"We can't do this alone," Twyford said. "If you know of properties that might be available over winter, such as seasonal worker accommodation or private rental homes, we'd like to hear about those.
"We'd also like to identify small land options suitable for temporary housing with power and water connections ready to go, such as marae and private land."
Property owners would be paid market rents, he said; they were not expected to simply donate properties.
"If there's a massive surge over winter, we need to have those other options in our back pocket.
"That's why we are considering relocatable [homes] and small-scale clusters of temporary housing."
Twyford and Prime Minister Jacinda Ardern also appealed to people who were struggling to get into homes to approach Work and Income. There have previously been concerns that homeless people were afraid or unable to get help from WINZ.
Ardern said she wanted a culture change within social services.
"Our call to them, and the instruction we have given, is when it comes to special needs grants, be flexible. Provide for those who are in need. That is what our social services are there for."
Of the $100m Budget funding, $37m was money the Ministry of Social Development had been allocated by the previous National Government but not spent. Every cent would be spent by the Labour-led Government, Twyford said, onfinding 1500 short-term emergency housing places, including social housing, motel units, and temporary shelters.
The remaining $63m would go into sustaining and expanding the Housing First programme, which places the most vulnerable homeless directly into permanent houses, rather than temporary shelters, before dealing with any mental health or addiction issues.
That was on top of $300m over four years for emergency housing which the National Government invested in 2016.
National's social housing spokesman Simon O'Connor saidthe new Government's commitment was a pale imitation of National's.
"[Twyford's] $100 million announcement today is a third of the size of National's package and it's not even all new money," he said.
The Government had limited its options by spending too much on tertiary fees and Shane Jones' regional fund, he said.
In all, National funded about 2200 emergency housing places and 900 Housing First places.
Labour's announcement will fund 1500 emergency housing places and 550 Housing First places, though Ardern said there would be further housing measures in the Budget on May 17.
The number of people waiting for social housing has been rising since mid-2015, and is now about 6200 people.
About 40,000 people are believed to be homeless in New Zealand, which includes not just rough sleepers but people in insecure housing.
Twyford warned today that homelessness was not just an Auckland problem. MSD was observing "acute levels of homelessness" in centres like Tauranga, Hamilton and Wellington, and smaller regional centres like Blenheim.
