Term
|
Definition
continuous and unobstructed path of vertical and horizontal egress travel from any point in a building or structure to a public way.
means of egress consists of three parts:
1. exit access
2. exit
3. exit discharge
these must lead to a public way. public way is any street, alley or similar parcel of land essentially unobstructed from the ground to the sky that is permanentyl appropriated to the public for public use and has a clear width of not less than 10' |
|
|
Term
|
Definition
portion of the means of egress that leads to the entrance to an exit
may include components such as rooms, spaces, aisles, intervening rooms, hallways, corridors, ramps, and doorways. exit access does not provide a protected path of travel. portion of the building where travel distance is measured and regulated. |
|
|
Term
|
Definition
portion of the egress system that provides a protected path of egress between teh exit access and the exit discharge. exits are fully enclosed adn protected from all otehr interior spaces by fire-resistance-rated construction with protected openings (doors, glass, etc.)
depending on building height, construction types, and passageway length, exits must have either a one or tow hour rating |
|
|
Term
|
Definition
portion of the egress system between the termination of an exit adn a public way. typically include portions outside the exterior walls such as exterior exit balconies, exterior ext stairways, and exit courts. exit discharge may also include building lobbies of multi-story buildings if one fo teh exit stariways opens onto the lobby and certain conditions are met.
conditions require that the exit door in the lobby is clearly visible, level of discharge is sprinklered, and that the entire area of discharge is separated from areas below by the same fire resistance rating as for the exit enclosure that opens onto it. |
|
|
Term
|
Definition
| number of people that a building code assumes will occupy a given building or portion of a building |
|
|
Term
| IBC requires occupant load be established by taking the largest number determined using one of the three methods |
|
Definition
1.establishing the actual number of occupants-the actual number of people the building or space is designed to accommodate becomes the occupant load
2.occupant load is determined by taking the area assigned to a particular use adn dividing by an occupant load factore as given in the code.
3. an occupant load from an accessory space exits through a primary space, the egress facilities from the primary space occupant load must include their own occupant load plus the occupant load of the accessory space. |
|
|
Term
|
Definition
| amount of floor area presumed to be occuped by one person. based on the generic usees of building spaces and is not the same as the occupancy groups |
|
|
Term
|
Definition
includes stairs, corridors, toilet rooms, mechanical rooms, closets, and interior partition thickness.
net floor area includes just the space actually used. |
|
|
Term
| in determining occupant load |
|
Definition
all portions of the building are presumed to be occupied at the same time. however, local building official may reduce the occupant load if the official determines that one area of a building would not normally be occupied while another is occupied. ie a lunchroom of a factory area wher eteh factory workers are either in the work area or teh lunchroom, but not both at the same time.
if there are mixed occupancies or uses, each area is calculated with its respective occupant load factor and then all loads are added together. |
|
|
Term
| what is the occupant load for a restaurant dining room that is 2500 sq. ft |
|
Definition
assembly area=15 sq ft
2500/15= 167 persons |
|
|
Term
| what is occupant load for an office with 3700 sq. ft taht also has two training classrooms of 1200 sq. ft each |
|
Definition
an office (b) has occupant load of 100 sq ft, so 3700/100 = 37 persons
classrooms=occupant load of 20
two class rooms (2400 sq ft/20)=60 each
60x2 + 37= occupant load of 157 |
|
|
Term
| number of exits or exit access dorrways required from a space, gropu of spaces, or an entire building is determined by several factors |
|
Definition
occupant load and occupancy of a space, the limitations on the common path of egress travel, adn specific requirements when large occupant loads are encountered
when the number of occupants of a space exceeds the number given in the code, then at least two exits must be provided. |
|
|
Term
| even if the occupant load of a space or building is less table 18.3, two exits are |
|
Definition
| still required if the common path of egress travel exceeds limits given in the code. |
|
|
Term
| common path of egress travel is that portion of an |
|
Definition
exit acess taht the occupants are required to traverse before two separate adn distinct paths of egress travel to two exits become available.
