It said: “The Group’s sales volumes have been affected by this recent weakening of activity, with brick and block volumes down in line with the overall market.
“Precast concrete sales have slowed in recent weeks despite good growth earlier in the year.
“Whilst a sustained improvement in productivity has now been achieved, the Bison precast business is unlikely to deliver the level of margin growth anticipated in the second half as a result of delays in a number of large contracts.”
Forterra bought the Bison precast business from Laing O’Rourke for £20m two years ago.
The company added: “As a result of the above factors, and recognising the current macroeconomic uncertainty, the Board now expects profit before tax to be modestly below last year’s result (2018: £64.8m).”
Forterra is building a new £95m brick plant at Desford where site clearance has been completed and foundations work is set to get underway.