The Yorkshire Air Ambulance was called to Travis Perkins on Sunday morning, landing in the premises off Pinfold Lane, just after 10.30am.
The business is not open to the public on Sundays but a man had suffered arm, leg and chest injuries after a serious fall and was taken to Hull Royal Infirmary for treatment.
A spokesperson for Travis Perkins said: "We can confirm that there was an incident at our branch in Bridlington last Sunday, where one of our contractors, who was undertaking roof-related work had a fall.
"Emergency services were immediately called.
"The injured contractor has been discharged from hospital, and we wish him a full and speedy recovery. We are now working to complete a full investigation into the circumstances of the incident."