Zien Service, Inc. was originally established in 1919 as Zien Plumbing.  Zien Plumbing operated as a family company starting in a small store front in the city of Shorewood and grew to a 45 million dollar company.  It later relocated to Milwaukee and was sold to a group of employees.  Zien operated as Zien Mechanical Contractors until 1989 when it was sold to the Barson family.  The name was changed to Zien Service, Inc. to emphasize the change from a large construction company to a service oriented company that also specialized in construction.  Service was no longer a side line but the direction of the company.  In 2008 a new 50,000 square foot shop was purchased and all activities were consolidated to the new location at 2303 W. Mill Road in Glendale, Wisconsin.