He explained that the Clutha had once supported a tenement building and the walls at the bottom were around one metre thick.
Mr Goodhew said removing the wall at the front of the building had not been an option for fear of further collapse.
He added: "The quantity of rubble was far greater than a normal roof and it was substantial in every area you looked at.
"Also walls collapsed inside the building, which again caused more rubble.
"The walls are substantial, constructed of sandstone and almost one metre thick.
"Struts and strapping were used to secure the fuselage to allow the helicopter to be lifted.
"It had already been lifted by approximately two feet to allow it to be secured and made ready for extraction.
"This has been a very delicate operation and we have had to take great care not to disturb the scene."