Construction added a strong 38,000 jobs in December but the industry’s unemployment rate showed mixed results, the federal Bureau of Labor Statistics has reported.

Construction’s December jobless rate rose to 5.1% from November’s 3.9% but improved from the year-earlier level of 5.9%, according to the latest monthly BLS employment report, released on Jan. 4.

The BLS unemployment rates aren’t adjusted for seasonal variations. Construction’s rates tend to rise in winter as the volume of building eases in some sections of the U.S.

Construction’s total workforce increased by 280,000, or about 4%, for the year ended Dec. 31, according to preliminary BLS figures.

The bureau also revised November’s preliminary construction job totals downward by 5,000, making that month’s total flat with October’s.

The industry’s December job gains were led by a surge of 16,300 in the heavy-civil engineering sector, an indicator of infrastructure work.

The nonresidential specialty trade contractors segment also posted solid results, adding 16,100.

The only category to show job losses was residential specialty trade contractors, which shed 2,900 positions.

Anirban Basu, Associated Builders and  Contractors chief economist, said in a statement that the BLS report  "reminds us that the U.S. economy continues to exapand and that many businesses, including construction firms, remain in growth mode,"

Architectural and engineering services, a separate BLS industry category, added a modest 1,400 jobs in December.

Construction pay increased in December by an average $1.13 per hour, or 3.9%, year over year, to $30.44, and by 15 cents per hour from November’s level, BLS reported.

Ken Simonson, Associated General Contractors of America chief economist, said in a statement, "Job growth and pay increases in construction are outpacing those in the overall economy." But he added that contracting firms "continue to have difficulty finding qualified workers, with the number of unemployed workers who have construction experience at the lowest December level in  19 years."

BLS also reported that thel U.S. economy added 312,000 jobs in December. It said that the overall unemployment rate increased to 3.9% from November's 3.7% but declined from the December 2017 level of 4.1%.