It wasn't immediately clear what caused the collapse, which occurred around 5 p.m. Wednesday in Little Egg Harbor Township.
Authorities say the workers were being treated at a hospital for "serious injuries," but the injuries were not considered life-threatening.
One worker suffered back, neck and foot injuries and was flown to a hospital, while the other two were being treated at another hospital for undisclosed injuries.
Authorities say one of the workers apparently fell from the home's top floor.