Queenslander houses in flood-prone areas could soon float above floodwaters, using a pontoon structure designed by James Davidson Architect (JDA).
The system is inspired by the certical posts that support the Queenslander building typology.
The pontoon works using vertical columns that run through the wall structure of the building. The upper floor is connected to a coupling system that uses the columns as guides – as the floodwater rises so does the top floor. The height the house can rise to depends on the height of the pylons.
James Davidson, principal of JDA, thought of the idea while working on a house on Lizard Island, north of Cairns on the Great Barrier Reef, which is a UNESCO World Heritage site.
Davidson and his team had to work out a way to get building materials over the World Heritage site and up to the location of the house.
“The idea that we came up with, together with the builder, was to float a pontoon out on to the reef. The barge pulls up on to the pontoon and then we pull the pontoon with all the building materials to the beach. From the beach we then used a sort of flying fox pulley system with a generator and we lifted all the materials up over the world heritage site to the top of the hill,” Davidson said.
As the team was building the pontoon on the beach, Davidson realized they were creating a system of pontoon-like structures that could work underneath Queenslanders.
Prior to this, JDA, along with the Australian Institute of Architects and Emergency Architects Australia, ran a pro bono building assessment program involving 60 architects that assessed the houses of uninsured homeowners after the 2011 floods in Ipswich, Goodna and Rocklea.
Davidson said through the assessment, JDA gained a greater understanding of what worked in floods and the firm started to become known for “wet-proofing,” a practice that allows water to run through the building without destroying it.
“We’ve done a number of houses like that and the clients are very happy, but at the same time there’s always been this issue in Brisbane: the flood line keeps getting revised,” Davidson said.
The minimum habitable floor level JDA worked on in 2011 had a flood level of 8.5 metres Australian Height Datum (AHD). But in 2014 the level was revised up to 9.5 metres AHD.
Around the same time, in September 2015, Davidson was invited to Bangkok to organize an international conference on amphibious architecture, involving people from all over the world.
He then realized his work with wet-proofing and the pontoon structure could work together to provide a solution for flood-prone houses.
Working with engineer Josh Neale of Westera Partners, JDA developed the pontoon structure for Queenslander houses.
Initially, Davidson was skeptical of floating houses due to the high costs of floating projects. However, he says the firm hopes the cost of the pontoon structure will be around $20,000–$30,000 more expensive than the average cost of raising a Queenslander.
Davidson hopes the pontoon device could be used to lower insurance premiums for houses in flood-prone areas. He says Suncorp insurance has expressed support for the idea.
“[Suncorp] is coming on board in a way because my interest is to not only make it affordable for people, but to put pressure on the insurance industry to accept the system so people could have their premiums lowered if they were to utilize a more resilient design system,” Davidson said.