Meet Our Leaders
Driven by a lifetime of hands-on grit and field-tested mastery, Marco has built a career centered on two simple principles: mastering his craft and making people genuinely happy. Rising through the ranks of union labor to earning his California C9 License, he has lived every level of the trade — giving him an intuitive understanding of both the art of building and the heart of leadership. Under his guidance, every job site operates on discipline, unyielding safety, and a culture of mutual respect.
For Marco, true success is never just about hitting deadlines or delivering perfectly square, straight framing — it’s about the joy of turning ambitious ideas into lasting realities. He approaches every build as the foundation for a long-term partnership built on total transparency and absolute dependability, ensuring MARK Builders Group delivers an unmatched client experience and a legacy of exceptional craftsmanship.
Marco Nunez
Chief Executive Officer
As Chief Financial Officer, Erika serves as the financial engine driving MARK Builders Group forward, pairing sharp fiscal discipline with a relentless focus on sustainable growth. With a detailed-oriented approach to capital allocation and real-time expense tracking, she ensures that every project operates with absolute transparency and cost efficiency. Erika actively stays ahead of industry best practices and modern financial strategy, continuously evolving the company’s systems to protect profitability, streamline cash flow, and eliminate operational waste.
Her leadership brings the exact same precision to the balance sheet that MARK Builders Group delivers on the job site. By building robust financial frameworks and maintaining rigorous oversight over every budget, Erika provides executive leadership with the clear, data-driven insights needed to scale operations nationwide. Driven by integrity and an unwavering commitment to operational stability, she ensures that as the company rapidly expands, it does so on a rock-solid foundation, protecting its financial health and securing its long-term future.
Erika Iriarte
Chief Financial Officer
As Chief Operating Officer, Monica serves as the engine of execution for MARK Builders Group, designing the scalable systems and unified workflows that power the company’s expansion. With deep expertise across field operations, scheduling, and organizational design, she bridges the gap between high-level vision and day-to-day execution. Monica eliminates bottlenecks and builds seamless communication channels between owners, field crews, administrative teams, and subcontractors, ensuring every department operates as one synchronized unit.
Her steady leadership creates the structure required for sustainable, long-term growth without ever compromising on precision or quality. By establishing clear SOPs, measurable accountability, and proactive problem-solving frameworks, Monica empowers teams to handle increasing project volumes with complete confidence. Driven by a passion for building organizations that grow stronger as they grow larger, she provides the strategic momentum and operational discipline that allow MARK Builders Group to execute at the highest level across every market it serves.
Monica Duncan
Chief Operating Officer
As Chief Estimator, Juan leads the estimating operations at MARK Builders Group, bringing over 16 years in the construction industry and more than a decade of dedicated preconstruction and estimating expertise to every bid. Having built his career across commercial, multifamily, tenant improvement, and public works projects, Juan has developed a rare fluency in turning complex architectural, structural, and MEP plans into precise, defensible numbers. Every takeoff, bid package, and cost forecast reflects the same standard of accuracy his clients and partners have come to expect throughout his career.
What sets Juan apart is his ability to see the full picture of a project before the first shovel hits the ground. By pairing sharp quantity takeoffs with real value engineering insight, he has consistently delivered stronger bid outcomes and meaningful cost savings across every firm he’s worked with. Juan joins MARK Builders Group to build out our estimating department and expand our pre-construction capabilities, bringing the same rigor and reliability to every bid that defines the way we build.
Juan Castellon
Chief Estimator
Happy Client, San Diego, CA