Major Structural Repairs Needed to Fix Sagging Floors in South Harlem HDFC Building

What began as a simple apartment sale at a 160-unit HDFC in South Harlem snowballed into major structural repairs. A shareholder wanted to sell her apartment, but there was a problem: the floors were sagging. A closer look uncovered several broken beams beneath the floorboards, which was bad news for the board. In order to repair the beams, “We had to rip out the entire apartment and gut it so we could get to the beams under the floor,” says Josh Koppel, president of H.S.C. Management, the company that manages the building. 

Sagging floors. Sagging floors are not uncommon in prewar buildings with wood framing, says Eugene Gurevich, a senior structural engineer at RAND Engineering & Architecture, who has expertise in this area but was not involved in this specific project. And they don’t always 

indicate a building-wide problem. It’s important to find out if load-bearing walls have been removed in the apartment below, which increases stress on the beams and joists above. In this case, the beam deterioration wasn’t the result of alterations, but simply the building’s age. “I don’t see how it could have been prevented,” Koppel says. 

Sistering. Visual investigations and probes at the five-story co-op resulted in a scope of work that involved pulling up the flooring and subfloor — the plywood layer beneath — to access and replace the broken beams. This involved a process called sistering, where framing is reinforced by attaching new, similar sized beams to the original material. “You double the strength or at least return the original strength of the framing,” Gurevich says. 

The floor repairs came with additional headaches. The position of plumbing lines, which obstructed the beam replacements, complicated the repairs. Pipes needed to be relocated to accommodate a main beam running through the area. 

The cost of the project was around $100,000. On the plus side, the seller is now able to market an apartment with significant improvements. “She basically got an old apartment turned into a brand new apartment because we had to gut it,” Koppel says. The takeaway is to take sagging floors seriously and fully diagnose the extent of the problem.  “It does happen with age where the floors start to sag a bit but it certainly needs to be investigated,” Gurevich says.