FactSheet

Confined Spaces in Residential Construction

OSHA has developed a standard for Confined Spaces in Construction (29 CFR 1926 

Subpart AA) that applies to spaces such as attics, basements, and crawl spaces. 

This Fact Sheet, developed after consultation with the National Association of 

Home Builders (NAHB), and a detailed Frequently Asked Questions (FAQs) document, 

clarify some of the standard’s provisions and their application to residential 

construction work. 

OSHA has developed a construction standard for 

Confined Spaces (29 CFR 1926 Subpart AA) — 

that applies to any space that meets the following 

three criteria:

• Is large enough for a worker to enter it;

• Has limited or restricted means of entry or 

exit; and

• Is not designed for continuous occupancy.

A confined space that contains certain hazardous 

conditions may be considered a permit-required

confined space under the standard. Permitrequired confined spaces can be immediately 

dangerous to workers’ lives if not properly 

identified, evaluated, tested and controlled. 

A permit-required confined space means a 

confined space that 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 

engulfing 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; 

• Contains any other recognized serious safety 

or health hazard.

How Employers Can Determine if 

Confined Spaces or Permit-required 

Confined Spaces Exist

Before beginning work on a residential 

homebuilding project, each employer must 

ensure that a competent person identifies 

all confined spaces in which one or more 

employees it directs may work, and identifies 

each space that is a permit-required confined 

space. The competent person does not have to 

physically examine each attic, basement or crawl 

space, provided that the competent person can 

reliably determine whether the spaces with the 

same or similar configuration contain a hazard or 

potential hazard that would require the permitspace classification. The initial evaluation may be 

done using existing experience and knowledge 

of the space by the competent person and does 

not need to be documented. For example, a 

competent person responsible for inspecting 

new homes being built to identical specifications 

with the same materials need not physically 

inspect each attic separately to determine if it is 

a permit-required confined space. 

How Common Spaces in Residential 

Construction are Impacted by the 

Standard 

 Spaces in a residential home may be considered 

confined spaces or permit-required confined 

spaces during the construction or remodeling 

process. However, the vast majority of the 

standard’s requirements only apply to permitrequired confined spaces, and attics, basements, 

and crawl spaces in a residential home — three 

common spaces – will not typically trigger these 

requirements.

Attics: In many instances, an attic will not be 

considered a confined space because there is 

not limited or restricted means for entry and 

exit. For example, an attic that can be accessed 

via pull down stairs that resemble the structure 

of a stationary stairway and do not require an 

employee to ascend /descend hand-over-hand 

would not be considered a confined space if 

there are no impediments to egress. 
Attics that are determined to be confined spaces 

would generally not be permit-required confined 

spaces because they typically do not contain the 

types of hazards or potential hazards that make a 

confined space a permit-required confined space 

(those that could impair an entrant’s ability to 

exist the space without assistance). 

However, extreme heat in an attic can be 

considered a serious physical hazard such that 

the attic could be considered permit-required 

confined space. OSHA has not quantified how 

hot it must be to trigger the permit-required 

confined spaces requirements. However, heat 

that is extreme enough to cause heat exhaustion 

(e.g., dizziness, headaches, severe sweating, 

cramps) may impede an entrant’s ability to exit 

the attic without assistance and would make a 

confined space permit-required.

Basements: Basements in a residential home 

that are designed for continuous occupancy by a 

homeowner are not considered confined spaces 

under the standard, provided the basement is 

configured as designed (e.g., has permanent stairs, 

a walk-out entry/exit, or an egress window installed).

Crawl Spaces: Crawl spaces in a residential 

home will not typically trigger the majority of the 

requirements of the standard unless they contain 

a physical hazard such as an exposed active 

electric wire.

For Employers

Regardless of the area, the competent person 

needs to pay particular attention to acute health 

hazards that may be present when assessing 

confined spaces, such as toxic (carbon monoxide), 

flammable, or explosive atmospheres. Safety 

Data Sheets (SDSs) must be maintained and 

reviewed to fully assess potential hazards prior to 

worker entry into a confined space to determine 

whether it is a permit-required space. 

Employers’ obligations under the standard will 

depend, in part, on what “type” of employer 

they are. However, most of the obligations in the 

standard apply to entry employers.

