Almost 200,000 construction jobs are at risk if access to the single market is lost because of Brexit, a new report warns.
Some of the country's biggest infrastructure projects will be threatened by such a huge loss of workers, said the Royal Institute of Chartered Surveyors (RICS).
Around 8% of construction workers in this country are EU nationals, showing their importance to the industry.
Construction is already in the grip of a skills crisis, warned RICS.
The group's head of UK policy, Jeremy Blackburn, said: "These figures reveal that the UK construction industry is currently dependent on thousands of EU workers.
"It is in all our interests that we make a success of Brexit, but a loss of access to the single market has the potential to slowly bring the UK's £500 billion infrastructure pipeline to a standstill.
"That means that unless access to the single market is secured or alternative plans are put in place, we won't be able to create the infrastructure needed to enable our cities to compete on a global stage."