When a pool cracked and buckled on the rooftop of an apartment building in Brewers Hill last week, it did not “impact the integrity of the primary building structure,” according to the engineering firm hired by the building’s owner.

The collapse last week at Axel Brewers Hill prompted the temporary evacuation of the just 4-year-old luxury apartment building. Residents were able to reenter their homes by Friday afternoon, and the engineering firm said the building remains safe for occupancy.

Excelsior Communities, the company that owns the building, hired Building Envelope Consultants and Scientists to evaluate the damage. A letter from the firm, dated Sept. 25, says engineers evaluated the building and found the pool shell was built in a structural “vault” that is independent of the primary building structure.

The pool shell was “lifted” from its original position, according to the letter, and an engineer with BECS and the original structural engineer of record found the building remained safe for occupancy.

Ami Notis, a vice president at Excelsior Communities, said in a written statement the company is “committed to restoring everything as quickly and safely as possible.”

Abi Aghayere, a professor in the Drexel University College of Engineering in Philadelphia, said that if the structure of the pool deck/lobby area of the building is independent and not connected to the multistory apartment towers, then the failure “will be localized” and not spread to the residences — agreeing with the firm’s assessment.

He did question, though, what caused the failure of the pool deck in the first place. It’s not clear from the engineer’s letter “why the pool deck failed at all in the first place, given that this building is only a few years old,” Aghayere said in an email.

An Excelsior spokesperson said in an email there’s no timeline yet for the removal of the pool shell or the construction of a new one. She said the company has a “preliminary understanding” of a potential cause of the pool’s failure, there won’t be a “definitive answer” until the shell is removed and they can conduct a more thorough inspection.

Two residents of the building filed a proposed class action lawsuit against Excelsior Communities, JDavis Architects (the firm that designed the complex), Wood Partners (the developer and construction company), and Brewers Hill Realty (which runs the building) late last week.

The complaint, filed in U.S. District Court in Baltimore, accuses the owners and other defendants of negligence and breach of contract, and seeks undisclosed damages and an order allowing residents to terminate their leases.