even if two exits are not required based on the occupant load, if the common path of travel exceeds 75' for all except H-1, H-2, and H-3 occupancies, then two exits from a space are required. the distance is increased to 100' in some occupances if certain conditions are met. ie in B, F, and S occupancies, if the building is fully sprinklered, the max length of a common path of egress travel is increased to 100 feet. |
|
|
Term
| final factor determining number of exits |
|
Definition
| is large occupant load. three exits are required when teh occupant load is between 501 and 1000, and at least four exits are required when the occupant load is greater than 1000. |
|
|
Term
| restaurant dining area of 167 persons |
|
Definition
would require two exits because 167 exceeds 50.
in the 18.2 example, total area of offices and classrooms would require two exits. in addition, each classroom would need two exits b/c the occupant load for each is 60..more than 50 |
|
|
Term
| when two exits are required |
|
Definition
| they must be placed at a distance apart equal to not less than one-half the length of the maximum overall diagonal dimension of the building or area to be served, as measured in a straight line between the exits. reason is to position the exits far enough apart so that a fire or other emergency would not block both exits. |
|
|
Term
| if three or more exits are required |
|
Definition
two exits must be placed a distance apart equal to not less than one-half the length of the max overall diagonal dimension of the building or area to be served, measured in a straight line.
new provision that reduces the minimum separation distance to one-third the max diagonal dimension of the room or are to be served if the building is fully sprinklered. |
|
|
Term
|
Definition
are based on the occupancy of the building and whether or not the building is sprinklered.
in previous UBC, max travel distances were 200 feet in an unsprinklered building and 250 feet in a sprinklered building. these distances coul be increased a max of 100 feet when teh increased travel distance was the last portion of the travel distance and was entirely within a 1-hour rated exit corridor. |
|
|
Term
| most codes allow a room to have one exit through and adjoining room if |
|
Definition
it provides a direct, and obvious and unobstructe means of travel to an exit corridor or other exit as long as the total max travel distances are not exceeded.
however, exiting is not permitted through kitchens, storerooms, rest rooms, closets, or spaces used for similar purposes. in ibc, foyers, lobbies, and reception rooms constructed as required for corridors (with a one hour rated wall) are not considered intervening rooms, so you can exit through these spaces. |
|
|
Term
| required min width of exits is determined by |
|
Definition
multiplying teh occupant load by the appropriate factor given in Table 1005.1 of IBC. resulting number is the total width in inches.
factors are higher for the H & I occupances because of teh increased risk they present. if a greater width is specified somewhere in the code, the larger number must be used. |
|
|
Term
| if two or more exits are required, the total width must be divided |
|
Definition
such that teh loss of any one means of egress does not reduce the available capacity to less than 50% of teh required capactiy
IBC also requires that if doors are part of the required egress width, their clear width must be used, not the width of the door. ie, a 36 inch door actually provides about 33" of clear width when the thickness of the door in teh 90 degree open position and the width of the stop are subtracted from teh full width |
|
|
Term
|
Definition
is 44"
for the doors, b/c at least two exits are required in this example, the total required exit width would be more than satisfied with two 3-foot-wide doors (with a clear opening width of about 33" each) b/c they give a total exit width of 66" |
|
|
Term
|
Definition
portion of an exit access leading to an exit. purpose is to provide a safe means of egress from a room or space to a building exit or to another approved exitway, such as a stairway.
when two exits are required, corridors must be laid out so that it is possible to travel in two directions to an exit.
dead-end corridors are generally limited to a max length of 20 feet. and some instances 50' |
|
|
Term
| minimum width of a corridor |
|
Definition
| in feet is determined by taking the occupant load it serves and multiplying by .2, .15, or another factor given in the code. however, absolute minimus width for most occupancies is 44" if the corridor serves an occupant load of 50 or more. for occupant loads of less than 50, min width is 36" |
|
|
Term
| width of corridor in schools according to IBC |
|
Definition
| must be 72" if occupant load is 100 or more |
|
|
Term
| width of a corridor must be unobstructed, but handrails and fully opened doors |
|
Definition
| can protrude a max of 7" total. other projections such as trim may extend into the width a max of 4" on each side. however, horizontal projections cannot reduce the minimum clear width of accessible routes. |
|
|
Term
| with a few exceptions, corridors must be built |
|
Definition
of one hour fire resistive construction when serving an occupant load of 10 or more in R-1 adn I occupancies and when serving an occupant load of 30 or more in other occupancies.
