A lawyer representing nearly 100 leaky building owners in a class action is welcoming a Supreme Court ruling.

READ MORE: Major leaky schools victory for Govt

The Ministry of Education has been cleared by the Supreme Court to take legal action against Carter Holt Harvey over alleged defective cladding sheets on hundreds of school buildings.

The Ministry claims Carter Holt's cladding sheets and system used in school buildings were inherently defective - and is taking a similar action.

Dan Parker, who is representing 89 people in a separate class action claiming losses of $25 million against James Hardie, said the ruling means more people can join his legal bid.

He said he has had interest from other property owners including rest homes, churches, and motels to join the class action, but noted a10-year limitation period to lodge a claim under the Building Act.

The Supreme Court ruled it's not building work within the meaning of the Building Act where a manufacturer is supplying cladding, and Parker said that's a very helpful ruling to have.

Parker's class action involves properties built from materials by James Hardie, Hardie Tex, and Titan Board.