Host employer: The employer who owns or 

manages the property where the construction 

work is taking place.

Controlling contractor: The employer who has 

overall responsibility for construction at the 

worksite (note that if the controlling contractor 

owns or manages the property, then it is both a 

controlling employer and a host employer).

Entry employer (Sub Contractor): Any employer 

who decides that an employee it directs will 

enter a permit-required confined space.

The standard makes the controlling contractor the 

primary point of contact for information about 

permit-required confined spaces at the work site. 

The controlling contractor passes information it 

has about permit-required confined spaces at the 

work site on to the employers whose workers 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. The controlling 

contractor is also responsible for making sure that 

employers outside a space know not to create 

hazards in the space, and that workers from 

different entry employers working in a space at 

the same time do not create hazards for each 

other.

Host/Controlling Employer Obligations

Before entry operations begin, a host employer 

with the following information must provide it to 

the controlling contractor: 

• Location of each known permit-required 

confined space; 

• Hazards or potential hazards in each space 

or the reason it is a permit-required confined 

space; and 

• Any precautions that the host employer or any 

previous controlling contractor/entry employer 

implemented for the protection of workers in 

the permit-required confined space.

Note: The above diagram shows the information flow and 

coordination between these employers
The multi-employer communication 

requirements only apply to host employers with 

employees who work at the worksite, regardless 

of when those workers are at the site and only 

apply to permit-required confined spaces. In 

addition, beyond this duties discussed above, 

host employers and controlling contractors are 

not responsible for compliance with the permitrequired confined space program provisions of 

the standard if they have no reason to anticipate 

that the employees they direct will enter a 

permit-required confined space.

Entry Employer Obligations

Inform employees: If a workplace contains 

a permit-required confined space, the entry 

employer must inform workers in the vicinity 

of each space of the location and danger posed 

by that space. This can be done by posting and 

positioning warning signs at each possible point 

of entry, or by other equally effective means. The 

employer must also either take steps to prevent 

its employees from entering that space or ensure 

that entry only occurs through a permit program 

or as otherwise allowed by the standard 

(alternative entry procedures).

Personal Protective Equipment: Entry employers 

allowing an employee to enter a permit space 

must attempt to eliminate or isolate the hazards 

in the space. When engineering and workpractice controls do not adequately protect 

employees, they must assess the space to 

determine what personal protective equipment 

(PPE) is needed to protect workers. Entry 

employers must provide workers with the 

required PPE and proper training on its use and 

about any related hazards before the work starts.

Training: The standard requires employers to 

ensure that their workers know about the existence 

and location of, and dangers posed by, each 

permit-required confined space, and that they may 

not enter such spaces without authorization. Entry 

employers must train workers involved in permitrequired 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. Workers 

not authorized to perform entry rescues must be 

trained on the dangers of attempting such rescues.

Written permit-required confined space entry 

program: The permit-required confined space 

program must establish a system for preparing, 

using, and canceling entry permits, which are 

written or printed documents that allow and 

control entry into permit spaces.

Rescue: Entry employers must ensure that 

properly trained rescue and emergency services 

are available before entry into permit-required 

confined spaces. For a full discussion of an entry 

employer’s obligations to provide rescue, see 

OSHA’s Fact Sheet entitled: Is 911 your Confined 

Space Rescue Plan?

Resources

For additional information see OSHA’s 

Confined Spaces in Construction webpage at 

www.osha.gov/confinedspaces.

How to Contact OSHA

For questions or to get information or advice, 

to find out how to contact OSHA’s free on-site 

consultation program, order publications, report 

a fatality or severe injury, or to file a confidential 

complaint, visit www.osha.gov or call 1-800-321-

OSHA (6742).

DOC FS-3914 06/2017

This fact sheet was developed by OSHA after consultation with NAHB. It does not impose any new 

compliance requirements. For a comprehensive list of compliance requirements of OSHA standards or 

regulations, refer to Title 29 of the Code of Federal Regulations. This information will be made available 

to sensory-impaired individuals upon request. The voice phone is (202) 693-1999; teletypewriter (TTY) 

number: 1-877-889-5627.