Roof ventilation is one of the most crucial factors with insulation. Without sufficient roof ventilation then your roof insulation will not work as supposed to. Roof ventilation isn’t just for winter it is for all year around.
In summer the lack of roof ventilation means the roof acts basically as a giant radiator, radiating trapped heat into your home, leading to both temperatures and energy bills skyrocketing.
In winter the lack of roof ventilation will see the build of moisture within the roof space leading to a number of problems occurring. Sufficient roof ventilation such as a whirlybird will ensure; Mould will not build up, insulation will stay dry and damp free leading to no roof structure damage will occur.
According to http://yourenergysavings.gov.au/ national statistics have found ventilation is one of the most clean, energy efficient ways to improve your home insulation. Statistics also found that homes without a whirlybird or other form of ventilation are paying 40% more than those who have sufficient ventilation such as a whirly bird installed.