The skilled labor shortage will eventually come back to haunt again.

You don’t hear contractors complain as much as they used to about the difficulty in finding good plumbers and fitters. A work shortage has pretty much done away with the worker shortage for the time being. But only for the time being.

Sooner or later (please let it be sooner) construction will boom again, and then the industry will be back to square one in coping with the task of finding enough trade professionals to build and service all the plumbing and piping systems that require their skills. This miserable recession momentarily put a damper on demand, but may well worsen the long-term problem because much training has been curtailed at a time when jobs are not available to accommodate newly minted journeymen.

Last September, UA Pipefitters Local 597 and the Mechanical Contractors Association of Chicago hosted a so-called Tripartite Conference consisting of union officials, their employers and end users to exchange ideas on working together. Keynote speaker for the event was UA General President Bill Hite, who addressed the looming labor shortage. According to him, the nonunion sector represents about 60 percent of the industry, yet trains less than 15 percent of the apprentices.

Most estimates put the nonunion market share even higher, upwards of 70 percent when residential construction is factored in. It’s unclear where Hite got his 15 percent share for nonunion training, but the figure sounds plausible. That’s because nonunion training is hampered by key structural deficiencies.

Even in good times, demand for construction labor vacillates from year to year, even month to month. So nonunion companies are understandably reluctant to invest time and money training people who may go to work for a competitor at any moment. In tough times particularly, training money forms a bulls-eye for cost-cutting CFOs. Nonunion multiemployer training programs try to mimic what the unions do and spread the cost around, but without collective bargaining agreements their programs rely upon voluntary contributions by business competitors whose vested interests do not usually mesh.

A nonunion contractor can save a lot of money and trouble by simply recruiting out-of-work union-trained craftsmen, and that’s exactly what many of them do. Whenever significant numbers of union members are on the bench, it’s almost senseless for a nonunion contractor to invest in training.

Union craft training dominates because it is supported by mandatory contributions backed by the force of labor law. The amount available for training ratchets up and down with manhours worked, but even in bad times some money always goes into training funds. Plus, the hiring hall and traveler system enables contractors who belong to a collective bargaining group to easily adjust work forces to market conditions.

Moreover, let’s give credit where it’s due. The training provided by the UA and its joint apprenticeship contractors is first-rate. They realize this is their lifeblood and they take pride in it. Hite said the UA and its local unions invest some $170 million a year in pipe trades training. I’ve never seen a comparable estimate for the nonunion sector at-large, but it’s almost certain the cumulative tally wouldn’t come close to the UA’s.

This is not to say the union side has it all figured out. Despite its vaunted training reputation, the UA still has trouble attracting talented young people to the pipe trades to replace its increasingly aging work force - now averaging around 50 years.

“We have to get more young blood into this industry,” Hite told participants at that Tripartite Conference. He noted that the average age of UA apprentices - now 27 - has been rising. He then revealed something that may shine a ray of hope on the industry’s future.

According to Hite, about half of the UA’s apprenticeship applicants are college graduates. Many of these likely are people who in earlier times would’ve entered the trades right after high school. Instead, they were steered by peer pressure and school counselors onto a college path, only to discover that B.A. degrees are a dime a dozen and not close to guaranteeing high pay or a satisfying career. The pipe trades may have trouble competing against glamorous jobs with lavish pay and plush offices, but in the real world the alternative all too often is waiting tables or mixing drinks.

High school graduates may not understand all this until they waste some of their youth and a hundred grand or more in pursuit of a sheepskin. But better late than never.