Wolverhampton-based building giant Tarmac is planning to axe 550 jobs and close one of its divisions, blaming "tough" market conditions.
Tarmac Building Products said it had been reviewing the future of its Precast Solutions and Flooring business.
The move is set to hit 217 jobs in Tallington, Lincolnshire and more than 100 in Henlade, Somerset, with the remainder going in Derby, Lound in Nottinghamshire and Dolyhir in Powys, Wales.
Chief executive Blair Illingworth said: "Tough underlying market conditions and continuing uncertainly of demand have led us to review the options for the future of our Precast Solutions and Flooring business, and we have taken the difficult decision to consider its closure.
"This affects five sites across the UK and, unfortunately, means that around 550 people are at risk of redundancy.
"It is not a decision we have taken lightly and we have begun a 90-day consultation period with employees affected by this. We are also liaising with our customers to discuss how this could impact them."