Grucon Corporation history

In 1974 he became president of the firm, while his father assumed the new positions of chief executive officer and chairman of the board.

Grunau's work with Miller peaked in 1978 when it boasted a record $175 million in revenues and employed more than 2,000 people, making it the country's second largest mechanical contractor, according to the trade publication Domestic Engineering.

In 1994 the company expanded again, this time establishing itself in a key location in the Midwest, opening an office in Youngstown, Ohio.

In 1999 Paul W. Grunau bought Grunau Company from his father.

Gould, Whitney, "Developing a Vision for the City," Milwaukee Journal Sentinel, June 9, 2002.

In 2003 Grunau Project Development was sold to Providence, Rhode Island-based Gilbane Building Company, and Gary Grunau became a senior vice-president of Gilbane's regional office located in Milwaukee.

In 2005 the company won a design-build and installation contract for the HVAC system in Wisconsin for a new General Electric Company's healthcare divisions' headquarters.

In the spring of 2006 he agreed to sell the business to St Paul, Minnesota-based APi Group. "As he researched options for aligning Grunau with larger financial partners," according to Plumbing & Mechanical, "he and APi found each other.