House building has helped fuel a surge in work among Northern Ireland's construction sector but the industry has warned about a slowdown in public sector jobs due to the collapse of Stormont.
Around two-thirds of firms surveyed by the Construction Employers Federation (CEF) and BDO said their books were full, or almost full, in the first six months of the year.
The survey showed sustained growth in the first six months of the year.
Much of that growth is within private housing, taking it to its highest level since 2011.
But the survey says firms are cautious in the next six months due to high costs and squeezed margins.
CEF managing director, John Armstrong, says the the industry remains concerned over a lack of representation at Stormont what Brexit will mean for the sector.
"There are four clear challenges that are emerging from the survey," he said.
"Industry concerns at a slowdown in public sector work resulting from the lack of a Northern Ireland Executive, the impact of a potential hard Brexit could have in companies' otherwise positive growth expectations.
"The significant skills shortage across many trades, and, how substantial rises in labour, material and plant costs are impacting on margins and firms' capacity to reinvest."
The survey results are based on a sample of 60 member firms, representing half of Northern Ireland's construction output.