Appeal 34979

1011.6 Stairway Landings

1011.6 Stairway Landings

There shall be a floor or landing at the top and bottom of each stairway. The width of landings, measured perpendicularly to the direction of travel, shall be not less than the width of stairways served. Every landing shall have a minimum depth, measured parallel to the direction of travel, equal to the width of the stairway or 48 inches (1219 mm), whichever is less.”

Decrease the size or clearances of stair landings in two stair landings to 43” and 41” ( two landings ) Adjacent stairs are 48” wide. Appeal decrease width at two landings in the building.

The requested clearance 43” upper landing and 41” lower landing is a wall to a guardrail support distance. Also Wall to a stair tread the distance is 44” upper landing and 42” lower landing. Background:The Building has two stair towers. The appeal addresses two situations that we have a clearance less than 48” clear at stair landings. The situation of and the ground floor where the stair exits to the exterior or into a lobby which exits from the building. The two stair towers are both 2 hour enclosures, fully sprinklered, with an emergency voice/alarm communication system. The two stair towers are 42’ apart, the southern tower is where we are requesting the decreased width. Note: This stair provides direct egress to the public right of way. The situation was discovered by construction site personnel in that the concrete stairwell was formed and poured 8” - 12” too short - creating a shortage to the stair/landing space. Each floor in the building has 8 or 9 units per floor, the 9 floors have an occupant load of .942 occupants per unit of “habitable space”. ( Not counting bathrooms, closets, mechanical spaces per 2023 OSSC) Rounded up to 1 occupant per unit, and an occupant load of 9 occupants per floor, (under 90 total occupants for the areas using the stair towers) which is served by two 2 hour, fully sprinklered , with alarm enclosures. We believe the design as built will provide adequate health, accessibility, structural capacity, and life safety protection with a decreased landing size at these locations. We interpret the code requirement for the stair egress components were overall designed to serve an occupant load of up to 500 occupants allowed by code for 2 stair towers. Each landing is 33.2 sf for the shortest and. 34.865 sf for the other. The original designed landing was 38 sf If one assumes 5 sf /per person “standing” on each landing (OSSC Table 1004.5 - 5 SF/Occ) then the shortest landing will have a capacity of 6.65 occupants and the other 6.97 occupants.The original design had a capacity of 7.6 occupants. The code requires, if one stairway was closed for any reason, the other has to accommodate “no less than 50 percent of the floor occupant load” , in this case 9 x 50 percent = 4.5 occupants, rounded to 5 occupants, so each described landing meets the intent of the code.

Note: Stair treads are 48” in this stair tower and per
"1009.3.2 Stairway Width"- the stairs do not need to be 48 clear since building is fully sprinklered. 48” is beyond the required minimum stair width.
Note: Building is equipped with an elevator.

Background:The Building has two stair towers. The appeal addresses two situations that we have a clearance less than 48” clear at stair landings. The situation arises of the ground floor where the stair exits to the exterior R.O.W of Park Avenue or into a lobby which exits from the building. See above discourse for more information.