The warning followed an industry survey which revealed most Scottish construction firms expect workloads to decline next year.
The Scottish Construction Monitor showed overall confidence within the sector fell for a fifth consecutive quarter.
Nearly 80% of respondents predicted industry activity would fall in 2011.
The Scottish Building Federation said almost two-thirds of respondents expected to reduce the size of their workforce next year, with only 5% expecting to be in a position to take on additional workers.
The federation said although the industry had witnessed modest signs of recovery in the course of 2010, this latest business confidence survey suggested its recovery was at risk of faltering.
It warned that more than 11,000 Scottish construction jobs could be lost next year, while output from the industry could fall by more than £600m.
Chief executive Michael Levack said: “Overall, as 2010 draws to a close, I think the mood amongst construction firms is very apprehensive.
“With the value of new orders apparently shrinking, with Scotland’s public capital budget facing a cut of more than 20% next year, and with many other sectors of the industry – not least housebuilding and commercial – continuing to struggle, our members are bracing themselves for tough times ahead.”