Understanding Egress Windows

There is a lot of confusion and misinformation about egress windows, even in the remodeling community. But there should not be. The standards are clear and easy to follow, once you understand them.

Every building code in use in the United States and Canada requires egress windows in bedrooms and basements. For example, the International Residential Code (IRC), which is the code in force in most localities, mandates that

"basements and sleeping rooms below the fourth story shall have at least one exterior emergency escape and rescue opening… Such opening shall open directly into a public street, alley, yard or court."

Or, in simpler language: a finished basement and each bedroom in a house must have an emergency exit leading to outside the structure. This exit or "egress" may be a door or window, but in either case, it must follow certain rules governing its size and location.

An emergency exit must be able to be opened from the inside without using a key or tools, or anything except your hands. Grills, bars, storm windows, or screens over emergency exits also must open from the inside without using tools or keys, and also comply with the opening size and location requirements for an emergency exit.

If the exit is a door, then its opening must be at least 20" wide. In most areas, the minimum width of a door, other than a closet door, used in a residence is 24", and exterior doors are typically 32"-36" wide. So, the width requirement is easily met.

The door must lead outside and not into another room. This is true even if the other room has an exit to the outside. If the door is on the second or third floor, other sections of the code require that it lead to a porch, balcony, or stair landing. It cannot lead to a drop-off or to a ladder attached to the house.

In most bedrooms, the emergency exit is usually going to be a window. An egress window is not a special type of window. It may be any of the usual window types: double-hung, casement, sliding, and so on, but it must have an opening large enough and close enough to the floor for an occupant to exit easily and quickly in an emergency, and to allow a firefighter wearing full turn-out gear, including a bulky oxygen tank, to gain entry.

All of this may seem a little confusing, but it's actually not that complicated if we break it down. Let's take a look at the different elements of an egress window.

To qualify as an egress window, a window must meet every one of the following requirements:

  1. The minimum width of the clear opening of the window must be not less than 20",
  2. The minimum height of the clear opening of the window must be not less than 24",
  3. The clear opening of the window may not be less than
    1. 720 square inches (5.0 square feet) in a first floor ("grade level") window, or
    2. 820 square inches (5.7 square feet) in a window located above ground level or in a basement,
  4. The distance from the finished floor to the bottom of the clear opening may not exceed 44 inches.

What is a Clear Opening?

The "clear opening" of a window is the unobstructed opening when the window is in a full open position. Many remodelers assume that the window opening is also the clear opening. This is not necessarily true. Illustration 1, for example, shows a casement window in a full open position. Due to the way the hinge operates, the butt of the window sash extends a few inches into the window opening. The distance that the butt extends into the opening must be subtracted to get the clear opening of the window.

This is a common problem with windows that hinge from one edge of the frame, like casement windows. Very often the sash does not completely clear the frame. Manufacturers have dealt with the problem in a variety of ways, including the use of special hinges (often called "egress hinges" or "zero clearance hinges") that do rotate the sash completely clear of the opening. Another solution, if space is available, is to simply make the window wider.

Width, Height, and Area

If you multiply the minimum width and minimum height of an egress opening, the result is not the minimum 820 square inch (5.7 square foot) opening as you might expect. It is only 480 square inches. (See Illustration 2, Window A).

This result causes some confusion since many believe that a window with a clear opening that is the minimum width and height also ought to have the minimum required area.

That's not the way it works. Height and width are independent of area. To reach 820 square inches the clear opening must be made either wider or higher than the minimums specified by the code.

With a 20" wide opening, the height of the opening must be at least 41" (Illustration 2, Window B).

With a 24" minimum height, the opening width has to be 34 3/16" (Illustration 2, Window C).

Height and Width Required for an 820 Sq/In Clear Opening
(Basement, 2nd and 3rd Floor Egress)
Width (inches)Height (inches)Width (inches)Height (inches)
204127 1/230
20 1/2402829 1/2
213928 1/229
21 1/2382928 1/2
223729 1/228
22 1/236 1/23027 1/2
2335 1/230 1/227
23 1/2353126 1/2
243431 1/226
24 1/233 1/23225 1/2
253332 1/225 3/16
25 1/2323325
2631 1/233 1/224 1/2
26 1/2313424
2730 1/2

As a window increases in width, it can decrease in height, and still have a large enough clear opening to qualify as an egress window. The Height and Width table shows the widths and corresponding heights required for an 820 square inch clear opening.

Distance From the Floor

The bottom of the clear opening can be no more than 44" above the finished floor. Many local communities have changed this specification to less than 44". In our area, it's a maximum of 42" from the finished floor.

It can be lower, down to about 20" or so. But if you go too low you will trigger another section of the building code that requires tempered glass in windows closer than 18" to the floor.

The purpose of this requirement is obvious. To get out of a window, an occupant must first climb up to the window, and the code authorities have decided that 44" is the highest a person should have to climb.

