Owners of modular homes built at a U.S. plant launched an $8 billion class action Friday, accusing the Canadian Standards Association of giving its seal of approval to a faulty product.

A statement of claim says the non-profit association was negligent and lacked the authority to certify the the ready-to-move homes, which were built at a Colorado plant for the Canadian market between 2002 and 2010.

Robert Granger of Edmonton, named as the plaintiff in the class action, says he checked for the CSA certification before buying his home.

But within six months, serious safety problems surfaced, including faulty electrical work, a lack of ventilation and trouble with heating, he said.

"I expected to move into a safe, comfortable home and instead I ended up with a nightmare that cost over $10,000 to repair." he told CBC News.

Allegations not proven

Allegations in the statement of claim have not been tested in court.

Champion Home Builders Co., the U.S. manufacturer, wanted the CSA to certify the homes so they would meet Canadian standards, the claim says.

But "tens of thousands of homes" sold to Canadians were built below Canadian standards, said Saskatchewan lawyer Tony Merchant, who launched the class action on Friday.

"The job wasn't being done properly," Merchant said of the CSA certification. "And … they didn't have the authorization to do the job."

The suit also names the Standards Council of Canada, a Crown corporation that Merchant says was created to protect Canadian consumers from such losses.

"When you buy a house, a breach of safety standards destroys value," he said. "Owners of these uncertifiable dwellings find their $200,000 to $400,000 homes are now valueless."

The Standards Council of Canada and the CSA would not comment on the case.