An attention-getting lawsuit like the one the Art Institute of Chicago just filed against the engineers of its acclaimed new Modern Wing sounds pretty unusual. In fact, tussles like this break out all the time, and big-name figures from the world of design are anything but immune to the legal rough-and-tumble. In 2007, the Massachusetts Institute of Technology sued the Pritzker Prize-winning Los Angeles architect Frank Gehry for a series of alleged flaws — cracked masonry, poor drainage, persistent leaks, even mold growth — at Gehry's Stata Center, a science building of boldly angled walls and swooping curves.

Now, here comes the Art Institute alleging that its engineers, the esteemed firm of Ove Arup & Partners International, were guilty of numerous flubs in the Modern Wing: faulty air-handling systems, cracked concrete subfloors, even a roof that would have whistled in the wind had openings in its curving steel blades not been sealed with silicon plugs.

In a 12-page filing in federal court on Tuesday, the museum accused the engineers of a "woefully inadequate" performance that has already cost millions of dollars to fix, with the tab expected to hit about $10 million. Not surprisingly, an Arup spokeswoman on Wednesday denied that the engineers are at fault

"We are, as you would expect, very disappointed by the recent filing by the Art Institute regarding the new Modern Wing because we are very proud of our contributions" to the project, said Trina Foster, director of U.S. marketing and communications for London-based Arup. Projects like the Modern Wing and the Stata Center are enormously complex pieces of design, engineering and construction. And so, legal experts say, it is often hard to figure out exactly who is at fault.

"The question is: Are the defects the result of defective design on the part of design professionals or are they due to faulty construction and failure to conform to the contract documents (blueprints)?" James Zahn, a Chicago construction lawyer, said Wednesday. "Most owners don't have the knowledge, even if they're as sophisticated as the Art Institute is, to determine who's at fault," he added. "That's why the lawsuits proceed."

Whichever side turns out to be right, the museum is at pains to make this clear: No paintings by Pablo Picasso or any other art treasures in the Modern Wing were damaged because they were displayed in subpar conditions. The faulty air-handling systems, as well as balky temperature and humidity controls, were corrected before the museum began installing art in the $294 million Modern Wing in March 2009, according to museum spokeswoman Erin Hogan. "Never — absolutely not," she said when asked if the problems put works in the museum's collection at risk.

The Modern Wing's architect, Renzo Piano of Italy, who like Gehry is a winner of the Pritzker Prize, is not targeted by the lawsuit. Indeed, the lawsuit alleges that subpar engineering undermined some of his design concepts. For example, the wing's vestibule facing Millennium Park, which was supposed to provide a transparent gateway into the building, apparently has been plagued by condensation on its glass walls. "The Art Institute has been forced to use portable heaters to try to improve the conditions," the lawsuit says.

At its opening celebration last year, with Mayor Richard Daley and White House chief of staff Rahm Emanuel cheerily sitting alongside each other, the Art institute made no mention of the problems. So why blow the whistle now? "We were hoping to resolve this more amicably with Arup," Hogan said.