Your roof’s ventilation is a vital part of the roofing system. It is directly responsible for the natural longevity of your roof. When the roof is under ventilated it will deteriorate at a faster rate. This mostly pertains to a composition shingle or rolled shingle roof.
When the attic heats up and the roof is not breathing properly it cooks from the inside out. This causes blistering which is an overall deterioration of the shingle. The granules will loosen and fall away from the mat and the mat will begin to deteriorate.
Most shingles today are composition shingles. This means that the mat is made up of asphalt and fiberglass threads. When a roof is severely blistered it will experience overall granular loss, or in more extreme cases, the mat will deteriorate down to the fiberglass threads. If your roof has a strange shine to it than that is most likely the fiberglass thread and the roof needs to be replaced.
60% of roofs are under ventilated at the completion of new construction. In Texas, because of the extreme heat, we tend to get only 50% of the estimated life out of a roof. When the roof is insufficiently ventilated that percentage will decrease dramatically. This is why it is important to use a knowledgeable contractor who can recommend the proper ventilation for your roof.