The leaky building class action against cladding manufacturer James Hardie is being heard in the High Court at Auckland this week.
The action claims James Hardie was negligent in its design, manufacture and supply of the Harditex and Titan Board cladding systems and involves more than 1000 owners of 365 buildings, including 29 large body corporates.
The James Hardie group of companies denies the claims.
Adina Thorn of Adina Thorn Lawyers said the plaintiffs alleged they had suffered financial losses and significant health issues arising from the use of non-performing cladding materials marketed as "Harditex", "Monotek" and "Titan Board".
Last month the High Court ruled that 15 new plaintiffs could join the action, a decision that had been contested by James Hardie.