Homes in Australia and around the world can leak a lot of air, especially if they have a conventional exhaust fan venting into a roof space and they dont have an integrated draft stopper or retrofit product.
In this video, we actually test a home with 2 exhaust fans, covered with and without a draught stopper.
The Exhaust tight product from tighthouse.com.au is a premium product that can be used to improve building performance. Integrated with a layer of insulation material and a radiant barrier. See how much of a difference air tightness changes with and without this product.