"I was upbeat though, it's just who I am. If I can still breathe I must be able to do something."
Mr Thammavong, a self-confessed adrenalin junkie, keen dancer and gym fanatic, said he checked the roof thoroughly for ice because it was a frosty morning but there was none.
As he stood up on the iron roof, he slipped and bounced off the edge but managed to twist his body as he fell to minimise the damage.
It is understood OSH and WorkSafe are investigating the incident.
"I was about to fall on my right shoulder and head but I twisted towards my feet ... I literally just cracked my heels and then landed straight on my face.
"The doctors just said I was really, really lucky. Everyone in my family's told me to change careers but, nah. I'll still go back to it. I'm just so glad it was me; it wasn't any of the other boys. One of them has five daughters, they've all got kids."
It's not the first time he's had a roofing injury - about six years ago, Mr Thammavong sliced off three fingers. They were sewn back on.
The profession was heavily regulated but even the safest construction site came with risks, he said.
A colleague fell off a roof at a previous site Mr Thammavong worked on and died instantly, he said.
Mr Thammavong's family were in Hamilton when they received calls about their son's accident, and immediately drove up to North Shore Hospital.
They did not know the extent of his injuries and feared the worst, said his mother, Manichanh Thammavong.
"I was really shocked. I just didn't speak, I didn't say anything."
His sister Emily Thammavong said the family were enjoying having the Auckland roofer back under their own roof so they could look after him.
Mr Thammavong said he would be housebound for two months and might need facial surgery but the doctors were expecting him to make a full recovery. The accident cemented the important things in life, he said.
"I want to travel more. But I already knew what I wanted. What do you do, you've got to live life.
"I used to be scared of heights, even when I started roofing. But for me, if I can beat my own fear then I'll do it."