Official figures show that employment in construction firms in December was 6.4% lower than in the same month a year earlier.
The Central Statistics Office's construction employment index has been falling since April last year, but December's fall was the steepest so far.
The figures cover building companies with five or more workers.
Separate CSO figures show that average earnings for public service workers rose by 4% in the year to September, bringing the average weekly wage to €918.31.
Overall, 363,900 people were working in the public sector in September, up 10,400 on a year earlier.
