Performance Based Design

Apartment Smoke Movement Analysis

Fire modeling analysis to demonstrate smoke movement from open exterior balconies



During permit plan review, the AHJ challenged the provision of NFPA 101 which states that “outside stairs shall be arranged to restrict the accumulation of smoke”. Due to the unique architecture of these buildings, the AHJ wanted confirmation that the arrangement of the exit access balconies openings would support natural smoke movement to maintain safe egress.


We performed fire modeling to simulate likely fire scenarios and smoke movement from the open exit access breezeways. We determined that the building was provided with sufficient openings to maintain tenability throughout the means of egress.

Bottom Line

Fire modeling analysis supported the open balcony arrangement without any design changes

Resolved AHJ comment without providing enclosed stairs

Assisted the Client in avoiding significant project delays and cost overruns

Services Provided

Performance Based Design


NFPA 101 Section

Outside Stair (NFPA 101)

Outside Stair 50% open

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