ID 234 Building Codes Fall 2012 Means of Egress Chapter 4

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

Key terms Building core Common path of travel Corridor Means of egress Means of escape Natural path of travel Occupant load Passageway Stairway Story Tenant Evacuation Defend in Place

Simplest scenario: One story

Next simplest: multi-story

OK, now it’s getting complicated…

Defend in place: @ stair

Defend in place: horizontal exit

Evacuation vs. Defend in Place

Egress system components Exit Access – anything (occupied room, space, doorway, aisle, corridor, stair, or ramp) on the way to the exit Exit – any protected, fully enclosed space between the exit access and the exit discharge Area of refuge – a protected waiting place within the egress system Exit discharge – any portion of a means of egress between the termination of the exit and the public way Public way – 10’w x 10’h Area of refuge – temporary holding space for an emergency evacuation

Exit passageways: extension of the exit

Diagram of system components: you should be able to do this

What are the parts of the egress system?

What are the parts of the egress system?

Stairs and ramps

General requirements for stairs Minimum width 44” (non-residential) Rise and run dimensions Cannot get more narrow Landings based on vertical rise Guard rails when drop >27” Handrails both sides (non-residential)

Overall stair dimensions

Stair dimensions

Areas of Refuge

Guard rails

Ramp railing dimensions

Corridors

Corridor clearances

Door clearances

Exit Access travel distance Choose the most remote part of plan to the furthest exit

Exit Signs

Aisles and Accessways: an aisle accessway gives you access to the aisle

Egress system capacity First calculate occupant load Number of exits Capacity of Exits Capacity of corridors

Calculating Occupant Load Use chart in code to identify Specific Occupancy Areas (in 781 CMR Ch. 10) Create/import Occupancy Calculations schedule and fill out for each room from Revit Create 1/32” scale Occupancy Plan and add color scheme Adjust areas for circulation, furniture, etc, and enter into chart for each level Chart calculates toilets, egress component dimension Fix your plans to comply

Area Allowance per occupant

Gross area

Net area

Sample calculation

Posted Occupant Load

Maximum number of occupants

Number of Exits

Emergency Lighting Required when two or more exits are required Emergency electrical system or battery General exit lighting and exit signs must be lit at all times

Separation of Exits

Half Diagonal Rule (1/3 with sprinklers)

Exit Access Travel Distance

Travel Distance Example Your diagram: On title page Show only longest path

Doorways and Doors

Exit Widths

521 CMR Section 25 Entrances

Door Dimensions

Another Checklist

Use a key for specific occupancy types

Other information can be shown

Applying this knowledge: For a non-sprinklered project with 6000 sf restaurant Total number of occupants Required number of exits Total minimum dimension of egress components

Area Allowance per occupant

Number of Exits

Exit Widths

You want extra credit, right? Code Analysis for new science center (in the Academic Center corridor) Identify the following: Occupancy of the building Construction Type of the building Total occupancy of the building and by floor Total number of exits on the main floor Number of fire rated stairs Number of fire rated shafts Fire rating of those fire rated walls