A ducted hood traps fats in grease filters and then removes steam odours from your kitchen and directs them outside. If you’ve ever walked past a neighbour’s house and thought mmm that smells good, it’s probably because their cooker hood has been ducted out. If you plan to duct out your cooker hood, its always better to have it as close as you possibly can to an outside wall. If you’re having an island or ceiling hood, consider the joists because the ducting needs to run in the same direction.