Under what condition is venting air space required in roofing?

Venting air space in roofing is generally required when insulation is located below the roof deck. This is important because when insulation is placed below the roof deck, it can create an environment where condensation may develop due to moisture-laden air coming into contact with the cooler roof surfaces. Without proper ventilation, this moisture can accumulate, leading to issues such as mold growth, deterioration of roofing materials, and potential structural damage over time.

Therefore, incorporating ventilation allows the airspace to be adequately ventilated, helping to control temperature and humidity levels, which mitigates the risk of condensation forming beneath the roofing system. Proper ventilation is key to ensuring the longevity and performance of the roofing assembly, especially in colder climates where temperatures can vary significantly.