The average hourly union wage for plumbers in a 20-city survey is $36.62 (up 3.3 percent), according to Engineering News-Record magazine. The average hourly union wage for pipefitters in that same 20-city survey is $36.14 (up 3.3 percent), and $36.23 (up 3.8 percent) for sheet metal workers. The rate per hour includes base rate plus fringe benefits.