TATA Steel is axeing 180 jobs at its site in Deeside.
The company, previously known as Corus, plans to close its Living Solutions business in Shotton.
Living Solutions was set up in 2003 to make buildings from the company’s steel for the construction industry.
But Tata say the business has never been profitable and a weak construction market, coupled with the end of a contract supplying the defence accommodation sector, had added to its problems.
Andrew Black, managing director of Tata Steel Building Systems, said: “It is with great regret that, following a detailed review of the Living Solutions business, we have proposed to withdraw from this business activity.
“Clearly this is a very difficult time for our colleagues at Living Solutions and I would like to pay tribute to everyone who has worked so hard to try to develop this business venture.”
A spokesman for Tata added: “Many employees have put their heart and soul into making this business work but sadly this economic crisis has dealt a severe blow and the business feels it cannot go on.”
A consultation process is due to take place with trade unions and employee representatives, and with all employees on an individual basis.
Tata has said it will explore all opportunities to redeploy employees and support those leaving the business.
The company has said the closure of Living Solutions will not affect its other businesses in Shotton, which include Tata Steel Colors, Panels and Profiles.
Community Union general secretary Michael Leahy OBE said: “Community Union is obviously disappointed that Corus has chosen to back away from this investment at the cost of so many jobs.
“It is hoped that these job losses will not have a knock on effect through other parts of the business.
“Community Union will take every step possible to avoid hard redundancies. Unfortunately, the nature of the Shotton site means that there will be few opportunities for cross matching and Community will look to the Welsh Assembly to provide the training and support networks to help these workers re-enter the jobs market.”
A Welsh Assembly Government spokesman said: “This is very disappointing news and we will be seeking a meeting with Tata as soon as possible to discuss this decision.
“Tata is a central part of the Welsh economy and we hope the company can avoid any compulsory redundancies and find jobs for these workers in other parts of the organisation.”
Alyn and Deeside MP Mark Tami and AM Carl Sargeant have urged Tata to do everything in their power to find alternative jobs for the workers.
Mr Tami said: “The company desperately needs to work with trade unions in avoiding compulsory redundancies and I have today spoken with them about re-deploying as many people as possible to other areas of the business.”
Mr Sargeant said: “These people have been loyal to the company and deserve to be protected from unemployment.”
Delyn MP David Hanson added: “I am deeply concerned about the potential job losses at the plant. I have spoken to Alyn & Deeside MP Mark Tami on this matter and I will be supporting him as he takes this issue up with management at the site.”