Builders' merchant and Wickes chain owner Travis Perkins has revealed plans to close more than 30 branches in a move impacting 600 jobs across the group.
Travis Perkins said the branches would be shut across its trade businesses, while it is also closing 10 smaller distribution centres and reviewing its plumbing and heating division as it warned over full-year profits amid "uncertain" trading.
All 600 staff impacted are aware of the changes, it added.
There are branches of the company in Sunderland, Hartlepool, South Tyneside, Durham, Middlesbrough and Newcastle.
Travis, which employs 28,000 staff group-wide, said it hoped to relocate some of the affected staff to other sites.
Branches are expected to close across its trade brands, such as Travis Perkins, kitchen and joinery arm Benchmarx and plumbing and heating businesses BSS and PTS.
The overhaul comes as Travis Perkins said full-year underlying earnings would be "slightly" lower-than-expected, while it cautioned over the outlook for 2017.
It said: "Given that levels of future demand remain difficult to predict, the group has chosen to implement a number of efficiency programmes and branch closures to further optimise the network.
"This work includes the closure of 10 smaller distribution and fabrication centres, the write-off of certain IT legacy equipment and over 30 branch closures in our trade businesses."
The group said the heating and plumbing division will see the bulk of the branch closures after a "disappointing" performance in the third quarter and in the face of worsening trading conditions.
It plans to report back on its review of the business next year.
But it said its general merchanting business saw better trading in the quarter, while consumer-facing chains Wickes and Toolstation and its contracts businesses put in "very strong performances".
Overall like-for-like sales grew 2% in the third quarter, Travis said.
John Carter, chief executive of Travis, said: "It is still too early to predict customer demand in 2017 with certainty and we will continue to monitor our lead indicators closely."
Travis is half-way through a five-year overhaul of the group, which is seeing it shut unprofitable stores and expand in better performing areas.
It is revamping its Wickes stores and said it has refitted 50 shops.