Westbury said it was uncertain how long the factory, called Space 4, would be closed. A spokesperson said: "It is hoped that the investigations will be completed very shortly and that production will thereupon immediately recommence; however, this outcome cannot be certain."
At the time of going to press, the HSE said the investigation was to last until at least Thursday 13 December.
John Bennett, finance director at Westbury, said shutting the factory could cost up to £8000 a day. The factory supplies materials to the housebuilding industry and is the largest of its kind in Europe.
The company said its thoughts were with the employee's family, and described the death as "tragic".
Westbury bought the factory in April 2000, with the aim of producing 5000 houses a year.