The inquiry is looking into the partial roof collapse that killed two women June 23, last year, and the emergency response to the incident.
Architect John Clinckett said he was retained by the owner of the centre, Eastwood Mall, in 2007 to find a solution for chronic leaking.
He said he advised the owner that the roof-over-the-roof idea would not fully solve the problem.
"The cars would still be driving in. They would have snow on them, ice and salt. They would be driving in on the deck, dripping water, and it would leak through," Clinckett testified.
Clinckett also described how a structural engineer found the weight of a second roof would be a problem.
Clinckett said he suggested a water-proofing membrane and asphalt topping could be used.
But, he said, the mall owner then sought a second opinion.
Evidence at the inquiry indicated that engineers had determined that Clinckett's suggested fix would exceed the load capacity of the roof.
This came after more questions were raised by Tom Derreck on Monday about why nothing was done about the leaking. Derreck was hired as Elliot Lake's chief administrative officer in 2006.
He testified he tried to get the problems fixed at the Algo Centre, but was fired before the matter was resolved.
When he took on the job of running the city, he said, he was surprised to learn the city had very little record of problems at the centre.
"I found that a little astounding. You could literally walk out the back door of the city hall and spit hard and you could hit the mall. So I just couldn't understand how no one knew about this," Derreck said. Soon after he was hired, he said, he pressed a city official to issue a notice of violation to the mall owners. That required an engineer to assess the condition of the mall structure. But shortly before the engineer's report was due, Derreck was fired.
The reason for his firing has never been made public.
"There are certainly suspicions that the significance of the mall, and its importance to the city, may have been part of why the building code and the city's building standards were not enforced as vigorously as they should have been to prevent something like this," said lawyer Roger Oatley who represents the families of the women who died in the centre's collapse.
A former long-time Elliot Lake mayor will testify later this week and is expected to answer to some of the questions that have been raised.