Work Excellence

Ensuring the highest level of construction performance is what makes us the company you want on your next project

Who Are We?

Harold Brothers Mechanical Contractors, Inc. is a privately held, open shop mechanical construction company in Eastern Massachusetts. Part of Being a full service organization for the Commercial Construction Industry, we have the ability to provide a total mechanical construction package including HVAC, process piping, refrigeration, plumbing, pre-fabrication, rigging, energy management and temperature control. We provide our customers with a single contact able to offer a comprehensive approach to their mechanical systems.

We work all over the state of Massachusetts including Cape Cod and the islands and into Southern New Hampshire.

Our Services

  • Fabrication
  • HVAC
  • Plumbing
  • Design Build & Design Assist
  • Process Piping
  • Coordination


We operate a full production shop for the fabrication of piping systems for plumbing and HVAC. The controlled environment allows us for better quality and we can produce more in a shorter period of time. Our fab shop has helped our customers with both completion time and money spent on projects.



From a routine installation to a complex fast-track design/build project, we can provide any type of HVAC service, including new construction, intricate process piping, and tenant fit-up and retrofit.



We offer a wide range of commercial plumbing services. Our plumbers have a broad experience in many facilities, including biological and chemical research laboratories, medical centers, universities, retail, and hi-rise condos.


Design Build & Design Assist

Harold Brothers has experience working side by side with engineers and owners. The design assist process helps to streamline the entire process from design and equipment selections to install while simultaneously value engineering the project saving the owner time and money. Better yet – Need an engineer? HBMI can handle it. We have 3rd party engineers we work along with to streamline your systems to fit any architectural layout.


Process Piping

Our skilled work force installs process piping for a variety of sectors, including heavy industrial, pharmaceutical and hospital facilities. From small tenant fit-outs to design build services we can handle any of your process needs.



The CAD department use the engineered plans as the basis to coordinate and design the mechanical and plumbing systems within the constraints of the architectural layout, resolving design conflicts with other trades as needed along the way.

In addition to the coordination, the CAD department uses the newly coordinated model to generate our fabrication and spooling sheets for use in the fabrication shop.


Our Services


“We can depend on Harold Brothers Mechanical from start to finish. They are always a team player and have earned the reputation as a premier subcontractor from performance, safety and quality with Callahan Construction.”

Patrick Callahan, President
Callahan Construction Managers

“Harold Brothers has been a trusted partner for many years on projects both large and small. They have always been extremely responsive, professional, and team oriented which is why they are such a pleasure to work with which is rare to find. I look forward to doing business for many more years to come!”

Michael Fish, President & CEO
Dellbrook I JKS

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We look forward to working with you

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