After March 1 if an unlicensed builder, sub-contractor or designer carried out the restricted work, or supervised it, then he could be fined up to $20,000 by the department.
Grant Florence, chief executive of Certified Builders Association of New Zealand based in Tauranga, said the registration process was a positive move for the industry.
"It will help remove the cowboys from the industry and set some standards. Maybe many of the cowboys have already left but the industry has had low entry barriers. Anyone could call themselves a builder, but our association was formed to support the qualified builders," he said.
"If they want to do work in their own right, then they have to be licensed - or get someone else to sign off their work. I think there will be a bit of a mad rush to get registered."
He said most of his 200 members in the Western Bay would register. "We have been actively involved since the changes were announced and have regularly contacted our members. There will be one or two who are too old and don't want to do it."
The builders and their contractors have had just over four years' warning to comply with the new regulations. During the Building Act 2004 review, the department established the LBP scheme in November 2007.
They have to demonstrate their competency to the department and the scheme is broken into seven licence classes: designers, builders/carpenters, external plasterers, bricklayers and blocklayers, foundation specialists, roofers and on-site supervisors or managers.
Architects, gasfitters, plumbers, electricians, drainlayers and chartered engineers are already registered with their professional authorities and are considered licensed.
Once registered, they will all produce an identification card to the homeowners and local councils, which issue building consents, and to retain their licences they will need to show the department records of training and upskilling.
"There will be more paperwork required from the builders - but with that comes the responsibility of tidying up the industry," said Mr Florence. "This is one of the most significant changes in the building industry. It's putting a minimum standard in place and I'd like to think that better houses will be built."
Pete Roden, past president of Tauranga Registered Master Builders Association, said: "We needed some structure that everyone could work to. The first step is the licensing. The system is never going to be perfect initially and it will take time to sort itself out, but it is giving us some basic rules to work with."
He said it wasn't in the builders' nature to do paperwork but documentation was now the reality of the new world, and putting together a home for people was a big responsibility.
Mr Roden said most of the local association's 90 members would register. "Some of older guys who have worked 40 years may not bother and retire, but the vast majority will voluntarily or feel pressured into signing up."
Putting together the new rules had been tricky, Mr Roden said. "Kiwis have considered it their patriotic right to pick up a hammer and saw, and they will continue to do some work on their home. But you can't afford to have a house that goes on the market turning to custard."
Rex Olsen, who founded Mount Maunganui Roofing, said his industry had been trying for a number of years to get recognition as a specialist trade, and the (licensing) move by government was confirmation of that.
"Plumbers, electricians and drainlayers have been policing themselves for 85 years and you haven't seen too many disaster stories in those trades," he said.
"Registering as a licensed practitioner will lift the standard in the industry and that can only be a good thing.
"It's all about the water-proofed envelope of the building and those responsible for the weather proofing can now be accountable," said Mr Olsen, a roofer for nearly 40 years.
"The licensing means you have to make a written commitment to sign off on the job and you are dealing with bone fide people. It takes the cowboy element out of the industry."
He said Tauranga was quite good in terms of standard and supervision because of the leaky home issues. "Everyone is gun shy and short cuts are not a thing they do anymore."
Mr Olsen said some roofers, nearing the end of their time, might not register and they would concentrate on non-permitted maintenance and like-for-like roofing work.
There will be some fine tuning over the next few years and, when the market lifts again and new houses are being built, licensed people will be too busy to worry about re-roofing. No one would be servicing that market, he said.
Mr Olsen employs seven tradesmen and he said four of them - based on qualifications - would initially be licensed.
Rob Wickman, Tauranga City Council's building services manager, said his team was changing the building consent application forms.
"Designers and builders will make a statement that what they are producing meets the building code and that's a big change for them. The council will hold those records.
"At the end of the job, the contractors must supply licensing certificates or have named practitioners.
"If they don't do that, then we can't issue a code of compliance and they only have themselves to blame," he said.