The Victorian Building Regulations (Items 157 & 158) state that a Class 1, 2, 3, 4, 9a, 9b or 10a building in a Bushfire Prone Area (BPA) must be built to a minimum of BAL 12.5.  Refer to Section 5 - Construction Requirements for BAL 12.5.

A dwelling is a Class 1a building, and a shed, garage or carport is a Class 10a building.