Building insurance costs vary widely because insurers assess factors such as the property’s rebuild cost, location, construction materials, age, security features and exposure to risks including floods, storms and bushfires. The sum insured should reflect the likely cost to rebuild, not the property’s market value or land value. Your premium may also change depending on the excess, optional cover and claims history. Comparing quotes and checking each policy’s inclusions, exclusions and limits can help, but the final price is set by the insurer after assessing your circumstances.