The survey found that the "trades, services and engineering" sector was just one per cent female.
The construction and infrastructure sector was four per cent female with a wage gap of four dollars an hour.
The manufacturing, production and logistics sector was 12 per cent female with a one dollar per hour gap.
The survey also included commercial services and hospitality workers. That sector had pay parity but was also dominated by female workers - at 69 per cent.
"There is definite under-representation of females within the industrial sectors that we looked at," said OneStaff group general manager Jonathan Ives. "And in those sectors where they were underutilised it looks to be that they are underpaid."
The survey showed pay rates tended to rise the longer people had worked within a sector and it was possible that was skewing the average rates to some degree, he said.
It was only in the last couple of years - perhaps due to the skills shortages - that there had been more women engaging in these sectors so the female workforce was probably younger, he said.
He was hopeful the gap would start to close as the trades started to see a higher proportion of women coming through into more senior roles.
"Although some work and effort has gone into removing the unconscious bias that exists in the market, it's still there to an extent," he said.
There was a risk of the industry being "short-sighted" about the opportunity, Ives said.
The survey had highlighted a big opportunity for expanding the workforce in sectors where there were significant skill shortages.
"You're talking about 50 per cent of the population that are being excluded. There is a lot more that can be done by the industry."
The survey also mapped average pay rates around the country. The best paid regions were Auckland and Northland - both with average hourly rates of $25 per hour.
The lowest paid were the West Coast and Palmerston North, Whangarei district.
This reflected where most of the work was happening in the country, Ives said.
The survey also found that those people that travelled furthest for work tended to paid more.
Ives said OneStaff had noticed these kind of surveys typically focused on salaried workers and higher level roles and wanted to provide more data for industry.
"So we did this to add some transparency so people can make informed decisions."
The full report includes a detailed index of hourly wage rates around different regions for a large range of specific jobs across all the surveyed sectors.