CH 8: MEANS OF EGRESS

The means of egress consists of three parts, which must lead to a public way

1. Exit access 2. The exit 3. Exit discharge

Tread

>11" min depth >10" min depth for private stairways with less than 10 occupants

Exits through Intervening Spaces

>Exiting not permitted through kitchens, storerooms, rest rooms, closets, etc.

What is the exception of the two exits required

>Group R-2 and R-3 occupancies (apartments and condominiums) only one exit is permitted when the occupant load is 20 or less >This allows large apartments to be up to 4000 sqft in area

Temporary Certificate of Occupancy (TCO)

>This allows client to occupy a portion of the space while remainder is completed >May also be called a Partial Certificate of Occupancy

FIre rated door classifications

1. Corridors partition 1 hour or less partition | 20 min door (Door must pass positive pressure fire testing) 2. Smoke barriers partition 1 hour | 20 min door (Door must pass positive pressure fire testing) 3. Fire partition 1 hour | 45 min 4. Occupancy separation 1 hour | 45 min 5. Exit passageway partition 1 hour | 1 hour door 6. Exit stairs partitions 1 hour | 1 hour 7. Exit stairs 2 hours | 1.5 hours

Corridor

>Portion of an exit access leading to an exit >Purpose is to provide safe means of egress from a space to a building exit (i.e. stairway) >When 2 exits are required, they must be laid out so it is possible to travel in two directions to an exit (If one path is blocked, there will always be another route) >For most corridors serving occupant load of 50 or more, min width must be 44" >For corridors serving occupant load of 50 or less, min width is 36"

Public way

Any street, alley, or similar parcel of land essentially unobstructed from the ground to the sky not less than 10'

Corridor width must not be obstructed except the following:

1. Doors opening into path of egress may reduce required width up to 1/2 during swing, but when fully open, it may not project more than 7" into required width 2. Handrails can't protrude more than 4 1/2" on each side 3. Non structural horizontal projections (ie. trims) can project max. 1 1/2" horizontally from either side 4. Structural elements (light fixtures, furnishings etc.) may project max 4" horizontally, at height of 27-80" above walking surface

Required number of exits or exit access doorways determined by several factors:

1. Occupant load & Occupancy of a space 2. Limitations on common path of egress travel 3. Specific requirements when large occupant loads are encountered

IBC allows egress to pass through stockroom in Group M occupancy for 4 conditions:

1. Stock in stockroom must be same hazard classification as found in main retail area 2. Not more than 50% of exit access can be through the stockroom 3. Stockroom can't be subject to locking from egress side 4. Must be demarcated aisle with 44" min. width

4 common Interior exit stairways exceptions to being enclosed

1.In other than Group I-2 and I-3, Exit access stairways tat serve only 2 stories 2. For single residential dwelling in Group R-1, R-2 or R-3 3. Group B or M, if building has sprinklers, if the area of floor opening between stories is not greater than twice the horizontal projected area of stairway, and opening protected by draft curtain and closely spaced sprinklers in accordance with NFPA 13 4. Occupancies other than B and M if occupancy complies with all items in previous exception AND floor opening doesn't connect more than 4 stories

Interior Exit stairway & interior exit ramp

> An exit component that serves to meet 1 or more means-of-egress requirements

Corridors and fire construction

> Must be 1-hour fire resistant serving occupant load of 10 or more in Group R-1 and I occupancies and when serving more than 30 in other occupancies >All group I occupancies must have a 1 hour rated corridor regardless of occupant load >Sprinklered buildings of Group A, B, E, F, I-2, I-4, M, S and U, corridors don't have to be fire rated >If ceiling of entire story is 1-hour rated, than rated corridor walls can terminate at ceiling, otherwise 1-hour rated corridors must extend through the ceiling to the rated floor above >IBC lists when corridor required to be fire-resistance rated based on OCCUPANCY, OCCUPANT LOAD, and if building is SPRINKLERED

Stairway

>1 or more flights of stairs, with necessary landings and platforms connecting them, forming continuous passage from one level to another >Landings must be provided at top and bottom and min. dimension must not be less than width of stairs but need not be more than 48" if stairs run straight

Exits required based on LARGE OCCUPANT LOADS

>3 exits are required when occupant load between 501-1000 >At least 4 exits required when occupant load greater than 1000

