The leaky home owners suing cladding manufacturer James Hardie are applying to the High Court for their case to be brought as a class action.
More than 500 owners of leaky homes have come forward to explore whether they can be part of a claim against James Hardie.
Leaky building law firm Parker & Associates announced in August they had lodged High Court proceedings against the Australian-stock exchange listed cladding firm on behalf of Wellington leaky home owners Tracey Cridge and Mark Unwin.
The couple's Island Bay home used James Hardie's Harditex cladding and the lawsuit alleges the firm was negligent in designing, manufacturing and supplying that particular product.
Today Parker & Associates said they had filed an application to bring the proceedings as a class action.
"For a class action you have to generally get the court's permission to do it...we are asking the court to approve the class action and grant an opt-in period which enables anyone who considers they are eligible to opt into the class action," said lawyer Dan Parker.
The firm said a second class of plaintiffs, comprising of properties clad in James Hardie's Titanboard product, was also being assembled to be added to the claim.
James Hardie has been involved in a number of leaky building cases in New Zealand, and as at March 31, held a US$2 million provision, net of third-party recoveries, against potential weather-tightness claims, and flagged it could face an extra US$500,000 of losses due to the uncertainties over the claims.
It reported a US$4.3 million income benefit on its weather-tightness claims in the 2015 financial year due to a lower provision, increased rate of claim resolution, fewer claims at the end of the period, and a reduction in the number of claims received.
The building materials maker was initially named as a defendant by the education ministry in its suit against cladding manufacturers, and later reached a deal with the government agency, which the parties said would support the remediation of weather-tightness issues in existing school property and support future developments across the country.