THE MAC TEAM

One Team Under One Roof

Everybody at MAC design + build, from the owners to the architects to the construction clean-up crew is on the same team – your team. We are all accountable for meeting your expectations.

  • Benjamin Carstoiu, Architect, NCARB

Derek Leiter

Owner and Vice President

Derek’s responsibility at MAC design + build is business development — sales, estimating and design, however, his role is to take clients to wherever their goals are for their projects. He is the first person to meet with clients and the one who drives the entire project, assembling teams, assigning project managers, and staying in touch with the client on a weekly basis.

"We approach our business from a customer service point of view, not as a usual contractor," he says. "We consider it a privilege to work on each customer’s home, and enjoy helping people and creating beautiful designs."

Derek studied physics and engineering in college, but always returned to his love of architectural style. He worked for more than 15 years, selling home improvement products and remodeling services and learning the various trades involved, before co-founding MAC design + build. He is married with two daughters and enjoys volleyball, wine tasting and international travel.

Justin O'Connell

Senior Estimator

Justin O’Connell is a Senior Estimator at MAC Design Build, bringing over 15 years of experience in residential remodeling and construction management. Known for his calm and thoughtful approach, Justin excels at listening closely to clients and translating their goals into clear, achievable plans.

His expertise in value engineering and practical problem-solving helps align scope, budget, and schedule early in the process, ensuring each project begins with clarity and confidence.

Outside of work, Justin enjoys spending time with family and friends, working in his garden, and appreciating the craftsmanship and creativity that define great design.