After a record month in February, the pace of growth in activity in the construction sector has now eased back for both March and April.
The latest purchasing managers index from Ulster Bank fell to to 56.4 in April from 62.3 in March.
Ulster Bank said that although the latest reading continued to signal marked growth of construction activity, the rate of expansion slowed for the second month in a row and was the weakest since last November.
The monthly survey of participants in the sector is designed to measure changes in activity and sentiment.
The April reading indicates growth was slower across all three sub-sectors monitored - housing, commercial and civil engineering.
A slower rise in employment was also recorded, but the rate of job creation remained marked as companies said that the signing of new contracts had led them to take on extra staff.
Ulster Bank said that construction firms also reduced their usage of sub-contractors for the first time in 14 months during April.
Sentiment, however, rose to its second highest level in the history of the index as more than two thirds of the respondents said they expected further growth over the coming year.
Commenting on the figures, Ulster Bank's chief economist Simon Barry said the decline in the index needed to be seen in the context of the exceptional strength recorded earlier in the year which saw the main PMI - as well as the housing sub-index - establish new record highs in February.
"So while this slippage in momentum bears careful monitoring in the months ahead, it is important to note that these results are still very much consistent with a sector comfortably in expansion territory," Mr Barry said.