Properly sizing and placing intake and exhaust vents in an aluminum roof system is crucial to ensure good airflow, reduce moisture buildup, and extend the life of your roofing materials. Intake vents typically go near the eaves or soffits to allow cool air to enter the attic or roof space, while exhaust vents are placed near the ridge or high points to let warm, moist air escape. The general rule is to provide a balanced ventilation system, often offering a 1:300 or 1:150 ratio of net free vent area (NFVA), depending on whether a vapor barrier is installed. This means for every 300 square feet of attic floor space, you need about 1 square foot of total vent area split equally between intake and exhaust. This ratio helps maintain consistent airflow, prevents heat buildup beneath the metal panels, and reduces chances of condensation that can lead to corrosion or mold growth. Aluminum's high thermal conductivity makes ventilation especially important to avoid overheating and reduce cooling costs.
You can perform some simple DIY checks by inspecting your attic or roof space for signs of poor ventilation—look for uneven temperatures, musty smells, or any visible condensation on the underside of the roof. Feel for air movement near your intake and exhaust vents on a breezy day to ensure both are working. However, avoid closing off vents or making significant modifications without professional advice, as improper changes can void manufacturer warranties and affect the metal’s performance. When calling a roofing professional, ask specifically, “How do you calculate the proper vent size and placement for my aluminum roof considering local building codes?” and “Can you verify that the installation complies with warranty requirements and metal roofing best practices?” A trained contractor will inspect your attic ventilation, account for your roof’s slope and insulation, and suggest a balanced venting approach that protects your investment over time.