Properly sizing and placing intake and exhaust vents for an EPDM (ethylene propylene diene terpolymer) roofing system is essential to maintain balanced attic ventilation and prolong the roof’s lifespan. Intake vents, usually placed along the eaves or soffits, allow cool air to enter the attic space, while exhaust vents located near the roof ridge or higher points let warm, moist air escape. The general rule is to provide a balanced system, ideally with an equal net free ventilation area (NFVA) for intake and exhaust. Typically, you need about 1 square foot of ventilation (combined intake and exhaust) per 150 square feet of attic floor area if you don’t have vapor retarders, or per 300 square feet if you do. EPDM roofs, being rubber membranes, don’t generate moisture themselves but improper attic ventilation can lead to condensation underneath the roof deck, which can cause mold or wood rot. Simple DIY checks include inspecting the attic during warm, humid days for signs of moisture or mold, and making sure vents are clear of debris or blockages.
If you’re unsure about sizing or proper location for your vents, it’s wise to call a roofer or ventilation specialist who understands both EPDM roofing and local climate conditions. Ask your contractor whether they will calculate ventilation needs based on your attic size and vapor barrier presence, and how they plan to ensure the intake and exhaust vents will work together without allowing moisture intrusion under the roofing membrane. Also, check if their design complies with local building codes and roofing manufacturer warranties, since improper ventilation can sometimes void EPDM warranties. With the right balance, your EPDM roof system will stay cooler in summer, dry in winter, and last many decades with minimal maintenance.