Steel mesh in some homes could be non-compliant
Thousands of homes built in the Waikato since 2012 may have steel mesh in their concrete slab foundations that doesn't meet the building code.
Since January 2012, 5860 building consents have been granted in the Hamilton and Waikato district. It is unknown how many of those consented homes are affected.
The Waipa District Council refused to comment on the new houses built in its area since 2012.
Investigations by the Commerce Commission this year discovered three of five New Zealand manufacturers of steel mesh - Euro Corp, Brilliance Steel and Steel and Tube - failed the stretchability and ductile tests required by the building code. United Steel, which is the largest supplier in New Zealand, and Fletcher building were found to be compliant.
In March, the Commission instructed Brilliance Steel Ltd and Euro Corporation Ltd to stop selling some of their steel mesh products. Steel and Tube, New Zealand's second largest supplier of steel mesh, pulled its product from the market in April.
Steel mesh is required in concrete slabs to act as a bridge to bind concrete together, strengthening the foundation.
When Christchurch was partially destroyed by a series of earthquakes in 2010 to 2011, regulators decided it was time to tighten the Building Code. And part of the regulations increased the ductility, or stretchability, of steel mesh from 2 percent to 10 percent, meaning the mesh would be more flexible and not snap when large earthquakes hit.
And while councils grant consent to new buildings and inspect the process, there's no way it would know if the steel mesh used is compliant or not, Hamilton City Council building unit manager Cory Lang said.
Checking the mesh's compliance is not the responsibility of councils when granting consent, he said. Councils only check that the designs are up to standard.
"We don't get involved in the testing or the sourcing of the product or the manufacturer," Lang said.
"If a design has been laid with E500 [also known as 500E] mesh, then our responsibility is to ensure that E500 mesh has been installed."
If the label is incorrect, which has been found in the Commerce Commission investigation, there's no way councils or builders would know.
Lang had no idea how many houses built in Hamilton could have the non-compliant mesh installed.
"Sorry, I couldn't give you any numbers or figures on that. It depends on the specific design.
"Design parameters are different. Some people enjoy concrete floors, others enjoy timber flooring."
But Lang doesn't think there is anything to worry about for those living in houses built in the Waikato since 2012.
"The building code is designed in such a way to accommodate or to factor in any sort of movement, disasters, earthquake legislations."
If people have concerns, Lang suggested they seek technical advice.
Local builder Wayne Warlow, of RPS Quality Homes, agreed with Lang's sentiments.
"A lot of stuff gets blown out of proportion," Warlow said.
Almost all of the new homes will have steel mesh in their foundation slabs, he said. RPS uses Fletcher Building steel mesh, he says, so RPS Homes are unaffected. He did not know suppliers for other builders in the area.
He believes Waikato, which is not earthquake prone, is paying for the Christchurch earthquakes. He thinks people who build homes in the Waikato are being hit with unnecessary costs.
Increasing the ductility requirement from 2 to 10 percent was a knee-jerk reaction without thinking about a reasonable approach to building regulations, he said.
"The houses should be safe" in the Waikato, even if they contain mesh not up to current code, he said.
Auckland lawyer Adina Thorn disagrees. She is trying to launch a class-action suit against the affected steel companies, saying they have put people at risk.
She has the financial backing of Harbour Litigation Funding, the UK's largest litigation funder.
"It will cost people nothing to sign up and what do they have to lose?" Thorn said.
"You stand to recover your costs or the reduction in house value if you do join up."
Insurers might decline to cover costs if the build is found to be defective, she said.
And Thorn did not agree with Warlow and Lang's thinking that Waikato houses should be safe.
"There's got to be some good reason for the law change. They don't just do it for fun.
"You just never know."