Retailers are being hit by an international shortage of some building products, such as timber and steel.
Industry groups say it's part of an Australia-wide problem, partly prompted by the HomeBuilder stimulus measures.
Businesses say trade is still brisk, but they are encouraging customers to order products ahead of time.
Bendigo Timber co-owner Peter Norman said most items were still available, but where the business used to keep a stock of some, customers now needed to order months in advance.
Mr Norman, based in central Victoria, named construction timber, such as framing, laminated veneer lumber and beams as the key product affected.
He said for Bendigo Timber it meant educating customers so they knew to order ahead. Most customers were in trade, so they were in the same boat, he said.
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Mr Norman said the whole industry was in the same position, which dated from about the end of 2020.
"We're still busy and we're still supplying, but we're just having to let everyone know they can't just rock in off the street and pick up [everything] they need," Mr Norman said.
"We're still busy, business is still good, we can't complain at all. Things will eventually right themselves ... but it's just a matter of time."
California Gully store Fitzpatrick's Home, Timber and Hardware, in Bendigo, Victoria, managing director Shane Fitzpatrick said timber framing was the main issue, affecting suppliers across Australia and more broadly.
"There's such a big demand for it ... because of the first homeowners scheme and everything, it's put a lot of people under pressure to supply and build," he said.
Mr Fitzpatrick said the store had found locally manufactured products were easy to find, but imported products - or those with imported components - were harder to get.
Bendigo's Abbott Supply wholesale manager Jill Woodman said the business had experienced a few supply issues, but they were mainly sorting themselves out now.
Ms Woodman said the Suez Canal crisis had probably added to the issue.
Master Builders Victoria chief executive Rebecca Casson said members were reporting significant shortages of key building materials, particularly timber and steel.
Mrs Casson said stimulus measures such as HomeBuilder had created unprecedented demand in the building and construction industries.
She said HomeBuilder had been great for the industry, but some builders were getting pressure from clients because of the shortage.
Mrs Casson said the supply shortages were largely to do with supply and demand across the globe.