Missouri Egress Window Code
A window must meet certain requirements to pass the state of Missouri's egress window code. This building code ensures inhabitants have a second means of exit from a basement living space, in the event of an emergency.
Make sure that your new egress window meets the Missouri egress window requirements by using our Egress Window Calculator and by purchasing from a trusted company like The Great Egress Company.
What are the Missouri Egress Window Requirements?
- The window must be openable from the inside without the use of keys, tools, or special knowledge.
- If there is more than one sleeping room in a basement, a means of egress is required in each sleeping room.
- It must provide an unobstructed opening with a minimum area of 5.7 sq. ft. (This requirement drops to 5 sq. ft. for grade floor or below grade openings).
- The height of the clear opening must be at least 24" and the width must be at least 20".
- The sill height must not be more than 44" above the floor.
- If the sill height is below grade, the window must have a window well.
- If required, the window well must be at least 9 sq. ft. in an area with a horizontal projection and a width of at least 36" each.
- Window wells deeper than 44" must have permanent steps or a ladder that do not impede the opening of the window.
What are Egress Windows?
Egress means to go out. Egress windows are windows you can use to leave your home. While they may seem like a regulatory burden, these windows furnish occupants with natural light, provide a source of ventilation, and can become a lifesaver in an emergency.
For example, if there is a fire in your home, a single stairwell may become unusable, leaving family members and tenants without a clear path to safety. For bedrooms on floors with multiple doors that lead directly outside, these windows are not strictly necessary. This is because there are clear escape routes that can be taken in the case of an emergency.
In basements, egress windows are essential and, if there is a bedroom, they are required by law in the State of Missouri.
The Missouri Residential Code
Section R310: Emergency Escape and Rescue Openings.
R310.1 Emergency escape and rescue opening required.
Basements, habitable attics and every sleeping room shall have not less than one operable emergency escape and rescue opening. Where basements contain one or more sleeping rooms, an emergency escape and rescue opening shall be required in each sleeping room. Emergency escape and rescue openings shall open directly into a public way, or to a yard or court that opens to a public way.
Exception: Storm shelters and basements used only to house mechanical equipment not exceeding a total floor area of 200 sq. ft.
R310.1.1 Operational constraints and opening control devices.
Emergency escape and rescue openings shall be operational from the inside of the room without the use of keys, tools or special knowledge. Window opening control devices complying with ASTM F 2090 shall be permitted for use on windows serving as a required emergency escape and rescue opening.
R310.2 Emergency Escape And Rescue Openings.
Emergency escape and rescue openings shall have minimum dimensions as specified in this section.
R310.2.1 Minimum Opening Area.
Emergency and escape rescue openings shall have a net clear opening of not less than 5.7 sq. ft. The net clear opening dimensions required by this section shall be obtained by the normal operation of the emergency escape and rescue opening from the inside. The net clear height opening shall be not less than 24" and the net clear width shall be not less than 20".
Windows A and B meet all of the area and dimensions requirements and would pass egress in Missouri. Window C, while meeting the dimension requirements, does not meet the area requirement and would not pass egress.
Exception: Grade floor or below grade openings shall have a net clear opening of not less than 5 sq. ft.
Windows D and E meet all of the area and dimensions requirements for floor grade and below grade window openings in Missouri.
R310.2.2 Window Sill Height.
Where a window is provided as the emergency escape and rescue opening, it shall have a sill height of not more than 44" above the floor; where the sill height is below grade, it shall be provided with a window well in accordance with Section R310.2.3.
R310.2.3 Window Wells.
The horizontal area of the window well shall be not less than 9 sq. ft, with a horizontal projection and width of not less than 36". The area of the window well shall allow the emergency escape and rescue opening to be fully opened.
Exception: The ladder or steps required by Section R310.2.3.1 shall be permitted to encroach not more than 6" into the required dimensions of the window well.
R310.2.3.1 Ladder and steps.
