Means of Egress Chapter 4 Definition A Means

Means of Egress Chapter 4

Definition A Means of Egress is a continuous and unobstructed path of travel from any point in a building to its exterior or public way. Vertical and horizontal passageways Doorways Corridors Stairs Ramps Enclosures and intervening rooms Does not include elevators and escalators

Types of Means of Egress Each code divides a means of egress into four main categories: Exit Access (path of travel leading to the exit) Exit (doors, or stairwells, have higher fire rating) Exit discharge (main lobby, vestibule, courtyard, alley) Public way (sidewalk)

Exit Access Components Requirements for: Doors Stairs Ramps corridors

Doors Minimum of 6’-8” high Minimum of 32” clear (36” door) Doors must swing in the direction of travel (except rooms with occupancies under 50) Doors cannot reduce landing widths. Doors cannot project more than 7” into the egress corridor. Doors cannot be wider than 4’. If you need 60”, you would plan for 2 doors. Maximum force of 5 lbs Thresholds not higher than ½” (1/4” with bevel on both sides for ADA)

Door Clearances

Doors Cont… Special hardware (48” AFF max. ) Lever Push U-shaped Door Closures Sweep period of 5 seconds at 5 lbs Door Signage Center at 60” on latch side of door Braille Contrasting colors

Elevators Not typically considered a means of egress To be part of the means of egress, it must: Standby power Be adjacent to area of refuge Building with one elevator must have at least one accessible elevator with the exception of some 2 story buildings

Exit Access Stairs Exit Access stairs are not exit stairs. Do not require fire rated walls unless connecting more than two floors

Stairs Once the riser height is determined, it cannot fluctuate more than a small fraction from step to step. Each run of stairs must have a landing at the top and the bottom.

Stairs cannot rise more than 12 feet without an intermediate platform or landing. Most stairs require handrails on both sides. Wide stairs will require intermediate rails. Handrails must extend 12” beyond the top and bottom step.

Hand rails Handrails are often the only guide available when stairs are full of smoke.

Ramps Maximum ratio of rise to run is 1 to 12. For every vertical rise of 1”, the horizontal run must extend 12 inches.

Exit Access Corridors Any corridor leading to the exit in a building. Non-rated 1 hour rated Both the width and length (travel distance) are limited by codes. Codes will require special clearances for: Minimum clearances that must be met Passing spaces in extra long corridors Maximum depth of objects protruding into the corridor

Exit Access Aisles Created by furniture and equipment Fixed seating Panel systems Tables Details on Corridors and Aisles a will be discussed later in lecture

Aisle and Aisle Accessways

Adjoining/ Intervening Rooms Be as direct as possible OK to pass through: Reception areas Lobbies foyers Exit access corridors cannot pass through: Storerooms Restrooms Closets Bedrooms Rooms subject to locking

Exits Components include: Exterior Doors Exit Stairs Horizontal Exits Exit Passageway

Exits An exit is the portion of the means of egress that is separated from all other spaces of the building. Fully enclosed and fire rated (1 – 2 hours) Exit doors: located in an exterior wall Exit Stair: fire rated enclosure, doors swing in direction of egress Horizontal Exit: leads to an area of refuge Exit passageway: fire rated corridor leading to an exit

Exit Discharges Components: Main Lobby Foyer/Vestibule Discharge Corridor Exit Court Small alley or sidewalk

Exit Discharges The part of a means of egress that connects an exit with a public way, typically on the ground floor. Main Lobby: most common interior exit discharge Foyer or Vestibule: a small enclosure on the ground floor Discharge corridor: not recommended, usually must have sprinklers Exit court: an exterior courtyard or patio Small alley or sidewalk: width less than 10’ is not a public way. An exterior exit discharge leading to a larger alley , sidewalk or street.

Means of Egress Capacity Number of exits Exit widths Arrangement of exits Travel distance

Means of Egress Capacity The questions, how many, how large, and what locations must be answered on each project whether you are changing a room, tenant space, working on one floor or an entire building.

Number of Exits Determined first Most codes require a minimum of 2 exits Based on occupancy load of the space or building Use table 2. 8 in Chapter 2 for O. L. 1 -500 requires 2 exits 500 -1000 requires 3 exits Over 1000 requires 4 exits

Number of Exits The floor with the largest o. l. determines the number of exits below that floor. In a multistory building, you cannot decrease the number of exits as you proceed along the egress path toward the exit public way. When designing a portion of an existing building, it is your responsibility to check with the other areas to make sure the existing exits will accommodate the addition you are working on. You may need to add an exit.

