Mark III Construction is a full-service MEP contractor headquartered in Sacramento, California, founded in 1976. Originally a single-trade electrical contractor, the company has grown to self-perform electrical, HVAC, plumbing, process piping, underground utilities, prefabrication, and MEP design across California and Nevada. It operates from a second office in Sparks, Nevada, and is planning a move to a new 340,000-square-foot headquarters at McClellan Park, expected by Q2 2026.
The company operates through three business units: M3 MEP, which handles construction projects; M3 Service, which provides 24/7 emergency and preventative maintenance; and M3 Components, focused on manufacturing and industrialized construction. Supporting these units is a 62,000-square-foot centralized manufacturing facility serving five core trades. Mark III Construction was named ENR California's Specialty Contractor of the Year in 2019.
The company serves clients across several sectors, including healthcare, higher education, industrial, life science, and technology. Its integrated model - branded internally as the "Power of One" approach - means all trades are self-performed under one organisation rather than subcontracted, which the company positions as a way to reduce scheduling complexity and scope gaps across projects.