- 1. Means of Egress
- The function of an egress system is to conduct occupants of a
building to a safe place in case of fire or other emergency.
- A safe place is usually a public way or other large open space
at ground level.
- For the occupants of the upper floors of a tall building, or
for people who are incapacitated or physically restrained, the safe
place may be a fire-protected area of refuge within a
building.
2. M E A C N O S M P O O F N E E N G T R S E S S 3. Means of
Egress
- Components of an Egress System
- Exit Access a corridor, an aisle, a path across a room, or a
short stair or ramp that conducts the occupants of a building to an
exit.
- Exit a protected means of evacuation (door opening, an enclosed
and protected exit passageway leading to a door, or an enclosed
exit stair or ramp) from an exit access to a safe discharge point,
must be of 2 hour construction with self closing doors rated at 1
1/2 hrs.
- Exit Discharge a means (door, protected exit corridor, path
across a ground floor vestibule or lobby) of moving from an exit to
a safe discharge point (public way or other large open area.)
4. Two Remote Exits
- Most buildings require at least two separate exits. These must
be as remote from each other as possible and arranged to minimize
the possibility that a single fire or other emergency condition
could simultaneously render both exits unsafe or inaccessible.With
only minor exceptions, the access path to an exit may not pass
through kitchens, restrooms, storerooms, workrooms, bedrooms,
hazardous areas, or rooms subject to being locked.
5. Distance Between Exits
- The minimum distance between exits is one-half the diagonal
measurement of the building or the space served by the exits. On an
open floor, this is measured as a straight-line distance between
exits. Where the exits are joined by an exit access corridor that
is protected from fire as specified by the building code, this
distance is measured along the path through the corridor.
6. Dead-End Corridors
- Dead-end pockets in exit access corridors are undesirable, but
they are tolerated for most building occupancies within the length
restrictions listed in each model code.
- General Rule is that a dead-end corridor must be 20 or less in
length.
7. Maximum Travel Distance
- Maximum travel distance to the nearest exit is specified by the
code.Travel distance is always measured along the actual path
occupants must take to reach an exit.There are two way to measure
as shown on the diagram.The code will dictate which way you must
measure it.
8. Doors
- Doors should always swing in the direction of egress travel in
all buildings except single family dwellings and in all rooms
except those with fewer than 50 occupants.
- Obstructions of the required egress width are allowed as
follows:
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- Half of required width when door is open 90 degrees
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- 7into the required width of a corridor or aisle when door is
fully open
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- 3 into the required width of a stair or stair landing
- Even locked, doors along an exit path must be easily openable
in the direction of egress travel
- Exit access corridors must be enclosed in fire-resistant walls
and accessed via fire-resistant doors.One-hour walls with 20-minute
doors are required in most buildings.
9. Doors 10. Direct Exit
- The simplest exit is a door opening directly from an interior
room to a public way, as it might from an exhibition hall, theater
or classroom
11. Exit Stairway
- The most common type of exit is an enclosed stairway. The
enclosure must be of 2-hour construction with 1 hour self-closing
doors that swing in the direction of egress travel. (In other
words, doors must swing into the stairway enclosure except at the
level of exit discharge, where they must swing out.)Stairway and
landing widths are determined in accordance with the occupant load
they serve and are calculated according the guidelines in the
prevailing codes.
12. Exit Stairway 13. Exit Passageway
- An exit passageway is a horizontal means of exit travel that is
protected from fire in the same manner as an enclosed interior exit
stair (2-hour walls, 1 1/2-hour self-closing doors).An exit
passageway has several uses: It may be used to preserve the
continuity of enclosure for an exit stair whose location shifts
laterally as it descends through the building. It may be used to
eliminate excessive travel distance to an exit. And it may be used
as part of an exit discharge, to connect an enclosed stair to an
exterior door.
- The widths of passages, doors, landings, and stairs used as
exits must be determined in accordance with values given by the
various codes.
14. Exit Passageway 15. Misc. Means of Egress Concepts
- Smokeproof Enclosure designed to limit the penetration of smoke
and heat from a fire into an exit stairway to such an extent that
the stairway is likely to remain usable throughout the course of a
fire in a building.It is a place of safe refuge for people unable
to use stairs.
- Outside Stairways and Fire Escapes exterior means of egress
with either solid treads (outside stairway) or open treads (fire
escape), they must meet all the requirements of inside fire
stairs
16. Misc. Means of Egress Concepts
- Horizontal Exits a way of passage through a fire-resistant wall
to an area of refuge on the same level in the same building, must
have tight fitting, self-closing1 hour doors
- Stair Proportions Maximum riser height is 7, minimum tread
depth 11
- Ramp Proportions 1:8 for general exit ramps, 1:12 for
handicapped exit ramps (1:20 is better for handicapped exit
ramps)
17. Means of Egress Problems
- Problem #1:Design an exit for a department store basement,
sprinklered, dimensions 105-0 x 292-6.
- Problem #2:Design the exits for a lecture hall, sprinklered,
dimensions 84-0 x 80-0.
- Problem #3:Design the exits for a night club, not sprinklered,
dimensions 162-0 x 100-0.
- Problem #4:Design the exits for a lecture hall, sprinklered,
dimensions 63-0 x 80-0.