The U.S. construction industry added 20,000 jobs in November, a quarter of which came in the nonresidential sector, according to the Bureau of Labor Statistics.

October’s overall construction estimate was revised downward from 12,000 to 7,000 net new jobs, and nonresidential construction lost 2,100 jobs in October, after revisions.

“Nonresidential construction added nearly 5,000 jobs in November, and the outlook remains positive,” says Associated Builders and Contractors chief economist Anirban Basu. “It is important to note that the greatest constraint on nonresidential job growth may no longer be a lack of demand for construction services, but rather a lack of supply of sufficiently skilled workers.

“Growing demand for human capital coupled with tighter labor markets strongly suggests that industry wage pressures will expand in 2015, perhaps to the extent that margins will be rendered too thin for many firms, even in the face of rising demand for services.”

Nonresidential building construction employment fell by 2,400 jobs for the month but is up by 9,500 jobs, or 1.4 percent, since November 2013. And while the 20,000-job increase is a five-year high for the month of November, Associated General Contractors of America officials caution that the latest figures include signs that demand for public-sector and nonresidential construction may be weakening.

“November was another good month overall for construction workers and businesses,” says Ken Simonson, the association’s chief economist. “Yet the recent declines in public works and nonresidential building construction employment may indicate some underlying weakness in the construction market.”

Construction employment totaled 6,109,000 in November, the highest total since April 2009, with a 12-month gain of 213,000 jobs or 3.6 percent, Simonson notes. Nonresidential contractors hired a net of 3,600 workers for the month and 90,100 (2.4 percent) since November 2013. However, the heavy and civil engineering construction segment lost 1,300 jobs in November, while nonresidential building construction lost 2,400 jobs.