The damning technical report catalogues a host of design changes which resulted in the cost of the waterfront scheme ballooning from £17.6 million to almost £40 million when the project was pulled in February this year.
Among the alterations to the original plans - mooted by design and build contractor Edmund Nuttall - was the need to lengthen the piles used to secure the gallery to the seafloor from 20m up to 45m.
This change alone would have pushed up the costs of the building by £5.65 million. Other hikes included a rise of £150,000 for rock armouring at the base of the gallery, £1 million for specialist ball bearings needed for the link bridge between the building and the pier, and an additional £4.65 million for an extra 1,200 tonnes of structural steel.
The council, which has now appointed David Chipperfield to draw up replacement gallery plans, also highlighted a number of 'unresolved' design-related issues, including the external paint finish to the steel gallery hull.
There were also doubts about the piling methods which 'had changed markedly from the earlier design proposals' and the installation of the gallery building itself.
A more detailed review of the report can be found in this week's AJ.