Cameron Dick has told attendees at Thursday’s housing summit that Queensland should have 55,000 more rental dwellings than it currently does.

Treasury analysis found much of the shortfall can be attributed to rental properties being bought by owner-occupiers, a slow-down in construction of new homes or being taken out after being damaged in recent floods.

However, Dick said the analysis found a shortage of 20,000 rental homes “cannot be explained by available data.”

“In my language that is: we don’t know,” he said.

“So, I’ve asked Treasury to keep looking and try and explain to me the available data, I’ve asked officials to keep looking at that issue.

“But what’s happened in the housing market very unique, very unusual, and has not happened before in Queensland.”

The missing rentals could be explained by people using their investment properties to work from home during the Covid-19 pandemic, or holding them for sale or for use as holiday homes.

However, Dick said the shortfall hasn’t necessarily been caused by an uptick in short-term rentals.

Earlier, Premier Annastacia Palaszczuk said about 5600 new social and affordable homes would be built by 2027, on top of the 6365 promised by 2025.

She said the government will double its Housing Investment Fund to $2 billion, which will create annual returns of $130 million to be invested in dwellings.

“That’s a good portion of money that’s dedicated for building new homes,” Ms Palaszczuk said.

“This additional investment also recognises the impact that rising cost of building materials and labour is having on prices right across the construction sector to secure much needed additional supply.”

More than 100 representatives from three levels of government – and from social services, charities, property, construction and industry bodies – are taking part in Thursday’s summit.

Short-term rentals, interstate migration, planning rules, land use and social housing are set to be examined at the one-day event.

Tenants Queensland CEO Penny Carr told the summit the tight rental market has left tenants vulnerable to rent rises.

“We had two clients … one had a $170 a week increase, and the other had a $120 a week increase,” she said.

“They were both in the market with the same landlord for five and six years.”

Planning Institute of Australia’s Matt Collins said policymakers should put more focus on security of tenure, rather than solely home-ownership.

“(So) they’re not at risk arbitrarily of having that tenancy end and having to relocate … particularly in a market like we have now that can have really significant impacts,” he said.