Egress Window Requirements: Understanding Size and Locations

Have you ever applied for a building permit to change out your old outdated windows with new energy efficient windows for your home only to find out that some of the windows don’t meet the window egress requirements?

This is a very common problem. Building codes change over time and what was once acceptable in older homes might not be under current code when an alteration occurs.

Please note that these requirements can be specific from city, county, or state therefore it is best to contact your local authority having jurisdiction to see what these requirements are.

As for a general understanding of these requirements, let us look at the 2015 International Residential Code (IRC) for what the minimum standards are.

What is an Egress Window?

An egress window is a window of a certain size that provides a safe exit from a building in case of an emergency. These windows are typically installed in bedrooms, basements, and sleeping rooms to ensure that occupants can escape in the event of a fire, earthquake, or other emergency situation. Egress windows must meet specific size requirements to allow for an easy exit and access.

A lot of people will refer to the term “Egress Windows” when in reality the code references “Emergency Escape and Rescue Opening”. These requirements can be found in Section R310 of the IRC. Again the intent is to provide a means of escape and access for rescue in the event of an emergency, for example a fire.

These means of escape and access can be achieved by an operable exterior window, door, or similar device that meet the minimum size and dimensions of Section R310.

In this article, we will go over the minimum required windows sizes as well as where they are required to be located.

Where Are Egress Windows Required? (R310.1)

Egress Window Locations

The code requires every basement, habitable attic, and every sleeping room to have at least one operable emergency escape and rescue opening. If a room is used as such, it must provide a means of escape.

Also note that if basements have multiple sleeping rooms, each sleeping room is individually required to provide a means of escape and rescue. These openings must open directly to the outside such as a public way or yard and need to be operational from the inside of the room without much effort.

What is the Minimum Size Requirement of Egress Windows? (R310.2)

Egress Window Size and Dimensions

First lets look at the minimum opening area required. The minimum required dimensions of the window must include compliance with all of the following: the net clear opening area, net clear height opening, and net clear width opening.

Here is a visual look at these clear opening dimensions and how they apply to different window types:

Casement Egress Window

Here is a graphic of what casement windows look like:

Single/Double Hung Egress Window

Here is a graphic of what single-hung and double-hung windows look like:

Horizontal Slider Egress Window

Here is a graphic of what horizontal slider windows look like:

Also note that if a window is being used to meet the egress requirements, in addition to the above, the sill height of the window shall not be more than 44 inches above the finished floor.

Fun Tip: Some windows, like windows located on the second floor, have minimum sill height requirements therefore to learn about Window Fall Protection requirements per the International Residential Code (IRC), be sure to check out this POST.

When a door is being used to meet the egress requirements, it must be either a side-hinged door or a slider. It must meet the minimum opening area requirements stated above in a fully open position.

If the door is located below the adjacent ground elevation, it must provide a bulkhead enclosure with a minimum headroom height equal to the door when it is in the fully opened position.

Does a Basement Need an Egress Window?

Basement Egress Windows

Yes, as we noted above the code requires every basement, habitable attic, and every sleeping room to have at least one operable emergency escape and rescue opening.

If a basement contains a habitable room or is used as such, it must provide a means of egress, such as an egress window.

When the sill height of the egress basement window is located below grade (common for egress windows provided for a basement) a window well must be provided.

Window Well Code Requirements (R310.2.3)

Egress Window Well Size

The area of a window well shall not be less than 9 square feet with a horizontal length/width of no less than 36 inches. This is to ensure that there will be a sufficient amount of space to allow occupants to escape or for fire fighters to enter.

If the depth of the window well is greater than 44 inches, a ladder or steps are to be provided and permanently fixed to provide access and by no means are allowed to encroach within the required window well dimensions by more than 6 inches.

The inside width dimension of ladders or rungs (a horizontal support on a ladder for a person’s foot) shall not be less than 12 inches and must project no less than 3 inches from the wall.

The vertical spacing shall not be more than 18 inches on center throughout the entire height of the window well. Although the design of the steps are not mentioned within the code provisions, the design of the ladder is.

Also since the bottom of the window well is located below grade, providing proper drainage is recommended.

Emergency Escape and Rescue Openings in Summary

So this basically sums up the code for egress window requirements and their dimensions. Therefore let us recap on the residential emergency escape and rescue opening requirements:

For more information, see Section R310 of the 2015 International Residential Code for a more in-depth look at emergency escape and rescue openings.

Reference Source – 2015 International Residential Code – [Buy on Amazon]