ID 234 Building Codes Fall 2012 Vertical Components of Egress

Multi-step process Design compartmentation (egress) system Design compartmentation (egress) system Calculate occupancy Calculate occupancy Calculate width of stair Calculate width of stair Calculate rise and run of stair Calculate rise and run of stair Lay out stair on all levels Lay out stair on all levels Lay out adjacent spaces (areas of refuge, lobbies) Lay out adjacent spaces (areas of refuge, lobbies)

Means of Egress: A continuous and unobstructed path of travel from any point in a building to it’s exterior or public way.

Step 1

multi-story egress diagram

…with a lobby

Defend in place: no sprinklers

Areas of Refuge

Step 2

Half Diagonal Rule (1/3 with sprinklers)

Practice problem: 1-4 Offices 5 Cafe

Practice problem: 14’-0” Floor to floor height 14’-0” Floor to floor height Fully sprinklered Fully sprinklered How many exits required? How many exits required? What is minimum separation of exits? What is minimum separation of exits? What is dimension of the stairs What is dimension of the stairs

Step 3

Area Allowance per occupant

Sample calculation

Number of Exits

Step 4

780 CMR Section 10

Step 5

dimensional requirements Minimum width 44” (non-residential) Minimum width 44” (non-residential) Rise = 7” maximum Rise = 7” maximum Run = 11” minimum Run = 11” minimum Cannot narrow from top to bottom Cannot narrow from top to bottom Landings every 12’-0” vertical (maximum) Landings every 12’-0” vertical (maximum) Guard rails when drop >27” Guard rails when drop >27” Handrails both sides Handrails both sides Handrail extensions Handrail extensions

Stair dimensions

Overall stair dimensions

Guard rails

in our practice problem… What is riser dimension? What is riser dimension? What is the length of the stair? What is the length of the stair? What is the dimension of the stairwell? What is the dimension of the stairwell?

other constraints still apply Door push and pull clearance Door push and pull clearance Panic bars required Panic bars required Minimum head height = 80” Minimum head height = 80” Protruding objects: 4” maximum Protruding objects: 4” maximum Threshold dimensions Threshold dimensions Door closers required Door closers required Maximum area of glass in door: 144 sq. in. Maximum area of glass in door: 144 sq. in. No windows allowed No windows allowed Minimum light level: 11 lux (1 footcandle) Minimum light level: 11 lux (1 footcandle)