The Plumbers, Gasfitters and Drainlayers Board is concerned about health and safety risks associated with unqualified tradies. (File photo)

A gasfitter has been suspended after failing to properly supervise unqualified staff working on Canterbury University's new science block.

David Browne, a Christchurch-based director and manager of David Browne Contractors, had his licence suspended and was fined $7000 plus ordered to pay $6000 in costs.

His case was amongst 20 to 30 prosecutions a year by the Plumbers, Gasfitters and Drainlayers Board (PGDB), with the boom towns of Auckland, Christchurch and Queenstown seeing the bulk of complaints.

Last year, the regulator launched an app for complaints called Report A Cowboy. A third of all complaints through the app came from Auckland.

READ MORE:

* Builder's botched gas cooker job earns $4500 fine

* Canterbury police find over $100,000 of stolen tools while looking for suspect

* Building consents continue to trend downward in Canterbury

About half of all complaints were about plumbers, and 20 per cent each about gasfitters and drainlayers.

PGDB chief executive Martin Sawyers said the organisation received complaints from all over the country but the three cities experiencing building booms were of greatest concern.

He added Canterbury had been "a lot better" in the last year. "We're not seeing as much unauthorised work now as there once was."

Sawyers said PGDB dealt with complaints about faulty work and unregistered tradespeople.

He said its focus was on ensuring the health and safety of the public and, from that perspective, unregistered tradies were a bigger concern than faulty work.

"That's probably quite obvious for something like gasfitting, because if you get it wrong you can blow things up.

"But equally if you think about it, plumbing and drainlaying are a pretty essential part of public health. You need those services to work well or people will get sick."

Sawyers said as well as prosecutions, the board handled more than 100 complaints a year that did not result in prosecution.

"We prosecute the cases that are the most serious."

Browne's prosecution followed a complaint to the board about his lack of proper supervision of employees who were not qualified to do gasfitting.

They were working on a project to install about 12,000 metres of copper pipe in the university's new science block. More than 1400m of the copper pipe was for carrying LPG throughout the large multi-storey complex.

"Mr Brown's actions potentially compromised public health and safety," Sawyers said.

"It is simply unacceptable to allow unqualified untrained and unlicensed people to do gasfitting work at a public institution."