Founded by Sean Duffy and Erik Harley in 2009, H&D Mechanical is a mid-size mechanical contractor based in Upper Marlboro, Maryland. H&D has an established record of superior work in a variety of settings that include medical, scientific and commercial projects. H&D provides protection to its customers by building safe, workable environments. Our work with the commercial entities exemplifies our commitment to protection. We enhance the value of our clients by ensuring quality work that is not only well-designed but increases the efficiency of the workspace. In addition, we improve the life of the people who ultimately use our hospitals, airports, schools and other structures by creating efficient and comfortable buildings where professional