A phenomenal breakdown on single stairs from Tom Jaleski, an architect and code analyst with SGH.
1/ “The building code debate over Single Egress Stair buildings misframes the entire question. It's not "can one stair be as safe as two stairs?"
It's "are prevention-based protection measures more effective than redundancy-based compensation?"
The data says yes.
Three protection layers in SES buildings:
Layer 1 - Automatic Suppression
NFPA research: 98% of fires in sprinklered residential buildings were controlled by the sprinklers.
Only 4% exceeded room of origin.
Sprinklers prevent the failure mode that redundancy compensates for.
Layer 2 - Comprehensive Detection
Smoke detection in all corridors and stairs provides warning BEFORE egress paths fail.
Detection intervenes at step 4 of the failure chain; redundancy provides value at step 5, after the failure is complete.
Layer 3 - Evacuation Speed
Minnesota DLI study: 30-second fire floor evacuation in SES buildings.
Large buildings: 60+ seconds with queuing at stair doors, using both stairs.
At T+30s when SES fire floors are clear, large buildings still have 100+ occupants in corridors.
If compartment breach occurs at T+45s (unlikely), SES has zero exposure; large building has dozens of exposed occupants.
Quote
Jason,
@jasonc_nc
I’m beating a dead horse at this point but the other dumb thing is it isn’t about cost savings from eliminating stairs. The starting assumption shows a complete lack of understanding.
The purpose of single stair is the ability to design small infill buildings, with more family x.com/CGYFireFighter…
