Home Fire Safety

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BEFORE THE ARCHITECT – BACKGROUND – ARTICLES

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Residential elevator stairway fire safety

and

residential stairway fire safety

By Before The Architect

Copyright 2005-2007 Before The Architect

YOU MAY FREELY QUOTE THE AG WITH PROPER ATTRIBUTION

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RESIDENTIAL ELEVATOR FIRE SAFETY DESIGN GUIDELINES:

Sure did surprise Before The Architect: Residential elevators seem to be installed without a shred of fire safety code to be had across the fruited plain far as this old boy can tell so far. (Now, there is a U. S. elevator code in the form of ASME A17.1 Safety Code for Elevators and Escalators, which addresses essential safety concerns, e.g., access, switching, guardrails, and such – but not residential fire safety.)
 
An elevator shaft, or hoistway, could make a swell chimney, and double the peril by holding within the cab those who could be the most physically vulnerable folks in the house.
 
Much codified ado is made of residential fire-blocking, but nothing specific about fire safety that the author can reckon in regard to the potentially airflow-permissive [read: smoke and flame flow-permissive] elevator shaft. (Fire safety regarding vertical shaft enclosures gets some considered attention, e.g., IBC 2000 707.1ff, but not “…for openings totally within an individual dwelling unit and connecting four stories or less." IBC 2000, 707.2, Exception 1.)
 
In regard to residential elevators, what’s at stake here is fire-degraded wood stud walls and wood ceiling joists collapsing within a hoistway, or shaft, engaging cab and contents, including human contents, in smoke and fire.

 

Residential Elevator Fire Safety Guidelines
bulletA residential elevator shaft, or hoistway
bulletshall be framed with lightweight, or cold-formed, steel - not wood
bulletwhere exterior surfaces are available for wallboard application, exterior walls
bulletshall be finished with not less than 1 layer-5/8" Type-X gypsum wallboard glued, screwed and taped and
bulletshall be mudded not less than 3 coats, paying particular attention to screw pocks which shall be taped, too
bulletwhere the interior wall surface
bulletshall be finished with not less than 2 layers-5/8" Type-X gypsum wallboard glued, screwed, and taped and
bulletshall be mudded not less than 3 coats, paying particular attention to screw pocks which shall be taped, too
NOTE: Remember to adjust the elevator system's manufacturer's shaft framing dimensions to accommodate thicker interior clad; advise the elevator system manufacturer (and your local Fire Marshal) of your specific intentions in regard to residential fire safety methods and materials early-on.
bulletthe shaft ceiling
bulletshall be framed and sheathed on exterior and interior as the walls (see above)
bulletshall be enclosed by not less than 1 door at each stop, which door
bulletshall be not less than 1-hour fire-rated
bulletshall be self-closing
bulletshall be self-latching, and
bulletshall be smoke-sealing
bulletwithin the cab, outside the door at each stop, a smoke detector
bulletshall be applied according to manufacturer instruction
bulletshall be permanently connected to each other overall throughout the residence such that when one or more alarm, all alarm throughout the entire house
bulletshall run on both permanent 120V and replaceable battery
bulletshall feature a combination of ionization and photoelectric sensors
bulletshall not disconnect by wall switch
bulletshall be connected to a 120V line as first load on a frequently used lighting circuit with overcurrent protection at the panelboard suitable for a double tap
bulletwithin the cab, there shall be not less than 1 dry-chemical, portable fire extinguisher rated not less than 2A:10B:C mounted at 3'-6" above finish floor level to carrying handle.
bulletat each stop, a hallway or other space to which there is direct access from the cab shall have passage within line of sight at two linear feet outside the cab door on-center to not less than two means of egress, not more than one of which means may be an emergency egress window
Please note that an electrical box attached to steel frame shall be metal and grounded to Code.
 
In sum, the steel’s there to break down more slowly when engaged, to wrack and sag but not to cinders and ash; the tight sealing is intended to counter smoke intrusion; the extra layers of Type-X are there to better hold its form and hold flames from you on your travel through the hoistway.

