According to your countryīs (stateīs) regulation, every roof construction system has to allow the air flow in and out the space between the roofing material and roof inulation layer.
Purpose of roof ventilation
The
purpose of the roof venting is to convey the moisture from the roof construction and also to avoid the incidence of the thermic tensions (cold air meeting the warm roof surface) on the level of the roofing material or (worse) within the roof construction (roof skeleton, trusses, beams, etc.). Roof ventilation systems bring (even if this sounds strange to you) also
savings of the heatng costs and it definitely extends the life-cycle of all used roof component...
