Everything old is new again at W. 55th St. building.

The construction of comparatively few new office buildings and other market factors have favored the redevelopment of Manhattan's older buildings in recent years. As owners witness fresh demand for buildings that would have been marginal just a few years ago, architects and engineers have devised a fountain of youth for aging structures.

Shmerykowsky Consulting Engineers, has been active in the retrofit of vintage properties despite its core expertise in new high-rise buildings.

Shmerykowsky worked with Iu & Bibliowicz Architects to convert the Winter Organization's 250,000 s/f building at 423 W. 55th St. from light manufacturing to office use. The surrounding neighborhood had evolved and the owner needed to rationalize a building that had seen many ad-hoc adaptations.

Built in 1913, the 12-story structure had been altered to serve various tenants with little regard for its future appearance and operations. The building needed a street presence, but misplaced loading docks and switchgear room, an entry five feet above grade, insufficient elevators, excess stairwells and a 12-story bearing wall each stood in the way.

The design team would have to reclaim space and redistribute loads around a proposed new curtain wall at the entrance lobby. Shmerykowsky performed multiple probes and determined that the foot-thick brick facade was self supporting. Since the installation of the new glass curtain wall would carve a large hole at the brick base, the engineers had to support the brick facade above while transferring loads to the structure below.

A large horizontal beam above the two-story glass entrance wall would help transfer loads and bear the weight of 10 stories above, but would also be subject to deflection or sagging. Deflection, in turn, could lead to cracks in the facade. A prestressed structural framing system was devised to preload the brick facade above the transfer beams so that no deflection would occur when the temporary shores were removed.

Finally, steel columns were reinforced to pick up the brick facade loads and transfer them back to the foundation. Successful coordination between the construction manager, the contractor and the structural engineers resulted in a secure facade.

Other structural revisions supported the expanded lobby at the building's east entrance, a stair replaced by two new elevators, reconfiguration of emergency egress, and an expanded machine room bulkhead.

The existing truck loading berths and a 30' x 44' area of the first floor were demolished. In their place, new floor framing was constructed so that the top of slab of the newly expanded lobby was lowered to match grade level at the entrance. The portion of the former truck loading berths that was not incorporated into the lobby was raised from grade level to match the top of slab at the first floor.

Modifications to the floor framing at the main lobby entrance necessitated the reinforcement of two existing steel columns because the bracing originally provided by the first floor was now five feet lower. Also, the original floor framing made extensive use of cantilevered beams and girders. As some of these members were cut to integrate the new framing, new steel beams were installed as reinforcing.