J.M. Brennan, Inc. is one of Wisconsin’s oldest and most reputable mechanical contractors. With complete in-house capabilities, from design and installation to service and maintenance, we’re a single source resource for HVAC, plumbing, process piping, industrial sheet metal, controls, HVAC Service and more. As mechanical contractors, we draw on our in-depth understanding of the mechanics of every component in your building—from boilers to software—to offer novel solutions to satisfy even the most demanding projects. The commitment and quality of our people and our customer-driven approach to doing business are the main factors behind our longevity and lengthy list of repeat customers.