An egress window is one that possesses certain characteristics that make it safe and easy for exit in case of an emergency. The International Residential Code sets standards for egress windows, determining their minimum width, height and net clear opening area. Maximum distance from the floor and the way in which the window may be opened are also governed by code. All rooms used for sleeping in homes that are either newly built or remodeled must be equipped with one egress window that conforms to code. There are different types of windows that are suitable for egress. As long as they meet the necessary requirements, the code does not dictate what type of window it has to be.
There are three common types of windows installed in newly-built and remodeled homes that are used for egress. They include double hung, sliding and casement windows. An egress window must open at least 24 inches high, 20 inches wide and possess a net clearance area of 5.7 square feet. Depending on the window type, in order to meet egress requirements, the total size of each type of window will vary due to their different methods of operation.
1. Double Hung Windows
A common style of window found on both old and new homes are double hung window. Consisting of two sashes which overlap horizontally in the middle of the window, the bottom half of a double hung window opens upward. Some double hung windows open from top to bottom, but it is not as common. Applying the egress requirements to double hung windows, in order to reach the minimum opening area, the opening pane must clear 24 inches top to bottom and be at least 34 inches wide. That means the entire window must be more than 48 inches high.
2. Sliding Windows
Sliding windows also consist of two different sections, but they open from side to side rather than up and down. Much like a sliding door, sliding windows move along a track. Given that egress windows must open to a width of at least 20 inches, to meet the area requirement, it would have to be a minimum of 41 inches high. With both vertical sections include, a sliding window would be at minimum a total of about 40 inches wide.
3. Casement Windows
Casement windows open in or out like a door on a hinge. They can either be controlled by a handle and pulled open or by a rotating lever. Casement windows work best for basement egress because they open out as opposed to up or to the side. Because the entire window opens, the whole thing can be smaller and still meet the minimum requirements. Thus, a casement window could either be as small as 24 inches high by 34.2 inches wide or 20 inches wide by 41 inches high. These are the same dimensions as with the previous two windows. The difference is with casement windows, the dimensions represent the size of the entire window.
Whatever window type you use for egress, its sill must be no higher off the ground than 44 inches. Basement egress windows must additionally be equipped with egress wells that allow space to exit.