The grandmother of two was among eight finalists selected from 350 competitors around New Zealand to compete in the finals in South Auckland tomorrow.
Reuben started roofing when she was 19 after helping her then boyfriend on a work site.
"He turned into my husband," she laughed.
Both her husband and son are also roofers.
"Around the dinner table, it's 'roofing this', 'roofing that'," she said.
The 54-year-old stopped roofing for a while but returned to it last year, asking her former boss from THC Roofing Tauranga for her old job back.
"He tested me out and said yep we'll give you a try."
She worked in a roofing gang of 22 men doing mostly large commercial builds in Tauranga - some up to 16m high.
"I was nervous on my first big height, but you start to get used to it. New Zealand has strict safety codes for roofers, we have to wear hard hats and harnesses.
"I like working on commercial [projects] as you have lots of others to help you, and there's cranes now to help with big lifts."
The three-hour competition is an NZ Metal Roofing Manufacturers initiative and will be held on the final day of the Roofing Association of NZ conference tomorrow at the Vodafone Events Centre in South Auckland.
The eight competitors will be judged on their delivery and understanding of good trade practice, the quality of their work, housekeeping and safety in the work area, and time taken to complete the exercise.
The highest scoring four skilled fixers will be chasing a $5000 travel prize and the four highest scoring intermediate level fixers will compete for travel worth $2500.