Elevator and Stairway-An elevator shaft or hoist way could be a potential chimney and double the peril by bearing what could be the most vulnerable people in the house.
Surprisingly, there are still some residential elevators in modern construction that are installed without a shred of fire safety code.
Keeping standards up to code is more commonly found in fire-blocking wall and floor structure (and stairway structure to an extent). The eminently more airflow-permissive elevator shaft or for that matter the stairwell itself, is all too often overlooked.
Details of today’s Residential Elevator and Stairway Fire Safety Standards are described below.
In regard to residential elevators and stairwells, what’s at stake is fire-degraded wood stud walls and wood ceiling joists collapsing within hoist way or stairwell, engaging cab or stairway. Mid-landings in winders and longer runs, too.
As for residential elevator fire safety, this passage is from Before The Architect’s House Construction Design Standards 1Q06 draft (edited from outline form):
A residential elevator shaft, or hoist way, shall be framed with lightweight, or cold-formed, steel. Where exterior surfaces are available for wallboard application, exterior walls shall be finished with 1 layer-5/8″ Type-X gypsum wallboard taped and mudded not less than 3 coats, and where the interior wall surface with 2 layers-5/8″ Type-X gypsum wallboard taped and mudded not less than 3 coats (remembering to adjust shaft framing dimensions to accommodate thicker interior clad).
Similarly, the shaft ceiling shall be framed and sheathed on exterior and interior by a door at each stop fire-rated, self-closing, self-latching, and smoke-sealed.
Within the cab and outside the door at each stop a smoke detector shall be applied according to manufacturer instruction, shall be permanently connected to each other overall throughout the residence such that when one or more alarm, all alarms throughout the entire house, shall run on both permanent 120V and replaceable battery with each alarm to feature a combination of ionization and photoelectric sensors and shall not disconnect by wall switch.
As for residential stairway fire safety particularly to structure, this passage also is from Before The Architect’s 1Q05 e-book: For other than the spiral staircase, sheathing shall be fastened underneath from outer stringer to outer stringer including header cleat with 1 layer, 5/8″ Type-X gypsum wallboard [existing standard].
Where walls run below or immediately next to outside stringers, walls shall be framed with lightweight, or cold-formed, steel and exterior sheathed with 1 layer-5/8″ Type-X gypsum board.
If continuous Type-X envelope cannot be applied on the vertical below a staircase, then contractor shall frame with lightweight, or cold-formed, steel and sheathe the interior with 2 layers-5/8″ Type-X gypsum wallboard and where applicable on the exterior of the wall sheathe with 1 layer-5/8″ Type-X gypsum wallboard.
“Before the Architect” by Ralph Press (House Building)