Egress windows are required to meet minimum criteria:
- Minimum width of clear opening: 20 in.
- Minimum height of clear opening: 24 in.
- Minimum net clear opening: 5.7 sq. ft…(Ground floor window net clear openings shall be a minimum of 5.0 sq. ft.)
- Maximum sill height above floor: 44 in.
New windows must meet International Energy Conservation Code (IECC) insulation requirements…(Existing windows are presumed to have met the code requirements at the time of their installation)
Don’t just read the dimensions and stop here. You may miss, or misunderstand key things about the requirements for an egress window…
Are basement egress windows a special type of window?
Special, yes because their size, opening and ease of use, are all pertinent factors in their selection; but nearly any type of window excluding a fixed pane window can be used as an egress window as long as the net clear opening is large enough to meet egress requirements. “Net clear opening” is the key term when it comes to egress windows as it refers to the actual overall free and clear space that exists when the window is fully open.
There are also other deciding factors like; the device that opens the window must be operational from inside the room without any keys or special tools. Bars, grilles and grates can be installed over an egress window but they too must be operational without tools, keys special knowledge or force greater than that which is normally required to open the window and they must still allow for a minimum net clear opening of 5.7 sq. ft. For some 5.7 sq. ft. may seem rather large but in reality; the opening has to not only make allowances for a person escaping the room during a home fire; but also for a fire fighter wearing full gear or carrying equipment attempting to enter into the house during a home fire.
IMPORTANT: An egress windows net clear opening is not based on the window size, but the actual opening or space that a person can crawl through when the window is fully open. This is where some can easily get confused. They’ll measure a windows overall size or the window pane size in order to determine whether or not the window meets the requirements for egress. That method is incorrect. The area that needs to be measured is the free and clear space when the window is fully open and an individual’s ease of being able to access the open window, i.e. height from floor. A windows size, type and location can all be major deciding factors when it comes to selecting the correct basement egress window.
Residential new construction homes and basement remodels require at least one egress window to be installed in the basement. On new construction it is required even if the basement is not being finished. Each sleeping room is required to have emergency egress and rescue opening, so if you have 2 bedrooms below grade each will require an egress window. There is an exception for basements used only to house mechanical equipment and not exceeding a total floor area of 200 sq. ft.
Consumers or building contractors select window styles that best meet the architectural, aesthetic, space and budget requirements for a home, but a big consideration always needs to be egress, particularly when it comes to bedroom windows. There are some window types that simply work much better than other types depending on their location and application. The following is a list of window types commonly used in homes.
Casement Windows: Casement windows, or as they are sometimes called “crank-outs” can be smaller than other window types and still meet the necessary requirements for egress. They work particularly well in areas where there just isn’t a lot of open space. Depending upon how far the operator arm allows the window to open also determines how much of the clear opening can be included in the overall “net clear opening”. Often times with casement windows a larger percentage of the window size can be included in the net clear opening. Some manufacturers even install special operator arm that allows the window to open wider by simply pushing it open further. These types of windows meet egress requirements as long as the “PUSH HERE”label is always visible and in place on the window.
Glider/Slider Window: Glider/Slider windows have sashes that fill half or more of the possible clear opening. This requires a window nearly twice the size of say a casement window in order to meet egress requirements. Glider/slider windows are sometimes wider than they are tall while other window types are often just the opposite excluding possibly a fixed picture window, an awning window or double window set. Even though 50% of the glider/slider windows size is unusable in the net clear opening many building contractors prefer the glider/sliders for basement windows because of their ease of operation and lack of mechanical parts that can fail. So for some, if the space allows the glider/slider window is their first choice as a basement egress window.
Double Hung Window: Double hung windows just like sliders have sashes that fill half if not more of the possible net clear opening. Again they require a window nearly twice the size of say a casement window in order to meet the egress requirements. Even when they are fully open, 50% or more of the double hung window is blocked by glass. In order to meet egress requirements a window sized 28 in. wide would need to be at least 60 in. in height. The tall height of the window may make it impractical as a basement egress window unless it’s located on the open side of the walkout basement. Double hung windows can however work very well as 2nd floor bedroom egress windows which also require a net clear opening of 5.7 sq. ft.
Awning Window: Based on the information already covered it should nearly go without saying that an awning window would typically be a poor choice for basement egress window unless it was a fairly large window. Like the slider and double hung 50% or more of the window is blocked when open; particularly with center operator arm opening types. Some manufacturers offer models that have detachable operators which allow them to meet egress requirements. But as stated under casement windows; no special tools or keys must be required to remove the operators or open the window. All instructions like “PUSH-, PULL-, or LIFT- HERE” must be labeled clearly on the window.
Window Wells: There are also specific guidelines for window wells and the clearance required within the wells in order to be egress complient. The minimum horizontal area of the window well is required to be 9 sq. ft. with a minimum horizontal projection and width of 36 in. Window wells deeper than 44 in. need to be equipped with a permanently affixed ladder or steps usable when the window is in a fully open position. Ladder-rungs shall have a minimum inside width of 12 in. shall project at least 3 in. from the wall of the well and be spaced no more than 18 in. on center vertically. Ladder-rungs or steps are allowed to encroach a maximum of 6 in. into the required dimensions of the window well. Escape and rescue openings shall open directly into a free space area, or a yard or court open to a public way.