Jefferson County, MO Building Safety: Door Locking Hardware (2026)
Key Facts
- Minimum door width
- 36 inches clear, door open 90°
- Minimum door height
- 80 inches clear height
- Locking rule
- No key needed to open from inside
- Door type
- Side-hinged egress door required
- Governing section
- § 500.400, amending IRC § R311.2
Summary
Every dwelling unit in Jefferson County needs at least one side-hinged egress door at least thirty-six inches wide and eighty inches tall that opens from inside without a key, special knowledge, or extra effort. The county's amendment to IRC Section R311.2 bars deadbolts or hardware that trap occupants inside during a fire or emergency.
R311.2. Delete and insert in lieu thereof the following: Egress door. Not less than one (1) egress door shall be provided for each dwelling unit. The egress door shall be side-hinged, and shall provide a clear width of not less than thirty-six (36) inches where measured between the face of the door and the stop, with the door open ninety degrees (90°) (1.57 rad). The clear height of the door opening shall be not less than eighty (80) inches in height measured from the top of the threshold to the bottom of the stop. Other doors shall not be required to comply with these minimum dimensions. Egress doors shall be readily openable from inside the dwelling without the use of a key or special knowledge or effort.
Full Breakdown
2 of the 2015 International Residential Code requires every dwelling unit to have not less than one egress door, and sets the door's minimum dimensions: a side-hinged door with a clear width of at least thirty-six inches, measured between the face of the door and the stop with the door open ninety degrees, and a clear height of at least eighty inches from the top of the threshold to the bottom of the stop. Other doors in the home are not held to those minimum dimensions, only the designated egress door.
The operative locking-hardware rule sits in the same amended section: the egress door must be readily openable from inside the dwelling without the use of a key, special knowledge, or special effort. That standard rules out double-keyed deadbolts, hardware that requires a tool, and any lock an occupant cannot operate quickly from inside during a fire or other emergency. 3, which require a landing at least as wide as the egress door and at least thirty-six inches deep in the direction of travel outside the door, so the required exit is both operable and physically usable in an emergency.
350, and a door that locks with a key from the inside will fail that inspection until it is replaced or the hardware is changed.
Violations & Fines
Installing or leaving in place egress-door hardware that requires a key, tool, or special knowledge to open from inside is a Building Code violation under Section 500.300, a misdemeanor carrying a fine up to one thousand dollars, imprisonment up to one year, or both. The Code Official can withhold final inspection approval and occupancy under Section 500.350 until the hardware is corrected.
Frequently Asked Questions
Can I put a keyed deadbolt on my front door in Jefferson County?
How wide does my home's exit door have to be?
Will inspectors check my door hardware before I can move in?
Sources & Official References
Other rules in Jefferson County
Compare Jefferson County to another location·View the Missouri building safety overview
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