Proper roof ventilation has two main components:
- Intake vents, allowing cool fresh air into the attic
- Exhaust vents, allowing warm, moist air out of the attic
In summer, a hot attic will heat up your roofing underlayment which can become brittle and ineffective. Insufficient venting will cause a build-up of warm, moist air which can result in significant damage to the structure of your roof. As a result of proper roof ventilation you can extend the life of your roof system and protect the structural integrity of your home.
Also, some asphalt shingle manufacturers have a clause in their warranty regarding refusal of warranty based on insufficient attic ventilation. Proper ventilation is a necessity to validate those warranty terms.
Furthermore, having proper roof ventilation can help reduce the temperature of the attic floor, interior ceilings and ductwork, reducing the strain on your air conditioning unit, therefore lowering your cooling costs.
In winter, when the warm air from your home is not exhausted properly it can warm up the underside of your roof causing melting and re-freezing. This is known as ice damming. Ice damming can eventually tear off shingles, gutters and even soffits in some cases. As a result of proper roof ventilation, you can eliminate the potential for ice damming.