The next UK government must ensure the construction sector has enough skilled workers to keep its housing and infrastructure manifesto pledges, the Federation of Master Builders (FMB) has said.
And the construction trade body called on the UK's main political parties to recognise the importance of migrant labour to the construction sector.
FMB chief executive Brian Berry said: "The UK construction sector's demand for skilled migrant workers from the EU and beyond cannot be overstated. In London alone, there are more than 157,000 non-UK construction workers constituting almost half of the industry's workforce in the capital.
"Pre-Brexit, 60% of small construction firms are already having trouble hiring bricklayers and that's before the UK abandons the free movement of people."
The FMB has also said that a skills shortage is threatening growth in the Northern Ireland construction sector, with a lack of carpenters and joiners a particular obstacle to complete recovery.