Nine out of ten roofs will need ventilation and it's always standard when we replace a roof. Ventilation is important because it inhibits the growth of mold and rot and circulates air through the attic. Ventilation actually extends the life span of a roof because it prevents the backside of the roof from baking from the inside out. Heat that rises from the backside of a roof will lessen its lifespan. The sun will damage the outside and special coatings are used in roofing materials to resist UV penetration. It is important to circulate the air through the roof cavities in order to prolong the life of your roof.
Attic fans are intended to cool hot attics by drawing in cooler outside air from attic vents (soffit and gable) and pushing hot air to the outside. However, if your attic has blocked soffit vents and is not well-sealed from the rest of the house, attic fans will suck cool conditioned air up out of the house and into the attic. This will use more energy and make your air conditioner work harder, which will increase your summer utility bill.