OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at https://www.osha.gov.

September 13, 2001

Mr. Dennis Vance
Safety Specialist
Safety Services
711 Low Gap Road
Princeton, WV 24740

Re: Fall protection; HVAC; confined space;

Dear Mr. Vance:

This is in response to your July 4, 2001 e-mail message to Jule Jones at the Occupational Safety and Health Administration's (OSHA) Directorate of Construction. You represent a company that both installs and services heating, ventilation, and air conditioning (HVAC) systems, and you mention the standard industrial classification (SIC) code of 1711 for this work. You ask how to apply the fall protection standard to repair work for both residential and commercial HVAC systems. Additionally, you ask if a crawl space under a house or building would be considered a confined space.

Construction - Fall Protection
To determine which OSHA standards and policies apply to a particular work site, the Agency evaluates the activity being performed, not necessarily the company's SIC code. If the HVAC work is construction, and not maintenance, and the work is not covered by the interim fall protection guidelines for residential construction (found in compliance directive STD 3-0.1A), then the general fall protection provisions in 29 CFR 1926.501(b) would apply.

The specific provision depends on the work activity and the type of hazard. Typically, HVAC workers exposed to falls of 6 feet or more would be covered by §1926.501(b)(1), which requires conventional fall protection such as guardrail systems, safety net systems, or personal fall arrest systems.

We have re-evaluated and clarified certain provisions that may be of interest to you. For example, in a May 12, 2000 interpretation letter to Barry A. Cole [enclosed], we stated that there is a safe distance away from a hole or edge if certain criteria are met. This letter states in part:

...[W]e will consider the use of certain physical barriers that fail to meet the criteria for a guardrail a de minimis violation of the guardrail criteria in 1926.501(b) where all of the following are met: (1) A warning line is used 15 feet or more from the edge (or the nearest edge of a hole);
(2) The warning line meets or exceeds the requirements in §1926.502(f)(2);
(3) No work or work-related activity is to take place in the area between the warning line and the hole or edge; and
(4) The employer effectively implements a work rule prohibiting the employees from going past the warning line.

HVAC work performed in attics and on roofs during residential construction is an activity covered in STD 3-0.1A. In STD 3-0.1A, workers in Group 3 installing HVAC systems are allowed to use alternative fall protection measures in lieu of conventional systems. These alternative measures include appropriate staging of materials and equipment, restricting access to the areas below and adjacent, eliminating impalement hazards, ceasing work during adverse weather conditions, and permitting only properly trained workers to use the alternative measures when in attics and on roofs.

[This document was edited on 12/5/12 to strike information that no longer reflects current OSHA policy.]

General Industry - Fall Protection
When performing HVAC maintenance on roofs,1 OSHA's general industry standard §1910.132(a) would apply. On commercial roofs, HVAC units typically are located near the center of the roof, which may significantly reduce the fall hazard exposures. However, where the potential for falls exists, protection must be provided.

Construction - Confined Space
You ask if a ventilated crawl space under a house or a building would be considered a confined space. The construction confined space provisions are in §1926.21(b)(6). As referenced in paragraph (b)(6)(ii), a confined or enclosed space means "any space having a limited means of egress, which is subject to the accumulation of toxic or flammable contaminants or has an oxygen deficient atmosphere." This section provides examples of confined or enclosed spaces which "include, but are not limited to, storage tanks, process vessels, bins, boilers, ventilation or exhaust ducts, sewers, underground utility vaults, tunnels, pipelines, and open top spaces more than 4 feet in depth such as pits, tubs, vaults and vessels."

We assume that the ventilation you refer to is from a permanent part of the building's mechanical ventilation system, and that the system is running. Whether it would be considered a confined space would depend on the size, configuration, and potential hazards created by utility lines, or work activities (for example, use of refrigerants, a torch, etc.). Typically, especially for a crawl space in a house, it would depend in large measure on the size and amount of ventilation.

General Industry - Confined Space
A similar general industry confined space scenario is interpreted in the October 27, 1995 letter addressed to Mr. James Sharp, which is on OSHA's website www.osha.gov. This letter explained that all ventilated crawl spaces may not present hazards that would render the space as a permit-required confined space. A confined space in General Industry standards is a space that:

  1. Is large enough and so configured that an employee can bodily enter and perform assigned work; and
  2. Has limited or restricted means for entry or exit (for example, tanks, vessels, silos, storage bins, hoppers, vaults, and pits are spaces that may have limited means of entry.); and
  3. Is not designed for continuous employee occupancy.

A permit-required confined space (permit space) is defined as:

  A confined space that has one or more of the following characteristics:

  1. Contains or has the potential to contain a hazardous atmosphere;
  2. Contains a material that has the potential for engulfing an entrant;
  3. Has an internal configuration such that an entrant could be trapped or asphyxiated by inwardly concerning walls or by a floor which slopes downward and tapers to a smaller cross-section: or
  4. Contains any other recognized serious safety or health hazard.

For example, leaking utility service lines (i.e., sewage, natural gas, fuel oil, water, and steam), could present hazards that would elevate a confined space to a permit-required confined space classification.

While the general industry standard §1910.146, Permit-required confined spaces, does not apply to construction work, the safety practices prescribed in that standard may be helpful in identifying, controlling, and abating confined space hazards.

If you need further clarification, please do not hesitate to contact us again. Thanks for your interest in occupational safety and health.


Russell B. Swanson, Director
Directorate of Construction


1Fall protection requirements for skylights and edges and openings in floors, as opposed to roofs are in §1910.23. [back to text]