Appeal 26182

OSSC 705.8.2 Protected Openings and 706.5.1 Exterior Walls

Reconsideration text for Appeal ID: 25110, Item 12:

The Imaginary Property Lines have been adjusted such that a path to compliance is achieved. Details of opening protection via water curtain has been provided indicating sprinkler head location for the openings. Graphics of each location have been updated with the updated Imaginary Property Line locations.

Please see Exhibits: SK-3A, SK-3B, SK-3C, and SK-3D, SK-3E and, SK-3F, and SK-3 Details, for revised information.

Where the fire wall intersects exterior walls, the fire-resistance rating and opening protection of the exterior walls shall comply with one of the following:

1. Exterior walls shall have a 1-hour fire resistance with ¾-hour protection where opening protection is required per 705.8. The fire resistance rating of the exterior wall shall extend not less than 4 feet each side of the intersection of the fire wall to exterior walls.
2. Buildings or spaces on both sides of the intersection fore walls shall assume to have an imaginary lot line extending beyond the exterior of the fire wall. The relation of the imaginary lot line shall be such that exterior wall rating and opening protection complies with 705.5 and 705.

705.8.2 Opening protectives are not required where the building is equipped throughout with an automatic sprinkler system in accordance with Section 903.2.1.1 and the exterior openings are protected by a water curtain using automatic sprinklers approved for that use.

Automatic sprinkler water curtain protection of window openings at fire wall termination per 705.8.2.

The historic school building has large existing openings adjacent to the intersection of fire walls at exterior walls. Design proposes the fire walls terminate in accordance with 706 and to protect the openings within 4 feet of intersection with water curtain automatic sprinkler coverage. The existing building walls are URM load-bearing walls with equivalent to 2-hour fire rating. New intersecting exterior walls are 1-hour rated at the fire wall intersections for a distance of 4’-0” minimum.

Locations:

1. Building E to Building A – West window and door – Unprotected openings are within 3 feet from intersection of Fire Walls.
2. Building C to Building B – NW Corner - West Wall – Unprotected opening is within 3 feet from intersection of Fire Walls.
3. Building G1 to Building E – West window and door – Unprotected openings are within 3 feet from intersection of Fire Walls.
4. Building H to Building F – North wall of Building H – West Corner – Unprotected openings are within 4 feet from intersection of Fire Walls.

The existing and new opening size exceeds the allowable area of unprotected opening area per story (see exhibits for size and location). Design provides window opening protection with standard-coverage quick-response fire sprinkler heads located within 12-inches of the interior side of window on the interior side of openings. Fire sprinklers protecting windows will be located at least 6 feet from adjacent fire sprinklers.

Buildings will be equipped throughout with automatic sprinkler system per 903.1.1.1 (NFPA 13).
Window opening size, exterior wall ratings and wall lengths vary.

Reason for Alternate: (Describe why the alternate is required and how it will provide equivalent health, accessibility, structural capacity, energy conservation, life safety or fire protection to what the code requires).

This appeal seeks to document the ‘approval’ for protection of openings with water curtain coverage per 705.8.2 and records the use of 1-hour fire resistance with ¾-hour protection where opening protection is required per 705.8. The fire resistance rating of the exterior wall shall extend not less than 4 feet each side of the intersection of the fire wall to exterior walls.

Building E to A: The existing historic windows and door openings of Building E North-West vestibule are within load bearing masonry walls equivalent to 2HR fire resistance and return walls to the North and South have load bearing masonry walls equivalent to 2HR fire resistance. Preserving the historic façade is a condition of approval by the Landmarks Commission.

Building C to B: The existing historic window of Building C are within load bearing masonry walls equivalent to 2HR fire resistance, and the Building B exterior walls are finished with brick and 1 HR fire resistant. Openings in Building B’s exterior are more than 4 feet from the intersection in excess of the 4 feet minimum distance. The conditions meet the intent of the code providing fire resistance exterior walls and opening protection at the intersection of exterior walls and beyond.

Building G1 to E: The new windows and doors in existing historic openings are within load bearing walls equivalent to 2HR fire resistance and the Building E exterior walls are load bearing masonry walls equivalent to 2HR fire resistance. Preserving the historic façade is a condition of approval by the Landmarks Commission.

Building H to F: The new windows and door in Building H are located 3’-1” from the intersecting fire wall. The windows and door openings provide the necessary views for visual surveillance of the exit doors and student entry into the building. Additionally, the windows provide natural daylight for the interior stairs, staff areas and circulation areas reducing the energy use for the school and contributing to its sustainability.

Water curtain coverage in lieu of protected windows is an allowed exception where the buildings are equipped throughout with automatic sprinklers. While not required by code, the design proposes an additional measure providing exterior wall fire rating where the exterior walls abut the existing building facades. In conclusion, the proposed design meets the intent of the code and provides additional measures for the safety of the building occupants.