Most windows on the first and higher floors of a house easily meet this requirement. But in basements, windows are often as high as 7' above the floor, and some serious structural modification may be required to install a qualifying egress window.

Police vs. Fire…
The Battle of the Badges

Kitchens, baths, additions and remodeling in Lincoln, Nebraska. Contact us for egress windows.

When it comes to fire safety vs. crime prevention, building codes can be a constant battleground between police, who want to make houses hard to get into, and fire officials who want to make them easy to get out of.

The problem is that buildings that are easy to get out of are also usually pretty easy to get into. This makes the burglary rate go up, which makes the police unhappy.

The egress window requirements are one part of the code where the police lost.

The egress opening part of the residential building code actually prohibits some basic security practices. For example, you cannot cover your egress window with any barrier that cannot be easily opened or removed from the outside to let firefighters get in.

Key locks on egress windows are prohibited. And, if you install a separate screen or storm window over your egress window, it must also provide a clear opening that meets egress window requirements and open from the inside without tools.

Egress window wells are a special problem. Escape wells are great places for burglars to quietly work on your window locks while completely hidden from view.

A locking grill over the well, the normal crime prevention measure, is banned by most building codes. You can have a grill, but it cannot prevent a firefighter from getting in. Of course, if a firefighter can get in, so can anyone else.

Grills or covers are still a good idea to prevent leaves from accumulating in your well, and kids, pets, and distracted adults from falling in. But they cannot be locked, latched, or permanently attached so they cannot be removed or opened from the outside.

Our resident security consultant, formerly on the faculty of the National Crime Prevention Institute, suggests that an alarm is also not a good idea. Blowing leaves and falling snow will give you so many false alarms that eventually you will disable it anyway just to eliminate the nuisance.

He believes that the only practical security measure available is a strong light aimed at the well, activated by a motion detector, and placed high enough on your house that a burglar cannot just reach up and unscrew the bulb.

Burglars don't like light, and it usually chases them away.

But, make sure it is aimed at the well and not at your neighbor's house, or you might greatly impair neighborliness.

If the bottom of the opening is more than 44" above the finished floor, some code authorities will permit you to build one step under the window, no more than 7 3/4" high, permanently attached to the wall, floor, or both. A temporary step is not allowed.

Do You Have to Add Egress Windows to Your Old House?

If your old house was built before 1983 there is a good chance that your basement and bedrooms do not have windows that comply with today's egress requirements. Before 1983 an egress window needed only 720 square inches of clear opening to quality. Earlier just 620 square inches were enough. Before 1950 there were no egress requirements at all in most communities, so if your house is pre-War, there is a good chance that none of your windows meet current egress requirements.

The easy way to test your windows is to open them up all the way and measure the opening. Multiply the width of the clear opening times its height and see if it is 820 square inches or larger. Also, check to see if the width of the opening is at least 20" and the height at least 24".

Structural Changes

If you don't have qualifying egress windows, you are not required to add them to an existing bedroom or basement. But, if you remodel and make any structural changes to the wall that contains the window, you must, in almost every case, add a qualifying egress window or door. The code enforcers are not picking on you, they just want you, and any subsequent owner of your home to be safe. (You may also have to add one or more hard-wired smoke detectors for the same reason.)

If you remodel the room but do not make structural changes to the wall that holds the window, you get a break. You do not have to enlarge the existing window opening to accommodate the larger egress window required by contemporary building codes. But, you are required to install the largest egress window that will fit in the existing opening.

Replacing Windows

If all you are doing is replacing your windows, most local codes allow you to replace your windows with the same type and size of window without regard to egress requirements. This exception was enacted so homeowners would not be discouraged from replacing old windows when they need to be replaced by the added expense of converting windows to egress requirements. But, if you change the type of even one window, you may have to meet egress requirements and use the largest egress window that will fit into the existing rough opening. It more or less depends on where you live and how strict your local code enforcement is.

Some homeowners (and even some professional remodelers) think they can cleverly get around egress window requirements by calling a room a den or home office rather than a bedroom. It's not a good idea, and it rarely works — for two reasons.

First, it's not a good idea to try to bypass safety codes. They are there for a reason.

Second, code officials have seen the same ruse tried about 10,000 times, and are unlikely to be fooled.

They will consider any room that has a closet a likely bedroom no matter what you choose to call it. And, then there's the smell test. If the room looks like, smells like, or feels like it might eventually, someday, by someone, for some reason, be turned into a bedroom, it's a bedroom and must include an emergency egress.

The Special Challenge of Basement Egress Windows

In former days it was legal to finish a basement without including an egress window. Today it's not. If any part of the basement is finished, whether or not it includes a bedroom, then there must be a legal emergency egress from the basement. This may be a door or a qualifying egress window.

If the basement includes a bedroom, then an egress must be located in the bedroom, even if you already have an egress window someplace else in the basement. If more than one bedroom is added, then each bedroom must have its own legal egress.

