When installing torch-down roofing, properly sizing and placing intake and exhaust vents is crucial for maintaining good attic ventilation and prolonging the life of your roof. Ventilation helps remove excess heat and moisture from the attic, preventing damage to both the roof deck and the torch-down membrane. The general rule is to have a balanced intake and exhaust system, where the amount of intake vent area near the eaves matches the exhaust vent area near the ridge or higher points. You can calculate vent size by considering the total square footage of your attic space. Most building codes recommend 1 square foot of net free vent area for every 150 square feet of attic floor space, split evenly between intake and exhaust vents. Net free area refers to the actual open space that allows air to flow, not the size of the vent covering or grille. Under-ventilated attics lead to heat buildup, which deteriorates the torch-down material and increases energy costs, while over-ventilation can cause moisture intrusion.
For a DIY check, inspect existing vents for visible blockages, damage, or signs of poor air movement such as mold or uneven roof temperatures. It’s safe to measure the dimensions of your vents and compare to your attic space to see if they meet the recommended net free vent area. Also look inside the attic with a flashlight to confirm air flow near the intake and exhaust points. If you notice stagnant air or excessive heat under the roof, it’s a sign your ventilation may be improperly sized or placed. At that point, it’s wise to call a professional roofer experienced with torch-down systems to evaluate your roof’s ventilation. Ask them about their approach to balancing intake and exhaust vents as well as how they ensure torch-down membrane warranty compliance when making modifications. A good question to ask is, “How do you calculate the needed ventilation for a torch-down roof on my specific attic size?” and “What guarantees do you provide that ventilation improvements won’t void my roof warranty?”