Shoppers patronize the SoNo Collection mall FRiday, November 27, 2020, in Norwalk, Conn.

The developer of the SoNo Collection mall in Norwalk is accusing the architect of the development of sigificant design flaws in the building that cost $11 million to fix, according to a lawsuit filed in state Superior Court.

Brookfield Properties claims several mistakes by a Connecticut affiliate of architecture firm CallisonRTKL, which has offices globally and ample experience with major commercial projects, including those in complex city settings. The sides have discussed a possible settlement, according to a court filing.

Brookfield says the design bill for the South Norwalk mall added up to more more than $14 million, including amounts to subcontractors. Brookfield sued for the $11 million in repairs, as well as the costs of the lawsuit it was incurring. Spokespeople for Brookfield could not be reached immediately on Thursday for any further details on the settlement talks and its claim.

“CRTKL knew or should have known of the deficiencies,” Brookfield attorneys state in their original complaint.

In a formal court response and counterclaim for $1 million it says it is still owed, CallisonRTKL denied any liability while citing several legal doctrines it claims shield it. In a court filing at the end of May, the parties disclosed they were in settlement talks ahead of an early August court proceeding, in advance of a prospective civil trial date next year.

“CallisonRTKL has no comment on progress toward a settlement with Brookfield,” general counsel for the company aid in a statement. “As to the matters in the Complaint, CallisonRTKL’s position is set forth in its pleadings filed with the Court. CallisonRTKL performed its services consistent with the standard of care and delivered a beautiful, award-winning project to the Owner.”

Brookfield alleges defects included a defective steel girder that cost $3 million to replace; and insufficient supports for masonry in the mall’s parking garage to withstand big gusts of wind, with the fix exceeding $1 million.

A mall elevator and stairway also had to be rebuilt to pass muster, Brookfield claimed, as well as a portion of the roof and other structural elements. And the company says it had to excavate to install needed plumbing it says CallisonRTKL designers failed to anticipate.

A New Jersey plumbing firm sued its general contractors in U.S. District Court in October 2019, after relying on what it claimed was a flawed CallisonRTKL blueprint to install plumbing at the Vassar Brothers Medical Center in Poughkeepsie, N.Y. Describing the plumbing design as “riddled with defects”, a judge dismissed portions of the lawsuit last year, on grounds the plaintiff made no claim that the general contractors had control over the design of the plumbing.

The SoNo Collection debuted in October 2019 with Nordstrom and less than 20 other stores opening their doors at the outset, with others following through the holiday season and into the following year.

One highly visible gap in its original lineup remains, along the street-level facade that greets customers turning onto West Avenue from Interstate 95. Along a planned restaurant row, Yard House opened last year but two other slots remain vacant.

In a 2020 court proceeding, the Norwalk Land Development company Brookfield controls won a court order to evict a proposed restaurant called Yong Kang Street Dumplings and Noodle House that never completed a fit-out of the premises on West Avenue.

Brookfield took over the SoNo Collection’s construction through its 2018 acquisition of General Growth Properties, then sold its majority ownership interest to other investors weeks after opening the mall for $304 million. Brookfield continues to manage the mall’s operations including leasing.

Brookfield has sued the city of Norwalk four times since 2018 over what it has labeled “grossly excessive” appraisals in state Superior Court lawsuits, with those amounts determining property tax assessments on the mall. The city has denied that characterization of its appraisal in formal responses in court.

Alex.Soule@scni.com; 203-842-2545; @casoulman