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Confined Spaces in Construction



The general industry confined space standard does not apply to construction employers and does not specify the appropriate level of employee protection based on the hazards created by construction activities performed in confined spaces. Compared to general industry, the construction industry experiences higher employee turnover rates, with construction employees more often working at multiple worksites performing short-term tasks.

Unlike most general industry worksites, construction worksites are continually evolving, with the number and characteristics of confined spaces changing as work progresses. Multiple contractors and controlling contractors are found more often at construction worksites than at general industry worksites.

Also, in contrast to general industry, OSHA believes many contractors who perform construction work in sewer systems are unfamiliar with the hazards associated with these worksites. Therefore, OSHA’s new construction confined space standard places more emphasis in this standard on assessing hazards at sewer worksites than it did in the general industry confined-spaces standard.

New Confined Space Standard

The new standard, Subpart AA of 29 CFR 1926 will help prevent construction workers from being hurt or killed by eliminating and isolating hazards in confined spaces at construction sites similar to the way workers in other industries are already protected.

The 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

The new construction rule requires employers to determine:

  • what kinds of spaces their workers are in,
  • what hazards could be there,
  • how those hazards should be made safe,
  • what training workers should receive, and
  • how to rescue those workers if anything goes wrong.

If there is a confined space, the employer should determine if there are existing or potential hazards in the space. If there are such hazards, the employer should classify the space according to the physical and atmospheric hazards found in it.

The four classifications are:

  • Isolated-Hazard Confined Space
  • Controlled-Atmosphere Confined Space
  • Permit-Required Confined Space
  • Continuous System-Permit-Required Confined Space

Each type of confined space is tailored to control the different types of hazards. You can learn more about the different types of construction confined spaces in 29 CFR 1926.1203–Definitions.

Construction Employer Classifications

The host employer owns or manages the property on which construction is taking place.

The controlling contractor is the employer that has overall responsibility for construction at the worksite.

If a host employer has overall responsibility for construction at the worksite, then it is both a host employer and controlling contractor.

The subcontractor is the junior or secondary contractor who contracts with the controlling or “prime” contractor perform some or all of contractual-obligations under the prime contract.

The entry employer is usually a subcontractor who directs workers to enter a confined space for work or rescue.

Coordinating Confined Space Entry

This diagram shows the information flow and coordination among employers.
(Click to enlarge)

The rule makes the controlling contractor, rather than the host employer, the primary point of contact for information about permit spaces at the work site. The host employer must provide information it has about permit spaces at the work site to the controlling contractor, who then passes it on to the employers whose employees will enter the spaces (entry employers).

Likewise, entry employers must give the controlling contractor information about their entry program and hazards they encounter in the space, and the controlling contractor passes that information on to other entry employers and back to the host. As mentioned above, the controlling contractor is also responsible for making sure employers outside a space know not to create hazards in the space, and that entry employers working in a space at the same time do not create hazards for one another’s workers.

Key Requirements


There are 5 key requirements in the new construction rule, and several areas where OSHA has clarified existing requirements. The five new requirements include:

  1. There are more detailed provisions that require coordinated activities when there are multiple employers at the worksite. This will ensure hazards are not introduced into a confined space by workers performing tasks outside the space. An example would be a generator running near the entrance of a confined space causing a buildup of carbon monoxide within the space.
  2. It requires a competent person to evaluate the work site and identify confined spaces, including permit spaces.
  3. It requires continuous atmospheric monitoring whenever possible.
  4. It requires continuous monitoring of engulfment hazards. For example, when workers are performing work in a storm sewer, a storm upstream from the workers could cause flash flooding. An electronic sensor or observer posted upstream from the work site could alert workers in the space at the first sign of the hazard, giving the workers time to evacuate the space safely.
  5. It allows for the suspension of a permit, instead of cancellation, in the event of changes from the entry conditions list on the permit or an unexpected event requiring evacuation of the space. The space must be returned to the entry conditions listed on the permit before re-entry.

In addition, OSHA has added provisions to the construction rule that clarifies existing requirements in the General Industry standard. These include:

  1. Requiring that employers who direct workers to enter a space without using a complete permit system prevent workers’ exposure to physical hazards through elimination of the hazard or isolation methods such as lockout/tagout.
  2. Requiring that employers who are relying on local emergency services for emergency services arrange for responders to give the employer advance notice if they will be unable to respond for a period of time (because they are responding to another emergency, attending department-wide training, etc.).
  3. Requiring employers to provide training in a language and vocabulary that the worker understands.

Crawl Spaces and Attics

crawl 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)
  • electrocution (e.g., using electrical equipment in wet conditions, unprotected energized wires)
  • standing water
  • poor lighting
  • structural collapse
  • asbestos insulation

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

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. As with other space, pits may contain hazardous atmospheres.

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

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

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. It's important to remember that hazardous atmospheres is the most common hazard in all confined spaces.

Confined Spaces in Sewer Systems

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.

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

For more information about hazards in the construction industry read OSHA’s Anatomy of Confined Spaces in Construction.

For a more complete discussion of confined space safety, be sure to take OSHAcademy Course 713, Confined Space Program.

Confined Spaces in Sewer Systems

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Before beginning this quiz, we highly recommend you review the module material. This quiz is designed to allow you to self-check your comprehension of the module content, but only focuses on key concepts and ideas.

Read each question carefully. Select the best answer, even if more than one answer seems possible. When done, click on the "Get Quiz Answers" button. If you do not answer all the questions, you will receive an error message.

Good luck!

1. Who has overall responsibility for construction at the worksite?

2. Which of the following should occur in the event of changes from the entry conditions list on the permit or an unexpected event requiring evacuation of the space?

3. Employers should present confined space training in _____.

4. What is the most common hazard in all confined spaces?

5. High level noise is just one hazard in this type of confined space on a construction site?

Have a great day!

Important! You will receive an "error" message unless all questions are answered.