Multi-level parking garage under multi-story apartment --> accumulating occupant load

[cambrea]

I'm calculating stair width for a building. Starting from the top,

- 6th floor: Apartment : Occupant Load = 60

- 5th floor: Apartment : Occupant Load = 60

- 4th floor: Apartment : Occupant Load = 60

- 3rd floor: Parking Garage for apartment : Occupant Load = 90

- 2nd floor: Parking Garage for apartment : Occupant Load = 90

- 1st floor: Retail Use .... (not counting occupant load for stair width calculation)

Total number of occupant from 2nd to 6th floor is 360.

However, parking garage will be used by residents who will live on top of parking garage.

Should I use total accumulated occupant load?..... Or only 180 (either occupant number for residential above)?

Thank you in advance.

 

[mark handler]

The Total occupant load is the primary space plus the number of occupants egressing from the accessory area.

 

[cda]

Welcome....

 

[mark handler]

And welcome....

 

[cda]

http://publicecodes.cyberregs.com/icod/ibc/2009f2cc/icod_ibc_2009f2cc_10_par026.htm?bu2=undefined

 

[Francis Vineyard]

Also review 1004; http://publicecodes.cyberregs.com/icod/ibc/2009f2cc/icod_ibc_2009f2cc_10_sec004.htm?bu2=undefined

 

[north star]

@ ~ @ ~ @

cambrea,

Welcome to The Building Codes Forum !

@ ~ @ ~ @

 

[Paul Sweet]

You would design the stairs on the upper stories for 30 occupants, and the lower stories for 45 (the number from each floor who use the stair for egress). This is based on the occupant load being the total per floor,and there being 2 stairways.

By the time the occupants from an upper floor have reached the lower floor, the occupants from the lower floor will be going down the stairway, so you don't have to design for the cumulative number of occupants. The exception is when a basement stair (where people are going up to exit) and a stair from upper levels converge.

 

[mark handler]

You would design the stairs on the upper stories for 30 occupants, and the lower stories for 45 (the number from each floor who use the stair for egress). This is based on the occupant load being the total per floor,and there being 2 stairways.By the time the occupants from an upper floor have reached the lower floor, the occupants from the lower floor will be going down the stairway, so you don't have to design for the cumulative number of occupants. The exception is when a basement stair (where people are going up to exit) and a stair from upper levels converge.

Provide code section. ....

 

[mtlogcabin]

1004.1.1 Cumulative occupant loads.

Where the path of egress travel includes intervening rooms, areas or spaces, cumulative occupant loads shall be determined in accordance with this section.

1004.1.1.1 Intervening spaces.

Where occupants egress from one room, area or space through another, the design occupant load shall be based on the cumulative occupant loads of all rooms, areas or spaces to that point along the path of egress travel.

1004.1.1.2 Adjacent levels.

The occupant load of a mezzanine or story with egress through a room, area or space on an adjacent level shall be added to the occupant load of that room, area or space.

1005.3.1 Stairways.

The capacity, in inches (mm), of means of egress stairways shall be calculated by multiplying the occupant load served by such stairway by a means of egress capacity factor of 0.3 inch (7.6 mm) per occupant. Where stairways serve more than one story, only the occupant load of each story considered individually shall be used in calculating the required capacity of the stairways serving that story.

 

[mtlogcabin]

Legacy codes did have a cascading factor if I remember correctly

 

[jdfruit]

Cascade factor from legacy codes replaced with story maximum width based on occupant load to be maintained in egress direction.

 

[mark handler]

1005.3.1 Stairways.

The capacity, in inches (mm), of means of egress stairways shall be calculated by multiplying the occupant load served by such stairway by a means of egress capacity factor of 0.3 inch (7.6 mm) per occupant. Where stairways serve more than one story, only the occupant load of each story considered individually shall be used in calculating the required capacity of the stairways serving that story.

Well that's a new section, for CA

Thanks for pointing it out to me

 

[JBI]

Cumulative only used for the level above and below exit discharge, as those will arrive at the exit door at about the same time. With no below grade levels it is not required.