Rob Young, who was appointed by the building contractor Gralio Precast (Pty) Ltd to investigate the collapse of part of the mall, said two columns, identified as columns 319 and 243, had severe “design deficiencies”.
“The collapse is totally caused by the under-designed columns,” he told the inquiry investigating the collapse, in Tongaat.
Two people were killed and 29 injured in the collapse on November 19 last year.
On Monday, the commission heard that a beam, identified as beam seven, had been responsible for the collapse. However, Young said that despite several of the reinforcing steel rods missing from the beam, he believed it still had sufficient strength and was not the cause of the collapse.
The two columns should have had double their carrying capacity.
“All these things [columns] were hovering around half their strength,” he said.
He said once the collapse started it put pressure on beam seven, which collapsed. This put pressure on a neighbouring concrete slab that swung around. This slab collapsed as the columns under it could not handle the swinging motion.
Young said had the columns under this slab been braced, the collapse would have been limited.
The foundations of the two columns were not designed for the load they were meant to carry.
Young said the structural engineer Andre Ballack, who was responsible for the mall’s structural design, should have exercised a greater role in checking that work followed the design.
“He didn’t meet his professional obligations,” said Young.
The inquiry resumes on Wednesday.