Occupant load factor

>Amount of floor area presumed to be occupied by one person >Based on generic function of building spaces

Area of Refuge

>An area where persons unable to use stairways can remain temporarily to await instructions/assistance during emergency evacuation

Stair

>Change in elevation consisting one or more risers

Means of Egress

>Continuous and unobstructed path of vertical and horizontal egress travel from any point in a building or structure to a public way

To calculate occupant load with fixed seating

>Determined by taking number of fixed seats installed and adding the occupant load of areas in which fixed seating is not installed (i.e. waiting spaces and wheelchair spaces >For fixed seating without dividing arms, the occupant load is based on one person for each 18" >For fixed seating in booths, it is based on 24" per person

Travel Distance (Exit access travel distance)

>Distance that an occupant must travel from most remote point in the occupied portions of the exit access to the entrance to the nearest exit >Because exit access areas are not protected, the codes limit how far someone must travel to safety >Max. travel distance based on OCCUPANCY and whether building is SPRINKLERED or not

Exits required based on COMMON PATH OF EGRESS TRAVEL DISTANCE LIMITATIONS

>Even if occupant load is less than required in the code, if the common path of egress travel exceeds limits in code, then two exits are required

Horizontal exit

>Exit through a minimum 2 hour rated wall that divides a building into two or more separate exit access areas to afford safety from fire and smoke

Exit passageway

>Horizontal, fully enclosed portion of an exit that is only used as means of egress >Leads from exit doorway to exit discharge/public way >I.E. exit from door at ground level of interior stairway that leads through the building to an outside door

To calculate occupant load without fixed seating

>IBC requires that areas without fixed seating be determined by taking the area assigned to a particular use and dividing by an occupant load factor given in code

Exits required based on OCCUPANT LOAD:

>If number of occupants of a space exceeds the maximum occupant load number given in the code, then at least two must be provided

Widths of Exits

>In general, min. width of exits determined by multiplying occupant load by a factor of 0.3" for stairways and 0.2" for egress components other than stairways >With sprinklers, multiplying factors are 0.2" for stairways and 0.15" for egress components other than stairways >WIth multiple stairs, widths calculated from occupant load of each story separately rather than combined occupant load >This results in minimum total exit width in inches; however min width can't be less than specified elsewhere in code >If 2 or more exits are required, the total width must be divided such that the loss of any one means of egress does not reduce the available capacity to less than 50% of the required capacity >If doors are part of required egress width, their clear width must be used

Net floor area

>Includes space that is actually used

Gross floor area

>Includes stairs, corridors, toilet rooms, mechanical rooms, closets, and interior partition thicknesses

Exit access stairway

>Interior stairway that's not a required interior exit stairway

Glass in fire-rated corridors

>It may be used only if it is listed and labeled as 3/4-hour fire-protection rating and total area does not exceed 25% of length of corridor wall of the room that it is separating from the corridor >If fire-resistance-rated glazing is used (ASTM E119) then there is no limitation on percentage of glazing that may be used

Width of stairways serving occupant load of 50 or more:

>Min 44" wide OR as wide as multiplying occupant load by 0.3 or 0.2

Interior Exit stairway

>Must be completely enclosed >with 4 or more stories (including basement), must have 2 hour rated walls >With less than 4 stories, 1 hour rated walls required

Handrails

>Must be provided on both sides of stair >If stairways wider than 5', then must have intermediate handrails >must be located 34-38" above nosing of treads, and extend not less than 12" beyond top riser and less than depth of one tread beyond bottom riser >Space between wall and handrail at least 1.5"

Doors in fire-rated corridors

>Must have min. 20 min fire rating, and include approved smoke and draft control seals around door >Must have self-closing device or be auto closing by actuation of a smoke detector >Both door and frames must have label of testing agency i.e. UL

Occupant load

>Number or people that a building code assumes will occupy a given building/portion of a building >Based on OCCUPANCY CLASSIFICATION >It assumes that certain types of use will be more densely packed with people than others and that exiting provisions should respond accordingly i.e. auditorium needs more exits to allow safe evacuation than does an office space of the same area >When 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 (This provision requires that occupant loads should be cumulative as occupants exit through intervening spaces to an ultimate exit)

Common Path of egress travel

>Portion of exit where occupants are required to traverse before two separate and distinct paths of egress travel to two exits become available

