7.2 Multi-Family Residential Occupancy

Multi-family residential buildings are unique because they tend to house more elderly, handicapped, and children than do office buildings, which tend to have more able-bodied occupants within working age (18-65). Office buildings of course can have a certain percentage of less-able-bodied populations, depending on the tenancy (e.g., medical offices, social services, or child care centers), and such populations need to be accounted for in the design of these buildings as well. In any case, the occupancy will have a major effect on the evacuation and rescue efforts.

For multi-family residential buildings, it becomes more imperative that primary egress routes, including hallways leading to stairwells, remain as clear of debris and smoke as possible during the evacuation period. This criterion demands a higher level of protection than has been discussed for office buildings. Some recommendations for providing enhanced protection to facilitate evacuation and rescue of distressed populations are listed below.

• Place hallways in a protected location away from the building exterior.
• Do not use glass in the hallways used for primary egress.
• Egress routes should lead to exits that are as far as possible from high-risk areas such as the lobby, mail room, and delivery entrance.
• Create pressurized safe havens in elevator vestibules and stairwells using tightly constructed, air-tight enclosures placed in a protected core area of the building.
• Emergency exits should be easily accessible by emergency vehicles and should be spacious enough to accommodate rescue workers entering the building as well as injured persons exiting the building.
• The side(s) of the building with emergency exits should be free of any canopies, overhanging balconies, or other ornamentation that may fall and block the exits.
• Emergency power should provide sufficient lighting and or phosphorescence to lead persons safely out of the building.
• Avoid using false ceilings in hallways. These can become falling debris that interferes with evacuation.
• Attach light fixtures to the floor system above to avoid hazardous debris in the exit path and to provide emergency lighting.

Multi-family residential construction is more likely than office building construction to incorporate flat plate/slab or pre-fabricated components and therefore tends to be more structurally vulnerable. To improve performance, robust connection detailing becomes paramount to ensure that the connections are not weaker than the members to which they are attached. Also, balconies are more common in multifamily residential buildings. These present a debris hazard due to their inherent instability and connection weakness.