About Us

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At Principal Builders, we understand that the only way to build a project that meets our clients' needs is by truly listening to them. As contractors, we must first understand your goals and visions before bringing those visions to life. We have built our company with this knowledge as our cornerstone. Our goal has always been not only to build structures, but to build relationships that will last generations. We pride ourselves on getting to know you, which allows us to get things right the first time.


Principal Builders is family-owned and both of our partners, Joseph Pirelli and Timothy Williams, have strong ties to their community. We have diverse backgrounds in finance and construction management, having held positions as assistant CFOs and Project Managers in large construction firms throughout Massachusetts. We are licensed Unrestricted Massachusetts Construction Supervisors and have over 18 years of experience specializing in commercial, retail and residential construction. We have a thorough understanding of construction, from planning and estimating to completion and turnover. We have formidable records for completing various types of construction projects and fulfilling all of our clients’ needs.

We began Principal Builders to provide the administrative services and quality workmanship that one would expect when using a larger general contractor, but with a more personal approach. We have continuously achieved this through our ability to self-perform and through our strong attention to detail.

Throughout our first year of business, we used our residential construction backgrounds to take on remodeling projects, such as kitchens, bathrooms, additions and basement renovations. Our quality of work, strong communication, and ability to deliver a project on time, on budget and meeting specifications were widely recognized. We quickly became a true full-service residential general contractor with the ability to perform ground-up construction work and the capacity to take conceptual ideas through to design and then complete construction.

Over the next few years we were presented with opportunities to perform a number of non-profit and commercial construction projects. We quickly realized that this industry niche also fit our company well. This type of work has become a key focus as our company continues to grow.

Our years of experience, numerous industry contacts, loyal client base and strong ties to our community continued to create more opportunities for our company. As we grow and expand, remaining true to the ideals that have provided us such vast opportunities is essential. We always want to offer the capabilities of a larger general contractor with the hands-on approach and strong communication that has continually satisfied our clientele.

We are proud to be able to provide our renowned level of service and give back to the community that has provided us with so much.


Principal Builders’ commitment to be a business that “gives back” to the cities and towns where we perform work in is not just a slogan; it is one of the core values held by our partners and workforce. We have been involved with a number of local and national charitable organizations such as: Habitat for Humanity, hunger relief organizations, The Pan Mass Challenge, religious organizations, Hurricane Sandy Relief work and more. Whether we are volunteering our skills locally or providing much needed monetary funding to these organizations, our desire to give back to our communities in any way possible is evident in all that we undertake. This mentality has led to a large focus in non-profit work. We have felt the biggest reward in work completed for Boston’s more socioeconomically challenged areas. Whether it is rebuilding a gymnasium for the Eliot Church in Roxbury, or performing rehab work in The Boys & Girls Club in Dorchester, each project has a uniquely and mutually gratifying result.