An architecture firm that has worked on New York City public schools and is designing the new PATH train station at the World Trade Center site is being sued in New Jersey over structural defects in an elementary school it designed.

The Newark, N.J.-based firm, STV Inc., oversees structural repairs on damaged school buildings for the New York City Department of Education. It is one of two firms that won the contract to design an ambitious new train station at ground zero, in collaboration with the architect, Santiago Calatrava. Another Newark-based firm named in the lawsuit, El Taller Colaborativo, also does design work for the city Department of Education.

The lawsuit, brought by the state attorney general, Stuart Rabner, on behalf of the New Jersey School Construction Corporation, alleges that the two firms are responsible for the shoddy construction of a three-story elementary school in Irvington, including installing steel beams that buckled visibly under the weight of the upper floors.

Plaintiffs are demanding compensation for the $3.5 million it cost to repair the defects in the $22.2 million school project, which was delayed because of the problems.

In New York City, STV has replaced the floors of a Bronx elementary school, P.S. 195; overseen renovations on the exterior of the Curtis School in Staten Island, and replaced school boilers, among other work, according to an education department spokeswoman, Marge Feinberg. The firm’s work often involves overseeing designs and subcontracting to other companies that do the actual construction work.

The New Jersey lawsuit alleges that a subcontractor that was building the school contacted STV and El Taller Colaborativo when it appeared the designs were defective, but that the firms directed the subcontractor to continue with the work anyway.

To bid on contracts in New York City schools, the two firms had to go through an extensive qualification process, Ms. Feinberg said, and neither is on the department’s list of disqualified vendors.

“They have been qualified to do the work and they continue to have contracts with us,” she said. “They have to bid like everybody else.”

An STV spokeswoman, Jill Bonamusa, said it was company policy not to comment on ongoing litigation. She directed questions about the firm’s work to Ms. Feinberg.

Phone calls to El Taller Colaborativo were not returned.

The New Jersey School Construction Corporation is currently trying to recover from years of mismanagement and corruption, during which it lost millions of dollars. A spokesman, Larry Hanover, said it planned more lawsuits to recover money lost to design errors, although he added that the agency was not targeting any specific firms.

David Wald, a spokesman for the New Jersey attorney general, said that while the lawsuit does not ask that the two firms be disqualified from future projects in New Jersey schools, the School Construction Corporation in a separate process could seek “debarment.”