Basement Egress Window Requirements

Basement egress windowBasement windows do a lot more than provide daylight and ventilation, they provide an egress, or emergency escape. Egress windows are now a safety feature that is required by the International Residential Code (IRC). An emergency egress opening is required in more places than just basements but this article will focus on basement egress windows because of their unique specifications.

IRC Code

The IRC Code is one of over 14 building codes issued by the International Code Council ( The ICC is a collaborative effort to develop comprehensive, standardized building codes rather than having different jurisdictions with their own code. The IRC code covers one and two family dwellings and much of it addresses fire safety and egress standards.

Code requirements

Every sleeping room and any habitable room in a basement shall have at least one operable emergency escape door or window. The code applies to new construction as well as remodeling if a sleeping room is added or if a room is converted to a sleeping room. Each sleeping room must have its own egress.

All habitable rooms must have a source of natural light with an area that is no less than 8% of the floor space of the room (bathrooms, closets, halls, storage and utility space does not count toward the floor space), with a minimum of 10 square feet.

Habitable rooms also must have a source of natural ventilation which is no less than 4% of the floor space of the room, with a 5 square foot minimum. Emergency egress windows can help meet these requirements.

Egress window requirements

Size requirements

  • Minimum opening height of 24 inches (61.0 CM)
  • Minimum opening width of 20 inches (50.8 CM)
  • Provide an opening space of no less than 5.7 square feet (if a window is on the ground level the minimum opening is 5.0 square feet)

Location requirements

  • The bottom sill should be no higher than 44 inches from the floor
  • The top of the window well must be at least 48 inches from the bottom of any deck or porch
  • The egress window must also be located such that once a person is outside they can easily get away from the building
  • An egress window that swings out must not interfere with a window well ladder

Window well requirements

  • Be at least 36 inches wide
  • Be at least 36 inches deep
  • Provide at least 9 square feet of “floor” space (a window that swings out counts against the floor space calculation)
  • Be no more than 44 inches high (unless there is a permanently attached ladder)
  • Must allow the egress window to open fully (not a factor if the window swings in)

Ladder requirements

  • Ladder steps must be at least 12 inches wide
  • A ladder must not extend beyond the top of the window well by more than 3 inches
  • Rungs or steps must stick out from the wall at least 3 inches
  • Rungs or steps must not stick out from the wall more than 6 inches
  • The distance between the rungs must be 18 inches or less

Styles of egress windows

Much like the rest of the windows in your home, egress windows are available in a number of styles and configurations, including double pane windows. Energy efficient Energy Star rated egress windows are available as well. Popular egress windows include single and double hung windows as well as casement style windows.

Because egress windows serve a function (providing an emergency escape route) and their installation and location are governed by code, some special considerations come into play when selecting a window. The primary requirement is the opening size of a window, not just it’s dimensions. The way a window opens often means that it must be twice the size to meet code.

Even though a window may meet the minimum 24 inch by 20 inch size, if it is a double hung window where the lower half of the window slides up the opening will be only half the size of the window and therefore not up to code. The same goes for sliding windows.

Special double hung egress windows are available that let you open the window in the normal manner for ventilation but also have a special latch that when pulled the entire window swings open.

Casement windows open in a swinging manner and are the most popular casement window style. You can get in-swing casement windows and out-swing casement windows. Which you choose will depend first on your window well since a window must be able to open fully and, when open, cannot encroach on the minimum floor space of a window well or on the ladder. If an in-swing casement window will work in your room they make a great choice because then you don’t have to worry about interfering with the window well.

Window wells

Window wells can be custom made for each home and even for each window to match the style of the home, the landscaping or the terrain/slope of the yard. Common window well construction materials include treated lumber, brick, masonry block and steel. Pre fabricated window wells are also very popular.

Pre fabricated window wells are often made of steel, fiberglass and polyethylene. Pre fabricated window wells are available in many different sizes, last a long time, are quick to install and an easy do-it-yourself project. Those over 44 inches tall have built in ladders that are sure to meet code requirements and are available with built-in hinged covers and screens to keep leaves and animals out and prevent children from falling in.

By code, a window well cover must open from the inside and must not require a key or special tool to open. Covers are available in a variety of styles and even in clear polycarbonate.

Pre fabricated window wells are available in many different colors as well as with decorative and architectural features to make them more visually appealing. Some popular styles are faux stone and brick and even with ledges for plants.

Installing an egress window

Installing an egress window in a location that does not have already have a window is trickier than just replacing a smaller window with one that meets current building code. Enlarging the height of an existing window opening is much easier, and cheaper, than enlarging the width because the existing bulkhead can be used.

The cost to install a basement egress window is typically between $2,000 and $4,000 but depends on a number of factors. If you are fairly handy, installing an egress window yourself often costs only $500 and takes about two days. Two people are generally required to do the job.

The cost of egress windows

Just like regular home windows, the cost of an egress window depends on many things. Some of the main things affecting the price are the size of the window, the number or panes, the construction material and any energy efficient treatments. Egress windows use the same window rating system as ordinary windows.

Read more about egress building codes here

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