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Councils are making it harder for businesses to get approval to lay wood, wood laminate and vinyl flooring in new homes, say National's Andrew Bayly and industry leaders.

Bayly, the party's construction spokesman, said the popular flooring products weren't being banned in kitchens, laundries and bathrooms of new and renovated buildings.

But it was now harder to get consent from some councils after the new Ministry of Business, Innovation and Employment guidance, he said.

"Where is the evidence that there is a systemic issue with leaking floorboards? It would be nice to know the case for that before we charge headlong into changing the regulations."

He said it was alarming that officials at some councils were trying to apply new rules but could not give people guidance about what was required.

"So are we just frustrating an industry at a time when we're trying to build houses as quickly as possible and putting in place blocks to that?"

The ministry has confirmed the changes, which came into effect late last year.

Jeff Henry, Flooring Association of New Zealand technical advisor, said he was unaware of any previous problems with floor coverings in kitchens, bathrooms, laundries or other wet areas in the last four decades.

He questioned why the change had been made.

"If we had a problem, we'd have known about it. If there was an issue in the last 40 years, we would have known," he said.

MBIE wanted to ensure there were no flooring issues via changes to the Building Code but there were some entities interpreting that differently, Henry said.

"The suppliers of the vinyl timber planking products are working now with councils to try to provide technical information and independent testing so their products can be approved as an alternative solution," Henry said.

An MBIE spokesperson confirmed the changes but said that those did not specify the three types of products because the Building Code was performance-based and did not specify the use of any particular products.

MBIE provides acceptable solutions to the Building Code to enable consenting, but the code's performance requirements could also be met using alternative solutions.

"The Building Code requires that floor surfaces used around sinks, toilets and in bathrooms be impervious to stop water and other liquids from passing through," she said.

In 2020 MBIE announced a new compliance solution for clause E3 of the Building Code – internal moisture.

The new acceptable solution E3/AS1 aimed to improve internal waterproofing in bathrooms, kitchens and laundries.

"The changes removed some materials - timber and timber-based products - from the acceptable solution that were deemed to comply with the internal moisture requirement, however builders and designers can still use these products if they are consented as an alternative solution," she said.

The transition period to use the previous requirements ended last November.

The change included removing timber floor linings as deeming to comply because not all timber products would be suitable for use as floor surfaces.

Frequently, joints in panelised flooring were a weak point and not sealed to be impervious, resulting in moisture accumulating under the panelling, she said.

"The intent of the change was to ensure that designers actually checked the flooring materials to ensure that they met the requirements of the Building Code.

"This change means that, in order to use timber products in this application, designers will have to demonstrate compliance with an alternative solution," the MBIE spokesperson said.

Engineered wood finishes, vinyl and laminates could still be used but now the burden of proof was on the supplier or specifier to ensure they are of adequate quality and met Building Code requirements.

"They will have to satisfy the building consent authority that the product/surface is impervious or sealed with a suitable durable coating to be impervious.

"Under the Building Act 2004, it is up to the building consent authority to be satisfied on reasonable grounds that the building complies with the Building Code in order to issue a building consent," the MBIE spokesperson said.

Another industry chief expressed concern about the changes.

It now took longer to get new buildings approved he said, and houses were affected but so were office buildings and other types of properties.

The change blindsided specifiers and product suppliers and everyone was left to their own devices to try to establish how they could get products through councils.

But he emphasised the last thing he wanted portrayed was that such products could no longer be used. They could, he stressed.

It was just that MBIE unrolled a far-reaching change in the Building Code, he said, and people were coming to terms with that and how to get approval via councils.

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