Number of Exits If a business tenant space is occupied by 50 or more people and contains more than 2000 sq. feet, it will require 2 exits.

Exit Widths Determined the same way in all codes and the LSC. The minimum width determined must be maintained throughout the path of travel to the exit discharge or public way. Based on O. L. of an area or floor In multistory buildings, it will be based on the floor with the larges O. L. Exit widths must also be determined for every enclosed area and separate tenant space.

Exit Widths Most common variables Vary from code to code (page 156) 0. 3 for exit stairs 0. 2 for level exits

Example 1 – Tenant Determine Exit width for Area A Space A requires 2 means of egress (more than 50 occupants) 125 (o. l) x 0. 2 (level factor) = 25” div. by 2 = 12. 5 inches. Therefore, two 36” doors will be required. Alcove must be 36” + 18” + 4” or 58” wide.

Example 2 – Stair width Determine Stair exit width Fig. 4. 17 page 156 says use. 3 as width factor for stairs. Determine o. l for entire floor. (324 occupants) 324 x. 3 = 97. 2 inches or 97 Divided by 2 = 48. 5 “ or 49 The stair widths must be a minimum of 49 inches wide

Example 3 - corridor width Figure Corridor width leading to exit stairs Each stair will serve ½ of the total occupants 324 divided by 2 = 162 x 0. 2 = 33” Door leading to exit can be 36” width Corridor minimum is 44” per code 36” + 4” + 12” = 52” min. The alcoves will allow the 60” for wheelchair turn around space.

Arrangement of Exits Must be located as remotely from each other as possible so that if one becomes blocked during an emergency the other(s) may still be reached. Half-Diagonal Rule: the distance between two exits must be at least half of the longest diagonal distance within the building. Keep in mind that codes also place a maximum travel distance on the length of an exit access.

Example 1 The shape does not matter Find the longest diagonal, then take ½ of the length. This result will indicate how far apart the exits must be. This is a minimum number.

Arrangement of Exits Some codes will have exception to the rule if the entire building is equipped with an automatic sprinkler system. The ½ measurement may reduce to 1/3. In addition to the ½ diagonal rule, the IBC requires exits to be a minimum of 30 feet apart to assure that the exits are not too close. Ideally, the best scenario is to allow every occupant the choice of two exit paths no matter where he or she is located.

Example 2 Building with a fire rated corridor Find the diagonal length for the entire floor Find the diagonal length for the tenant space The ½ diagonal distance between the exits is measured along the path of travel within the rated corridor.

Travel Distance Travel distance is the measurement of an exit access. It is the measurement of the distance between the most remote occupied point of an area, room or space to the exit that serves it. Codes dictate: travel distance within a single space (known as the common path of travel) Length of travel distance from anywhere in a building to the exit

Travel Distance Within a Single Space Travel distance within a single space is important if only one exit is required. If it takes more than 75’, a second exit will be required even if not required by the O. L. The addition of a sprinkler system will change this requirement. (100 feet)

Travel Distance for an Entire Building Each code has its own table. It is not measured in a straight line Measure from the most remote point (corner of a room) and move in a direct path toward the exit, moving around any obstructions such as walls, furniture and equipment. Maximum of 200’ for unsprinkled and 250’ for sprinkled.

Example 1 Measuring travel distance: 1 st calculate number of exits required based on O. L. Start measuring 1 foot from wall and 1 foot from all obstacles. Stop at center of exit access door and total the measurement Longest is 57 feet which does not exceed the 75’ rule (a second exit is not required)

Example 2 Calculate the travel distance to the exit of the building floor. Begin at most remote point as previously determined, but continue to the center of the exit door. Total is 81 feet which meets the requirement of 200 and 250 feet. This layout meets codes.

Dead End Corridors A corridor with only one direction of exit. Must retrace your steps to get out. Can be deadly in a fire. Maximum of 20 feet is most common.

Signage Required wherever two or more exits are required for a particular floor space. Must be installed at all doors of stair enclosures, exit passageways and horizontal exits. Installed at all exterior exit doors. No point within the exit access can be more than 100 feet from the nearest visible sign. use signs with arrows to indicate direction to nearest exit. Ceiling mounted or wall mounted, 80” AFF.

Exit Signs Note: No point within the exit access can be more than 100 fee from the nearest visible sign.

Exit Lighting Also known as emergency lighting. Connected to a backup system in case of a power failure. Must be lit at all times. 1 foot candle.

Egress Exercises