Decisions are being delayed and projects cancelled, a poll of industry leaders shows - though there were also some positives.
More than half of bosses in the construction industry say they have already felt the impact of Brexit, new figures compiled for Sky News show.
The poll of 2,500 leaders from the sector, conducted by the organisers of UK Construction Week, found 59% said they were being affected.
Of those, 75% said it was because of clients delaying decisions and 33% said it was because of a slowdown in the housing market.
Meanwhile 45% said budgets had been cut and 29% had seen projects cancelled altogether.
But some of the impacts had been positive, with 25% seeing more foreign investment and 19% seeing projects brought forward.
In other positives from the poll, 64% said Brexit would force the industry to solve its skills crisis by training and investing in younger generations, while half said they would use more domestic suppliers and 34% said leaving the EU would cut red tape.
The finding that the looming EU divorce is causing delays and work drying up chimes with a recent economic survey that blamed a "Brexit blight" of uncertainty for holding back the sector.
Peter Caplehorn, deputy chief executive of the Construction Products Association, told Sky News: "We've seen a lot of commercial clients hesitating on developments, on production.
"Clearly that is now starting to work its way through and it affects everybody in the industry, mainly because of uncertainty, and so we need to go forward with a clear plan."