Appeal 33507

1006.2.1

Two exits or exit access doorways from any space shall be provided where the design occupant load or the common path of egress travel distance exceeds the values listed in Table 1006.2.1.

To allow an egress balcony to serve as a second means of exit access to a single interior exit stair from the 2nd level above grade.

The proposed design is to add an exterior non-combustible egress balcony at level 02 that leads directly to a second entrance into the existing exit stair. The approach would be similar to the existing egress balconies at levels 03, 04, 05 at this same building, previously approved through Appeal B-17 #1 dated 01/17/01.

This added egress balcony would provide a second means of exit access from level 02 to meet the requirement of two exit access points required by OSSC 1006.2.1. The proposed two points of exit access would both use the existing interior exit stair as a path to the point of exit discharge, though 1006.3.3 requires the number of exits be maintained until arrival at the exit discharge. However, the egress balcony would provide access to the existing exit stair that is a pressurized stairwell within a 2-hour rated CMU shaft. The two points of exit access at level 02 would meet the minimum requirement of 1/3 the overall diagonal required by 1007.1.1.2. The proposed egress balcony at level 02 on the east courtyard side of the building would be in compliance with the requirements of 1021.1 through 1021.4.

The existing Cellar building level 02 space has a single exit stair serving an occupiable space of 3,300 square feet. The building design and renovations of the Cellar building conducted in the early 2000s documented this space as mercantile with a potential interior exit access stair in addition to the rated exit stair, however the exit access stair was never constructed and is no longer feasible for the building owner and level 01 tenant. At the same time, egress balconies we’re approved through appeal and provided at levels 03-05 to create a second point of exit access to the single interior exit stair from those floors.

The occupant load from the planned level 02 occupied areas is 98 occupants resulting in an occupant load at each point of exit access of 49. This load of 98 occupants would be in addition to the cumulative load from levels 03-05 of 43. The total resulting building occupant load on the existing exit stair would be 141, significantly lower than the stair occupant load capacity of 220 (44” stair / .2”). Additionally, the egress balcony to the existing exit stair would meet the common path of travel and maximum travel distances required by 1007.1.1.2 for a building with an automatic sprinkler system. The Cellar building is non-combustible and fully sprinklered and we propose the approach provides an equivalent level of safety.

705.2, 705.3

Exterior balconies extending beyond the exterior wall shall conform to projection requirements and be 40” minimum from Fire Separation Line to deck’s Face of Projection (705.2.) Buildings on the same lot shall be assumed to have an imaginary line between them (705.3.)

To shift the position of an established imaginary property line (also known as assumed property line.)

The proposed design is to construct a deck at level 02 of the Cellar building, accessed from inside that same building and level. The supporting steel columns would be anchored at both the ground level and top of existing patio level and be placed to avoid obstructing the existing loading zone.

The placement of the two southern columns and the deck’s southern Face of Projection would overlap with the established imaginary (previously documented as “assumed property line” in Appeal B-15 #13 dated 01/17/01) property line. To comply with the requirements of 705.2 and 705.3 the proposed design would shift the imaginary property line along the deck’s southern Face of Projection south by 8’-4” so that a 40” minimum distance from the Face of Projection to the imaginary property line is maintained. The resulting property line at the deck would be 24’-4” from the Cellar building and 23’-6 from the Brewhouse building. The existing distances in this location are 16’-0” from the Cellar building and 31’-10” from the Brewhouse building.

To maintain access in the loading zone between the Cellar building and the existing patio associated with the Brewhouse building, and to avoid conflict with below grade utilities, the southern structural column line placement is proposed on the existing pile cap that is integral to the existing patio. This column line placement would not meet the 40” minimum distance to the existing imaginary property line.

There is a substantial distance between the existing Cellar and Brewhouse buildings and shifting the imaginary property line south by the proposed distance of 8’-4” would not create an imbalance of separation distance between the two existing buildings. At the shifted location the proposed, revised position of the imaginary property line would be nearly equal. Allowing this proposed imaginary property shift would provide the required distances for compliance with 705.2 and 705.3.

603.1

On buildings of Type I and II construction, three stories or less above grade plane, fire-retardant-treated wood shall be permitted for decks not used as a required exit (603.1.)

To permit a deck at level 02 of a 5 story building to use ipe wood decking material on a steel frame.

The proposed design is to construct a deck at level 02 of the Cellar building, accessed from inside that same building and level. The deck would be constructed of a structural steel primary frame and ipe wood decking floor. The ipe wood decking would be connected to the steel frame with a non-combustible clip system attached to fire retardant treated wood sleepers anchored to the steel frame. An automatic fire sprinkler system with up and down heads at the underside of the horizontal framing would protect the steel frame and wood decking. Ipe decking has been previously tested to be a NFPA Class A material per ASTM E84, see attached testing report.

The proposed deck would not be used as a required exit and will be constructed of non-combustible materials with additional protection provided by an automatic sprinkler system. The deck will be structurally independent of the building and would be at level 02, below the three stories above grade plane limit of 603.1.1.4. This appeal proposes the approach provides an equivalent level of safety as allowed by 603.1.1.4.