Since Gerry Wiegmann ventured on his own to start Wiegmann Associates in 1995, two things have remained constant for the company — the mechanical contractor specializes in HVAC systems, and a Wiegmann has always been heavily involved in the company’s operations.

But nearly everything else about the business has changed.

Today, the team at St. Charles-based Wiegmann Associates — led by founder and CEO Gerry Wiegmann and his sons, President Chad Wiegmann and Director of Business Development and Preconstruction Grant Wiegmann, has gone through a series of innovations in how it builds HVAC systems. Industry trends now favor emphasizing energy efficiency and design-build projects, in which the company designs systems and then builds them, too.

Wiegmann Associates works nationwide on projects for multiple industries, but one of Chad Wiegmann’s goals is to never believe that what has worked in the past will also work well in the future.

“It’s so easy to become complacent and get overly comfortable in what you do and assuming that the way you do it now will always work,” Chad Wiegmann said. “With our industry, you constantly have to be looking forward and make sure you’re always improving and always keeping up with the times.”

Although founder Gerry Wiegmann is proud that his sons are so heavily involved in day-to-day operations, he is quick to point out that the company has always thrived because of strong employees from outside the family, too. That tradition continues with today’s leadership team of David Boschert, vice president of field operations; Dan Ebert, CFO; Todd Jacks, engineering manager; Rick Creed, controls manager; and Kyle Boschert, service manager.

As an essential business, Wiegmann has grown during the Covid-19 pandemic to $64.45 million in revenue, ranking fifth on the Business Journal’s list of top mechanical contractors in St. Louis. The company has 105 employees.

“We’ve fortunately developed specializations in a lot of different areas of construction, which has helped us to stay really nimble,” Grant Wiegmann said.

The company started diversifying ahead of time after surviving significant challenges through the years during construction down times or recessions, Gerry Wiegmann said.

“We’ve never had to have a significant layoff because, even when the economy turned down, we were able to maneuver, find work outside St. Louis, do different types of work,” the CEO said.

The company’s long list of St. Louis projects includes the Bunge headquarters, an Amazon distribution center, the $150 million Streets of St. Charles development, multiple federal buildings and the $30 million Soldier’s Memorial renovation. Work might have been more stable in St. Louis than it would have been in other cities, the founder said.

“In many ways it’s a blessing being in St. Louis — St. Louis doesn’t boom or bust, it’s pretty steady. It seems like other areas of the country vacillate way up and way down,” Gerry Wiegmann said. “Some of the best talent in contracting, general contracting, mechanical contracting and electrical contracting is in St. Louis, so we’re competing against some really good firms in this community and that helps grow our national competitiveness. We like being from St. Louis. People here have a good work ethic and, from that perspective, St. Louis has a lot to offer.”