Real estate development, urbanism. Fire trucks are too big, streets are too wide, and the IBC kills good development. Tree canopy aficionado. Sometime restaurateur.
Jason Cox
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The one with 12 units per floor, or the one with just 2?
Reality is the left has a much greater fuel load, far more area to spread, higher risk of large scale collapse, and 6x more spaces & people to clear. And this example is smaller than the norm.
In practice the difference between the two is even greater.
Common single stair limits are a total floor area of just 4,000 sq ft. A double loaded corridor can be 46,000 sq ft.
That’s 11x the size and resulting life safety risk in a fire.
In a single stair building the exit distance to the stairs is ~0 feet and people can evacuate much faster, leaving any remaining numbers far lower than a two-stair building with one of its two stairs compromised.
Arguments against single stair buildings don’t hold up once you see what’s considered a safe distance currently.
Fire code allows a 250 ft corridor for a sprinklered apartment building. You might say “but they have 2 stairs if one is compromised”. Except code also allows a 50’ dead-end corridor.
The total number of units at risk per floor in this example is 4. Common single stairs proposals have limits of 4-6 suites per floor - placing them equal to or less than what current code already allows.
If the top is, by code, safe then claims the bottom is a danger to public safety falls apart.
The top example here is 2 units per stair. The right is 8. Even if you accept the attack stair argument that means 8x more people need to evacuate from a single escape stair. 16x more if we’re assuming the worst case of a stairway itself being compromised.
Choosing single stair rather than point access block as the common term has been a disservice. It’s led to firefighters reflexively seeing “one stair” and rejecting the idea, rather than actually looking at scale and response.
The core, real question re: single stair buildings to rank and file firefighters should be this:
Which of these 2 buildings would you prefer in an active fire? Which is more likely to reach a point where you need to call in more help, delaying full response and increasing risk for anyone inside?
The even better point is that code officials should not let firefighters dictate building science. They don’t know what they’re talking about.
How many units in this top example sit on the “wrong side” of the two stairs at each end, meaning they would be trapped if that stairway was compromised? You’ll count 6 each.
Meanwhile single stair buildings have little to no corridor. (See the small building example at bottom).
Jason Cox
Jason Cox
Jason Cox
Jason Cox
Jason Cox
Jason Cox
Jason Cox
Jason Cox
Push The Needle
Jason Cox
The core, real question re: single stair buildings to rank and file firefighters should be this:
Which of these 2 buildings would you prefer in an active fire? Which is more likely to reach a point where you need to call in more help, delaying full response and increasing risk for anyone inside?
How many units in this top example sit on the “wrong side” of the two stairs at each end, meaning they would be trapped if that stairway was compromised? You’ll count 6 each.
Meanwhile single stair buildings have little to no corridor. (See the small building example at bottom).
Jason Cox
Jason Cox
How many units in this top example sit on the “wrong side” of the two stairs at each end, meaning they would be trapped if that stairway was compromised? You’ll count 6 each.
Meanwhile single stair buildings have little to no corridor. (See the small building example at bottom).
