and those that don't.
What Is a Permit-Required Confined Space vs. a Non-Permit Space?
Essentially, the difference between a permit-required confined space and a non-permit space is whether there are hazards inside.
There are a few circumstances that make a confined space permit-required. An entry permit is required when the "confined space has one or more of the following characteristics:
- Contains (or has the potential to contain) a hazardous atmosphere,
- Contains a material that has the potential for engulfment of an entrant,
- 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
- Contains any other recognized serious safety or health hazard."
A non-permit confined space is defined as a confined space that does not contain (or, for atmospheric hazards, have the potential to contain) any hazard capable of causing death or serious physical harm.
What Are OSHA's Confined Space Requirements?
There are actually three OSHA confined space standards: General Industry (§1910.146), Construction (§1926 Subpart AA), and Shipyard (§1915 Subpart B).
The confined space regulations in each industry are similar, with General Industry establishing the broad requirements and the Construction and Shipyard standards getting specific on unique circumstances encountered in those environments.
When a workplace has a confined space, an employer is required to do a few things in order to comply with the appropriate standard.
And since confined space work is often performed by contractors, it's worth noting that the confined space standard differentiates between the duties of host employers (who own the building or property), the controlling employer (who arranges for the contractor to be brought in), and the entry employer (who comes on-site and performs the work).
Evaluate the Confined Space for Hazards
Employers must evaluate any confined space for hazards, including (but not limited to) the atmospheric, engulfment, or configuration hazards specified in the definition.
Atmospheric hazards cover any conditions that expose employees to risk of death, incapacitation, impairment to self-rescue, injury, or acute illness. That can include:
- Flammable gas, vapor, or mist in excess of 10% of its lower flammable limit (LFL)
- Airborne combustible dust at a concentration that meets or exceeds its LFL
- Oxygen concentration below 19.5% or above 23.5%
- Hazardous substances with an established permissible exposure limit (PEL)
- Any other atmospheric condition that is immediately dangerous to life or health (IDLH)
Engulfment hazards are liquids or finely-divided "flowable solids" (like grain or dirt) that can cause death or injury by aspiration, strangulation, constriction, or crushing.
If, at some point, the confined space's use or configuration changes, then the employer is required to reevaluate the space's hazards and classification.
Get a Permit (If Necessary)
If the employer finds hazards in the space that merit an entry requirement, then they're required to get a permit before anyone enters the space.
Inform Employees of the Risk
OSHA requires employers to warn potentially exposed employees about the existence and location of the permit-required confined space, as well as the dangers it poses.
This requirement can be met with signs "or by any other equally effective means."
Implement Safety Controls
Permit-required confined spaces have hazards that have not been eliminated, but that doesn't mean employers shouldn't control those hazards. In fact, it's required.
The exact requirements depend on the specific hazards, the work being performed, the industry standard being followed, and more.
A few examples of possible safety controls include:
- Taking effective measures to prevent entry
- Developing and implementing a written permit space program
- Erecting a temporary barrier when entrance covers are removed to prevent accidental entry or falling objects
- Performing pre-entry atmospheric testing
- Using forced air ventilation to eliminate atmospheric hazards
- Providing PPE, ingress/egress equipment, and other necessary equipment
- Arranging for an outside attendant to monitor and assist the entry worker
- Developing a rescue plan
Train Workers Who Will Enter
The confined space requirements include worker training because the confined space standard is a lot more complicated than you can learn in a blog article, and compliance can be a matter of life and death.
Employers must provide training to each affected employee before they begin their duties, any time there's a change in permit space operations that affects hazard exposure, and whenever they suspect inadequate knowledge on an employee’s part.
Although the standard doesn't establish a required frequency, many employers choose to require regular refresher training to help employees stay knowledgeable about the rules.
Can You Change Your Confined Space Classification?
A permit-required confined space can be reclassified as a non-permit space if you eliminate the potential hazards.
This means you've:
- Tested, inspected, and confirmed a lack of actual or potential atmospheric hazards
- Eliminated other potential hazards without entry into the space
- Documented the basis for determining a lack of hazards with a signed certification
- Made the certification available to all employees entering the space
For the purpose of confined space classification, atmospheric hazards cannot be considered "eliminated" through forced air ventilation.
Once a confined space is reclassified, it can remain non-permit for as long as non-atmospheric hazards remain eliminated.
Meet Confined Space Training Requirements Online
Part of OSHA's confined space standards is a mandatory training requirement.
Online training with an OSHA-authorized training provider like us can be an effective and convenient way to keep up with OSHA's confined space training requirements (among others). Employees can take the training at their own pace for the best comprehension, and we'll make sure they understand the key points with assessment questions.
We offer courses on both the General Industry Confined Space standard and the Construction Confined Space standard. Enroll today!