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RESIDENTIAL STAIRWAY FIRE SAFETY DESIGN GUIDELINES:

Much codified ado is made of fire-blocking wall and floor structure.
Comment: This codified ado even sort-of includes residential stairway structure. See IRC 2003, R311.2.2 “Under stair protection. Enclosed accessible space under stairs shall have walls, under stair surface and any soffits protected on the enclosed side with ½-inch (12.7mm) gypsum board." For fire safety, it’s a beginning. Note, please, that there’s no mention of fire-rated gypsum board and heavier weight material as are referenced elsewhere – and have been for quite a long while – for garage wall and ceiling surfaces abutting habitable space.
And there are the high-value references to smoke alarms in building codes nationwide, references albeit at minimum levels of materials and methods, in the author’s opinion.
Comment: Minimums? That’s what this author thinks. Following are plan set stipulations that Before The Architect writes into smoke alarm methods and materials to extend codified minimums, among them –
bulletshall run on both permanent 120V and replaceable battery
bulletshall feature a combination of ionization and photoelectric sensors and
bulletshall not disconnect by wall switch
bulletshall connect to a 120V line as first load on a frequently used lighting circuit with overcurrent protection at the panelboard suitable for a double tap
bullet[for sleeping areas] shall install according to manufacturer’s specifications on either side of any passage between a sleeping area and a path to egress
So, what about the eminently more airflow-permissive stairwell itself?
In a house aflame, a residential interior stairway can occasion two events:
bulletthe passage of both occupants to safety and firemen for the sake of safety
bulletthe passage of smoke and flame between interior floor levels
It might seem as though an interior stairway, this key locus of interior structure in interior fire conditions – good (human transport) and bad (smoke and fire transport) – is at least largely forsaken by residential building authorities having jurisdiction.
What to do? What to do?
In regard to stairwells, what’s at stake is fire-degraded stairway, wood stud walls and wood ceiling joists collapsing within the stairwell, engaging stairway and its contents, including people contents, and thereby precluding occupants' easy physical movement between floor levels.

 

Residential Interior Stairway Fire Safety Guidelines
A residential, interior stairway, other than a spiral staircase –
bulletBelow the stringer
bulletshall be sheathed
bulletfrom outer stringer to outer stringer including header cleat
bulletwith not less than 1 layer of 5/8" Type-X gypsum board glued, screwed, and taped
bulletshall be mudded not less than 3 coats, paying particular attention to screw pocks which shall be taped, too
bulletWhere walls run below or immediately next to outside stringers
bulletshall be framed at walls with lightweight, or cold-formed, steel
bulletshall be sheathed on the exterior with 1 layer-5/8" Type-X gypsum board glued, screwed, and taped
bulletshall be mudded not less than 3 coats, paying particular attention to screw pocks which shall be taped, too
bulletIf continuous Type-X envelope cannot be applied on the vertical below a staircase, then contractor
bulletshall frame with lightweight, or cold-formed, steel
bulletshall sheathe
bulletthe interior with 2 layers-5/8" Type-X gypsum board glued, screwed, and taped
bulletwhere applicable, the exterior sheathed with 1 layer-5/8" Type-X gypsum board glued, screwed, and taped
bulletshall be mudded not less than 3 coats, paying particular attention to screw pocks which shall be taped, too
bulletWhere stairwell wall extends above a stringer as, for example, a stairwell, or below a stringer as, for example, a mid-landing, contractor
bulletshall frame the wall in lightweight, or cold-formed, steel
bulletshall sheathe the interior with 2 layers-5/8" Type-X gypsum board and, where applicable on the exterior of the wall sheathe with 1 layer-5/8" Type-X gypsum board
bulletshall sheathe the exterior with 1 layer-5/8" Type-X gypsum board glued, screwed, and taped
bulletshall be mudded not less than 3 coats, paying particular attention to screw pocks which shall be taped, too
bulletshall be sealed at a protrusion with fire-stopping materials conforming to not less than most current ASTM E84 and E814, which sealing shall not necessarily exclude consideration of tumescent sealant
bulletUnder stair in closet, cabinet, niche, alcove, bookcase, or similar
bulleta high-voltage electrical device or appliance shall not be sited
bulletsteel frame shall be sheathed continuously, fastened, and mudded at all abuts before other finish clad is applied, that is, the first exterior clad to steel frame below a staircase shall be at least 1 layer-5/"Type-X gypsum board applied as above

In sum, the steel’s there to break down more slowly when engaged, to wrack and sag but not to cinders and ash; the extra layers of Type-X are there to better hold its form and hold flames from you on your way up or down the steps.

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