A law firm leading a class action against a cladding manufacturer says many homeowners don't know they have leaky homes until a decade or so after they are built.
Parker and Associates has filed a second case against James Hardie in two months, accusing the company of negligence in the design and supply of its Harditex cladding system.
It's also asked the Wellington High Court to let it take on up to 500 other potential claimants that have come forward since August.
The firm's partner, Dan Parker, said Harditex was widely used in construction between the 1980s and 2003, but the water damage it caused was not immediately clear.
He said some homeowners were only now starting to find the damage.
