1. ID 234 Building Codes
Fall 2012
Means of Egress
Chapter 4

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

3. 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

4. Simplest scenario: One story

5. Next simplest: multi-story

6. OK, now it’s getting complicated…

7. Defend in place: @ stair

8. Defend in place: horizontal exit

9. Evacuation vs. Defend in Place

10. 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

11. Exit passageways: extension of the exit

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

13. What are the parts of the egress system?

14. What are the parts of the egress system?

15. Stairs and ramps

16. 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)

17. Overall stair dimensions

18. Stair dimensions

19. Areas of Refuge

20. Guard rails

21. Ramp railing dimensions

22. Corridors

23. Corridor clearances

24. Door clearances

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

26. Exit Signs

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

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

29. 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

30. Area Allowance per occupant

31. Gross area

32. Net area

34. Sample calculation

35. Posted Occupant Load

36. Maximum number of occupants

37. Number of Exits

39. 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

40. Separation of Exits

42. Half Diagonal Rule (1/3 with sprinklers)

43. Exit Access Travel Distance

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

45. Doorways and Doors

46. Exit Widths

47. 521 CMR Section 25 Entrances

48. Door Dimensions

49. Another Checklist

51. Use a key for specific occupancy types

53. Other information can be shown

54. 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

55. Area Allowance per occupant

56. Number of Exits

57. Exit Widths

58. 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