Confined Spaces in Construction

Confined spaces can present conditions that are immediately dangerous to workers if not properly identified, evaluated, tested, and controlled.

On May 4, 2015, OSHA issued a new standard for construction work in confined spaces, which will be effective starting August 3, 2015. Confined spaces can present physical and atmospheric hazards that can be avoided if they are recognized and addressed prior to entering these spaces to perform work.

OSHA has developed a new construction standard for Confined Spaces (29 CFR 1926 Subpart AA)— any space that meets the following three criteria:

Is large enough for a worker to enter it;
Has limited means of entry or exit; and
Is not designed for continuous occupancy.

A space may also be a permit-required confined space if it has a hazardous atmosphere, the potential for engulfment or suffocation, a layout that might trap a worker through converging walls or a sloped floor, or any other serious safety or health hazard.


The new Confined Spaces standard requires employers to ensure that their workers know about the existence, location, and dangers posed by each permit-required confined space, and that they may not enter such spaces without authorization.

Employers must train workers involved in permit-required confined space operations so that they can perform their duties safely and understand the hazards in permit spaces and the methods used to isolate, control or protect workers from these hazards. Workers not authorized to perform entry rescues must be trained on the dangers of attempting such rescues.

Safe Entry Requirements

The new Confined Spaces standard includes several requirements for safe entry.

Preparation: Before workers can enter a confined space, employers must provide pre-entry planning. This includes:

• Having a competent person evaluate the work site for the presence of confined spaces, including permit-
required confined spaces.
• Once the space is classified as a permit-required confined space, identifying the means of entry and exit,
proper ventilation methods, and elimination or control of all potential hazards in the space.
• Ensuring that the air in a confined space is tested, before workers enter, for oxygen levels, flammable and
toxic substances, and stratified atmospheres.
• If a permit is required for the space, removing or controlling hazards in the space and determining rescue
procedures and necessary equipment.
• If the air in a space is not safe for workers, ventilating or using whatever controls or protections are necessary so that employees can safely work in the space.

Ongoing practices: After pre-entry planning, employers must ensure that the space is monitored for hazards, especially atmospheric hazards. Effective communication is important because there can be multiple contractors operating on a site, each with its own worker needing to enter the confined space. Attendants outside confined spaces must make sure that unauthorized workers do not enter them. Rescue attempts by untrained personnel can lead to multiple deaths.

Confined Spaces in Pits

Even though a pit is typically open on top and over 4 feet deep, it can still be a confined space or permit-required confined space. Additionally, pits can be completely underground or below grade, such as a utility vault within a sewer system or a pit within a pit in a wastewater treatment plant.

Pits are found in many environments. Examples include sump pits, valve pits or vaults (e.g., wastewater treatment plants, municipal water systems), electrical pits/vaults, steam pits/vaults, vehicle service/garage pits, elevator pits, dock leveler pits, industrial chemical waste pits, and many more. Many of these spaces qualify as permit-required confined spaces.

Employers must take all necessary steps to keep workers safe in confined spaces, including following the OSHA Construction Confined Spaces standard. This standard applies to both new construction in a pit and alterations and/or upgrades. Among the pit-related tasks covered by the standard are:

Opening or closing valves during renovation work.
Installing or upgrading pump equipment, cables, or junction boxes.

Confined Spaces in Sewer Systems

Types of sewer systems include sanitary (domestic sewage), storm (runoff), and combined (domestic sewage and runoff). Sewer systems are extensive and include many different components that are considered confined spaces, including pipelines, manholes, wet wells, dry well vaults, and lift/pump stations. Therefore, employers conducting work in sewer systems will likely have workers who will encounter confined spaces.

Sewer systems also consist of wastewater treatment plants, where confined spaces include digestion and sedimentation tanks, floating covers over tanks, sodium hypochlorite tanks, and wastewater holding tanks, among others. Many of these components may also qualify as permit-required confined spaces.

Employers must take all necessary steps to keep workers safe in confined spaces, including following the OSHA Construction Confined Spaces standard. This standard applies to both new construction within an existing sewer and alterations and/or upgrades.

For example:

Installing or upgrading a manhole.
Altering or upgrading sewer lines.
Making nonstructural upgrades to joints, pipes, or manholes.
Demolition work.
Installing new or upgraded pump equipment, cables, wires, or junction boxes.

Hazards Associated with Sewer Systems

Sewer systems can present a host of confined space hazards, including:

Atmospheric hazards (low oxygen, toxic or flammable gases).
Chemicals in piping and from roadway runoff (may harm lungs, skin, or eyes).
Engulfment and drowning.
Electrocution (e.g., using electrical equipment in wet working conditions).
Slips, trips, and falls.
Falling objects.
High noise levels, low visibility, limits to communication, and long distances to exits.

Crawl Spaces and Attics as Confined Spaces

Crawl spaces and attics can be both confined spaces and permit-required confined spaces under the new standard. For instance, working in an attic and applying a large amount of spray foam (or another chemical) in a short period of time can expose a worker to low oxygen levels or a hazardous atmosphere.

In addition, changes to the entry/exit, the ease of exit, and air flow could create a confined space or cause the space to become permit-required.

Hazards in Crawl Spaces and Attics

Crawl spaces can present many confined space hazards, including:

Atmospheric hazards (e.g., flammable vapors, low oxygen levels, heat, humidity)
Electrocution (e.g., using electrical equipment in wet conditions, unprotected energized wires)
Standing water
Poor lighting
Structural collapse
Asbestos insulation
Entanglement due to configuration of space

Working in attics can also present confined space hazards, such as:

Atmospheric hazards (e.g., poor ventilation)
Heat stress
Mechanical hazards (e.g., attic ventilators, whole house fans)
Electrical hazards (e.g., damaged or frayed wires, open electrical boxes)
Slip, trip and fall hazards
Asbestos insulation

All Construction work can create confined spaces, even if there are none at the start of a project. Changes to the entry/exit, the ease of exit, and air flow could produce a confined space or cause one to become permit-required.

Personal protective equipment: Employers should assess the worksite to determine what personal protective equipment (PPE) is needed to protect workers. Employers should provide workers with the required PPE and proper training on its use and about any related hazards before the work starts.

For questions or to get information or advice, call ABC of WI Safety Department at 1 800-236-2224 or (608) 244-5883.

By Don Moen, ABC of Wisconsin Safety Director

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