Fletcher Building has laid off about 90 staff, mainly in Auckland, as part of its restructuring to save $30 million each year, its boss says.

Chief executive Ross Taylor spoke more about the job losses after the half-day investor briefing in Sydney on Thursday.

"There's been about $30m in cost savings from salaries of the people who have left the business," he said referring to the amount being mainly salaries which the business would not now pay.

But the savings were not just from the reduced work force cuts, he stressed.

"We've shrunk back to save money," he said, referring to Fletcher's rent bill reducing because office space needs contracting from the smaller work force and as well as savings in computer and IT.

The 90 staff were mostly in the head office at Penrose, he said.

"They had various roles in procurement, manufacturing excellence and group marketing and sales," Taylor said.

At the investor briefing, Taylor talked about the practical changes he was making, including simplifying the business and he mentioned one example.

"We're trying to run the pay roll system out of Penrose," he said, adding that it was "hard enough" to run an Australian-wide pay roll system because of differences between states let alone running it all from New Zealand.

Taylor vowed to double Fletcher's margins from its Australian businesses. Fletcher's Australian margins have been compared unfavourably with Australian peers including CSR and Boral.