Exit Signs Required by Building Code: Placement, Power, and ADA Rules

Exit signs are required by building code in nearly every commercial, public, and multi-family residential building in the United States. The rules come from three overlapping sources: the International Building Code (IBC), which most local jurisdictions adopt; NFPA 101, the Life Safety Code; and OSHA’s exit route regulations, which apply to workplaces. The specifics shift with occupancy type and local adoption, but the core mandate is the same everywhere. If people occupy the building and the way out isn’t obvious, illuminated exit signs must show them the path, stay lit during a power failure, and be kept in working order.

Which Buildings Must Have Exit Signs

Both the IBC and NFPA 101 require exit signs in most occupied buildings, including assembly venues, offices, schools, hotels, retail stores, and apartment complexes. Under the IBC, every exit and exit access door must be marked by an approved exit sign that is “readily visible from any direction of egress travel.”¹ NFPA 101 imposes the same rule for assembly, educational, hotel, mercantile, and business occupancies.²

For workplaces, OSHA requires each exit to be “clearly visible and marked by a sign reading ‘Exit,'” with additional signs posted along the exit access showing the direction of travel when the route isn’t immediately apparent.³

Where Signs Are Not Required

Both codes carve out the same exception: main exterior exit doors that are obviously and clearly identifiable as exits do not need a sign.⁴ A glass front entrance leading straight outside is the classic example. The IBC also exempts individual bedrooms, dwelling units, and rooms with only one exit or exit access door. Single-family homes and the interiors of individual apartment units are not covered, though common hallways and stairwells in apartment buildings are.

How the Sign Must Be Built

Codes are specific about how an exit sign looks. The word “EXIT” must appear in plainly legible letters at least 6 inches high, with the principal strokes of each letter at least three-quarters of an inch wide. Individual letter width must be at least 2 inches (except the letter “I”), with at least three-eighths of an inch of spacing between letters.¹ OSHA mirrors the 6-inch height and three-quarter-inch stroke width for workplaces.³

Every exit sign must be continuously illuminated, either by an internal source such as built-in LEDs or by an external light shining on the sign face. Externally illuminated signs need a light intensity of at least 5 foot-candles at the sign face.¹ The letters must show high contrast against the background and remain legible whether or not the illumination source is energized.

Red or Green?

OSHA requires exit signs to be “distinctive in color” but does not specify red or green.³ Both are widely accepted in practice. Some local jurisdictions do prefer one over the other, so confirm with your local fire marshal or building department before ordering signs. The IBC focuses on contrast and legibility rather than dictating a color.

Placement and Visibility

A compliant sign in the wrong place fails the reader when it counts. The IBC requires that no point in an exit access corridor or exit passageway be more than 100 feet from the nearest visible exit sign, or the sign’s listed viewing distance, whichever is shorter.¹ Signs typically sit above exit doors, and nothing—decorations, furnishings, other signage—can block the line of sight.

Where the direction to an exit isn’t immediately apparent, arrow indicators must appear on or beside the exit sign to guide occupants around corners and through complex layouts. OSHA imposes the same directional requirement for workplaces.³

Low-Level Signs in Hotels

Hotels and similar lodging (Group R-1 under the IBC) face an added requirement: low-level exit signs in all areas serving guest rooms. The bottom edge must sit between 10 and 18 inches above the floor, mounted flush against the door or wall within 4 inches of the door frame on the latch side.¹ Smoke rises and collects at the ceiling first, so a sign at ankle height stays visible after an overhead sign disappears.

“Not an Exit” Marking

Any door or passage along an exit route that could be mistaken for an exit must be marked “Not an Exit” or labeled for its actual use, such as “Closet” or “Storage.” OSHA states this requirement explicitly.³ It is one of the most commonly overlooked requirements. A door near an egress corridor that opens on a mechanical room or dead-end hallway can pull confused occupants into the wrong space during an emergency.

Tactile and Braille Signs Under the ADA

Separate from the illuminated overhead signs, the ADA Accessibility Standards require tactile exit signs at specific locations. Doors at exit stairways, exit passageways, and exit discharge points must have signs with raised characters repeated in Grade 2 Braille.⁵

Tactile signs have their own technical requirements:

Characters raised at least 1/32 inch, uppercase, sans serif. Italic, script, and decorative fonts are prohibited.
Character height between 5/8 inch and 2 inches.
Mounting height between 48 and 60 inches above the floor, measured from the baseline of the characters.
Non-glare finish with sufficient color contrast for visual readability.
Grade 2 Braille placed below the raised text, separated by at least 3/8 inch from the tactile characters.

Tactile signs go beside the door on the latch side rather than above it, and a clear floor space of at least 18 by 18 inches must be centered on the sign so a person can stand close enough to read by touch.⁵ Owners often install a compliant overhead sign and forget the separate tactile sign entirely.

Backup Power and the 90-Minute Rule

A sign that fails when the lights fail defeats its purpose. Both the IBC and NFPA 101 require exit signs to stay illuminated for at least 90 minutes after a loss of normal power.¹ The backup source can be a battery inside the sign, a central battery system, or an on-site generator. Emergency lighting along exit routes must activate within 10 seconds of a power failure, and the same standard applies to exit sign illumination.²

Photoluminescent and Self-Luminous Signs

Photoluminescent signs absorb ambient light during normal operations and glow when the power goes out. Both the IBC and NFPA 101 permit them as an alternative to electrically powered signs when they carry a UL 924 listing and meet the same letter sizing and 90-minute visibility standards. They require a reliable charging light of roughly 5 foot-candles at the sign face during occupied hours. Self-luminous and electroluminescent signs are also permitted under OSHA regulations.³

Inspection and Testing Requirements

Installing compliant signs is only the start. NFPA 101 and OSHA both require documented ongoing maintenance.

Every exit sign must be visually inspected at least once every 30 days to confirm the illumination source is working.² Battery-powered signs need a monthly functional test as well: disconnect the main power (most signs have a test button) and verify the sign stays lit for at least 30 seconds.

Once a year, each battery-powered exit sign must undergo a full 90-minute discharge test to confirm the battery can sustain illumination through the full emergency duration.² A sign that passes a 30-second test can still fail at 45 minutes as the battery degrades. Every inspection and test result must be documented, and any sign that fails must be repaired or replaced promptly.

What Happens If You Don’t Comply

Missing or non-functional exit signs can trigger enforcement from more than one direction. Fire marshals conducting routine inspections can issue code violations and order corrections, sometimes with daily fines until the deficiency is fixed. OSHA can cite employers for exit sign violations under its exit route standards, with serious-violation penalties running into the thousands of dollars per violation and willful or repeated violations carrying substantially higher fines.

Financial exposure grows when someone is injured. If a missing or dark exit sign contributes to a person being hurt during an emergency, the building owner faces premises liability claims, and a code violation documented before the incident becomes strong evidence of negligence. Property owners, business operators, venue managers, and employers can each face liability depending on who controls the space. Against the modest cost of installing and maintaining compliant signs, the exposure from skipping them is difficult to justify.

1
International Code Council. 2024 International Building Code – Chapter 10 Means of Egress
2
National Fire Protection Association. Verifying the Emergency Lighting and Exit Marking
3
eCFR. 29 CFR 1910.37 – Maintenance, Safeguards, and Operational Features for Exit Routes
4
Office of Compliance. Exit and Related Signs – Proper Placement and Visibility Are Essential for Emergency Evacuation
5
U.S. Access Board. Guide to the ADA Accessibility Standards – Chapter 7 Signs