Sean Duffy

A third-generation plumber, Sean has worked at all levels of the industry, starting out as a plumber with Cornell-AEC in 1987. He was quickly promoted to Foreman and then Project Manager, establishing a record of exceptional leadership that prepared him to strike out on his own.

Sean founded Duffy Mechanical Corporation in 1994, and hired a team of goal-oriented managers and staff with in-depth knowledge of the industry, including Erik Harley, Sean’s current business partner, who served as Vice President. Under their leadership, Duffy Mechanical grew into a multi-million dollar company and tackled complex projects at a variety of installations, including Prince William Hospital, Dulles and Baltimore Washington International Airports, and the Ronald Reagan Office Building. As CEO, Sean strove to foster an environment committed to innovation and team-work, encouraging managers and staff to continue developing their expertise through additional training and mentorship programs, a philosophy he says benefits individuals as much as the company as a whole.

In 2009, Sean and Erik founded H&D Mechanical, accomplishing superior work in a variety of settings, including medical, scientific and commercial projects. Sean’s vision for strategic growth and expansion has helped H&D become a dominant player in the market. In 2014, the pair launched Harley & Duffy, the residential services branch, filling a need for quality home plumbing and HVAC services in Southern Maryland.

Sean obtained his bachelor’s degree from Marist College in 1986, and completed a 5-year apprenticeship with the Plumbers Union in 1991, graduating with Salutatorian Honors. He is President-Elect of the Mechanical Contractors Association of Metropolitan Washington, having served on the Board of Directors since 2010.