The roof collapse of a mall in Sarnia, Ont., is not a new phenomenon in Canada, the catastrophe had a familiar ring to some in Atlantic Canada.

In 1987, the roof of the Sears store in St. John's, Newfoundland caved in because the snow had built up. Fortunately, no one was injured.

And in 1995, three roofing joists in a warehouse collapsed under heavy snowfall. At the time engineers blamed the cave-ins on joists made by Robb Engineering of Newfoundland.

Joists are a set of parallel supporting beams made of wood or steel.

The company settled out of court with the mall owners.

The company, located in Amherst, Nova Scotia, went out of business after 20 years of operation. Another company has taken its place.

But the Robb legacy remains. Thousands of buildings in Atlantic Canada are made with Robb joists including hospitals and schools.

"The chances of this happening are 1 in 10 000 but 1 in 10 000 is too big a chance to take," says Gerry Moores of the Association of Professional Engineers in Newfoundland.

Engineers sent out a warning in 1996 to governments and private owners of buildings with Robb joists.

Since then, governments in Atlantic Canada have spent more than $15 million inspecting and repairing Robb joists.

Roberto Sani is with an engineering company hired by the government to inspect buildings. Sani found welds that had split apart and gaps. They were fixed.

"I wouldn't say that it's an alarming situation, because it's not," cautions Sani.

Robb joists were sold primarily in Atlantic Canada and it's unlikely they were used in the construction of the Lambton mall. But officials say they are checking it out.

Meanwhile, the Newfoundland government and a grocery chain are suing the company that took over Robb Engineering.