entire roof. There is a requirement of one square foot of venting of 250300 per cubic foot of air through the attic or the space immediately below the roof. Normally, it is always worthwhile to have an expert watch at the roof and then provide the ventilation. Ideally, the ventilation system is structured both the roof is built. But over time, a trend some blockages and other external factors to loosen the ventilation system. It needs recheck and resizing the ventilation of the roof. Care should be practical that the ventilation ducts and pipes are not blocked and sufficient air circulation is potential and allowable in the roof structure. This will guarantee the longevity of the building and also make sure there are no leaks and problems with your roof for a long duration.