The plumbing section closed about five years ago, although the retail section remained open.
Mr Stewart said it has been hard to make a profit and so the final decision to close the doors was agreed on by the family.
He said the closure was not a shock to the staff and one person had already found other employment.
"It wasn't unexpected when they were told it was closing," he said.
"The family have been happy to keep it going to support the staff and the community, but there's a limit to how far you can keep going."
He said it was hard to make a profit out of a business that size in Carterton.
"I think many of our customers are very upset," Mr Steward said.
"It's been here for many years. It's certainly iconic."
Other parts of the business, such as the septic tank cleaning sector and key cutting machine, have also been sold.
Mr Stewart said there has been interest in buying the building but nothing is confirmed.