Exit discharge

>Portion of means of egress between the termination of an exit and a public way >Areas typically include portions outside the exterior walls (balconies, exterior exit stairways etc.) >May also include building lobbies of multi-story buildings if one of the exit stairways opens onto the lobby and certain conditions are met (Conditions: exit door in lobby is clearly visible, level of discharge is sprinklered, area of discharge is separated from areas below by the same fire-resistance rating as for the exit enclosure that opens onto it.) >IBC: exterior exit stairways and ramps considered exits, not exit discharge

The Exit

>Portion of the means of egress that provides a PROTECTED path of egress between the exit access and exit discharge >Fully enclosed, and protected from all other interior spaces by FIRE-RESISTANCE-RATED construction with protected openings >May include: exterior exit door at ground level, or exit enclosures for stairs, exit passageways etc. >Depending on building height, construction type, and passageway length, exits must have either a 1 or 2 hour rating >IBC: exterior exit stairways and ramps considered exits, not exit discharge

Exit Access

>Portion of the means of egress to lead to the entrance of an exit >May or may not be protected, depending on code based on OCCUPANCY and CONSTRUCTION type >Include these spaces: hallway, corridors, ramps, rooms etc. >Where travel distance is measured and regulated

Egress Doors

>Provided when serving any hazardous area or an occupant load of 50 or more >Must be pivoted/side hinged and swing in direction of travel >Min. clear width must be 32" >Max. clear width swinging is 48" >Min height must be 80" >Must be operable from inside without use of special knowledge (i.e. panic hardware) >Must have automatic closers and hardware to be approved >Glass in egress doors to be wired glass, and total area limited depending on door's fire rating

Egress doors in fire resistance rated partitions

>Required to have fire rating >Specific fire rating depends on fire rating of partition >In addition to having 20 min fire rating, doors in corridors and smoke barriers require to pass the positive pressure fire testing >If sprinklered, corridors in Group A, B, E, F, I-2, I-4, M, S and U occupancies don't have to have fire rating so fire-protection rated doors not required

Positive pressure fire testing

>Simulates actual fire conditions where positive pressure on fire side of door above a certain part and negative pressure below this point >In these conditions, greater tendency for smoke and gasses to be forced through crack between door and frame >Therefore door must have approved gasketing/intumescent material along its edge or frame

Certificate of Occupancy (CO)

>Sometimes called a letter of occupancy or a use and occupancy (U and O) letter >This document allows client to occupy the space

Riser

>Vertical component connecting 2 treads >4" to 7" height >7.75" min height for private stairways with less than 10 occupants

Arrangement of Exits

>When 2 exits required, they must be placed a distance apart equal to not less than 1/2 the length of max overall diagonal dimension of the building or area to be served >Reasoning is to position exits far enough so fire won't block both exits >If sprinklered building, then exits can't be less than 1/3 the length of max overall diagonal dimension >If 3 or more exits, 2 exits must be placed at distance not less than 1/2 or 1/3 length of max. overall diagonal dim of the building

Residential exiting

>basements and bedrooms must have escape window min. open area of 5.7 sq.ft., with window sill max. 44" a.f.f.; min. clear opening height 24", min. clear width 20" (These requirements in Group R and I-1 occupancies) >Because occupant load less than 50, corridors may be min. 36" wide, and occupant load less than 10, doors may swing into rooms

Dead end corridors

>means of only one exit, generally limited to maximum length of 20' >If building is sprinklered, dead end corridor increased to 50' for certain occupancies >In Group I-3 occupancies of Conditions 2, 3 or 4 maybe have dead end corridor increased to 50' (Conditions refer to specific security arrangements in detention facilities) >Dead ends not limited in length when length of corridor is less than 2 1/2 times narrowest part of dead-end corridor

Width of stairways serving occupant load of 49 or less:

>min. 36" wide

Egress court

A court/yard (part of exit discharge) that provides access to a public way for one or more required exits

Exit access doorway

A door/Access point along path of egress travel from an occupied room, area, or space where path of egress enters an intervening room, corridor, unenclosed exit access stair, or unenclosed exit access ramp

Exit enclosure

A fully enclosed portion of an exit only used as means of egress and provides protected path of egress either in vertical/horizontal direction. In most cases, exit enclosures mean protected stairways. Depending on construction and building type, must have 1 or 2 hour rating, all openings must be protected. This must lead to an exit discharge/public way.