If you have a basement bedroom, then this is one place we strongly suggest an egress window be installed even if not required by your local code. A basement bedroom is an underground fire trap. Without an egress window or door, there may be no way out of a fire. If the bedroom is used by children, adding an egress door or window is even more urgent.

Escape Wells

On the first or any higher floor, outside of your windows is air. It's easy to exit into air.

In your basement the outside is dirt. It's impossible to exit into dirt. You have to dig a hole in the dirt to install the window. This hole is called an "escape well". You are also going to have to cut a hole in the basement wall. Unlike the framed walls upstairs, this wall is probably concrete or masonry, which requires a heavy-duty diamond blade concrete saw and a lot of skill to cut a straight line.

Any well must meet basic minimum common-sense requirements, not all of which are spelled out in the building code. At a minimum the well…

  1. Must not fill with water when it rains. There are few things more irritating in life than water leaking through your brand new egress window.
  2. Must not become a trap for small children or pets. A grill or clear plastic cover over the well is an excellent idea.
  3. Must be big enough to allow your escape window to fully open while an often very large firefighter is crouched in the well in full turn-out gear. The most common window used as a basement egress window is a single casement. This window must be able to swing out to its fully open position without hitting any part of the window well. Because this can be a problem, casement windows that swing in rather than out are commercially available as egress windows.
  4. Must allow an occupant to climb out of the well without hindrance
As you might already suspect, the minimum requirements have been reduced to a set of detailed regulations in your local building code, and the well must meet every one of the rules.
  1. The well must be a minimum of 36" out from the window, at least 36" wide, and contain at least 9 square feet of floor area. Any wall can be longer than the required minimum 36", but it cannot be shorter. For example, a well 24" by 52" contains the minimum 9 square feet of floor space, but does not comply with the code because one wall is shorter than 36".
  2. If the depth of the well measured from ground level ("grade") to the floor of the well exceeds 44", then a permanently attached ladder or steps must be installed.
    • A ladder must be a minimum of 12" wide and project not less than 3" from the wall, but not more than 6". The 3" projection requirement is to ensure there is enough space behind the ladder for your foot to fit. The 6" maximum is to make sure the ladder does not encroach too much on the required 9 square foot minimum floor space of the well.
    • The ladder or steps cannot be obstructed by the open egress window or prevent the window from fully opening.
    • Steps cannot be more than 18" high and the rungs on the ladder cannot be more than 18" apart.
  3. If the well is located under a porch or deck (and, yes, an escape well can be located under a porch or deck), then the distance from the top of the window well to the lowest overhead deck or porch member must not be less than 36". This allows enough room for a person to crawl out from under the deck or porch.

Types of Egress Windows

Just about any type of window can be an egress window, but the most common type is the casement or "crank out" window. The outswinging or inswinging casement is popular as an egress window because it has the largest clear opening in relation to the window's size.

Illustration 3 shows the same clear opening in a casement and a double-hung window. The double-hung window has to be more than twice the overall size of the casement window to meet minimum egress requirements because only half of the double-hung window can be opened at one time. Sliding windows have the same problem. Only half of the window can be opened, so to get the required clear opening, the window has to be twice as large as the minimum egress requirement.

Some types of windows do not make very good egress windows. Jalousie or louvered windows, for example, cannot possibly open wide enough for egress. A hopper window, because it hinges at the bottom, would be difficult to crawl over to get out. An awning window, that hinges at the top, is not suitable for use in a window well since it interferes with climbing out of the well. In many areas awning windows in wells are prohibited, and in all the other areas you are going to have to build a bigger well if you want to use an awning window.

The need for windows that maximize egress opening size has renewed interest in some European windows. The most common window in Northern Europe is a side-hinged window that opens inward — sometimes called a "French swing" window in this country because it operates like a French door. These not only provide a large clear opening for the size of the window but do away with the casement crank which can make opening a window a slow, laborious process.

The newest version of the side-hinged window is the tilt-and-turn. This window opens to the side like a normal side-hinged window, but also can tilt out at the top for ventilation without compromising security.

Installing an Egress Window

Installing an egress window on an above-ground floor requires moderate skills and is well in reach of a do-it-yourselfer with some experience at installing replacement windows (To assess your own skills, see: Can I Do It Myself?). You will need a permit in most jurisdictions. Codes enforcers are getting pretty fussy about windows. They want to make sure you are putting the right window in the right place. So consult early and often with code officials.

For a basement egress window, we suggest you hire a professional. Not only is cutting through concrete and digging a well back-breaking work, but it is easy to make a mistake that compromises the foundation of your house, causes a leaky basement, or fails to meet code requirements.

Modifications to a house foundation are not governed just by egress window codes, but by a number of other sections of the building code, all of which you have to follow. And, you must pay close attention to proper drainage.

The most frequent mistake made in building escape wells is failing to provide adequate drainage. The best drainage solution is to tie a drain at the bottom of the well to the building's perimeter (or "french") drain. If the building does not have a french drain, then a drain field filled with permeable gravel or coarse sand must be provided.

Rev. 07/11/20