Steel & Tube chief executive Dave Taylor is resigning just shy of eight years in the role.
He took charge in October 2009 and has led the company through a weaker earnings patch caused by project delays, higher costs, and tough competition.
It made a profit of $20 million in the year to June, compared with $25.8m the year before, which included a gain on an asset sale.
Problems with the quality and testing of steel mesh also caused the Commerce Commission to prosecute the firm for false and misleading representations.
It's not the only company to raise problems, the country's biggest construction firm, Fletcher Building, reported a big fall in profits because of major losses on two big projects in its building and interiors division.
Steel & Tube chair Susan Paterson thanked Mr Taylor for his contribution to the company.
Mr Taylor said he was ready to go.
"Now is the right time to step down to enable me to focus on other interests," he said.
Mr Taylor will leave on 22 September.
The company's board has started the process of finding a replacement.