Nat Hall, 29, who has physical and intellectual disabilities, was perched on the roof of his Magellan St apartment for about 90 minutes before being rescued by members of the community.

His housemate Mel, as well as the occupants of three other units, were also rescued.

"I was absolutely terrified," he said.

"We were on the roof. There was no other way. The doorway to get out of the apartment was under water."

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Mr Hall, who has lived in Lismore since he was a child, said the speed of the rising floodwaters took him by surprise.

"At first we didn't think it would be too bad, we didn't think it would be as bad as the 2017 floods," he said.

"It ended up being 100 times worse than 2017 and there's still more to come."

"Watching the water pull poles out of the ground, pull trees out of the ground; it was absolutely terrifying."

Mr Hall said he was taken to safety on a jet ski, while his neighbours were rescued in a boat.

He took his birth certificate and some other bare essentials with him. He is now safe at his brother's house at Goonellabah.

"When we left the water was up the inside stairwell and just about to go into the apartments," he said.

"I'm absolutely devastated to see how much damage there is going to be."

Mr Hall said he would be "eternally thankful" to his rescuers.

"I have many disabilities, I suffer panic attacks, so I am just so thankful to have been rescued," he said.