East Midtown Plaza wins concrete restoration award

Real Estate Weekly, Nov 17, 1993

The international Concrete Repair Institute selected Wank Adams Slavin Associates (WASA) to receive an award for the restoration of exterior concrete facades at the East Midtown Plaza residential complex in Manhattan. The project was the winner in the High Rise category at the first annual International Awards program.

Developed by the City of New York in the 1970s to provide affordable cooporative housing for 746 families, East Midtown Plaza is comprised of three towers and four low-rise residential buildings united by a large central plaza. The site is spread over two city blocks, from East 25th Street to East 23rd Street between First and Second Avenues.

In the 20 years since its construction, the multi-building complex had been experiencing an acute series of concrete problems along the seven miles of exposed concrete spandrel beams and balcony fascias. The severity of the concrete spalling presented a safety hazard to the public in the area.

Repeated repair projects using cementitious patches had failed to provide a lasting solution. WASA performed a major condition assessment to evaluate the reinforced concrete structures, including exposed spandrel beams at every floor and brick panels composed of eight-inch square bricks between spandrels and aluminum frame windows.

The study revealed approximately 11,000 spalls on the seven buildings - approximately 70 percent were at patch failure; the other 30 percent were new spalls. The concrete spalling had occurred because in most locations on the building there was inadequate concrete coverage over the reinforcing steel. WASA determined that another concrete patching program would only provide a short term repair resulting in ongoing spalling and patch failure,

Following the evaluation of many different repair methodologies, WASA developed an innovative solution that would provide a permanent repair. The solution, which had never been used before in New York City, involved the removal of the exterior face of the existing concrete to 1/2" behind the reinforcing steel and recasting of all seven miles of exposed concrete spandrels and balcony edges. Concrete was removed up to a depth of three inches. New high density concrete was cast in place using reusable formwork. A new concrete surface area was created one inch beyond the original profile. This method of repair simultaneously reestablished the alkalinity of the concrete while providing adequate coverage and minimizing the reocurrence of new spalls in the original carbonated concrete.

The recasting included removal of the brick course directly above the spandrels, facilitating the installation of new flashing to alleviate water penetration of the spandrel through the cavity wall. The new high density repair concrete, coated with a water repellant, is compatible with the original concrete but allows less water penetration.

The recasting process presented such a permanent solution that both the contractor, Richardson Lucas, and material supplier, Fosroc, guaranteed all materials and labor for ten years, an extraordinary guarantee in the concrete repair industry.

Wank Adams Slavin Associates is a New York City-based architectural, engineering and preservation firm with offices in Parsippany, NJ and Ithaca, NY. Some of its most recent projects include the design of an academic building and an athletic center at Jersey City State College; restoration work at the Manhattan Municipal Building and the New York County Courthouse; and numerous projects for Fordham University and Columbia University.