Banksia Pty Ltd wished to build a new office building on land it owned in Hawthorn. It entered into a building contract with Mario Bros Pty Ltd (Mario) for $1.5 million, with a 6 months completion time. Work commenced on 1 June 2019. On 1 October 2019, an unusually strong cyclone caused a lot of building damage in northern Australia. As a result of the unexpected increase in demand for building workers needed to fix the many damaged buildings there, Mario had difficulty finding enough tradespeople to complete the contract by the due date on 1 December 2019. This resulted in completion being delayed till the 30 June 2020 and the cost of the project also increased by $250,000.

Mario wishes to claim the additional costs of completing the project. Advise Banksia and Mario of their legal rights.

Your answer must include case law (where relevant)