More than 30,000 people could lose construction jobs in Northern Ireland by the end of next year because of cuts to the public building programme.
The Northern Ireland Executive must act quickly to avoid disaster, the Construction Employers' Federation warned.
Around 21,000 people have lost their livelihoods since the end of 2007.
Federation manager Ciaran Fox said: "If that sort of rate continues there will be well over 30,000 jobs lost from the sector by the end of 2011.
"Whether or not that disaster actually happens depends largely on the actions of the Northern Ireland Executive.
"A continuation of this rate of job losses is almost inevitable if the Executive decides to reduce spending on building and maintaining our infrastructure."
He said thousands of jobs could be saved if the necessary spending cuts were made in other lower priority areas.
Mr Fox added: "Pound for pound, very few spending areas can rival the economic and social benefits provided through investment in construction."
Building work in Northern Ireland is at its lowest level for 10 years.
The Royal Institution of Chartered Surveyors (RICS) found more of its Northern Ireland members reported declining workloads than in any other region of the UK. Most said they expect business to worsen further over the next year.
Parts of the Northern Ireland construction industry found work declining faster between April and June, with no area showing growth.
In the mid-2000s, rapidly rising property prices here were behind an intensive period of new developments, but the rapid fall of the housing market has meant troubling times for the construction industry.