The UK’s biggest builders merchant, Travis Perkins, whose businesses include DIY chain Wickes, is closing 30 branches, putting 600 jobs at risk.
The branches will be shut across its trade businesses, while it is also closing 10 smaller distribution centres and writing off IT equipment.
The 600 affected workers have been told of the changes, Travis Perkins said.
The group operates almost 2,000 stores in the UK, including branches of Travis Perkins, BSS, Tile Giant, as well as Wickes.
It said profits would be lower than expected this year because of disappointing sales in its plumbing and heating division.
Wickes - and its other consumer-facing business Toolstation - were not included in the process, it confirmed.
The company’s chief executive John Carter said: “It is still too early to predict customer demand in 2017 with certainty and we will continue to monitor our lead indicators closely.
“Given this uncertainty we will be closing over 30 branches and making further efficiency driven changes in the supply chain, resulting in an exceptional charge of £40-50 million this year.”
The FTSE 100 firm said it was taking the steps due to an “uncertain UK outlook” for next year.
Travis Perkins was one of the biggest fallers on the FTSE 100 following the Brexit vote on fears of a hit to the UK’s property and construction sectors.
Shares in the company are still down 22% since the referendum.