Window wells with a vertical depth greater than 44" shall be equipped with a permanently affixed ladder or steps usable with the window in the fully open position. Ladders or steps required by this section shall not be required to comply with Sections R311.7 and R311.8. Ladders or rungs shall have an inside width of not less than 12", shall project not less than 3" from the wall and shall be spaced not more than 18" on center vertically for the full height of the window well.
Window wells shall be designed for proper drainage by connecting to the building’s foundation drainage system required by Section R405.1 or by an approved alternative method.
Exception: A drainage system for window wells is not required where the foundation is on well-drained soil or sand-gravel mixture soils in accordance with the United Soil Classification System, Group I Soils, as detailed in Table R405.1.
R310.2.4 Emergency Escape And Rescue Openings Under Decks And Porches.
Emergency escape and rescue openings shall be permitted to be installed under decks and porches provided that the location of the deck allows the emergency escape and rescue openings to be fully opened and provides a path not less than 36" in height to a yard or court.
R310.2.5 Replacement Windows.
Replacement windows installed in buildings meeting the scope of this code shall be exempt from the maximum sill height requirements of Sections R310.1 and Sections R310.2.1 and R310.2.2, provided the replacement window meets the following conditions:
1. The replacement window is the manufacturer’s largest standard size window that will fit within the existing frame or existing rough opening. The replacement window is of the same operating style as the existing window or a style that provides for an equal or greater window opening area than the existing window.
2. The replacement window is not part of a change of occupancy.
R310.3 Emergency Escape And Rescue Doors.
Where a door is provided as the required emergency escape and rescue opening, it shall be permitted to be a side-hinged door or a slider. Where the opening is below the adjacent ground elevation, it shall be provided with a bulkhead enclosure.
R310.3.1 Minimum Door Opening Size.
The minimum net clear height opening for any door that serves as an emergency and escape rescue opening shall be in accordance with Section R310.2.1.
R310.3.2 Bulkhead Enclosures.
Bulkhead enclosures shall provide direct access from the basement. The bulkhead enclosure shall provide the minimum net clear opening equal to the door in the fully open position.
Bulkhead enclosures shall be designed for proper drainage by connecting to the building’s foundation drainage system required by Section R405.1 or by an approved alternative method.
Exception: A drainage system for bulkhead enclosures is not required where the foundation is on well-drained soil or sand-gravel mixture soils in accordance with the United Soil Classification System, Group I Soils, as detailed in Table R405.1.
R310.4 Bars, Grilles, Covers And Screens.
Bars, grilles, covers, screens or similar devices are permitted to be placed over emergency escape and rescue openings, bulkhead enclosures, or window wells that serve such openings, provided that the minimum net clear opening size complies with Sections R310.1.1 to R310.2.3, and such devices shall be releasable or removable from the inside without the use of a key, tool, special knowledge or force greater than that required for the normal operation of the escape and rescue opening.
R310.5 Dwelling Additions.
Where dwelling additions occur that contain sleeping rooms, an emergency escape and rescue opening shall be provided in each new sleeping room. Where dwelling additions occur that have basements, an emergency escape and rescue opening shall be provided in the new basement.
- An emergency escape and rescue opening is not required in a new basement that contains a sleeping room with an emergency escape and rescue opening.
- An emergency escape and rescue opening is not required in a new basement where there is an emergency escape and rescue opening in an existing basement that is accessible from the new basement.
R310.6 Alterations Or Repairs Of Existing Basements.
An emergency escape and rescue opening is not required where existing basements undergo alterations or repairs.
Exception: New sleeping rooms created in an existing basement shall be provided with emergency escape and rescue openings in accordance with Section R310.1.
Complying With Missouri Egress Window Code
To put it simply, if you are renovating your basement in Missouri, you will need an egress window that has a wide clearance and can be easily opened.
The Great Egress Company provides a curated collection of windows that meet egress window requirements in Missouri. The easiest way to get your hands on a code-compliant egress window is to let us ship one straight to your door. Have a look for yourself.
Our windows come in several types and sizes that will pass the egress window code in Missouri. Contact our team if you have additional egress window questions.