UK construction companies in September reported the sharpest fall in activity since just after June 2016's Brexit vote, as clients put projects on hold due to uncertainty over the economy.
Although construction makes up just 6% of the UK economy, the survey suggested it was likely to drag on official third-quarter growth figures, just as the Bank of England gets ready to raise interest rates.
The IHS Markit/CIPS construction purchasing managers' index (PMI) sank to 48.1 in September from August's reading of 51.1.
This was its lowest level since July 2016 and was far below all forecasts in a Reuters poll of economists. Anything below 50 is considered a contraction.
IHS Markit said the prospect that the Bank of England will raise rates next month for the first time in a decade was also a factor behind slower house building.
Business investment overall has grown since the Brexit vote, but many business leaders say the government is not making enough progress in Brexit talks with the European Union.
Construction - which has long lead times for projects, and relies heavily on labour from the EU - has been particularly hurt.
Official data last month showed construction orders fell more than 12% year-on-year in the three months to June, and the PMI has shown lower orders for the past three months.
Expectations for the future were at their second-lowest level since 2013, today's survey also showed.
However, shares in housebuilders have gained in recent days after the Conservative Party announced plans to revive a £10 billion house-building subsidy.
The manufacturing PMI published yesterday showed a slowdown in growth although it remained solid, and a survey of Britain's huge services industry due tomorrow will give a clearer idea of third-quarter growth.
The UK economy has suffered its weakest growth so far this year since 2012.
Consumer demand has borne the brunt of a rise in inflation to its highest in nearly five years, which is largely due to the pound's tumble after the Brexit vote.
The PMI data showed the cost of building supplies rose at its fastest rate in seven months in September.