234 ID CHAPTER 2

Chapter 4ID 234 Building CodesFall 2012

Means of EgressA continuous and unobstructed path of travel from any point in a building to its exterior or public way.

Key termsBuilding coreCommon path of travelCorridorMeans of egressMeans of escapeNatural path of travelOccupant loadPassagewayStairwayStoryTenantEvacuationDefend in Place

Simplest scenario: One story

Next simplest: multi-story

OK, now its getting complicated

Defend in place: @ stair

Defend in place: horizontal exit

Evacuation vs. Defend in Place

Egress system componentsExit Access anything (occupied room, space, doorway, aisle, corridor, stair, or ramp) on the way to the exitExit any protected, fully enclosed space between the exit access and the exit dischargeArea of refuge a protected waiting place within the egress systemExit discharge any portion of a means of egress between the termination of the exit and the public wayPublic way 10w x 10hArea of refuge temporary holding space for an emergency evacuationExit 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 rampsGeneral requirements for stairsMinimum width 44 (non-residential)Rise and run dimensionsCannot get more narrowLandings based on vertical riseGuard rails when drop >27Handrails both sides (non-residential)Overall stair dimensions

Stair dimensions

Areas of Refuge

Guard rails

Ramp railing dimensions

CorridorsCorridor clearances

Door clearances

Exit Access travel distanceChoose the most remote part of plan to the furthest exitExit Signs

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

First calculate occupant loadNumber of exitsCapacity of ExitsCapacity of corridors

Egress system capacityCalculating Occupant LoadUse 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 RevitCreate 1/32 scale Occupancy Plan and add color schemeAdjust areas for circulation, furniture, etc, and enter into chart for each levelChart calculates toilets, egress component dimensionFix your plans to complyArea Allowance per occupant

Gross area

Net area

Sample calculation

Posted Occupant Load

Maximum number of occupants

Number of Exits

Emergency LightingRequired 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 pageShow only longest pathDoorways and DoorsExit Widths

521 CMR Section 25 Entrances

Door Dimensions

Another Checklist

Use a key for specific occupancy types

Other information can be shownApplying this knowledge: For a non-sprinklered project with 6000 sf restaurantTotal number of occupantsRequired number of exitsTotal minimum dimension of egress componentsArea 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 buildingConstruction Type of the buildingTotal occupancy of the building and by floorTotal number of exits on the main floorNumber of fire rated stairsNumber of fire rated shaftsFire rating of those fire rated walls