Egress Windows - Sizing and Requirements Explained!

Key Takeaway: Egress windows are required in all sleeping rooms for projects falling under the IRC and in many sleeping rooms for projects falling under the IBC. When required, the openings must meet specific egress window sizing requirements, and when provided below grade, must open into an area well.

​If you are working on a residential design or construction project, an important design consideration is the requirement for egress windows. While most people in the design community understand what you are referring to with this term, “egress windows” is not actually defined in the code. The International Building Code (IBC) and International Residential Code (IRC) both refer instead to Emergency Escape and Rescue Openings (EEROs).
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In this article, we’ll refer to egress windows and EEROs interchangeably, but remember that the code only defines EEROs. A window can be used to meet the EERO requirements, but doors and other openings are also an option. All references are to the 2021 IBC and IRC.

A basement emergency escape and rescue opening (egress window).

What is an Egress Window?

Egress Windows, or as the code calls them, EEROs, are defined in the IBC as “an operable exterior window, door or other similar device that provides for a means of escape and access for rescue in the event of an emergency.

Essentially, an egress window or EERO is a way for a building occupant to escape in the event of an emergency or for a first responder or other personnel to access a building for the purposes of rescue. A fire is the obvious emergency that comes to mind, but the openings could be used for any emergency situation.

When are Egress Windows Required?

If you are working on a residential project in the United States, your building likely falls under one of two codes: the International Building Code or the International Residential Code. While the adoption of these codes varies by State and local jurisdiction, generally the IBC applies to apartments and larger residential facilities while the IRC applies to one and two family dwellings and townhouses. Many jurisdictions amend these codes, so be sure to check the applicable code enforced by your local authority having jurisdiction.

IBC Requirements

If your project falls under the IBC, emergency escape and rescue openings are required in the following occupancies (IBC 1031.2):

• Group R-2 occupancies located in stories with one one exit or access to only one exit
• Group R-3 and R-4 occupancies

If you meet either of these conditions, then the IBC requires you to provide emergency escape and rescue openings in any basement or sleeping room below the fourth story above grade plane. There are numerous exceptions where EEROs would not be required:

• Basements with a ceiling height of less than 80 inches
• Basements or sleeping rooms with an exit or exit access door opening directly into a public way, yard, or court. This exception would also apply if the door opens onto an exterior egress balcony that opens to a public way.
• Basements less than 200 square feet in floor area with no habitable spaces
• Storm shelters complying with ICC 500
• In fully sprinklered Group R-2 and R-3 buildings, individual dwelling/sleeping units located in a basement are not required to have EEROS when the basement as a whole has one means of egress and one EERO or two means of egress.​​

You can also check out a past blog post regarding how certain code officials interpret this IBC requirement.

IRC Requirements

If your project falls under the IRC, Emergency Escape and Rescue Openings are required in basements, habitable attics and every sleeping room. If the basement contains more than one sleeping room, an EERO is required in each sleeping room (IRC 310.1).
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There are numerous exceptions where EEROs would not be required:

• Storm shelters and basements used only to house mechanical equipment not exceeding a total floor area of 200 square feet
• In fully sprinklered buildings, sleeping rooms located in a basement are not required to have EEROS when the basement as a whole has one means of egress and one EERO or two means of egress.

Egress Window Sizing Requirements

Both the IBC and IRC have the same dimensional sizing requirements for EEROs:

• Minimum of 5.7 square feet of net clear opening area
• Minimum of 24 inches of net clear opening height
• Minimum of 20 inches of net clear opening width

There is an exception that the minimum net clear opening area for grade-floor EEROs is 5 square feet.

Dimensional requirements for emergency escape and rescue openings.

These dimensions are required to be a result of the normal operation of the window or door - you cannot break or alter the window/door in order to achieve the required dimensions.

Basement Egress Windows

Area wells are required to be a minimum of 9 square feet in area with a minimum dimension of 36 inches in both length and width. The area well must also be of sufficient size to allow the EERO to fully open.

If the area well has a depth of more than 44”, a ladder or steps are required. The egress window or door opening into the area well cannot obstruct the ladder or steps when fully open. 

Dimensional requirements for area wells.

If you choose to provide a ladder for the area well, the ladder must have an inside width of at least 12 inches, must project at least 3 inches from the area well wall and the ladder rungs must be spaced no more than 18 inches apart for the entire height of the area well.

If you choose to prove steps for the area well, the steps must have a minimum width of 12 inches, a minimum tread depth of 5 inches and a maximum riser height of 18 inches for the entire height of the area well.

Finally, area wells are required to be connected to the buildings foundation drainage system unless the building is located on well-drained soil or sand-gravel mixture soils as defined by IBC 1803.5.1 and IRC 405.1

Bars, Grilles, Covers and Screens over Egress Windows

When bars, grilles, covers, screens or other similar devices are placed over EEROs or area wells, these devices cannot reduce the minimum required dimensions described above. Additionally, the bar, grilles, cover or screen must be releasable or removable from the inside without a key or tool and cannot require a greater force than what is required to open the EERO itself.

Summary

​Egress windows, which the code refers to as “Emergency Escape and Rescue Openings” (EEROs) are required in all sleeping rooms for projects falling under the IRC and in many sleeping rooms for projects falling under the IBC.
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When required, EEROs must meet the following size requirements:

• Minimum of 5.7 square feet of net clear opening area
• Minimum of 24 inches of net clear opening height
• Minimum of 20 inches of net clear opening width

If the EERO is below grade level, a minimum 36” x 36” area well is required. If the area well is more than 44” deep, a ladder or steps are required.