An executive of the company that supplied the roof-decking of the ill-fated Algo Centre Mall in Elliot Lake, Ont., says salts are damaging to concrete but said waterproofing the material is strictly out of the firm's hands.

Doug Harman said Coreslab Structures makes no recommendations about waterproofing its product either.

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Douglas Harman, vice president of Coreslab, the company that made the concrete slabs for the roof at the Algo Centre Mall, said the firm isn't responsible for waterproofing methods. That responsiblity rests with the architect, he said. (Supplied )

Harman made the statement Thursday during the public inquiry into last June's collapse of the mall's roof-top garage that killed two women. He said waterproofing is up to the project architect or engineering team.

Coreslab made the precast hollow concrete slabs three decades ago that ultimately fell. Investigators believe water and salt penetration rusted out a critical weld on the underlying support structure.

Harman said he wasn't with the company in 1979 when the Algo Center Mall was built, but noted not much has changed in its product since.  CoreSlab installs the concrete, but it isn't responsible for waterproofing methods.

The inquiry heard more details about the building's roof from both Harman and Dave Monroe, whose companies or products were involved in the construction of the roof at the mall.

Monroe is the former vice president of Harry S. Peterson, which provided  the Algo Centre Mall roofing system. Harman is vice president and general manager of Coreslab, which supplied the concrete slabs for the parking deck.

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A woman checks out the damage after the roof collapsed at the Algo Centre Mall in Elliot Lake, on June 23, 2012. The partial collapse prompted a local state of emergency. Two women died in the incident. (Cora Richer/The Canadian Press)

Issues 'ignored'

The structural engineer who oversaw the building of the mall more than 30 years ago said Wednesday it was the worst construction work he has seen in his career — yet he still gave the project his seal of approval.

John Kadlec was the second witness to speak during the public inquiry being held in the community.

Kadlec said he saw evidence of shoddy workmanship from the time the mall was built in 1978 and noted the mall was built using crooked columns and rusted steel beams.

He said he tried to bring the issues to the attention of the mall owner and architect, but was "ignored."

Inquiry lawyer Joseph Bisceglia jumped on that during cross-examination. "It's your stamp that's going on the drawing, it's your stamp that's going on the certificate, that everything is fine," he said.

Kadlec concurred, adding that, even after he approved the Elliot Lake mall, he knew there were problems.

"I knew there was leaking, but I didn't know nothing had been done," he said.

Kadlec also said he helped design the Algo Centre Mall, without seeing the site or knowing what materials would be used.

He said he opposed putting the parking on the roof, which is where the fatal collapse happened.

Schedule of testimony:

March 4

Commissioner's opening remarks; preliminary matters 

March 5

Dale Craig, expert, engineer J.L. Richards, overview of the construction of a building and state of the art in roofing at time of construction

March 6John Kadlec, partner at Beta Engineering, structural engineer during construction of Algo Centre Mall 
March 7

Dave Monroe, former vice president of Harry S. Peterson, Algo Centre Mall roofing system

Doug Harman, vice president and general manager, Coreslab, supplied concrete slab

March 8Henry Jasskelainen, former supervisor of Harry S. Peterson, installed roofing system and conducted repairs
March 11James Keywan, architect, retained by Algoma Central Properties for the design of the Algo Centre Mall
March 12 & 13 

Barbara Fazekas, former chief librarian, Elliot Lake Public Library

Rod Caughill, former development supervisor, Algoma Central Properties

March 14Domenic Dell'Aquilla (Trow), engineer, hired by Algoma Central Properties

With files from The Canadian Press