this must include the walls and ceilings. if the ceiling of the entire story is one-hour rated, then teh rated corridor walls may terminate at the ceiling. otherwise, the one-hour rated corridors must extend through the ceiling to the rated floor or roof above. |
|
|
Term
| doors placed in one-hour corridors must have a fire rating |
|
Definition
| of at least 20 minutes and include teh approved smoke and draft control seals around the door. the door must be maintained self-closing (with a door closer) or be automatic closing by actuation of a smoke detector. both door and frame must bear the label of an approved testing agency, such as UL |
|
|
Term
| glass may be used in one hour rated corridor walls only if |
|
Definition
| it is listed and labeled as 3/4 hour fire protection rating and the total area does not exceed 25% of the area of the corridor wall of the room that is separating from the corridor. |
|
|
Term
| when a duct penetrates a rated corridor |
|
Definition
| is must be provided with a fire damper, which is a device that automatically closes in the event of a fire. |
|
|
Term
| new definition of a corridor makes it clear that |
|
Definition
| it is an exit access component that defines and provides a path of egress travel to an exit. |
|
|
Term
|
Definition
must have a one hour rated corridor if the occupant load is greater than 10, and all I occupancies must have one-hour corridor regardless of the occupant load.
one of the most significant changes is that in a sprinklered building of a,b, e, f, I-1, I-3, M, S, and U occupancy, corridors do not have to be fire-resistive rated. |
|
|
Term
| another change is 20-foot limitation |
|
Definition
| still basic provision, but now B and F occupancies may have 50 foot dead end corridors if the entire building is equipped with an automatic sprinkler system. also, dead ends are not limited in length wher eteh length is less than 2.5 times the least width of teh dead-end corridor. |
|
|
Term
| building code provisions apply to exit doors serving an area of |
|
Definition
| an occupant load of 10 or more. exit doors must be pivoted or side-hinged and must swing in the direction of travel when serving any hazardous area or when serving an occupant load of 50 or more. |
|
|
Term
| doors must also not swing into the path of travel |
|
Definition
such as into a corridor. in many instances you must recess doors that swing into corridors.
certain occupancies require panic hardware; hardware that unlatches the door when pressure is applied against it rather than requiring a turning motion with a door knob or lever handle. |
|
|
Term
| also requirements on the door on the |
|
Definition
| maximum force needed to unlatch the lock, set the door in motion, an dswing it to a full-open position. doors with adn without closers are both covered by these types of requirements. |
|
|
Term
| in no case can a door provide less than |
|
Definition
| 32" of clear width when the door is open at 90 degrees. basically means a 36" door must be used to allow for teh decrease in width due to the stop and thickness of the door when open. |
|
|
Term
| exit doors in fire-resistance partitions are required to have a |
|
Definition
fire rating. the specific fire rating varies depending on the rating of the partition.
in addition to having a 20-minute fire rating, dorrs in corridors and smoke barriers must meet the requirements for positive pressure fire testing.
*positive pressure fire testing simulates actual fire conditions where there is positive pressure on teh fire side of the door above a certain point on the door (called the neutral pressure level) and negative pressure below this point. |
|
|
Term
| to meet the requirements of positive prssure fire testing a door must have |
|
Definition
| approved gasketing or intumescent material along its edge or frame. *intumescnent material is one that swells and chars when exposed to heat to form a barrier to smoke and fire. |
|
|
Term
|
Definition
| automatic closers, and all hardware must be tested and approved for use on fire exits. when closed, must provide a tight seal against smoke and drafts. glass in exit doors must be wired glass, and its total area is limited depending on the door's fire rating. |
|
|
Term
| in most cases, special doors such as revolving, sliding, and overhead doors |
|
Definition
| are not considered required exits. power-operated and revolving are sometimes allowed if they meet certain requirements. revolving doors, for example, must have leaves that collapse under opposing pressure and must have a diameter of at least 6'6". there must also be at least one conforming exit door within 10 feet of the revolving door. |
|
|
Term
| stairways serving an occupant load of 50 or more must |
|
Definition
| be at least 44" wide or as wide as determined by multiplying the occupant load by .3 or another factor as discussed previously. those serving an occupant load of 49 or less must not be less than 36" wide. handrails may project into the required 4 1/2" on each side. |
|
|
Term
| the riser on the stair cannot be less than |
|
Definition
4" or more than 7", and the tread must be no less than 11". risers for barrier free stairs cannot exceed 7"; treads must have an acceptable nosing design.
