In 1880 Grainger married 22 year old Rosa (Rose) Aldridge, daughter of Adelaide publican George Aldridge. In the year of their marriage Grainger won the competition to design Princes Bridge over the Yarra River in Melbourne. He and Rose moved to Melbourne anticipating that he would supervise the bridge’s construction. Actual building work did not start until 1885 and the bridge took another three years to be opened.