Seasonally adjusted construction employment of 5.79 million in April was 6,000 less than in March, but 154,000, or 2.7 percent, higher than in April 2012, Simonson noted. Residential building and specialty trade contractors added 13,300 workers in the month and 83,700 (4.1 percent) over 12 months.

The unemployment rate for construction workers fell to the lowest level in five years in April despite a dip in employment last month, according to the Associated General Contractors of America (AGC). Contractors added more than 150,000 employees in the past year, and despite the monthly drop, the industry is likely to continue adding jobs for much of 2013.

The unemployment rate for jobseekers in the construction industry fell to 13.2 percent from 14.5 percent in April 2012, the lowest April level since 2008, according to the AGC analysis of government data. In April 2010, the rate was 21.8 percent. (The industry unemployment rate is not seasonally adjusted and can be compared to the same month in past years, but not month to month.)

"It is heartening to see that both nonresidential and residential segments of the construction industry added significant numbers of workers in the last 12 months, even though gains from March to April were limited to the residential side," said Ken Simonson, the AGC's chief economist. "The ongoing decline in the construction unemployment rate is only partly a result of [increasing job] opportunities "?(R)? many former workers have left the industry, perhaps permanently, which will make further recovery in construction more difficult."

If construction employment grows as expected during the coming months, finding qualified workers in expanding market regions will be increasingly difficult for employers, the AGC report said. A lack of domestic skill-based educational programs and arbitrary caps on the number of construction workers in immigration legislation under consideration in Washington, D.C., would make it harder for firms to keep up with growing demand.

"It will not take a lot of growth in demand before many construction firms are scrambling to fill positions with skilled workers," said Stephen Sandherr, the association's chief executive officer. "We need to provide significantly more opportunities for students to learn skills-based crafts like construction and avoid imposing artificial limits on the size of the construction workforce in immigration legislation."