The collapse happened around 8:00 Thursday morning in the 200 block of Belvedere Drive in Brandywine Hundred, Delaware.
The 40-year-old victim, who was reportedly a construction worker working on the installation of a swimming pool, was standing under the deck when it collapsed.
He was trapped under the deck for a total of two hours before being extricated by personnel from the Talleyville and Claymont fire companies and the New Castle County Technical Rescue Team.
The worker sustained injuries to his shoulder, leg, hip and abdomen as well as possible internal injuries. He was flown to Christiana Hospital by Delaware State Police helicopter and admitted to that facility in serious condition.
It is unclear what led to the collapse.