According to the U.S. Department of Housing and Urban Development, construction starts for privately owned houses in April sagged to an annual rate that was 7.4 percent below the March pace and a troubling 11.1 percent below the rate in April 2005.

Central Iowa builders report that activity is slowing here, too.

Now let’s throw in another factor that most of us probably haven’t considered. We might reassure ourselves that the demand for new homes will go on and on despite brief lapses, but who’s going to do the work? In the long term, labor could become the real problem.

Fortune magazine points out that the battle over immigration reform is a very big deal in the home construction industry, because “up to 40 percent of new-home construction in the U.S. is being done wholly or partly by undocumented immigrants.”

Fortune reported: “In May, Fischer Homes, a leading builder in Kentucky and Indiana, was raided by U.S. Immigration and Customs Enforcement (ICE), and four Fischer supervisors were charged with harboring illegal aliens.

“Court papers filed by ICE accuse Fischer of using subcontractors ‘to provide a layer’ between it and some 75 illegal workers. That layer, the feds contend, ‘does not relieve Fischer of the responsibility to ensure that their contractors are employing a legal work force.’

“A crackdown on undocumented workers would shrivel an already tight construction labor market. Lee Wetherington of Lee Wetherington Homes in Sarasota, Fla., estimates that 70 percent of the workers employed by his subcontractors are Hispanic immigrants.

“‘If for any reason we lose that work force, you’re going to see the time required to build a house double or triple and the cost of new homes increase 30 to 40 percent,’ Wetherington says.

“He insists that there just aren’t enough native-born workers available to meet demand and points to Sarasota County’s 2.3 percent unemployment rate.”

We don’t know how many undocumented workers are building Central Iowa’s homes. But we do know that Hispanic workers are a major part of our workforce and that the unemployment rate here is low.