The Building and Housing Minister, Nick Smith, says a greater number of building inspections are failing as new house construction ramps up.

He said the government needed to invest in skills, in terms of producing good apprentices, and was working with the industry to make sure the new homes being built were good quality.

Dr Smith said the problem had been getting worse over the past two years, as the pace of building had increased.

"Building inspectors across New Zealand are working every day on building sites, they are finding with the huge growth, we've got an extra 40,000 people working in home construction across New Zealand, that they are picking up issues of skills and resulting in a greater level of building inspections failing."

Nick Smith said it was a balance between trying to get as many new homes built as possible, while also keeping quality up.

"We don't want to be sitting down in 10 years time, having hugely increased the number of homes, but then having quality problems with the homes that have been built."

Removing tariffs opened competition - Smith

Meanwhile, Dr Smith is standing by a policy to remove tariffs on building products, even though prices have since gone up.

In 2014 the government removed duties on plasterboard, reinforcing steel bar and wire nails. It also got rid of tariffs on building products such as roofing, cladding, insulation, paints, electrical and plumbing fittings in order to increase competition and improve housing affordability.

A 2013 study by the Productivity Commission found that home building materials in New Zealand were as much as 30 percent more expensive than in Australia.

The removal of import tariffs on building supplies was expected at the time to remove $3500 from the cost of building a new house - about 1 percent of the total cost in 2014.

Dr Smith acknowledged that prices have increased since then, but he said they could be even higher had the government not removed the duties and tariffs.

He said the policy has definitely opened up more competition in the building supply market.