*for residential occupancies and private stairs serving an occupant load of less than 10, the max riser may be 7 3/4" and min tread may be 10" |
|
|
Term
| winding, circular, and spiral stairways may be used as exits |
|
Definition
in R-3 and in private stairways of R-1 and only if they meet design conditions as specified in the code.
landings must be provided at the top and bottom of every stair. min dimension in the direction of travel must not be less than the width of teh stair but need not be more than 44" if the stair is a a straight run. |
|
|
Term
| handrails must be provided on both sides fo the stair |
|
Definition
intermediate handrails are required so that all portions of the stairway width required for egress capacity are within 30" of a handrail. another way of stating is that stairways wider than 5' must have intermediate handrails.
*IBC defines a stair as one or more risers, so even one step now requires handrails. exception applies to decks, patios, and walkways, single risers at entry doors of R-3 and single risers in dwelling of R-2 and R-3 |
|
|
Term
| top of the handrail must be between |
|
Definition
| 34 and 38" above the nosing of the treads and must extend not less than one tread depth beyond the top riser adn not less than 12" plus teh depth of one tread beyond the bottom riser. ends must be returned to teh wall or floor or terminate in a newel post. gripping portion cannot be less than 1.25" or more than 2" in cross-sectional dimension. must be a space of at least 1.5" wide between the wall and the handrail. |
|
|
Term
| only one exit is required from teh basement or second story of a house |
|
Definition
| however, basements and bedrooms must have an escape window with a min. openable area of 5.7 sq. ft with the windowsill no more than 44" above the floor. min clear opening height is 24" and min clear width is 20" |
|
|
Term
| unlike most commercial construction, residential exits may pass through |
|
Definition
| kitchens, storerooms, and similar spaces. b/c the occupant load is less than 50, corridors may be a min of 36" wide (but too narrow for access.). also, b/c occupant load is less than 10, doors may swing into rooms so there is not a problem with the corridors being blocked. |
|
|
Term
|
Definition
| an area where persons unable to use stairways can remain temporarily to await instructions or assitance during emergency evacuation. |
|
|
Term
|
Definition
| enclosed exit access component that defines and provides a path of egress travel to an exit. corridor may or may not be protected depending on the particular requirements of the code. |
|
|
Term
|
Definition
| court or yard (considered part of an exit discharge) that provides access to a public way for one or more required exits. in IBC now called an egress court. |
|
|
Term
|
Definition
| fully enclosed portion of an exit that is only used as a means of egress and that provides for a protected path of egress either in a vertical or horizontal direction. in most instances, exit enclosures mean protected stairways. depending on construction type adn building type, an exit enclosure must have either a one hour or two hour rating, adn all openings must be protected. an exit enclosure must lead to an exit discharge or public way. |
|
|
Term
|
Definition
| fully enclosed portion of an exit that is only used as a means of egress and that provides for a protected path of egress either in a vertical or horizontal direction. in most instances, exit enclosures mean protected stairways. depending on construction type adn building type, an exit enclosure must have either a one hour or two hour rating, adn all openings must be protected. an exit enclosure must lead to an exit discharge or public way. |
|
|
Term
|
Definition
| horizontal, fully enclosed portion of an exit that is only used as a means of egress. exit passageway leads from an exit doorway to an exit discharge or public way. common example of an exit passageway is an exit from the door at the ground level of an interior stairway that leads through the building to an outside door. |
|
|
Term
|
Definition
| exit through a minimum two-hour rated wall that divides a building into two or more separate exit access ares to afford safety from fire and smoke. |
|
|
Term
|
Definition
| change in elevation, consisting of one or more risers |
|
|
Term
|
Definition
| one or more flights of stairs, either exterior or interior, with the necessary landings and platforms connecting them, to form a continuous adn uninterrupted passage from one level to another. |
|
|
Term
|
Definition
| measurement of teh distance between the most remote, occupiable point of an are or room to the entrance of the nearest exit that serves it. is part of the exit acess and is measured in a straight line along the path of exit travel. |
|
|
