Claims of shoddy roof design have led to legal action against the builders and engineers of Brisbane’s iconic Gabba sporting ground.

Courier Mail reports say Stadiums Queensland - a Queensland government body - is suing construction giant Watpac and engineering firm Robert Bird Group for $7.5 million.

The group in charge of maintenance at the Gabba is alleging negligence in the design and building of a cantilevered roof, part of which blew away when a small tornado hit during heavy storms in 2008.

The bizarre weather event also damaged a number of supporting pylons.

Stadiums Australia says Watpac’s work was not of a “good, proper and workmanlike” standard, and that engineers gave misleading information by claiming the roof could withstand winds up to the Australian standard of 216 kilometres per hour.

Watpac says it has no liability, and has launched a counter-claim against Robert Bird Group.

But the Robert Bird Group is denying any negligence too, and says it will file an expert report to explain itself.

The legal action compounds what is already a tough time for Watpac, after a 16 per cent slide in its first half profit and $20 million revenue hit earlier this month.

Watpac lost a lot of income when resource firm BC Iron announced it was terminating Watpac’s mining services contract for a project in the Pilbara region.