The National Distribution Union says news of closures or layoffs in the timber industry has become a daily occurrence and looks set to worsen in the coming weeks.
Three companies have talked to staff over the past week about possible layoffs, including a Fletcher Building particle board factory.
The Laminex factory in Kumeu, owned by Fletcher Building, manufactures particle board for laminated surfaces.
Staff were told on Tuesday the company would need to downsize.
The company says lack of demand means it is no longer cost-effective to continue production in New Zealand for export to Australia.
Laminex chief executive David Worley says particle board made here will be used only in New Zealand laminated surfaces, which means less is needed.
Mr Worley says a consultation period has begun which could take some weeks and it is possible there could be as many as 28 redundancies.